oldest scientific experiments

15 of the Longest-Running Scientific Studies in History

By austin thompson | oct 15, 2016.

Most experiments are designed to be done quickly. Get data, analyze data, publish data, move on. But the universe doesn’t work on nice brief timescales. For some things you need time. Lots of time.

1. THE BROADBALK EXPERIMENT // 173 YEARS

In 1842, John Bennet Lawes patented his method for making superphosphate (a common, synthetic plant nutrient) and opened up what is believed to be the first artificial fertilizer factory in the world. The following year, Lawes and chemist Joseph Henry Gilbert began a series of experiments comparing the effects of organic and inorganic fertilizers, which are now the oldest agricultural studies on Earth. For over 150 years parts of a field of winter wheat have received either manure, artificial fertilizer, or no fertilizer. The results are about what you’d expect: artificial and natural fertilized plots produce around six to seven tons of grain per hectare, while the unfertilized plot produces around one ton of grain per hectare. But there’s more . They can use these studies to test everything from herbicides to soil microbes and even figure out oxygen ratios for better reconstruction of paleoclimates.

2. THE PARK GRASS EXPERIMENT // 160 YEARS

Lawes and Gilbert started several more experiments at around the same time. In one of these experiments with hay, Lawes observed that each plot was so distinct that it looked like he was experimenting with different seed mixes as opposed to different fertilizers. The nitrogen fertilizers being applied benefited the grasses over any other plant species, but if phosphorus and potassium were the main components of the fertilizer, the peas took over the plot. Since then, this field has been one of the most important biodiversity experiments on Earth.

3. THE BROADBALK AND GEESCROFT WILDERNESSES // 134 YEARS

Yet another one of Lawes’ experiments: In 1882 he abandoned part of the Broadbalk experiment to see what would happen. What happened was that within a few years, the wheat plants were completely outcompeted by weeds—and then trees moved in [ PDF ]. In 1900, half of the area was allowed to continue as normal and the other half has had the trees removed every year in one of the longest studies of how plants recolonize farmland.

4. DR. BEAL’S SEED VIABILITY EXPERIMENT // 137 YEARS

In 1879, William Beal of Michigan State University buried 20 bottles of seeds on campus. The purpose of this experiment was to see how long the seeds would remain viable buried underground. Originally, one bottle was dug up every five years, but that soon changed to once every 10 years, and is now once every 20 years. In the last recovery in 2000, 26 plants were germinated, meaning slightly more than half survived over 100 years in the ground. The next will be dug up in 2020, and (assuming no more extensions) the experiment will end in 2100.

Even if it is extended for a while, there will probably still be viable seeds. In 2008, scientists were able to successfully germinate a circa-2000 year old date palm seed , and four years later, Russian scientists were able grow a plant from a 32,000 year old seed that had been buried by an ancient squirrel.

5. THE PITCH DROP EXPERIMENT // 86 YEARS

If you hit a mass of pitch (the leftovers from distilling crude oil) with a hammer, it shatters like a solid. In 1927, Thomas Parnell of the University of Queensland in Australia decided to demonstrate to his students that it was actually liquid. They just needed to watch it for a while. Some pitch was heated up and poured into a sealed stem glass funnel . Three years later, the stem of the funnel was cut and the pitch began to flow. Very slowly. Eight years later, the first drop fell. Soon the experiment was relegated to a cupboard to collect dust, until 1961 when John Mainstone learned of its existence and restored the test to its rightful glory. Sadly, he never saw a pitch drop. In 1979 it dropped on a weekend, in 1988 he was away getting a drink, in 2000 the webcam failed, and he died before the most recent drop in April 2014.

As it turns out, the Parnell-initiated pitch drop experiment isn’t even the oldest. After it gathered international headlines, reports of other pitch drop experiments became news. Aberystwyth University in Wales found a pitch drop experiment that was started 13 years before the Australian one, and has yet to produce a single drop (and indeed is not expected to for another 1300 years), while the Royal Scottish Museum in Edinburgh found a pitch drop experiment from 1902 . All of them prove one thing though: With enough time, a substance that can be shattered with a hammer still might be a liquid.

6. THE CLARENDON DRY PILE // 176-191 YEARS

Around 1840, Oxford physics professor Robert Walker bought a curious little contraption from a pair of London instrument makers that was made up of two dry piles (a type of battery) connected to bells with a metal sphere hanging in between them. When the ball hit one of the bells, it became negatively charged and shot towards the other positively charged bell where the process repeats itself. Because it uses only a minuscule amount of energy, the operation has occurred ten billion times and counting. It’s entirely possible that the ball or bells will wear out before the batteries fully discharge.

Although we don’t know the composition of the battery itself (and likely won’t until it winds down in a few hundred years), it has led to scientific advancements. During WWII , the British Admiralty developed an infrared telescope that needed a battery capable of producing high voltage, low current, and that could last forever. One of the scientists remembered seeing the Clarendon Dry Pile—also referred to as the Oxford Electric Bell—and was able to find out how to make his own dry pile for the telescope.

7. THE BEVERLY (ATMOSPHERIC) CLOCK // 152 YEARS

Sitting in the foyer of the University of Otago in New Zealand is the Beverly Clock. Developed in 1864 by Arthur Beverly, it is a phenomenal example of a self-winding clock. Beverly realized that, while most clocks used a weight falling to get the energy to run the clock mechanism, he could get the same energy with one cubic foot of air expanding and contracting over a six-degree Celsius temperature range. It hasn’t always worked; there have been times it needed cleanings, it stopped when the Physics department moved, and if the temperature is too stable it can stop. But it’s still going over 150 years later.

8. THE AUDUBON CHRISTMAS BIRD COUNT // 116 YEARS

Since 1900, folks from across the continent have spent time counting birds. What began as an activity to keep people from hunting our feathered friends on Christmas Day, has turned into one of the world’s most massive and long-lasting citizen science projects. Although the 2015 results aren’t ready yet, we know that in 2014 , 72,653 observers counted 68,753,007 birds of 2106 species.

9. THE HARVARD STUDY OF ADULT DEVELOPMENT // 78 YEARS

One of the longest running development studies, in 1938 Harvard began studying a group of 268 sophomores (including one John F. Kennedy ), and soon an additional study added 456 inner-city Bostonians. They’ve been followed ever since, from World War II through the Cold War and into the present day, with surveys every two years and physical examinations every five. Because of the sheer wealth of data, they’ve been able to learn all kinds of interesting and unexpected things. One such example: The quality of vacations one has in their youth often indicates increased happiness later in life.

10. THE TERMAN LIFE CYCLE STUDY // 95 YEARS

In 1921, 1470 California children who scored over 135 on an IQ test began a relationship that would turn into one of the world’s most famous longitudinal studies—the Terman Life Cycle Study of Children with High Ability .  Over the years, in order to show that early promise didn’t lead to later disappointment, participants filled out questionnaires about everything from early development, interests, and health to relationships and personality.  One of the most interesting findings is that, even among these smart folk, character traits like perseverance made the most difference in career success.

11. THE NATIONAL FOOD SURVEY // 76 YEARS

Starting in 1940, the UK’s National Food Survey tracked household food consumption and expenditure, and was the longest lasting program of its kind in the world. In 2000 it was replaced with the Expenditure and Food Survey, and in 2008 the Living Costs and Food Survey. And it’s provided interesting results . For instance, earlier this year it was revealed that tea consumption has fallen from around 23 cups per person per week to only eight cups, and no one in the UK ate pizza in 1974, but now the average Brit eats 75 grams (2.5 ounces) a week.

12. THE FRAMINGHAM HEART STUDY // 68 YEARS

In 1948 , the National Heart, Lung, and Blood Institute teamed up with Boston University to get 5209 people from the town of Framingham to do a long-term study of how cardiovascular disease developed. Twenty-three years later they also recruited the adult children of the original experiment and in 2002 a third generation. Over the decades, the Framingham Heart Study researchers claim to have discovered that cigarette smoking increased risk, in addition to identifying potential risk factors for Alzheimer’s, and the dangers of high blood pressure.

13. THE E. COLI LONG TERM EVOLUTION EXPERIMENT // 26 YEARS

While this one might not seem that impressive in terms of length, it has to be the record for number of generations that have come and gone over the course of the study: well over 50,000 . Richard Lenski was curious whether flasks of identical bacteria would change in the same way over time, or if the groups would diverge from each other. Eventually, he got bored with the experiment, but his colleagues convinced him to keep going, and it’s a good thing they did. In 2003, Lenski noticed that one of flasks had gone cloudy, and some research led him to discover that the E. coli in one of the flasks had gained the ability to metabolize citrate. Because he had been freezing previous generations of his experiment, he was able to precisely track how this evolution occurred.

14. THE BSE EXPERIMENT // 11 YEARS

Sadly, sometimes things can go terribly wrong during long-term experiments. Between 1990 and 1992, British scientists collected thousands of sheep brains. Then, for over four years, those prepared sheep brains were injected into hundreds of mice to learn if the sheep brains were infected with BSE (mad-cow disease). Preliminary findings suggested that they were, and plans were drawn up to slaughter every sheep in England. Except those sheep brains? They were actually cow brains that had been mislabeled. And thus ended the longest running experiment on sheep and BSE.

15. THE JUNEAU ICEFIELD RESEARCH PROGRAM // 68 YEARS

Attention to glacier retreat and the effects of global warming on the world’s ice fields has rapidly increased over the course of the last few decades, but the Juneau Icefield Research Program has been monitoring the situation up north since 1948. In its nearly 70 years of existence, the project become the longest-running study of its kind, as well as an educational and exploratory experience . The monitoring of the many glaciers of the Juneau Icefield in Alaska and British Columbia has a rapidly approaching end date though—at least in geological terms. A recent study published in the Journal of Glaciology predicts that the field will be gone by 2200 .

12 Ancient Scientific Instruments You Can Still See Today

These incredible tools were used to understand the world thousands of years ago..

Many hundreds of years before the development of modern science as we know it, people made incredible strides in understanding the world around them by developing groundbreaking scientific instruments. Sometimes made with primitive materials and limited resources, these technological tools helped people make remarkably accurate and advanced calculations and observations, paving the way for today’s observatories, clocks, and computers.

These mechanisms, some of which date back as far as 5,000 years ago, were developed on different continents by a wide range of cultures, from advanced metallurgy in India to the influential astronomical calendars of the ancient Maya. Amazingly, some of these ancient scientific instruments have been preserved through the millennia, and can be visited today. Each provides a window into how our ancestors made sense of the world around them. 

Antikythera Mechanism

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Gavazan Column at Tatev Monastery

Beijing Ancient Observatory

Bighorn Medicine Wheel

Jantar Mantar

Ulugh Beg Observatory

Iron Pillar of Delhi

Cheomseongdae

Medieval Clock

Dendera Light

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The world's longest-running experiments

The best science experiments are conducted carefully and often slowly, some taking years of painstaking work to yield results.

Sometimes, they run well after the scientists who began them are long dead.

When he set up the pitch drop experiment at Australia's University of Queensland in 1927, physicist Thomas Parnell had to know he would expire long before his test did. Examining the viscosity of the tar-like substance by the speed at which it flows from a funnel into a jar, the experiment has seen just eight drops fall in the eight decades since it began.

Parnell died in 1948, just two drops in.

The pitch drop test did win Parnell a posthumous "Ig Nobel" award in 2005, given out for achievements in science that "first make people laugh, and then make them think." Accepting on his behalf was co-winner John Mainstone, a retired UQ physicist and official custodian of the experiment since Parnell's death.

"It is the sort of experiment that does require patience," Mainstone said.

But Parnell's work falls decades short of the duration records set by other experiments.

In the field Deciding on what qualifies as the oldest science experiment is not an exact science, however. Because they vary so much in style and purpose they can't really be compared, experts say.

The pitch drop test is recognized by the Guinness Book of World Records as the longest-running laboratory experiment, but there are plenty of other, even lengthier scientific enterprises still on the go around the world:

An agricultural research field in the United Kingdom started in 1843. A clock in New Zealand that has ticked without being wound since 1864. A battery-powered bell at Oxford University that has rung continuously since 1840.

One of the longest-running experiments in the United States, a set of agricultural test-fields at the University of Illinois at Urbana-Champaign, is currently celebrating its 130th anniversary.

The United States was observing its centennial when the Morrow Plots were established in 1876.

Fewer than 40 million people — not one still alive today — lived in the United States at the time, more than two-thirds of them on farms. Wages for those farmers stood at fifteen cents a month, according to information provided by the university.

Despite being designated a National Historical Landmark in 1968, the corn fields are still in active use. The university takes samples from the site on a regular basis, with the rest of the corn going into storage to be sold at market later.

Like the pitch drop test, the Morrow Plots have also been able to keep with the times, according to the university's online history:  "Little has changed since 1903 and over almost 150 years of use, the plots have provided invaluable data on the effects of crop rotation, natural soil nutrient depletion, and effects of various man-made and natural fertilizers on crop yield."

Waiting for the next drop No one has ever seen a drop fall in Thomas Parnell's pitch experiment, even though the experiment is displayed prominently in a bell jar in the lobby of the university's physics department.

"It's that continuity that is really quite fascinating," Mainstone told LiveScience . "It used to be this thing that we kept locked in a cupboard, trotting it out only for some student demonstrations. But it really became a kind of industry," over time, he said, noting that students who graduated years ago still bring their families back to the campus to check on the pitch's progress.

The experiment continues to be relevant to modern science, too. Mainstone chats regularly about viscosity with engineers interested in polymers and liquids with properties similar to the pitch.

Being custodian of an experiment like the pitch drop or Morrow Plots is not for the glory-seeking scientist, Mainstone said. The next drop of his charge is expected to fall through the funnel by about 2012, he said, and the jar should remain undisturbed long after that. At its current rate, the last of the pitch won't descend for at least another hundred years.

A successor has already been chosen to carry the proverbial pitch drop torch, Mainstone said.

"He'll have to clear his schedule for media requests," he laughed, admitting that otherwise the job doesn't require much work.

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The Top 10 Science Experiments of All Time

These seminal experiments changed our understanding of the universe and ourselves..

Every day, we conduct science experiments, posing an “if” with a “then” and seeing what shakes out. Maybe it’s just taking a slightly different route on our commute home or heating that burrito for a few seconds longer in the microwave. Or it could be trying one more variation of that gene, or wondering what kind of code would best fit a given problem. Ultimately, this striving, questioning spirit is at the root of our ability to discover anything at all. A willingness to experiment has helped us delve deeper into the nature of reality through the pursuit we call science. 

A select batch of these science experiments has stood the test of time in showcasing our species at its inquiring, intelligent best. Whether elegant or crude, and often with a touch of serendipity, these singular efforts have delivered insights that changed our view of ourselves or the universe. 

Here are nine such successful endeavors — plus a glorious failure — that could be hailed as the top science experiments of all time.

Eratosthenes Measures the World

Experimental result: The first recorded measurement of Earth’s circumference 

When: end of the third century B.C.

Just how big is our world? Of the many answers from ancient cultures, a stunningly accurate value calculated by Eratosthenes has echoed down the ages. Born around 276 B.C. in Cyrene, a Greek settlement on the coast of modern-day Libya, Eratosthenes became a voracious scholar — a trait that brought him both critics and admirers. The haters nicknamed him Beta, after the second letter of the Greek alphabet. University of Puget Sound physics professor James Evans explains the Classical-style burn: “Eratosthenes moved so often from one field to another that his contemporaries thought of him as only second-best in each of them.” Those who instead celebrated the multitalented Eratosthenes dubbed him Pentathlos, after the five-event athletic competition.

That mental dexterity landed the scholar a gig as chief librarian at the famous library in Alexandria, Egypt. It was there that he conducted his famous experiment. He had heard of a well in Syene, a Nile River city to the south (modern-day Aswan), where the noon sun shone straight down, casting no shadows, on the date of the Northern Hemisphere’s summer solstice. Intrigued, Eratosthenes measured the shadow cast by a vertical stick in Alexandria on this same day and time. He determined the angle of the sun’s light there to be 7.2 degrees, or 1/50th of a circle’s 360 degrees. 

Knowing — as many educated Greeks did — Earth was spherical, Eratosthenes fathomed that if he knew the distance between the two cities, he could multiply that figure by 50 and gauge Earth’s curvature, and hence its total circumference. Supplied with that information, Eratosthenes deduced Earth’s circumference as 250,000 stades, a Hellenistic unit of length equaling roughly 600 feet. The span equates to about 28,500 miles, well within the ballpark of the correct figure of 24,900 miles. 

Eratosthenes’ motive for getting Earth’s size right was his keenness for geography, a field whose name he coined. Fittingly, modernity has bestowed upon him one more nickname: father of geography. Not bad for a guy once dismissed as second-rate.

William Harvey Takes the Pulse of Nature

Experimental result: The discovery of blood circulation

When: Theory published in 1628

Boy, was Galen wrong. 

The Greek physician-cum-philosopher proposed a model of blood flow in the second century that, despite being full of whoppers, prevailed for nearly 1,500 years. Among its claims: The liver constantly makes new blood from food we eat; blood flows throughout the body in two separate streams, one infused (via the lungs) with “vital spirits” from air; and the blood that tissues soak up never returns to the heart. 

Overturning all this dogma took a series of often gruesome experiments. 

High-born in England in 1578, William Harvey rose to become royal physician to King James I, affording him the time and means to pursue his greatest interest: anatomy. He first hacked away (literally, in some cases) at the Galenic model by exsanguinating — draining the blood from — test critters, including sheep and pigs. Harvey realized that if Galen were right, an impossible volume of blood, exceeding the animals’ size, would have to pump through the heart every hour. 

To drive this point home, Harvey sliced open live animals in public, demonstrating their puny blood supplies. He also constricted blood flow into a snake’s exposed heart by finger-pinching a main vein. The heart shrunk and paled; when pierced, it poured forth little blood. By contrast, choking off the main exiting artery swelled the heart. Through studies of the slow heart beats of reptiles and animals near death, he discerned the heart’s contractions, and deduced that it pumped blood through the body in a circuit.

According to Andrew Gregory, a professor of history and philosophy of science at University College London, this was no easy deduction on Harvey’s part. “If you look at a heart beating normally in its normal surroundings, it is very difficult to work out what is actually happening,” he says. 

Experiments with willing people, which involved temporarily blocking blood flow in and out of limbs, further bore out Harvey’s revolutionary conception of blood circulation. He published the full theory in a 1628 book, De Motu Cordis [The Motion of the Heart]. His evidence-based approach transformed medical science, and he’s recognized today as the father of modern medicine and physiology.

Gregor Mendel Cultivates Genetics

Experimental result: The fundamental rules of genetic inheritance 

When: 1855-1863 

A child, to varying degrees, resembles a parent, whether it’s a passing resemblance or a full-blown mini-me. Why? 

The profound mystery behind the inheritance of physical traits began to unravel a century and a half ago, thanks to Gregor Mendel. Born in 1822 in what is now the Czech Republic, Mendel showed a knack for the physical sciences, though his farming family had little money for formal education. Following the advice of a professor, he joined the Augustinian order, a monastic group that emphasized research and learning, in 1843. 

Ensconced at a monastery in Brno, the shy Gregor quickly began spending time in the garden. Fuchsias in particular grabbed his attention, their daintiness hinting at an underlying grand design. “The fuchsias probably gave him the idea for the famous experiments,” says Sander Gliboff, who researches the history of biology at Indiana University Bloomington. “He had been crossing different varieties, trying to get new colors or combinations of colors, and he got repeatable results that suggested some law of heredity at work.”

These laws became clear with his cultivation of pea plants. Using paintbrushes, Mendel dabbed pollen from one to another, precisely pairing thousands of plants with certain traits over a stretch of about seven years. He meticulously documented how matching yellow peas and green peas, for instance, always yielded a yellow plant. Yet mating these yellow offspring together produced a generation where a quarter of the peas gleamed green again. Ratios like these led to Mendel’s coining of the terms dominant (the yellow color, in this case) and recessive for what we now call genes, and which Mendel referred to as “factors.” 

He was ahead of his time. His studies received scant attention in their day, but decades later, when other scientists discovered and replicated Mendel’s experiments, they came to be regarded as a breakthrough. 

“The genius in Mendel’s experiments was his way of formulating simple hypotheses that explain a few things very well, instead of tackling all the complexities of heredity at once,” says Gliboff. “His brilliance was in putting it all together into a project that he could actually do.”

Isaac Newton Eyes Optics

Experimental result: The nature of color and light

When: 1665-1666

Before he was that Isaac Newton — scientist extraordinaire and inventor of the laws of motion, calculus and universal gravitation (plus a crimefighter to boot) — plain ol’ Isaac found himself with time to kill. To escape a devastating outbreak of plague in his college town of Cambridge, Newton holed up at his boyhood home in the English countryside. There, he tinkered with a prism he picked up at a local fair — a “child’s plaything,” according to Patricia Fara, fellow of Clare College, Cambridge. 

Let sunlight pass through a prism and a rainbow, or spectrum, of colors splays out. In Newton’s time, prevailing thinking held that light takes on the color from the medium it transits, like sunlight through stained glass. Unconvinced, Newton set up a prism experiment that proved color is instead an inherent property of light itself. This revolutionary insight established the field of optics, fundamental to modern science and technology. 

Newton deftly executed the delicate experiment: He bored a hole in a window shutter, allowing a single beam of sunlight to pass through two prisms. By blocking some of the resulting colors from reaching the second prism, Newton showed that different colors refracted, or bent, differently through a prism. He then singled out a color from the first prism and passed it alone through the second prism; when the color came out unchanged, it proved the prism didn’t affect the color of the ray. The medium did not matter. Color was tied up, somehow, with light itself. 

Partly owing to the ad hoc, homemade nature of Newton’s experimental setup, plus his incomplete descriptions in a seminal 1672 paper, his contemporaries initially struggled to replicate the results. “It’s a really, really technically difficult experiment to carry out,” says Fara. “But once you have seen it, it’s incredibly convincing.” 

In making his name, Newton certainly displayed a flair for experimentation, occasionally delving into the self-as-subject variety. One time, he stared at the sun so long he nearly went blind. Another, he wormed a long, thick needle under his eyelid, pressing on the back of his eyeball to gauge how it affected his vision. Although he had plenty of misses in his career — forays into occultism, dabbling in biblical numerology — Newton’s hits ensured his lasting fame.

Michelson and Morley Whiff on Ether

Experimental result: The way light moves

Say “hey!” and the sound waves travel through a medium (air) to reach your listener’s ears. Ocean waves, too, move through their own medium: water. Light waves are a special case, however. In a vacuum, with all media such as air and water removed, light somehow still gets from here to there. How can that be? 

The answer, according to the physics en vogue in the late 19th century, was an invisible, ubiquitous medium delightfully dubbed the “luminiferous ether.” Working together at what is now Case Western Reserve University in Ohio, Albert Michelson and Edward W. Morley set out to prove this ether’s existence. What followed is arguably the most famous failed experiment in history. 

The scientists’ hypothesis was thus: As Earth orbits the sun, it constantly plows through ether, generating an ether wind. When the path of a light beam travels in the same direction as the wind, the light should move a bit faster compared with sailing against the wind. 

To measure the effect, miniscule though it would have to be, Michelson had just the thing. In the early 1880s, he had invented a type of interferometer, an instrument that brings sources of light together to create an interference pattern, like when ripples on a pond intermingle. A Michelson interferometer beams light through a one-way mirror. The light splits in two, and the resulting beams travel at right angles to each other. After some distance, they reflect off mirrors back toward a central meeting point. If the light beams arrive at different times, due to some sort of unequal displacement during their journeys (say, from the ether wind), they create a distinctive interference pattern. 

The researchers protected their delicate interferometer setup from vibrations by placing it atop a solid sandstone slab, floating almost friction-free in a trough of mercury and further isolated in a campus building’s basement. Michelson and Morley slowly rotated the slab, expecting to see interference patterns as the light beams synced in and out with the ether’s direction. 

Instead, nothing. Light’s speed did not vary. 

Neither researcher fully grasped the significance of their null result. Chalking it up to experimental error, they moved on to other projects. (Fruitfully so: In 1907, Michelson became the first American to win a Nobel Prize, for optical instrument-based investigations.) But the huge dent Michelson and Morley unintentionally kicked into ether theory set off a chain of further experimentation and theorizing that led to Albert Einstein’s 1905 breakthrough new paradigm of light, special relativity.

Marie Curie’s Work Matters

Experimental result: Defining radioactivity 

Few women are represented in the annals of legendary scientific experiments, reflecting their historical exclusion from the discipline. Marie Sklodowska broke this mold. 

Born in 1867 in Warsaw, she immigrated to Paris at age 24 for the chance to further study math and physics. There, she met and married physicist Pierre Curie, a close intellectual partner who helped her revolutionary ideas gain a foothold within the male-dominated field. “If it wasn’t for Pierre, Marie would never have been accepted by the scientific community,” says Marilyn B. Ogilvie, professor emeritus in the history of science at the University of Oklahoma. “Nonetheless, the basic hypotheses — those that guided the future course of investigation into the nature of radioactivity — were hers.”

The Curies worked together mostly out of a converted shed on the college campus where Pierre worked. For her doctoral thesis in 1897, Marie began investigating a newfangled kind of radiation, similar to X-rays and discovered just a year earlier. Using an instrument called an electrometer, built by Pierre and his brother, Marie measured the mysterious rays emitted by thorium and uranium. Regardless of the elements’ mineralogical makeup — a yellow crystal or a black powder, in uranium’s case — radiation rates depended solely on the amount of the element present. 

From this observation, Marie deduced that the emission of radiation had nothing to do with a substance’s molecular arrangements. Instead, radioactivity — a term she coined — was an inherent property of individual atoms, emanating from their internal structure. Up until this point, scientists had thought atoms elementary, indivisible entities. Marie had cracked the door open to understanding matter at a more fundamental, subatomic level. 

Curie was the first woman to win a Nobel Prize, in 1903, and one of a very select few people to earn a second Nobel, in 1911 (for her later discoveries of the elements radium and polonium). 

“In her life and work,” says Ogilvie, “she became a role model for young women who wanted a career in science.”

Ivan Pavlov Salivates at the Idea

Experimental result: The discovery of conditioned reflexes

When: 1890s-1900s

Russian physiologist Ivan Pavlov scooped up a Nobel Prize in 1904 for his work with dogs, investigating how saliva and stomach juices digest food. While his scientific legacy will always be tied to doggie drool, it is the operations of the mind — canine, human and otherwise — for which Pavlov remains celebrated today.

Gauging gastric secretions was no picnic. Pavlov and his students collected the fluids that canine digestive organs produced, with a tube suspended from some pooches’ mouths to capture saliva. Come feeding time, the researchers began noticing that dogs who were experienced in the trials would start drooling into the tubes before they’d even tasted a morsel. Like numerous other bodily functions, the generation of saliva was considered a reflex at the time, an unconscious action only occurring in the presence of food. But Pavlov’s dogs had learned to associate the appearance of an experimenter with meals, meaning the canines’ experience had conditioned their physical responses. 

“Up until Pavlov’s work, reflexes were considered fixed or hardwired and not changeable,” says Catharine Rankin, a psychology professor at the University of British Columbia and president of the Pavlovian Society. “His work showed that they could change as a result of experience.” 

Pavlov and his team then taught the dogs to associate food with neutral stimuli as varied as buzzers, metronomes, rotating objects, black squares, whistles, lamp flashes and electric shocks. Pavlov never did ring a bell, however; credit an early mistranslation of the Russian word for buzzer for that enduring myth. 

The findings formed the basis for the concept of classical, or Pavlovian, conditioning. It extends to essentially any learning about stimuli, even if reflexive responses are not involved. “Pavlovian conditioning is happening to us all of the time,” says W. Jeffrey Wilson of Albion College, fellow officer of the Pavlovian Society. “Our brains are constantly connecting things we experience together.” In fact, trying to “un-wire” these conditioned responses is the strategy behind modern treatments for post-traumatic stress disorder, as well as addiction.

Robert Millikan Gets a Charge

Experimental result: The precise value of a single electron’s charge

By most measures, Robert Millikan had done well for himself. Born in 1868 in a small town in Illinois, he went on to earn degrees from Oberlin College and Columbia University. He studied physics with European luminaries in Germany. He then joined the University of Chicago’s physics department, and even penned some successful textbooks. 

But his colleagues were doing far more. The turn of the 20th century was a heady time for physics: In the span of just over a decade, the world was introduced to quantum physics, special relativity and the electron — the first evidence that atoms had divisible parts. By 1908, Millikan found himself pushing 40 without a significant discovery to his name. 

The electron, though, offered an opportunity. Researchers had struggled with whether the particle represented a fundamental unit of electric charge, the same in all cases. It was a critical determination for further developing particle physics. With nothing to lose, Millikan gave it a go. 

In his lab at the University of Chicago, he began working with containers of thick water vapor, called cloud chambers, and varying the strength of an electric field within them. Clouds of water droplets formed around charged atoms and molecules before descending due to gravity. By adjusting the strength of the electric field, he could slow down or even halt a single droplet’s fall, countering gravity with electricity. Find the precise strength where they balanced, and — assuming it did so consistently — that would reveal the charge’s value. 

When it turned out water evaporated too quickly, Millikan and his students — the often-unsung heroes of science — switched to a longer-lasting substance: oil, sprayed into the chamber by a drugstore perfume atomizer. 

The increasingly sophisticated oil-drop experiments eventually determined that the electron did indeed represent a unit of charge. They estimated its value to within whiskers of the currently accepted charge of one electron (1.602 x 10-19 coulombs). It was a coup for particle physics, as well as Millikan. 

“There’s no question that it was a brilliant experiment,” says Caltech physicist David Goodstein. “Millikan’s result proved beyond reasonable doubt that the electron existed and was quantized with a definite charge. All of the discoveries of particle physics follow from that.”

Young, Davisson and Germer See Particles Do the Wave

Experimental result: The wavelike nature of light and electrons 

When: 1801 and 1927, respectively 

Light: particle or wave? Having long wrestled with this seeming either/or, many physicists settled on particle after Isaac Newton’s tour de force through optics. But a rudimentary, yet powerful, demonstration by fellow Englishman Thomas Young shattered this convention. 

Young’s interests covered everything from Egyptology (he helped decode the Rosetta Stone) to medicine and optics. To probe light’s essence, Young devised an experiment in 1801. He cut two thin slits into an opaque object, let sunlight stream through them and watched how the beams cast a series of bright and dark fringes on a screen beyond. Young reasoned that this pattern emerged from light wavily spreading outward, like ripples across a pond, with crests and troughs from different light waves amplifying and canceling each other. 

Although contemporary physicists initially rebuffed Young’s findings, rampant rerunning of these so-called double-slit experiments established that the particles of light really do move like waves. “Double-slit experiments have become so compelling [because] they are relatively easy to conduct,” says David Kaiser, a professor of physics and of the history of science at MIT. “There is an unusually large ratio, in this case, between the relative simplicity and accessibility of the experimental design and the deep conceptual significance of the results.”

More than a century later, a related experiment by Clinton Davisson and Lester Germer showed the depth of this significance. At what is now called Nokia Bell Labs in New Jersey, the physicists ricocheted electron particles off a nickel crystal. The scattered electrons interacted to produce a pattern only possible if the particles also acted like waves. Subsequent double slit-style experiments with electrons proved that particles with matter and undulating energy (light) can each act like both particles and waves. The paradoxical idea lies at the heart of quantum physics, which at the time was just beginning to explain the behavior of matter at a fundamental level. 

“What these experiments show, at their root, is that the stuff of the world, be it radiation or seemingly solid matter, has some irreducible, unavoidable wavelike characteristics,” says Kaiser. “No matter how surprising or counterintuitive that may seem, physicists must take that essential ‘waviness’ into account.”

Robert Paine Stresses Starfish

Experimental result: The disproportionate impact of keystone species on ecosystems

When: Initially presented in a 1966 paper

Just like the purple starfish he crowbarred off rocks and chucked into the Pacific Ocean, Bob Paine threw conventional wisdom right out the window. 

By the 1960s, ecologists had come to agree that habitats thrived primarily through diversity. The common practice of observing these interacting webs of creatures great and small suggested as much. Paine took a different approach. 

Curious what would happen if he intervened in an environment, Paine ran his starfish-banishing experiments in tidal pools along and off the rugged coast of Washington state. The removal of this single species, it turned out, could destabilize a whole ecosystem. Unchecked, the starfish’s barnacle prey went wild — only to then be devoured by marauding mussels. These shellfish, in turn, started crowding out the limpets and algal species. The eventual result: a food web in tatters, with only mussel-dominated pools left behind. 

Paine dubbed the starfish a keystone species, after the necessary center stone that locks an arch into place. A revelatory concept, it meant that all species do not contribute equally in a given ecosystem. Paine’s discovery had a major influence on conservation, overturning the practice of narrowly preserving an individual species for the sake of it, versus an ecosystem-based management strategy.

“His influence was absolutely transformative,” says Oregon State University’s Jane Lubchenco, a marine ecologist. She and her husband, fellow OSU professor Bruce Menge, met 50 years ago as graduate students in Paine’s lab at the University of Washington. Lubchenco, the administrator of the National Oceanic Atmospheric Administration from 2009 to 2013, saw over the years the impact that Paine’s keystone species concept had on policies related to fisheries management.

Lubchenco and Menge credit Paine’s inquisitiveness and dogged personality for changing their field. “A thing that made him so charismatic was almost a childlike enthusiasm for ideas,” says Menge. “Curiosity drove him to start the experiment, and then he got these spectacular results.”

Paine died in 2016. His later work had begun exploring the profound implications of humans as a hyper-keystone species, altering the global ecosystem through climate change and unchecked predation.

Adam Hadhazy is based in New Jersey. His work has also appeared in New Scientist and Popular Science , among other publications. This story originally appeared in print as "10 Experiments That Changed Everything"

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• Long-term Thinking

Three of the longest scientific experiments still going

By Kevin Kelly

May 2, 02007

It just so happens that three of the longest running scientific experiments are located in the foyers of university physics departments. These three long-running tests were first reported as a set in a 1984 article in the European Journal of Physics. One of them, the pitch drop has achieved some internet fame. But it is not the oldest. The oldest experiment is the Oxford bell and it has been running about 160 years. All three were later updated in the Annals of Improbable Research in this 2001 article :

We are happy to report that three of the world’s longest-running scientific experiments are indeed still running. It has been a number of years since anyone checked on all three. With assistance from scientists in several nations, we have managed to do so. In 1984, the European Journal of Physics published three remarkable reports, each describing a different experiment that had been continuing for decades. The youngest — the pitch drop viscosity experiment at the University of Queensland in Brisbane — had been started in 1927. The oldest — the now-and-then-famous Oxford electric bell at Oxford University, was begun in 1840. The third experiment, the Beverly clock at the University of Otago in Dunedin, was commenced in 1864.

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The Secret Mission To Unearth Part Of A 142-Year-Old Experiment

Nell Greenfieldboyce

Researchers search for a bottle filled with seeds that was buried 142 years ago as part of a seed germination study. Derrick L. Turner/Michigan State University hide caption

Researchers search for a bottle filled with seeds that was buried 142 years ago as part of a seed germination study.

It was 4 o'clock in the morning, well before sunrise, and cold. A light wintry mix of rain and snow was falling. The lousy weather was a relief, as it meant even less of a chance that someone might randomly pass by. The small group of scientists didn't want anyone to see what they were about to do.

They'd brought flashlights, a shovel, a trowel, a tape measure and an old map. The map looked more like a blueprint than a pirate's guide to buried treasure. Still, it did show the secret location of something precious stashed away underground.

The researchers had gathered together to dig up part of an experiment: an unusual long-term experiment that started in 1879 on the campus of what is now Michigan State University.

A botanist named William Beal wondered how long seeds could remain viable underground. So he designed an audacious study to find out, knowing full well that the answer might not come in his lifetime.

Frank Telewski , a professor of plant biology at the university, explains that Beal got 20 glass bottles. "Those 20 bottles, he filled up with a sandy seed mixture," says Telewski. "And the sandy seed mixture contained 21 species of plants, with 50 seeds per plant."

The plants were just common weeds. The idea was to find out, if farmers faithfully weeded their plots, how long these annoying plants could keep coming up from seeds already in the dirt.

Beal buried the bottles in the ground, keeping the location private so it wouldn't get disturbed. Every five years, he dug up one bottle and checked to see if the seeds inside would germinate. In 1910, when Beal retired, he passed on the experiment to a colleague, who later passed it on to a colleague and so on.

The study has lasted far longer than Beal intended because its caretakers decided to stretch it out. Instead of every five years, they switched to digging up a bottle every 10 years. Then, every 20 years. Telewski helped unearth a bottle in 2000, when he took over the experiment from a colleague. That year, only a couple of different weeds were still able to sprout.

William Beal, standing at center, started a long-term study on seed germination in 1879. He buried 20 bottles with seeds in them for later researchers to unearth and plant. Michigan State University hide caption

William Beal, standing at center, started a long-term study on seed germination in 1879. He buried 20 bottles with seeds in them for later researchers to unearth and plant.

As Telewski thought about digging up his second bottle, which was supposed to happen in 2020 (the excavation got delayed until this month, because of the coronavirus pandemic), he thought about the future. "I decided we needed to pass this on to the next generation, as I turned 65 last year," says Telewski. He picked three relatively young colleagues at the university to be the new caretakers and join him as he dug up a bottle.

One of them was David Lowry , who recalls first hearing about this famous experiment 20 years ago, when he was an undergraduate student in California. "I was blown away by the length and time at which it was occurring," he says. "I never imagined I'd be involved as well."

Telewski went to Lowry's office a couple of years ago and handed him the map. "And [Telewski] said, you know, in case something happens to me, you have the map. And a couple of months later, he had a stroke," recalls Lowry. "Fortunately, he mostly recovered from that. But there was a moment where it was like, 'Wow, I'm really glad that that handoff had occurred.' "

Experiments That Keep Going And Going And Going

Even with the map and with Telewski healthy enough to lead the way, it was actually hard to find the right spot to dig in the dark. At first the team got slightly off track, then figured out its mistake and started digging again. Birds began waking up and chirping, and the team worried that it wouldn't be done before sunrise.

Lars Brudvig , another one of the new caretakers, said the whole experience of working on this felt different from the research he has done in the past.

"Almost like more pressure or something than normal," says Brudvig. "Because I'm part of this bigger process, it's bigger than me, and I really want to make sure that it's done right and carried forward properly — both for the generations of plant biologists in the past who have been involved, but also for those generations that are still to come who will be involved in the future."

He and Lowry watched as Marjorie Weber , the third new caretaker, got down onto the ground and stuck her head into the hole. She groped around in the dirt, feeling tree roots and then something smooth.

"I think I found it," she exclaimed, and everyone cheered. Then a moment later, she reported, "Wait — maybe not. ... Oh. It was a rock." Everyone groaned.

A microbiologist named Richard Lenski looked on. "The others were digging and trying to figure everything out, and I sort of held the map and held it under my jacket to keep it dry at one point. That was my hard work," says Lenski. "I was wondering if cops might show up at some point."

Lenski wasn't part of the Beal experiment; he'd asked to come along as an observer. He has a special interest in long-term studies because he has his own going on just across campus. He started it in 1988, to study bacterial evolution, and recently picked a younger successor to carry it on.

"I like to think of our experiment as long term, both in the past and going forward," says Lenski, but the Beal seed-viability experiment "puts our experiment to shame in that respect. This is a pretty amazing, unique aspect of science."

Finally, Weber said, "OK, I — for real — found it!" Telewski greeted the bottles as if they were old friends. "Wow!" he said. "Oh, wow! Hello, bottles!"

Weber says it was really cool to pull a bottle out of the ground, knowing that "the last person to touch it was professor Beal, 140 years ago, you know, this person who was writing letters to Darwin."

The researchers immediately took the bottle to a lab. They spread out almost all of the contents onto potting soil.

Frank Telewski spreads seeds from the Beal bottle in a tray in the growth lab in the Plant Biology Building. Derrick L. Turner/Michigan State University hide caption

Frank Telewski spreads seeds from the Beal bottle in a tray in the growth lab in the Plant Biology Building.

A molecular biologist named Margaret Fleming removed a couple of seeds, ones from a species that hasn't germinated in about 100 years. The plan is to analyze those seeds to see if any of the cellular machinery is still active inside, even if the seeds can't germinate, using genetic tools that were unimaginable in Beal's day. What's more, Fleming and Weber are the first females to work on this project in its long history, showing that it's more than technology that changes.

The researchers waited and waited for about a week. Then, on the afternoon of Friday, April 23, Lowry checked the tray of seeds and saw one tiny green seedling. That means at least one old seed could still germinate, and more could sprout in the days to come.

"We know that seeds can last a really long time in perfect conditions, like in seed storage vaults or the permafrost," says Weber, who notes that Beal's original question is still relevant. "We don't really know how long seeds can last in the soil. And that's where most of the seeds are."

She and the other new caretakers are all in their 30s and 40s now, but they'll eventually have to choose their successors to carry the study forward. Telewski thinks they should do it before the next excavation, in 2040.

"If I'm fortunate, I'll be 85," says Telewski, "and I sure hope I can be there as a spectator and can watch the team dig it up with their new colleagues."

But, like Beal, no one on the current team is going to see the end of this experiment. With four bottles left in the ground, the study should go on for another 80 years.

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One of the World’s Longest-Running Experiments Sends Up Sprouts

After lying dormant in buried bottles for 142 years, 11 seeds germinated on the Michigan State University campus after scientists planted them.

By Cara Giaimo

David Lowry was impatient for the very old seeds to wake up. For days, Dr. Lowry, an associate professor of botany at Michigan State University, had entered a basement room at the school, peeked into the growth chamber and seen only dirt.

But on April 23, he checked again and there it was: A tiny plant, its two leaves reaching upward. “It was kind of an amazing moment,” he said.

This was no average springtime sprout. Back in 1879, the botanist William James Beal plucked that seed and thousands of others from different weedy plants in and around East Lansing, Mich. He then stashed them in bottles and buried them in a secret spot on the Michigan State campus, with the goal of learning whether they’d still grow after years, decades or even centuries of dormancy. In mid-April, Dr. Lowry and four colleagues sneaked out under cover of night to dig one of the bottles up and plant its contents, thus continuing one of the longest-running experiments in the world.

Through late April and early May, more seedlings peeked above the soil — 11 as of Tuesday. One is a bit of a mystery, with leaves that are hairier and sharper-edged than those of the other sprouts.

The rest are most likely Verbascum blattaria, a tall, jaunty-flowered herb that has emerged as the experiment’s undisputed champ. Commonly known as moth mullein for its antenna-like stamens, this species was introduced to North America in the 1800s and lives an unassuming life in fields and meadows.

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Famous Scientists

10 Most Famous Scientific Theories That Were Later Debunked

By Scientist

The most genuine merit of science is probably its readiness to admit its mistakes (usually!). The theories in science are always being reconsidered and scrutinized. Modern research often rejects old ideas, hoaxes and myths.

Today’s post on our Science Blog will discuss ten of the most popular and influential scientific discoveries that were based on dubious data, and were consequently proven wrong, debunked and replaced with more reliable and logical modern theories.

1- Fleischmann–Pons’s Nuclear Fusion

Cold fusion is a supposed kind of nuclear reaction that would occur at relatively low temperatures compared with hot fusion. As a new type of nuclear reaction, it gained much popularity after reports in 1989 by famous electrochemists Stanley Pons and Martin Fleischmann. The craze about cold fusion became weaker as other scientists, after trying to repeat the experiment, failed to get similar results.

1a – One of Modern Science’s Greatest Misconceptions

The misconception that mass is destroyed in nuclear reactions.

2- Phrenology

Now widely considered as a pseudoscience, phrenology was the study of the shape of skull as indicative of the strengths of different faculties. Modern scientific research wiped it out by proving that personality traits could not be traced to specific portions of the brain.

3- The Blank Slate

The Blank Slate theory (or Tabula rasa), widely popularized by John Locke in 1689, proposed that individuals are born without built-in mental content and that their knowledge comes from experience and perception. Modern research suggests that genes and other family traits inherited from birth, along with innate instincts of course, also play a very important role.

4- Luminiferous Aether

The aether (or ether) was a mysterious substance that was thought to transmit light through the universe. The idea of a luminiferous aether was debunked as experiments in the diffraction and refraction of light, and later Einstein’s special theory of relativity, came along and entirely revolutionized physics.

5- Einstein’s Static (or Stationary) Universe

A static universe, also called a “stationary” or “Einstein” universe, was a model proposed by Albert Einstein in 1917. It was problematic from the beginning. Edwin Hubble’s discovery of the relationship between red shift obliterated it by completely demonstrating that the universe is constantly expanding.

6- Martian Canals

The Martian canals were a network of gullies and ravines that some 19th century scientists erroneously thought to exist on Mars. First detected in 1877 by Italian astronomer Giovanni Schiaparelli, modern telescopes and imaging technology completely debunked the myth. The “canals” were actually found to be a mere optical illusion.

7- Phlogiston Theory

First postulated in 1667 by German physician Johann Joachim Becher, Phlogiston Theory is an obsolete scientific theory regarding the existence of “phlogiston”, a fire-like element, which was contained within combustible bodies and released during combustion. The theory tried to explain burning processes such as combustion and the rusting of metals, which are now jointly termed as “oxidation”.

8- The Expanding or Growing Earth

The Expanding Earth or Growing Earth is a hypothesis suggesting that the position and relative movement of continents is dependent on the volume of the Earth increasing. Modern science has turned down any expansion or contraction of the Earth.

9- Discovery of the Planet Vulcan

A small planet that was supposed to exist in an orbit between Mercury and the Sun, French mathematician Urbain Jean Joseph Le Verrier coined the name “Vulcan” while trying to explain the nature of Mercury’s orbit. No such planet was ever discovered, while the orbit of Mercury was explained in detail by Albert Einstein’s theory of general relativity.

10- Spontaneous (or Equivocal) Generation

Spontaneous generation or equivocal generation is an obsolete principle concerning the origin of life from inanimate matter. The hypothesis was brought out by Aristotle who advocated the work of earlier natural philosophers. It was proven wrong in the 19th century by the experiments of Louis Pasteur , drawing influence from Francesco Redi who was an early proponent of germ theory and cell theory.

More from FamousScientists.org:

June 24, 2014 at 6:55 am

RITAHEAD, the bible is a BOOK. I could write a book that says the Earth is flat and the Moon is made of green cheese and would that make it true? Of course not! The Bible is wrong about many things. Including the value of the pi constant. Deal with it.

December 24, 2013 at 3:36 pm

Scientists use Hubble Telescope to comment the entire universe would be expanding.

How could Hubble Telescope work in reality? It simply works by collecting light from the sky through the use of primary mirror in this Telescope and then to reflect it upon a secondary mirror for analysis. However, the reflection of light by means of primary mirrors could result in obscure image in secondary mirror. The reason is simply lights could reflect in any directions and angles from any parts of primary mirror. As a result, overlapping of lights on secondary mirrors as a result of reflection from primary mirrors could be possible to the ultimate formation of obscure images. These collective obscure images could lead to false information that the entire universe could be expanding.

Hubble Space Telescope uses the same technique as Hubble Telescope to collect lights from the sky for analysis. Thus, false images could be gathered too.

Thus, fake images from the collection of lights from the sky through the reflective mirrors would cause information that would be gathered from Hubble Space or Hubble Telescope might not to be reliable.

November 20, 2013 at 5:54 am

I hope we can soon add the cholesterol theory of heart disease. It’s been debunked, but getting it to die is proving difficult.

September 7, 2013 at 3:00 pm

I wished they would have mentioned the carbon dating and radioactive dating. One thing I did learn in science is that to prove your theory, you have to have a control. How can they prove that bones are millions of years old? My bible tells me the earth is not that old.

September 4, 2013 at 12:32 pm

In genetics the definition of the “GENE” has changed over and over since it was coined by Johansson in 1909.

Gene as unit of function Gene as unit of recombination Gene as unit of mutation One gene one enzyme concept The central Dogma DNA->RNA->protein

All these views have been revised by newer concepts. An overview of all outmoded definitions and the problematic attempts to offer a current defention that is valid now, was published in http://genome.cshlp.org/content/17/6/669

September 4, 2013 at 12:24 pm

neo-darwinism is largely debunked as explanation for increasing biological complexity. This theory, largely composed of population genetic concepts to understand how selection could bring change is still valid to explain variability within species.

The major explanation for increase of organismal complexity, i.e. from prokaryotes to eukaryotes, from single cell to multicellular organisms, from primitive to complex species is not explained by neodarwinism.

Horizontal gene transfer, Genome duplication (polyploidization and subsequent genome fragmentation) are largely singular events caused by drift rather than mutation and selection.

It is hardly understood by lay people how the current genomic revolution is reshaping evolutionary concepts.

And I have not even mentioned the revival of Lamarckism.

I think this contemporary example is a much nicer example that outmoded phlogiston theories from times before modern sciences had its current rigour

July 8, 2013 at 12:37 pm

Some of these are dubious at best. For example, the luminiferous aether wasn’t debunked; it was not needed in the new theories, and so it dropped out of physics, but that’s a very different matter. Locke’s objection to innate ideas, principles, knowledge, etc., not only wasn’t a scientific theory, but isn’t touched by genetic theory, or by any scientific theory. Moreover, he was happy to accept that we have innate capacities and abilities, which is all that science has attempted to explain in terms of genetics, etc. No-one, to the best of my knowledge, claimed to have discovered Vulcan, nor was its existence a theory, it was part of a hypothesis designed 9as you point out) to explain the ways in which Mercury’s orbit failed to accord with Newtonian physics.

April 4, 2013 at 8:14 pm

A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of knowledge that has been repeatedly confirmed through observation and experiment.[1][2] Scientists create scientific theories from hypotheses that have been corroborated through the scientific method, then gather evidence to test their accuracy. As with all forms of scientific knowledge, scientific theories are inductive in nature and do not make apodictic propositions; instead, they aim for predictive and explanatory force.[3][4]

1 National Academy of Sciences, 1999 2 AAAS Evolution Resources 3 Schafersman, Steven D. “An Introduction to Science”. 4 American Association for the Advancement of Science, Project 2061

February 20, 2013 at 6:07 pm

Interesting piece. The only I have to point out it that the majorities of these were never widely held theories. Instead most of them were either hypothesis or were only believed to be true by a small percent of the scientific community. There is a big difference between hypothesis and scientific theory.

January 14, 2013 at 11:54 am

This is very wonderful. Science in its nature of existence is a circulating event in which its theories can be formulated and debunked. Thanks for the hard job done.

April 7, 2012 at 10:58 am

Well researched post, keep up the good work!

Alphabetical List of Scientists

Louis Agassiz | Maria Gaetana Agnesi | Al-Battani Abu Nasr Al-Farabi | Alhazen | Jim Al-Khalili | Muhammad ibn Musa al-Khwarizmi | Mihailo Petrovic Alas | Angel Alcala | Salim Ali | Luis Alvarez | Andre Marie Ampère | Anaximander | Carl Anderson | Mary Anning | Virginia Apgar | Archimedes | Agnes Arber | Aristarchus | Aristotle | Svante Arrhenius | Oswald Avery | Amedeo Avogadro | Avicenna

Charles Babbage | Francis Bacon | Alexander Bain | John Logie Baird | Joseph Banks | Ramon Barba | John Bardeen | Charles Barkla | Ibn Battuta | William Bayliss | George Beadle | Arnold Orville Beckman | Henri Becquerel | Emil Adolf Behring | Alexander Graham Bell | Emile Berliner | Claude Bernard | Timothy John Berners-Lee | Daniel Bernoulli | Jacob Berzelius | Henry Bessemer | Hans Bethe | Homi Jehangir Bhabha | Alfred Binet | Clarence Birdseye | Kristian Birkeland | James Black | Elizabeth Blackwell | Alfred Blalock | Katharine Burr Blodgett | Franz Boas | David Bohm | Aage Bohr | Niels Bohr | Ludwig Boltzmann | Max Born | Carl Bosch | Robert Bosch | Jagadish Chandra Bose | Satyendra Nath Bose | Walther Wilhelm Georg Bothe | Robert Boyle | Lawrence Bragg | Tycho Brahe | Brahmagupta | Hennig Brand | Georg Brandt | Wernher Von Braun | J Harlen Bretz | Louis de Broglie | Alexander Brongniart | Robert Brown | Michael E. Brown | Lester R. Brown | Eduard Buchner | Linda Buck | William Buckland | Georges-Louis Leclerc, Comte de Buffon | Robert Bunsen | Luther Burbank | Jocelyn Bell Burnell | Macfarlane Burnet | Thomas Burnet

Benjamin Cabrera | Santiago Ramon y Cajal | Rachel Carson | George Washington Carver | Henry Cavendish | Anders Celsius | James Chadwick | Subrahmanyan Chandrasekhar | Erwin Chargaff | Noam Chomsky | Steven Chu | Leland Clark | John Cockcroft | Arthur Compton | Nicolaus Copernicus | Gerty Theresa Cori | Charles-Augustin de Coulomb | Jacques Cousteau | Brian Cox | Francis Crick | James Croll | Nicholas Culpeper | Marie Curie | Pierre Curie | Georges Cuvier | Adalbert Czerny

Gottlieb Daimler | John Dalton | James Dwight Dana | Charles Darwin | Humphry Davy | Peter Debye | Max Delbruck | Jean Andre Deluc | Democritus | René Descartes | Rudolf Christian Karl Diesel | Diophantus | Paul Dirac | Prokop Divis | Theodosius Dobzhansky | Frank Drake | K. Eric Drexler

John Eccles | Arthur Eddington | Thomas Edison | Paul Ehrlich | Albert Einstein | Gertrude Elion | Empedocles | Eratosthenes | Euclid | Eudoxus | Leonhard Euler

Michael Faraday | Pierre de Fermat | Enrico Fermi | Richard Feynman | Fibonacci – Leonardo of Pisa | Emil Fischer | Ronald Fisher | Alexander Fleming | John Ambrose Fleming | Howard Florey | Henry Ford | Lee De Forest | Dian Fossey | Leon Foucault | Benjamin Franklin | Rosalind Franklin | Sigmund Freud | Elizebeth Smith Friedman

Galen | Galileo Galilei | Francis Galton | Luigi Galvani | George Gamow | Martin Gardner | Carl Friedrich Gauss | Murray Gell-Mann | Sophie Germain | Willard Gibbs | William Gilbert | Sheldon Lee Glashow | Robert Goddard | Maria Goeppert-Mayer | Thomas Gold | Jane Goodall | Stephen Jay Gould | Otto von Guericke

Fritz Haber | Ernst Haeckel | Otto Hahn | Albrecht von Haller | Edmund Halley | Alister Hardy | Thomas Harriot | William Harvey | Stephen Hawking | Otto Haxel | Werner Heisenberg | Hermann von Helmholtz | Jan Baptist von Helmont | Joseph Henry | Caroline Herschel | John Herschel | William Herschel | Gustav Ludwig Hertz | Heinrich Hertz | Karl F. Herzfeld | George de Hevesy | Antony Hewish | David Hilbert | Maurice Hilleman | Hipparchus | Hippocrates | Shintaro Hirase | Dorothy Hodgkin | Robert Hooke | Frederick Gowland Hopkins | William Hopkins | Grace Murray Hopper | Frank Hornby | Jack Horner | Bernardo Houssay | Fred Hoyle | Edwin Hubble | Alexander von Humboldt | Zora Neale Hurston | James Hutton | Christiaan Huygens | Hypatia

Ernesto Illy | Jan Ingenhousz | Ernst Ising | Keisuke Ito

Mae Carol Jemison | Edward Jenner | J. Hans D. Jensen | Irene Joliot-Curie | James Prescott Joule | Percy Lavon Julian

Michio Kaku | Heike Kamerlingh Onnes | Pyotr Kapitsa | Friedrich August Kekulé | Frances Kelsey | Pearl Kendrick | Johannes Kepler | Abdul Qadeer Khan | Omar Khayyam | Alfred Kinsey | Gustav Kirchoff | Martin Klaproth | Robert Koch | Emil Kraepelin | Thomas Kuhn | Stephanie Kwolek

Joseph-Louis Lagrange | Jean-Baptiste Lamarck | Hedy Lamarr | Edwin Herbert Land | Karl Landsteiner | Pierre-Simon Laplace | Max von Laue | Antoine Lavoisier | Ernest Lawrence | Henrietta Leavitt | Antonie van Leeuwenhoek | Inge Lehmann | Gottfried Leibniz | Georges Lemaître | Leonardo da Vinci | Niccolo Leoniceno | Aldo Leopold | Rita Levi-Montalcini | Claude Levi-Strauss | Willard Frank Libby | Justus von Liebig | Carolus Linnaeus | Joseph Lister | John Locke | Hendrik Antoon Lorentz | Konrad Lorenz | Ada Lovelace | Percival Lowell | Lucretius | Charles Lyell | Trofim Lysenko

Ernst Mach | Marcello Malpighi | Jane Marcet | Guglielmo Marconi | Lynn Margulis | Barry Marshall | Polly Matzinger | Matthew Maury | James Clerk Maxwell | Ernst Mayr | Barbara McClintock | Lise Meitner | Gregor Mendel | Dmitri Mendeleev | Franz Mesmer | Antonio Meucci | John Michell | Albert Abraham Michelson | Thomas Midgeley Jr. | Milutin Milankovic | Maria Mitchell | Mario Molina | Thomas Hunt Morgan | Samuel Morse | Henry Moseley

Ukichiro Nakaya | John Napier | Giulio Natta | John Needham | John von Neumann | Thomas Newcomen | Isaac Newton | Charles Nicolle | Florence Nightingale | Tim Noakes | Alfred Nobel | Emmy Noether | Christiane Nusslein-Volhard | Bill Nye

Hans Christian Oersted | Georg Ohm | J. Robert Oppenheimer | Wilhelm Ostwald | William Oughtred

Blaise Pascal | Louis Pasteur | Wolfgang Ernst Pauli | Linus Pauling | Randy Pausch | Ivan Pavlov | Cecilia Payne-Gaposchkin | Wilder Penfield | Marguerite Perey | William Perkin | John Philoponus | Jean Piaget | Philippe Pinel | Max Planck | Pliny the Elder | Henri Poincaré | Karl Popper | Beatrix Potter | Joseph Priestley | Proclus | Claudius Ptolemy | Pythagoras

Adolphe Quetelet | Harriet Quimby | Thabit ibn Qurra

C. V. Raman | Srinivasa Ramanujan | William Ramsay | John Ray | Prafulla Chandra Ray | Francesco Redi | Sally Ride | Bernhard Riemann | Wilhelm Röntgen | Hermann Rorschach | Ronald Ross | Ibn Rushd | Ernest Rutherford

Carl Sagan | Abdus Salam | Jonas Salk | Frederick Sanger | Alberto Santos-Dumont | Walter Schottky | Erwin Schrödinger | Theodor Schwann | Glenn Seaborg | Hans Selye | Charles Sherrington | Gene Shoemaker | Ernst Werner von Siemens | George Gaylord Simpson | B. F. Skinner | William Smith | Frederick Soddy | Mary Somerville | Arnold Sommerfeld | Hermann Staudinger | Nicolas Steno | Nettie Stevens | William John Swainson | Leo Szilard

Niccolo Tartaglia | Edward Teller | Nikola Tesla | Thales of Miletus | Theon of Alexandria | Benjamin Thompson | J. J. Thomson | William Thomson | Henry David Thoreau | Kip S. Thorne | Clyde Tombaugh | Susumu Tonegawa | Evangelista Torricelli | Charles Townes | Youyou Tu | Alan Turing | Neil deGrasse Tyson

Harold Urey

Craig Venter | Vladimir Vernadsky | Andreas Vesalius | Rudolf Virchow | Artturi Virtanen | Alessandro Volta

Selman Waksman | George Wald | Alfred Russel Wallace | John Wallis | Ernest Walton | James Watson | James Watt | Alfred Wegener | John Archibald Wheeler | Maurice Wilkins | Thomas Willis | E. O. Wilson | Sven Wingqvist | Sergei Winogradsky | Carl Woese | Friedrich Wöhler | Wilbur and Orville Wright | Wilhelm Wundt

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Sat / act prep online guides and tips, 37 cool science experiments for kids to do at home.

General Education

Are you looking for cool science experiments for kids at home or for class? We've got you covered! We've compiled a list of 37 of the best science experiments for kids that cover areas of science ranging from outer space to dinosaurs to chemical reactions. By doing these easy science experiments, kids will make their own blubber and see how polar bears stay warm, make a rain cloud in a jar to observe how weather changes, create a potato battery that'll really power a lightbulb, and more.

Below are 37 of the best science projects for kids to try. For each one we include a description of the experiment, which area(s) of science it teaches kids about, how difficult it is (easy/medium/hard), how messy it is (low/medium/high), and the materials you need to do the project. Note that experiments labelled "hard" are definitely still doable; they just require more materials or time than most of these other science experiments for kids.

#1: Insect Hotels

• Teaches Kids About: Zoology
• Difficulty Level: Medium
• Messiness Level: Medium

Insect hotels can be as simple (just a few sticks wrapped in a bundle) or as elaborate as you'd like, and they're a great way for kids to get creative making the hotel and then get rewarded by seeing who has moved into the home they built. After creating a hotel with hiding places for bugs, place it outside (near a garden is often a good spot), wait a few days, then check it to see who has occupied the "rooms." You can also use a bug ID book or app to try and identify the visitors.

• Materials Needed
• Shadow box or other box with multiple compartments
• Hot glue gun with glue
• Sticks, bark, small rocks, dried leaves, bits of yarn/wool, etc.

#2: DIY Lava Lamp

• Teaches Kids About: Chemical reactions
• Difficulty Level: Easy

In this quick and fun science experiment, kids will mix water, oil, food coloring, and antacid tablets to create their own (temporary) lava lamp . Oil and water don't mix easily, and the antacid tablets will cause the oil to form little globules that are dyed by the food coloring. Just add the ingredients together and you'll end up with a homemade lava lamp!

• Vegetable oil
• Food coloring
• Antacid tablets

#3: Magnetic Slime

• Teaches Kids About: Magnets
• Messiness Level: High (The slime is black and will slightly dye your fingers when you play with it, but it washes off easily.)

A step up from silly putty and Play-Doh, magnetic slime is fun to play with but also teaches kids about magnets and how they attract and repel each other. Some of the ingredients you aren't likely to have around the house, but they can all be purchased online. After mixing the ingredients together, you can use the neodymium magnet (regular magnets won't be strong enough) to make the magnetic slime move without touching it!

• Liquid starch
• Adhesive glue
• Iron oxide powder
• Neodymium (rare earth) magnet

#4: Baking Soda Volcanoes

• Teaches Kids About: Chemical reactions, earth science
• Difficulty Level: Easy-medium
• Messiness Level: High

Baking soda volcanoes are one of the classic science projects for kids, and they're also one of the most popular. It's hard to top the excitement of a volcano erupting inside your home. This experiment can also be as simple or in-depth as you like. For the eruption, all you need is baking soda and vinegar (dishwashing detergent adds some extra power to the eruption), but you can make the "volcano" as elaborate and lifelike as you wish.

• Baking soda
• Dishwashing detergent
• Large mason jar or soda bottle
• Playdough or aluminum foil to make the "volcano"
• Additional items to place around the volcano (optional)
• Food coloring (optional)

#5: Tornado in a Jar

• Teaches Kids About: Weather
• Messiness Level: Low

This is one of the quick and easy and science experiments for kids to teach them about weather. It only takes about five minutes and a few materials to set up, but once you have it ready you and your kids can create your own miniature tornado whose vortex you can see and the strength of which you can change depending on how quickly you swirl the jar.

• Glitter (optional)

#6: Colored Celery Experiment

• Teaches Kids About: Plants

This celery science experiment is another classic science experiment that parents and teachers like because it's easy to do and gives kids a great visual understanding of how transpiration works and how plants get water and nutrients. Just place celery stalks in cups of colored water, wait at least a day, and you'll see the celery leaves take on the color of the water. This happens because celery stalks (like other plants) contain small capillaries that they use to transport water and nutrients throughout the plant.

• Celery stalks (can also use white flowers or pale-colored cabbage)

#7: Rain Cloud in a Jar

This experiment teaches kids about weather and lets them learn how clouds form by making their own rain cloud . This is definitely a science project that requires adult supervision since it uses boiling water as one of the ingredients, but once you pour the water into a glass jar, the experiment is fast and easy, and you'll be rewarded with a little cloud forming in the jar due to condensation.

• Glass jar with a lid
• Boiling water
• Aerosol hairspray

#8: Edible Rock Candy

• Teaches Kids About: Crystal formation

It takes about a week for the crystals of this rock candy experiment to form, but once they have you'll be able to eat the results! After creating a sugar solution, you'll fill jars with it and dangle strings in them that'll slowly become covered with the crystals. This experiment involves heating and pouring boiling water, so adult supervision is necessary, once that step is complete, even very young kids will be excited to watch crystals slowly form.

• Large saucepan
• Clothespins
• String or small skewers
• Candy flavoring (optional)

#9: Water Xylophone

• Teaches Kids About: Sound waves

With just some basic materials you can create your own musical instrument to teach kids about sound waves. In this water xylophone experiment , you'll fill glass jars with varying levels of water. Once they're all lined up, kids can hit the sides with wooden sticks and see how the itch differs depending on how much water is in the jar (more water=lower pitch, less water=higher pitch). This is because sound waves travel differently depending on how full the jars are with water.

• Wooden sticks/skewers

#10: Blood Model in a Jar

• Teaches Kids About: Human biology

This blood model experiment is a great way to get kids to visual what their blood looks like and how complicated it really is. Each ingredient represents a different component of blood (plasma, platelets, red blood cells, etc.), so you just add a certain amount of each to the jar, swirl it around a bit, and you have a model of what your blood looks like.

• Empty jar or bottle
• Red cinnamon candies
• Marshmallows or dry white lima beans
• White sprinkles

#11: Potato Battery

• Teaches Kids About: Electricity
• Difficulty Level: Hard

Did you know that a simple potato can produce enough energy to keep a light bulb lit for over a month? You can create a simple potato battery to show kids. There are kits that provide all the necessary materials and how to set it up, but if you don't purchase one of these it can be a bit trickier to gather everything you need and assemble it correctly. Once it's set though, you'll have your own farm grown battery!

• Fresh potato
• Galvanized nail
• Copper coin

#12: Homemade Pulley

• Teaches Kids About: Simple machines

This science activity requires some materials you may not already have, but once you've gotten them, the homemade pulley takes only a few minutes to set up, and you can leave the pulley up for your kids to play with all year round. This pulley is best set up outside, but can also be done indoors.

• Clothesline
• 2 clothesline pulleys

#13: Light Refraction

• Teaches Kids About: Light

This light refraction experiment takes only a few minutes to set up and uses basic materials, but it's a great way to show kids how light travels. You'll draw two arrows on a sticky note, stick it to the wall, then fill a clear water bottle with water. As you move the water bottle in front of the arrows, the arrows will appear to change the direction they're pointing. This is because of the refraction that occurs when light passes through materials like water and plastic.

• Sticky note
• Transparent water bottle

#14: Nature Journaling

• Teaches Kids About: Ecology, scientific observation

A nature journal is a great way to encourage kids to be creative and really pay attention to what's going on around them. All you need is a blank journal (you can buy one or make your own) along with something to write with. Then just go outside and encourage your children to write or draw what they notice. This could include descriptions of animals they see, tracings of leaves, a drawing of a beautiful flower, etc. Encourage your kids to ask questions about what they observe (Why do birds need to build nests? Why is this flower so brightly colored?) and explain to them that scientists collect research by doing exactly what they're doing now.

• Blank journal or notebook
• Pens/pencils/crayons/markers
• Tape or glue for adding items to the journal

#15: DIY Solar Oven

• Teaches Kids About: Solar energy

This homemade solar oven definitely requires some adult help to set up, but after it's ready you'll have your own mini oven that uses energy from the sun to make s'mores or melt cheese on pizza. While the food is cooking, you can explain to kids how the oven uses the sun's rays to heat the food.

• Aluminum foil
• Knife or box cutter
• Permanent marker
• Plastic cling wrap
• Black construction paper

#16: Animal Blubber Simulation

• Teaches Kids About: Ecology, zoology

If your kids are curious about how animals like polar bears and seals stay warm in polar climates, you can go beyond just explaining it to them; you can actually have them make some of their own blubber and test it out. After you've filled up a large bowl with ice water and let it sit for a few minutes to get really cold, have your kids dip a bare hand in and see how many seconds they can last before their hand gets too cold. Next, coat one of their fingers in shortening and repeat the experiment. Your child will notice that, with the shortening acting like a protective layer of blubber, they don't feel the cold water nearly as much.

• Bowl of ice water

#17: Static Electricity Butterfly

This experiment is a great way for young kids to learn about static electricity, and it's more fun and visual than just having them rub balloons against their heads. First you'll create a butterfly, using thick paper (such as cardstock) for the body and tissue paper for the wings. Then, blow up the balloon, have the kids rub it against their head for a few seconds, then move the balloon to just above the butterfly's wings. The wings will move towards the balloon due to static electricity, and it'll look like the butterfly is flying.

• Tissue paper
• Thick paper
• Glue stick/glue

#18: Edible Double Helix

• Teaches Kids About: Genetics

If your kids are learning about genetics, you can do this edible double helix craft to show them how DNA is formed, what its different parts are, and what it looks like. The licorice will form the sides or backbone of the DNA and each color of marshmallow will represent one of the four chemical bases. Kids will be able to see that only certain chemical bases pair with each other.

• 2 pieces of licorice
• 12 toothpicks
• Small marshmallows in 4 colors (9 of each color)
• 5 paperclips

#19: Leak-Proof Bag

• Teaches Kids About: Molecules, plastics

This is an easy experiment that'll appeal to kids of a variety of ages. Just take a zip-lock bag, fill it about ⅔ of the way with water, and close the top. Next, poke a few sharp objects (like bamboo skewers or sharp pencils) through one end and out the other. At this point you may want to dangle the bag above your child's head, but no need to worry about spills because the bag won't leak? Why not? It's because the plastic used to make zip-lock bags is made of polymers, or long chains of molecules that'll quickly join back together when they're forced apart.

• Zip-lock bags
• Objects with sharp ends (pencils, bamboo skewers, etc.)

#20: How Do Leaves Breathe?

• Teaches Kids About: Plant science

It takes a few hours to see the results of this leaf experiment , but it couldn't be easier to set up, and kids will love to see a leaf actually "breathing." Just get a large-ish leaf, place it in a bowl (glass works best so you can see everything) filled with water, place a small rock on the leaf to weigh it down, and leave it somewhere sunny. Come back in a few hours and you'll see little bubbles in the water created when the leaf releases the oxygen it created during photosynthesis.

• Large bowl (preferably glass)
• Magnifying glass (optional)

#21: Popsicle Stick Catapults

Kids will love shooting pom poms out of these homemade popsicle stick catapults . After assembling the catapults out of popsicle sticks, rubber bands, and plastic spoons, they're ready to launch pom poms or other lightweight objects. To teach kids about simple machines, you can ask them about how they think the catapults work, what they should do to make the pom poms go a farther/shorter distance, and how the catapult could be made more powerful.

• Popsicle sticks
• Rubber bands
• Plastic spoons
• Paint (optional)

#22: Elephant Toothpaste

You won't want to do this experiment near anything that's difficult to clean (outside may be best), but kids will love seeing this " elephant toothpaste " crazily overflowing the bottle and oozing everywhere. Pour the hydrogen peroxide, food coloring, and dishwashing soap into the bottle, and in the cup mix the yeast packet with some warm water for about 30 seconds. Then, add the yeast mixture to the bottle, stand back, and watch the solution become a massive foamy mixture that pours out of the bottle! The "toothpaste" is formed when the yeast removed the oxygen bubbles from the hydrogen peroxide which created foam. This is an exothermic reaction, and it creates heat as well as foam (you can have kids notice that the bottle became warm as the reaction occurred).

• Clean 16-oz soda bottle
• 6% solution of hydrogen peroxide
• 1 packet of dry yeast
• Dishwashing soap

#23: How Do Penguins Stay Dry?

Penguins, and many other birds, have special oil-producing glands that coat their feathers with a protective layer that causes water to slide right off them, keeping them warm and dry. You can demonstrate this to kids with this penguin craft by having them color a picture of a penguin with crayons, then spraying the picture with water. The wax from the crayons will have created a protective layer like the oil actual birds coat themselves with, and the paper won't absorb the water.

• Penguin image (included in link)
• Spray bottle
• Blue food coloring (optional)

#24: Rock Weathering Experiment

• Teaches Kids About: Geology

This mechanical weathering experiment teaches kids why and how rocks break down or erode. Take two pieces of clay, form them into balls, and wrap them in plastic wrap. Then, leave one out while placing the other in the freezer overnight. The next day, unwrap and compare them. You can repeat freezing the one piece of clay every night for several days to see how much more cracked and weathered it gets than the piece of clay that wasn't frozen. It may even begin to crumble. This weathering also happens to rocks when they are subjected to extreme temperatures, and it's one of the causes of erosion.

• Plastic wrap

#25: Saltwater Density

• Teaches Kids About: Water density

For this saltwater density experiment , you'll fill four clear glasses with water, then add salt to one glass, sugar to one glass, and baking soda to one glass, leaving one glass with just water. Then, float small plastic pieces or grapes in each of the glasses and observe whether they float or not. Saltwater is denser than freshwater, which means some objects may float in saltwater that would sink in freshwater. You can use this experiment to teach kids about the ocean and other bodies of saltwater, such as the Dead Sea, which is so salty people can easily float on top of it.

• Four clear glasses
• Lightweight plastic objects or small grapes

#26: Starburst Rock Cycle

With just a package of Starbursts and a few other materials, you can create models of each of the three rock types: igneous, sedimentary, and metamorphic. Sedimentary "rocks" will be created by pressing thin layers of Starbursts together, metamorphic by heating and pressing Starbursts, and igneous by applying high levels of heat to the Starbursts. Kids will learn how different types of rocks are forms and how the three rock types look different from each other.

• Toaster oven

#27: Inertia Wagon Experiment

• Teaches Kids About: Inertia

This simple experiment teaches kids about inertia (as well as the importance of seatbelts!). Take a small wagon, fill it with a tall stack of books, then have one of your children pull it around then stop abruptly. They won't be able to suddenly stop the wagon without the stack of books falling. You can have the kids predict which direction they think the books will fall and explain that this happens because of inertia, or Newton's first law.

• Stack of books

#28: Dinosaur Tracks

• Teaches Kids About: Paleontology

How are some dinosaur tracks still visible millions of years later? By mixing together several ingredients, you'll get a claylike mixture you can press your hands/feet or dinosaur models into to make dinosaur track imprints . The mixture will harden and the imprints will remain, showing kids how dinosaur (and early human) tracks can stay in rock for such a long period of time.

• Used coffee grounds
• Wooden spoon
• Rolling pin

#29: Sidewalk Constellations

• Teaches Kids About: Astronomy

If you do this sidewalk constellation craft , you'll be able to see the Big Dipper and Orion's Belt in the daylight. On the sidewalk, have kids draw the lines of constellations (using constellation diagrams for guidance) and place stones where the stars are. You can then look at astronomy charts to see where the constellations they drew will be in the sky.

• Sidewalk chalk
• Small stones
• Diagrams of constellations

#30: Lung Model

By building a lung model , you can teach kids about respiration and how their lungs work. After cutting off the bottom of a plastic bottle, you'll stretch a balloon around the opened end and insert another balloon through the mouth of the bottle. You'll then push a straw through the neck of the bottle and secure it with a rubber band and play dough. By blowing into the straw, the balloons will inflate then deflate, similar to how our lungs work.

• Plastic bottle
• Rubber band

#31: Homemade Dinosaur Bones

By mixing just flour, salt, and water, you'll create a basic salt dough that'll harden when baked. You can use this dough to make homemade dinosaur bones and teach kids about paleontology. You can use books or diagrams to learn how different dinosaur bones were shaped, and you can even bury the bones in a sandpit or something similar and then excavate them the way real paleontologists do.

• Images of dinosaur bones

#32: Clay and Toothpick Molecules

There are many variations on homemade molecule science crafts . This one uses clay and toothpicks, although gumdrops or even small pieces of fruit like grapes can be used in place of clay. Roll the clay into balls and use molecule diagrams to attach the clay to toothpicks in the shape of the molecules. Kids can make numerous types of molecules and learn how atoms bond together to form molecules.

• Clay or gumdrops (in four colors)
• Diagrams of molecules

#33: Articulated Hand Model

By creating an articulated hand model , you can teach kids about bones, joints, and how our hands are able to move in many ways and accomplish so many different tasks. After creating a hand out of thin foam, kids will cut straws to represent the different bones in the hand and glue them to the fingers of the hand models. You'll then thread yarn (which represents tendons) through the straws, stabilize the model with a chopstick or other small stick, and end up with a hand model that moves and bends the way actual human hands do.

• Straws (paper work best)
• Twine or yarn

#34: Solar Energy Experiment

• Teaches Kids About: Solar energy, light rays

This solar energy science experiment will teach kids about solar energy and how different colors absorb different amounts of energy. In a sunny spot outside, place six colored pieces of paper next to each other, and place an ice cube in the middle of each paper. Then, observe how quickly each of the ice cubes melt. The ice cube on the black piece of paper will melt fastest since black absorbs the most light (all the light ray colors), while the ice cube on the white paper will melt slowest since white absorbs the least light (it instead reflects light). You can then explain why certain colors look the way they do. (Colors besides black and white absorb all light except for the one ray color they reflect; this is the color they appear to us.)

• 6 squares of differently colored paper/cardstock (must include black paper and white paper)

#35: How to Make Lightning

• Teaches Kids About: Electricity, weather

You don't need a storm to see lightning; you can actually create your own lightning at home . For younger kids this experiment requires adult help and supervision. You'll stick a thumbtack through the bottom of an aluminum tray, then stick the pencil eraser to the pushpin. You'll then rub the piece of wool over the aluminum tray, and then set the tray on the Styrofoam, where it'll create a small spark/tiny bolt of lightning!

• Pencil with eraser
• Aluminum tray or pie tin
• Styrofoam tray

#36: Tie-Dyed Milk

• Teaches Kids About: Surface tension

For this magic milk experiment , partly fill a shallow dish with milk, then add a one drop of each food coloring color to different parts of the milk. The food coloring will mostly stay where you placed it. Next, carefully add one drop of dish soap to the middle of the milk. It'll cause the food coloring to stream through the milk and away from the dish soap. This is because the dish soap breaks up the surface tension of the milk by dissolving the milk's fat molecules.

• Shallow dish
• Milk (high-fat works best)

#37: How Do Stalactites Form?

Have you ever gone into a cave and seen huge stalactites hanging from the top of the cave? Stalactites are formed by dripping water. The water is filled with particles which slowly accumulate and harden over the years, forming stalactites. You can recreate that process with this stalactite experiment . By mixing a baking soda solution, dipping a piece of wool yarn in the jar and running it to another jar, you'll be able to observe baking soda particles forming and hardening along the yarn, similar to how stalactites grow.

• Safety pins
• 2 glass jars

Summary: Cool Science Experiments for Kids

Any one of these simple science experiments for kids can get children learning and excited about science. You can choose a science experiment based on your child's specific interest or what they're currently learning about, or you can do an experiment on an entirely new topic to expand their learning and teach them about a new area of science. From easy science experiments for kids to the more challenging ones, these will all help kids have fun and learn more about science.

What's Next?

Are you also interested in pipe cleaner crafts for kids? We have a guide to some of the best pipe cleaner crafts to try!

Looking for multiple different slime recipes? We tell you how to make slimes without borax and without glue as well as how to craft the ultimate super slime .

Want to learn more about clouds? Learn how to identify every cloud in the sky with our guide to the 10 types of clouds .

Want to know the fastest and easiest ways to convert between Fahrenheit and Celsius? We've got you covered! Check out our guide to the best ways to convert Celsius to Fahrenheit (or vice versa) .

Christine graduated from Michigan State University with degrees in Environmental Biology and Geography and received her Master's from Duke University. In high school she scored in the 99th percentile on the SAT and was named a National Merit Finalist. She has taught English and biology in several countries.

Ask a Question Below

Have any questions about this article or other topics? Ask below and we'll reply!

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Holly R. "I am absolutely overjoyed and cannot thank you enough for helping me!”

Digging up 142-year-old seeds in the latest installment in the world's oldest experiment

These botanical time capsules were buried in 1879 to see how long seeds could survive.

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One night in April a small group of scientists met at three in the morning with shovels and a treasure map to a top secret location.  They were on a hunt for a scientific experiment that has spanned many generations. 

Prof. Frank Telewski , the director of the director of the W. J. Beal Botanical Garden and professor of plant biology at Michigan State University, is the current guardian of what is thought to be the oldest scientific experiment in the world. 

He told Quirks & Quarks' host Bob McDonald how this year's dig was the second time he took part in an excavation since he took guardianship the experiment over in the late 1990s.

The experiment began in 1879 when botanist  W.J. Beal buried 20 jars containing 21 different seed species to investigate how long seeds can remain viable. 

He devised this experiment to extend far into the future, beyond his death.

Beal likely couldn't imagine the kind of studies scientists can do today on his seeds, since he lived in a time when the theory of evolution was new, and there was no conception of things like DNA and molecular biology. With advances in understanding and techniques, the questions scientists can ask today have significantly expanded. 

Prof. Telewski says can now compare these older seeds to modern day versions in order to study how their genome may have evolved. 

The researchers will also be able to look into why 18 of the 20 seed species haven't germinated during the past couple of excavations, and investigate if they've retained any metabolic activity, even if they lacked the ability to germinate. 

He says since he'll be 85 years old when it's time to dig up the next bottle, he's tapped four other scientists to take it over.  The new team includes an evolutionary biologist, a population restoration ecologist, a physiological plant ecologist and a seed scientist.

Produced and written by Sonya Buyting

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To date, no one has ever witnessed a drop fall. There is no visual documentation of the dramatic event. The closet anyone ever came was in April 1979 when John Mainstone, the professor who now maintains the experiment, came to work on a Sunday afternoon. He noted that a drop was just about to touch down, but did not have time to stay. On returning the following morning, Mainstone saw to his chagrin that the drop had fallen. Even technology has been foiled in the attempt to capture evidence of the pitch’s clandestine maneuvers: A video camera placed to monitor the experiment failed at the very moment the eighth drop fell.

What is most interesting, and mysterious, about the apparatus is the internal composition of the 'dry pile' batteries.

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May 15, 2024

Don Pettit, NASA’s Oldest Active Astronaut, Is Going Back to Space

Veteran spacefarer Don Pettit is set to launch this summer on a half-year mission to the International Space Station to perform novel science experiments, snap unique orbital photos, and much more

By Rich Stone

Don Pettit in his Sokol launch and entry suit during crew qualification exams at the Gagarin Cosmonaut Training Center at Star City in Russia on February 28, 2024.

GCTC/Roscosmos/NASA

When chemical engineer Don Pettit, age 69, blasts off for the International Space Station (ISS) this summer, he will become the second-oldest NASA astronaut in space, after the legendary John Glenn, who spent nine days onboard the space shuttle Discovery at the age of 77 in 1998. Pettit will spend a full six months in orbit during a time of high tension between the U.S. and Russia. Space exploration is one of the few areas in which the two countries still cooperate , and Pettit, a veteran of three prior missions, is now training for ISS Expedition 72 in an area sometimes referred to as Star City on the outskirts of Moscow.

While some astronauts spend their scarce off-duty hours on the ISS with activities such as reading books, chatting with family back on Earth or surfing the Internet, Pettit carves out time for what he calls “science of opportunity.” During a mission in 2003, for instance, his observations of how grains of sugar, salt and coffee aggregate in air-filled plastic bags allowed him and his fellow scientist and astronaut Stanley Love to serendipitously shed light on an enigmatic early step of planetary formation. Pettit plans to venture into new science-of-opportunity territory on his latest mission, too.

An inveterate tinkerer who spent 12 years at Los Alamos National Laboratory before joining the astronaut program, Pettit has devised, among other things, a cup that uses surface tension to allow astronauts to sip coffee in microgravity as if on Earth—for which he and Mark Weislogel of Portland State University were granted the first patent for an invention made in space. And he is an ardent science communicator, having created two video series, Saturday Morning Science and Science off the Sphere, that were filmed on the ISS.

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Pettit and two Russian cosmonauts are slated to lift off on a Soyuz spacecraft from Baikonur Cosmodrome in Kazakhstan on September 11.

[ An edited transcript of the interview follows. ]

You caught the space bug as a kid watching John Glenn on the Mercury flights in the early 1960s, and then you applied to the astronaut program right out of grad school. NASA turned you down the first three times. Why did you keep at it?

PETTIT: For the same reason you keep at any kind of activity or enterprise that takes a while to master: you can’t expect to do something the first time and be an expert at it. NASA invites about the top 120 in for interviews. And then, the fourth time, I got a phone call that asked if I was still interested in being an astronaut.

You were onboard the ISS when the space shuttle Columbia broke up during reentry into Earth’s atmosphere, killing all seven crew members. How did that affect you mentally?

Three of my classmates were on that mission, and the other four crewmates were really close to my wife and me. At first there was shock and disbelief. And we had to compartmentalize this loss and get back to work because we’re riding on a vehicle that needs constant attention, and you can’t go off on an emotional bender.

In normal times, what is the daily rhythm on the station?

We are scheduled for 12 hours a day. There’s usually another hour, sometimes two hours, of catch-up work because you can’t get everything done. So it’s not uncommon for astronauts to average about 13 hours a day, five and a half days a week. We’re lucky if we get one day a week off. You can’t work a gazillion hours every day for six months without having some off-duty time, and what crews choose to do is up to the individual. What recharges my batteries is to take advantage of the orbital environment and make observations that you cannot do on Earth.

One important insight you made during your off-duty hours was explaining an early step of planetary formation.

How millimeter-sized particles agglomerate into fist-sized objects in [microgravity]—yes.

And from there the sizes continue to grow—until we have full-fledged planets! Has your work on this stood the test of time?

Yeah, it has. Stan Love and I had a lot of fun with it. I’ve done work on this planetary formation concept now on my past three missions. And I’m planning to make some more observations on the upcoming mission.

What is your all-time favorite science-of-opportunity insight?

Oh, gosh! The suite of photography that I’ve been able to do—capturing moments on orbit with compositions and exposures that I really think tell a story.

For the upcoming mission, you’re bringing an improved version of your so-called barn-door tracker for space photography. Can you break down what that is and what it can do?

The original barn-door tracker [that I made] was made from a bunch of junk I found on the station, and its purpose was to counteract orbital motion and take longish exposures of Earth. It’s really a simple piece of equipment that amateur astronomers use: two pieces of wood with a piano hinge and a bolt between the two. You mount the hinge line so it points towards the North Star. Then you put a camera on one of the platforms. You know what the thread pitch is, so you can calculate that turning the bolt a quarter of a turn every five seconds will move the board at the sidereal rate of Earth’s motion. The pictures I took using this barn-door tracker were really the first time we got high-resolution images of cities at night.

What improvements have you made to the tracker?

What I’m flying next is a wind-up device based on a kitchen timer. It will reduce the motion so that the shaft turns one revolution every 90 minutes—that’s the station’s orbital period. And the station will pitch down at a rate that makes one revolution about its center of gravity. That way, the same side of the station points towards Earth as it goes around. This pitch rate is about four degrees a minute. I made a little wind-up timer that will move a camera mount at the pitch rate, so that way I can do time exposures primarily intended for pictures of the stars. Right now, because of the pitch rate, you really can’t make an exposure much longer than three seconds, or [else] the stars [will be] blurry. A three-second exposure just doesn’t bring out the dazzle of what you can see with your eye.

What can you see up there that astrophotography images fail to capture?

One thing is that when you look out the station window when your eyes are dark-adapted, there are colors of stars that you just can’t discern from Earth.

A composite of a series of images captured by NASA astronaut Don Pettit using a mounted camera on the Earth-orbiting International Space Station, approximately 240 miles above Earth.

Don Pettit/NASA

Astronauts traveling to the ISS take along a preferred food package and a personal medical kit. How have you used this privilege to bring materials for personal science experiments?

We have these drink bags for coffee or whatever is your favorite beverage. I had the food people pack a couple of drink bags with unflavored gelatin. One of the things I would do is mix a little bit of instant mashed potato in with the gelatin solution and let it harden into a starchy, translucent sphere. From our first aid kit, I put a little drop of iodine on one side of this sphere, and you get to watch the diffusion of the iodine through the gelatin. It looked like it was developing Liesegang structures, where you have concentric logarithmic rings developed through a precipitation process.

Can you give a taste of other items you’re bringing on the upcoming mission?

So there’s sodium chloride on the station. It’s a saturated solution because a saltshaker wouldn’t work in space. With a colleague in Switzerland, [independent researcher] Pietro Fontana, we have published three peer-reviewed papers on the observations we’ve made from crystallizing the galley salt solution. The most recent paper was in [the Springer Nature journal] npj Microgravity . For the next mission, I’m bringing potassium chloride. We have a high-sodium diet on the space station. You could get upwards of 10 to 12 grams of salt a day. So I’m flying this salt substitute in my personal food, and I will also use it for crystallization experiments.

How does your scientific moonlighting mesh with the experiments NASA has you do as part of your job?

The programmatic experiments are all designed and conceived by people who have never been in space. They’re good experiments. But up there we come up with questions or observations that are completely different than what anybody on Earth could conceive of.

Has a science-of-opportunity insight led to a programmatic experiment?

Maybe two or three. The qualitative observations that Stan Love and I made showed there is something really interesting happening in particle aggregation in [microgravity]. A university team proposed and built hardware to continue, in a quantifiable way, this work.

Which Expedition 72 programmatic experiment excites you?

Some of my favorite involve human physiology in an environment we’re not intrinsically meant to be in. Using us as orbital guinea pigs is going to be one of the greatest legacies that come from the space station. Then there are physical science experiments, many dealing with combustion. When you have combustion in a weightless environment, you don’t get gravity-induced convection. For example, a normal candle will not burn because it won’t develop convection. It’ll consume the oxygen around it at a rate that’s faster than diffusion can provide new oxygen. The candle will burn for a handful of seconds and then snuff out.

What does that mean for fire risk on the station?

We know enough about combustion in a weightless environment to know what kind of materials you can use and what kind of materials you can’t use. For example, we used to have all kinds of Ziploc bags on the station. But some smart engineers on the ground figured out that polyethylene is way too flammable to leave out in the open cabin, and so they switched all our bags to Kynar.

Is a fire on the ISS your greatest fear?

That and [depressurization]. You get a little tiny leak, and maybe you have 24 hours to figure out how to plug it. Small leaks are not that big of a deal. The ugly scenario is having a module come unzipped. Think of a soda can that just goes bloop and explodes and just turns into a flat, crinkled piece of sheet metal. You’ve got a handful of seconds to figure out what to do.

Does that scenario ever creep into your thoughts on the ISS?

It’s always there in the back of your mind. We do a lot of training on the ground for both [depressurization] and fire. Tomorrow I’ll be in the simulator, and for that simulation we know ahead of time there’s gonna be a fire in the Russian segment of the space station. We’ll have to get in our Soyuz vehicle and do an emergency descent.

What’s the vibe like in Star City these days?

Some of the instructors here are the same I had the first time I came to Star City in 1999. We know each other’s spouses. We know each other’s children. Star City is a small community, and its sole purpose is to train cosmonauts and astronauts for space flight. So when I come here, there’s a certain joy from being with my Star City family. My sons were two years old when we first brought them to Star City, and one learned to walk here.

Are your twin sons interested in following in your footsteps?

They both graduated from Texas A&M [University]. One works at [NASA’s] Johnson Space Center as an engineer, and one worked for Blue Origin at Kennedy Space Center.

You’re the oldest active astronaut. How do you think your body’s going to hold up on the upcoming mission?

John Glenn went through full shuttle training at age 77. He had to fly in a T-38 . He had to train for egress in the water from the shuttle and inflate his life preserver and get in the life raft. He went through it with flying colors. I do the Russian training. This last winter we did survival training, and if you think about how cold it can be in Russia, you can imagine that that was an ordeal. I did that with my Soyuz crew, so I don’t see any issue with my age on this upcoming mission.

What do you miss in Star City? Any hobbies?

Well, I make homemade beer. I like really hoppy beer. I hate to admit that during almost two years of training for this mission, I haven’t had time to brew a batch.

What advice would you give a fellow scientist who wants to become an astronaut?

Excel in whatever field you’re in. Do something that sings to your heart and do it well. Then keep applying to NASA when there are selections, and don’t take “no” for an answer!

At the Smithsonian | June 27, 2024

What a 100-Year-Old Lie Detector and 150-Year-Old Arsenic Tests Tell Us About Forensic Science Today

An exhibition at the National Museum of American History examines how humans influence and judge investigation techniques

Arsenic tests for the Lydia Sherman trial of 1872

Brian Handwerk

Science Correspondent

Crime dramas like “CSI” are wildly popular—but the real stories of forensic science in the courtroom put our own beliefs on trial.

Forensic techniques and analyses, from hair to handwriting to DNA, have brought cutting-edge science into the American courtroom for over 150 years. But the history of forensic science isn’t just about technologies that can use traces of evidence like a fingerprint or a drop of blood to link a criminal to a crime.

The story of forensic science is also about the people who designed and created methods to uncover such scant evidence and turn it into convictions. And when evidence is in hand, the different ways that humans examine and judge forensic data are influenced both by their personal thoughts and by how other forensic cases have played out in the past.

These themes are explored in a new exhibition at the Smithsonian’s National Museum of American History, “ Forensic Science on Trial .” Opening Friday and running through next summer, the exhibition gathers artifacts from the museum’s extensive science collections, as well as special loans.

“You really get to see what the human hand is, in both making and understanding forensic science,” says exhibition curator Kristen Frederick-Frost.

Historically, many sexual assault cases have been a matter of one person’s word against another, with convictions hard to come by. In the 1970s, women’s rights advocate Martha “Marty” Goddard set out to change that. She pioneered a standardized system to increase the chances that perpetrators of rape and sexual assault would be caught and prosecuted. Goddard interviewed law enforcement, lawyers, hospital workers and others to learn how best to collect evidence of sexual assaults. On display is the kit she designed, the Vitullo Evidence Collection Kit for Sexual Assault Examination , which contains tools necessary to collect that critical evidence, such as a stylus for scraping under fingernails, combs, glass slides, swabs, evidence bags and instructions on how to best preserve the evidence for use in court.

“The kit was created when trace evidence was core in investigation and prosecution, before DNA was used,” explains Katherine Ott, a curator of medicine and science at the museum, alongside Frederick-Frost. “It was also a time when sexual assault was misunderstood, seldom reported and generally not taken seriously. Detectives, attorneys, and the nurses and doctors who dealt with it were not really talking with each other.”

DNA evidence is often key to such cases today, but it’s not infallible; DNA degrades and isn’t always present. “Other kinds of evidence, like fingerprints and shoe prints and the materials collected in Marty’s early version of the kit, are often key to solving the ‘he said, she said,’ problem,” Ott says.

While the sexual assault kit was an individual effort, the Central Records System Filing Cabinet and Index Cards, created around 1950 and on loan from the FBI, shows a large-scale initiative from the federal government to make a different kind of crime-fighting system. This widespread attempt to collect and organize fingerprint and other data in a central repository was used to try to match criminals to the trace evidence they left at crime sites.

“We pair these objects together because one of them is a grassroots effort to organize, and provide a solution for identification, while the other is a top-down effort,” says Frederick-Frost. “But in both cases, as always, you have to have buy-in to get people to think about what would be convincing evidence at any point in time.”

Though forensic evidence might seem like a matter of scientific facts rather than opinion, the way data is gathered, and the way it’s ultimately judged, has always been influenced by people’s personal beliefs. A 1921 polygraph on display was one of the first to be used to test for deception, created by a police officer and physiologist named John A. Larson. Larson’s device was designed to detect physiological responses to questioning, such as heart and breathing rate and blood pressure, that would indicate a suspect was lying.

But, because people react to interrogations differently, no one pattern of responses can actually indicate when someone is lying. Some people may be nervous even when being truthful, while practiced liars may not be particularly anxious while doing so. “With that polygraph, it kind of works best if you believe it works” Frederick-Frost says. “That’s fascinating to me, that your beliefs can impact what kind of data is produced.”

Human beliefs also took center stage in The People of the State of California v. Orenthal James Simpson (1994-1995). Investigators used DNA autoradiograph analysis to match blood from the crime scene to the defendant, O.J. Simpson, as well as bloodstains found on a sock in Simpson’s home to the murdered Nicole Brown Simpson. In the Simpson case, human judgments weren’t focused so much on how data was analyzed. Instead, they centered on confidence in the people and processes that provided that data to the lab. “Whether people believed the LAPD did or did not tamper with the evidence impacted how that data was received,” says Frederick-Frost.

While the history of forensics is one of advancing science, in which the latest and greatest technologies take center stage, the past often shapes how data is collected and presented for trial. During the 1860s and ’70s, all three of Lydia Sherman’s husbands and eight children—six of her own—died under suspicious circumstances. After an autopsy revealed that her last husband had been poisoned, Sherman was convicted of murder and sentenced to life in prison, largely on the strength of chemical analysis performed by George Frederick Barker.

Curiously, Barker subjected the organs of Sherman’s victims, some exhumed from the grave, to many different types of arsenic tests when one would have sufficed to identify the poison. Why? During the previous year a wealthy Baltimore widow named Elizabeth Wharton was accused of murdering General W. Scott Ketchum by poison but found not guilty. “She was able to bring in top medical experts to attack the evidence, and she did so successfully, and one of their lines of attack was that the antimony tests used for that trial were outdated,” Frederick-Frost notes. “Barker threw everything and the kitchen sink at the Sherman evidence,” she adds, “and he admitted later that he did that because of what had happened the year before.” The tests that helped convict Sherman are a focal point of the exhibition.

Few objects of forensic evidence are steeped in as much history as the pistol confiscated from Nicola Sacco, and a bullet that was recovered from the body of a victim who was allegedly killed by Sacco and Bartolomeo Vanzetti during an armed robbery in Braintree, Massachusetts, in 1920. The pair’s status as Italian immigrants and anarchists played a major role in their trial and subsequent appeals, which eventually ended with their execution and with widespread doubts concerning their guilt or innocence that linger to the present day.

“That particular bullet and that particular gun have been analyzed over and over and over again since 1921, using different techniques, with everyone thinking that the latest and greatest technique would be able to tell us definitely whether or not they did it,” Frederick-Frost says. Not one has been successful, and this contentious criminal case continues to inspire new ideas and theories.

“That case didn’t just occupy the imagination of the whole country, it was worldwide,” Frederick-Frost says.

Though few other cases have ever attained Sacco and Vanzetti stature, the exhibition notes other examples of the unique, enduring relationship between the media and forensic science. This includes the handwriting samples used to help convict Bruno Richard Hauptmann of kidnapping and killing the son of Charles Lindbergh, in a case that some dubbed a “crime of the century,” and a blood spatter head used in Showtime’s “Dexter.”

“Through the history of modern forensic science, dating from the 19th century, there has been kind of a back-and-forth trade-off between fiction and real life,” says Simon Cole , a criminologist at the University of California, Irvine, who specializes in the history and sociology of forensic science. “They are always kind of influencing each other.”

But unlike in fictional cases, which are often closed by forensic evidence without a shadow of a doubt, Cole warns that no matter how much technology advances, there is always a need for caution in real investigations. New techniques may be hailed as infallible, but time will show they have limitations. “To me the lesson is always, the next time someone tells you something is infallible, exercise some skepticism,” he says.

For Frederick-Frost, such limits on even the best techniques simply highlight the primacy of a human role in forensic science, from the development of forensic systems to the ultimate judgment of their value.

“In the end you always have to say either the data is good enough, or it isn’t good enough,” she says. “And that is a human judgment.”

“Forensic Science on Trial” is on view from June 28, 2024, through June 2025 at the National Museum of American History.

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Brian Handwerk | READ MORE

Brian Handwerk is a science correspondent based in Amherst, New Hampshire.

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June 27, 2024

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Most pristine trilobite fossils ever found shake up scientific understanding of the long extinct group

by University of Bristol

Researchers have described some of the best-preserved three-dimensional trilobite fossils ever discovered. The fossils, which are more than 500 million years old, were collected in the High Atlas of Morocco and are being referred to by scientists as "Pompeii" trilobites due to their remarkable preservation in ash.

The paper, "Rapid volcanic ash entombment reveals the 3D anatomy of Cambrian trilobites," was published in the journal, Science .

The trilobites, from the Cambrian period, have been the subject of research by an international team of scientists, led by Prof Abderrazak El Albani, a geologist based at University of Poitiers and originally from Morocco. The team included Dr. Greg Edgecombe, a paleontologist at the Natural History Museum.

Dr. Greg Edgecombe said, "I've been studying trilobites for nearly 40 years, but I never felt like I was looking at live animals as much as I have with these ones. I've seen a lot of soft anatomy of trilobites, but it's the 3D preservation here that is truly astounding.

"An unexpected outcome of our work is discovering that volcanic ash in shallow marine settings could be a bonanza for exceptional fossil preservation."

Due to their hard, calcified exoskeleton often being well-preserved in the fossil record , trilobites are some of the best studied fossil marine animals. Over 20,000 species have been described by paleontologists over the past two centuries.

However, until now, comprehensive scientific understanding of this phenomenally diverse group has been limited by the relative scarcity of soft tissue preservation. Owing to the fact the Moroccan trilobites were encased in hot ash in sea water, their bodies fossilized very quickly as the ash transformed to rock—meeting a similar end to the inhabitants of Pompeii following the eruption of Mount Vesuvius.

The ash molds preserved each segment of their bodies, their legs and even the hair-like structures that ran along the appendages. The trilobites' digestive tract was also preserved after it filled with ash. Even small "lamp shells" attached to the trilobites' exoskeleton remained attached by fleshy stalks as they were in life.

Lead author, Prof Abderrazak El Albani, says, "As a scientist who has worked on fossils from different ages and locations, discovering fossils in such a remarkable state of preservation within a volcanic setting was a profoundly exhilarating experience for me.

"I think pyroclastic deposits should become new targets for study, given their exceptional potential for trapping and preserving biological remains, including delicate soft tissues.

"These findings are anticipated to lead to significant discoveries about the evolution of life on our planet Earth."

Using CT scanning and computer modeling of virtual X-ray slices, the researchers discovered that appendages found at the edge of the mouth had curved spoon-like bases but were so small they had gone undetected in less perfectly preserved fossils.

In fact, it had previously been thought that trilobites had three pairs of head appendages behind their long antennae but both Moroccan species in this study showed that there were four pairs.

A fleshy lobe covering the mouth, called a labrum, was documented for the first time in trilobites.

Co-author Harry Berks, from the University of Bristol, added, "The results revealed in exquisite detail a clustering of specialized leg pairs around the mouth, giving us a clearer picture of how trilobites fed. The head and body appendages were found to have an inward-facing battery of dense spines, like those of today's horseshoe crabs."

Journal information: Science

Provided by University of Bristol

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Astronomers have discovered the oldest and farthest supernova ever

The new discoveries, based on data from the James Webb Space Telescope, provide a glimpse of the early universe.

Observing a distant supernova is like looking back in time. The explosions offer astronomers a peek at what our universe was like billions of years in the past. Now astronomers have discovered 10 times more distant supernovae than anyone had seen before, including the oldest   and farthest supernova ever observed.

The discoveries came from data captured by NASA’s James Webb Space Telescope. Announced at the American Astronomical Society meeting in Madison, Wisconsin, earlier this month, astronomers analyzed Webb images and found about 80 supernovae in just one tiny patch of the sky. Many of the supernovae are further out than those previously known, representing a time when the universe was a youthful two billion years old.

The telescope is an ideal tool to search for such distant points of light in the universe. “[Webb] is a big telescope, nearly 10 times bigger than the Hubble Space Telescope in terms of light collecting area,” says Justin Pierel, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland, who worked on the new research. In addition to seeing a larger part of the sky, Webb is also more sensitive to the longer light wavelengths that indicate the presence of supernovae. “We knew these faint and far-off supernovae existed, but we were unable to see them prior,” Pierel says.  

( Learn about what happens when stars explode .)

The increased size and sensitivity of Webb allowed it to pick up what other telescopes have not been able to detect. “I think it is great to see that these supernovae can be recovered in the Webb data,” says Harvard University astronomer Edo Berger , who was not involved in the new research. The new data add to a growing record of exploded stars from different times in the universe’s history. While finding around 80 distant supernovae in a small patch of sky is significant, Berger notes, “these are still a small fraction of all supernovae being discovered by wide-field and shallower surveys, in excess of 10,000 supernovae per year.” But many of those supernovae are younger and closer to Earth. The significance of the Webb finds is in uncovering supernovae that are further out, representing a much earlier time in the universe’s history.

Peek into the past

In order to find more distant and therefore more ancient supernovae, researchers compared multiple images taken by Webb over the span of a year. The astronomers looked for light sources that appeared or disappeared in the images, or what experts refer to as transients. Not only did the researchers detect dozens of supernovae, but the nature of the light indicated that the supernovae exploded billions of years before our present moment.

Webb can detect supernovae thanks to a phenomenon known as cosmological redshift . As light travels through space, its wavelength is pulled like taffy. Light’s wavelengths become longer, falling into the infrared part of the spectrum—invisible to the naked eye, but visible to a telescope with the right equipment.

Different redshift characteristics correspond to different times in the universe’s history, and the present day is redshift zero. The higher the redshift, the older the supernova is. So while a redshift of 2 indicates a supernova from when the universe was about 3.3 billion years old, one of the newly-found supernovae has a redshift of 3.6 and formed when the universe was about 1.8 billion years old. That puts the ancient supernova at 12 billion years old, the oldest ever detected. The data offers a way to get a sense of what the universe was like long before Earth even existed. “The universe is nearly 14 billion years old, but these supernovae are from a time when the universe was just a couple billion years old, the equivalent of being a teenager for humans,” Pierel says.

Early universe insights

The new data will provide a launching point for researchers to investigate the nature of the early universe, how stars formed, and what happened when they exploded. In fact, Pierel notes, distant stars are often too faint to see even with the most powerful telescopes. Exploding stars are brighter and easier to detect.  

Specific types of supernovae in the sample may provide some new insights, as well. Webb detected at least one supernova that astronomers categorize as Type 1a , which means it’s particularly bright and could be used to measure long distances in space. “Finding these higher redshift supernovae is important for making cosmological measurements,” Berger says, as well as studying phenomena like dark energy.

( Learn about the mysteries surrounding Type 1a supernovae .)

Exploding stars are an essential part to the universe we live in. “If stars did not explode, life as we know it would not be possible,” Pierel says. The elements that are so essential to life on Earth were flung out of such explosions when the universe was much younger, forming the basis for our planet and life upon it. Distant as they may be from us, the supernovae are an essential part of our own story.

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Scientists discovered the oldest termite mounds on Earth — and they're 34,000 years old

The world's oldest termite mounds have been collecting carbon from the atmosphere for thousands of years.

Scientists in South Africa have discovered the world's oldest known active termite mounds, which have been occupied for tens of thousands of years. 

"Recent radiocarbon dating has revealed that these mounds are far older than any previously known, with some dating as far back as 34,000 years — that's older than the iconic cave paintings in Europe and even older than the Last Glacial Maximum, when vast ice sheets covered much of the northern hemisphere," Michele Francis , the lead author of the study published in May in the journal Science of the Total Environment , said in a statement .

The massive insect dwelling was discovered along the banks of the Buffels River in Namaqualand, a region along the west coast of South Africa where around 20% of the landscape is covered by such mounds. The residents of these ancient "little hills," called "heuweltjies" in Afrikaans, are southern harvester termites ( Microhodotermes viator ). As they go about their daily forage, these termites collect pieces of wood that they add to their nests. Over the years, these organic materials pile up and form a carbon-rich reservoir.

An earlier study by Francis, who is an environmental scientist at Stellenbosch University, and her team estimated that each termite mound could harbor about 15 tons (14 metric tons) of carbon. 

So Francis was interested in understanding how groundwater, the atmosphere and the soil in these little hills interacted to lock away so much carbon. To do so, the team conducted a chemical analysis of the termite hills and characterized the chemical processes that transfer atmospheric carbon into the tiny hills. They found that as termites harvest organic materials and bring them into their nests, they disturb the soil and make it easier for water to infiltrate. Microbes in the soil then convert these caches of carbon into calcium carbonate , past research found. 

During heavy rains, calcium carbonate in the mounds then chemically reacts with carbonic acid, which forms when atmospheric carbon dioxide dissolves in rainwater. The chemical cascade increases the sequestration of atmospheric carbon dioxide .

This process locks new carbon about 3 feet (1 meter) below the surface in long-term storage, Francis wrote in The Conversation .

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— These Ancient Termite Mounds Are As Old As the Egyptian Pyramids. And They're Visible from Space.

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"By studying these mounds, scientists can gain a better understanding of how to combat climate change, utilizing nature's own processes for carbon sequestration," she said in the statement. 

The scientists estimated the age of these termite mounds through radiocarbon dating. The previously discovered oldest termite mounds found in Brazil were 4,000 years old. 

"The discovery of the world's oldest termite mounds in Namaqualand is a testament to the incredible history hidden beneath our feet," Francis said in the statement. "These mounds not only illuminate the past but also offer vital clues for our future. As we continue to uncover the secrets of these ancient structures, they stand as a reminder of the delicate interplay between climate, environment, and life on earth."

Kristel is a science writer based in the U.S. with a doctorate in chemistry from the University of New South Wales, Australia. She holds a master's degree in science communication from the University of California, Santa Cruz. Her work has appeared in Drug Discovery News, Science, Eos and Mongabay,   among other outlets. She received the 2022 Eric and Wendy Schmidt Awards for Excellence in Science Communications.

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Saudi Astronauts Begin Their Mission With 14 Scientific Experiments

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In the aim of improving researchers’ understanding of rain-seeding technology, which will contribute to increasing rainfall in many countries, the two Saudi astronauts will lead an artificial rain experiment, in which water vapor will be condensed on plankton and salt atoms in microgravity that simulate the cloud seeding process that is used in the Kingdom of Saudi Arabia and many other countries to increase precipitation rates. Results will help scientists and researchers devise new ways to provide suitable conditions for humans – including the work of artificial rain – to live in space colonies on the surface of the Moon and Mars.

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