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32 physics experiments that changed the world

From the discovery of gravity to the first mission to defend Earth from an asteroid, here are the most important physics experiments that changed the world.

Physics experiments have changed the world irrevocably, altering our reality and enabling us to take gigantic leaps in technology. From ancient times to now, here's a look at some of the greatest physics experiments of all time.

Conservation of energy

Energy conservation — the idea that energy cannot be created or destroyed, only transformed — is one of the most important laws of physics. James Prescott Joule demonstrated this rule, the first law of thermodynamics , when he filled a large container with water and fixed a paddle wheel inside it. The wheel was held in place by an axle with a string around it and then looped over a pulley and attached to a weight, which, when dropped, caused the wheel to spin. By sloshing the water with the wheel, Joule demonstrated that the heat energy gained by the water from the wheel's movement was equal to the potential energy lost by dropping the weight.

Measurement of the electron's charge

As the fundamental carriers of electric charge, electrons carry the smallest amount of electricity possible. But the particles are truly tiny, with a mass 1,838 times smaller than the already-minuscule proton.

So how could you measure the charge on something so small? Physicist Robert Millikan's answer was to drop electrically charged oil drops through the plates of a capacitor and adjust the voltage of the capacitor until the electric field it emitted produced a force on some of the drops that balanced out gravity — thus suspending them in the air. Repeating the experiment for different voltages revealed that, no matter the size of the drops, the total charge it carried was a multiple of a base number. Millikan had found the fundamental charge of the electron.

 "Gold foil experiment" revealing the structure of the atom

Once thought to be indivisible, the atom was slowly divided and split by a series of experiments during the late 19th and early 20th centuries. These included J.J. Thomson's 1897 discovery of the electron and James Chadwick's 1932 identification of the neutron. But perhaps the most famous of these experiments was Hans Geiger and Ernest Marsden's " gold foil experiment ." Under the direction of Ernest Rutherford, the students fired positively charged alpha particles at a thin sheet of gold foil. To their surprise, the particles passed through, revealing that atoms consisted of a positively charged nucleus separated by a significant empty space by their orbiting electrons.

Nuclear chain reaction

By the mid-20th century, scientists were aware of the basic structure of the atom and that, according to Einstein, matter and energy were different forms of the same thing. This set the stage for the wartime work of Enrico Fermi, who in 1942 demonstrated that atoms could be split to release enormous quantities of energy.

While working at the University of Chicago with an experimental setup he called an "atomic pile," Fermi demonstrated the first-ever controlled nuclear fission reaction. Fermi fired neutrons at the unstable isotope uranium-235, causing it to split and release more neutrons in a growing chain reaction. The experiment paved the way for the development of nuclear reactors and was used by J. Robert Oppenheimer and the Manhattan Project to build the first atomic bombs.

Wave-particle duality

One of the most famous experiments in physics is also one that illustrates, with disturbing simplicity, the bizarreness of the quantum world. The experiment consisted of two slits, through which electrons would travel to create an interference pattern on a screen, like waves. Scientists were stunned when they placed a detector near the screen and found that its presence caused the electrons to switch their behavior to act instead as particles.

First performed by Thomas Young to demonstrate the wave nature of light, the experiment was later used by physicists in the 20th century to show that all particles, including photons , were both waves and particles at the same time — and they acted more like particles when they were being measured directly.

Splitting of white light into colors

White light is a mixture of all the colors of the rainbow, but before 1672, the composite nature of light was completely unknown. Isaac Newton determined this by using a prism that bent light of different wavelengths, or colors, by different amounts, decomposing white light into its composite colors. The result was one of the most famous experiments in scientific history and a discovery that, alongside other contributions by Newton, gave birth to the modern field of optics.

Discovery of gravity

In perhaps the most widely repeated story in all of science, Newton is said to have chanced upon the theory of gravity while contemplating under the shade of an apple tree. According to the legend, when an apple fell and struck him on the head, he supposedly yelled "Eureka!" as he realized that the same force that brought the apple tumbling to Earth also kept the moon in orbit around our planet and Earth circling the sun. That force, of course, would become known as gravity .

The story is slightly embellished, however. According to Newton's own account, the apple did not strike him on the head, and there's no record of what he said or if he said anything, at the moment of discovery. Nonetheless, the realization led Newton to develop his theory of gravity in 1687, which was updated by Einstein's theory of general relativity 228 years later.

Blackbody radiation

By the turn of the 20th century, many physicists — having advanced theories that explained gravity, mechanics, thermodynamics and the behavior of electromagnetic fields — were confident that they had conquered the vast majority of their field. But one troubling source of doubt remained: Theories predicted the existence of a "blackbody" — an object capable of absorbing and then remitting all incident radiation. The problem was that physicists couldn't find it.

In fact, data from experiments conducted with close approximations of black bodies — a box with a single hole whose inside walls are black — revealed that significantly less energy was emitted from blackbodies than classical theories led scientists to believe, especially at shorter wavelengths. The contradiction between experiment and theory became known as the "ultraviolet catastrophe."

The discovery prompted Max Planck to propose that the energy emitted by blackbodies wasn't continuous but rather split into discrete integer chunks called quanta. His radical proposal catalyzed the development of quantum mechanics , whose bizarre rules are completely unintuitive to observers living in the macroscopic world.

Einstein and the eclipse

Following its publication in 1915, Einstein's groundbreaking theory of general relativity briefly remained just that — a theory. Then, in 1919, astronomer Sir Arthur Eddington devised and completed stunning proof using that year's total solar eclipse .

Key to Einstein's theory was the notion that space — and, therefore, the path that light would follow through it — was warped by powerful gravitational forces. So, as the moon's shadow passed in front of the sun, Eddington recorded the position of nearby stars from his vantage point on the island of Principe in the Gulf of Guinea. By comparing these positions to those he had recorded at night without the sun in the sky, Eddington observed that they had been shifted slightly by the sun's gravity, completing his stunning proof of Einstein's theory.

Higgs boson

In 1964, Peter Higgs suggested that matter gets its mass from a field that permeates all of space, imparting particles with mass through their interactions with a particle known as the Higgs boson .

To search for the boson, thousands of particle physicists planned, constructed and fired up the Large Hadron Collider . In 2012, after trillions upon trillions of collisions in which two protons are smashed together at near light speed, the physicists finally spotted the telltale signature of the boson.

Weighing the world

Although he's perhaps best known for his discovery of hydrogen, 18th-century physicist Henry Cavendish's most ingenious experiment accurately estimated the weight of our entire planet. Using a special piece of equipment known as a torsion balance (two rods with one smaller and one larger pair of lead balls attached to the end), Cavendish measured the minuscule force of gravitational attraction between the masses. Then, by measuring the weight of one of the small balls, he measured the gravitational force between it and Earth, giving him an easy formula for calculating our planet's density and — therefore, its weight — that remains accurate to this day.

Conservation of mass

Much like energy, matter in our universe is finite and cannot be created or destroyed, only rearranged. In 1789, to arrive at this startling conclusion, French chemist Antoine Lavoisier placed a burning candle inside a sealed glass jar. After the candle had burned and melted into a puddle of wax, Lavoisier weighed the jar and its contents, finding that it had not changed

Leaning Tower of Pisa experiment

Greek philosopher Aristotle believed that objects fall at different rates because the force acting upon them was stronger for heavier objects — a claim that went unchallenged for more than a millennium.

Then came the Italian polymath Galileo Galilei, who corrected Aristotle's false claim by showing that two objects with different masses fall at exactly the same rate. Some claim Galileo's famous experiment was conducted by dropping two spheres from the Leaning Tower of Pisa, but others say this part of the story is apocryphal. Nonetheless, the experiment was perhaps most famously demonstrated by Apollo 15 astronaut David Scott, who, while dropping a feather and a hammer on the moon, showed that without air, the two objects fell at the same speed.

Detection of gravitational waves

If gravity warps space-time as Einstein predicted, then the collision of two extremely dense objects, such as neutron stars or black holes , should also create detectable shock waves in space that could reveal physics unseen by light. The problem is that these gravitational waves are tiny, often the size of a few thousandths of a proton or neutron, so detecting them requires an extremely sensitive experiment.

Enter LIGO, the Laser Interferometer Gravitational-Wave Observatory. The L-shaped detector has two 2.5-mile-long (4 km) arms containing two identical laser beams. When a gravitational wave laps at our cosmic shores, the laser in one arm is compressed and the other expands, alerting scientists to the wave's presence. In 2015, LIGO achieved its task, making the first-ever direct detection of gravitational waves and opening up an entirely new window to the cosmos.

Destruction of heliocentrism

The idea that Earth orbits the sun goes back to the fifth century B.C. to Greek philosophers Hicetas and Philolaus. Nonetheless, Claudius Ptolemy's belief that Earth was the center of the universe later took root and dominated scientific thought for more than a millennium.

Then came Nicolaus Copernicus, who proposed that Earth did, in fact, revolve around the sun and not the other way around. Concrete evidence for this was later offered by Galileo, who in 1610 peered through his telescope to observe the planet Venus moving through distinct phases — proof that it, too, orbited the sun. Galileo's discovery did not win him any friends with the Catholic Church, which tried him for heresy for his unorthodox proposal.

Foucault's pendulum

First used by French physicist Jean Bernard Léon Foucault in 1851, the famous pendulum consisted of a brass bob containing sand and suspended by a cable from the ceiling. As it swung back and forth, the angle of the line traced out by the sand changed subtly over time — clear evidence that some unknown rotation was causing it to shift. This rotation was the spinning of Earth on its axis.

Discovery of the electron

In the 19th century, physicists found that by creating a vacuum inside a glass tube and sending electricity through it, they could make the tube give off a fluorescent glow. But exactly what caused this effect, called a cathode ray, was unclear.

Then, in 1897, physicist J.J. Thomson discovered that by applying a magnetic field to the rays inside the tube, he could control the direction in which they traveled. This revelation showed Thomson that the charge within the tube came from tiny particles 1,000 times smaller than hydrogen atoms. The tiny electron had finally been found.

Deflection of an asteroid

In 2022, NASA scientists hit an astronomical "bull's-eye" by intentionally steering the 1,210-pound (550 kilograms), $314 million Double Asteroid Redirection Test (DART) spacecraft into the asteroid Dimorphos just 56 feet (17 meters) from its center. The test was designed to see if a small spacecraft propelled along a planned trajectory could, if given enough lead time, redirect an asteroid from a potentially catastrophic impact with Earth.

DART was a smashing success . The probe's original goal was to change the orbit of Dimorphos around its larger partner — the 2,560-foot-wide (780 m) asteroid Didymos — by at least 73 seconds, but the spacecraft actually altered Dimorphos' orbit by a stunning 32 minutes. NASA hailed the collision as a watershed moment for planetary defense, marking the first time that humans proved capable of diverting Armageddon, and without any assistance from Bruce Willis.

Faraday induction

In 1831, Michael Faraday, the self-taught son of a blacksmith born in rural south England, proposed the law of electromagnetic induction. The law was the result of three experiments by Faraday, the most notable of which involved the movement of a magnet inside a coil made by wrapping a wire around a paper cylinder. As the magnet moved inside the cylinder, it induced an electric current through the coil — proving that electric and magnetic fields were inextricably linked and paving the way for electric generators and devices.

Measurement of the speed of light

Light is the fastest thing in our universe, which makes measuring its speed a unique challenge. In 1676, Danish astronomer Ole Roemer chanced upon the first estimate for light's propagation while studying Io, Jupiter's innermost moon. By timing the eclipses of Io by Jupiter, Roemer was hoping to find the moon's orbital period.

What he noticed instead was that, as Earth's orbit moved closer to Jupiter, the time intervals between successive eclipses became shorter. Roemer's crucial insight was that this was due to a finite speed of light, which he roughly calculated based on Earth's orbit. Other methods later refined the measurement of light's speed, eventually arriving at its current value of 2.98 × 10^8 meters per second (about 186,282 miles per second).

Disproof of the "luminiferous ether"

Most waves, such as sound waves and water waves, require a medium to travel through. In the 19th century, physicists thought the same rule applied to light, too, with electromagnetic waves traveling through a ubiquitous medium dubbed the "luminiferous ether."

Albert Michelson and Edward W. Morley set out to prove this conjecture with a remarkably ingenious hypothesis: As the sun moves through the ether, it should displace some of the strange substance, meaning light should travel detectably faster when it moves with the ether wind than against it. They set up an interferometer experiment that used mirrors to split light beams along two opposing directions before bouncing them back with distant mirrors. If the light beams returned at different times, then the ether was real.

But the light beams inside their interferometer did not vary. Michelson and Morley concluded that their experiment had failed and moved on to other projects. But the result — which had conclusively disproved the ether theory — was later used by Einstein in his theory of special relativity to correctly state that light's speed through a fixed medium does not change, even if its source is moving.

Discovery of radioactivity

In 1897, while working in a converted shed with her husband Pierre, Marie Curie began to investigate the source of a strange new type of radiation emitted from the elements thorium and uranium. Marie Curie discovered that the radiation these elements emitted did not depend on any other factors, such as their temperature or molecular structure, but changed purely based on their quantities. While grinding up an even more radioactive substance known as pitchblende, she also discovered that it consisted of two elements that she dubbed radium and polonium.

Curie's work revealed the nature of radioactivity, a truly random property of atoms that comes from their internal structure. Curie won the Nobel Prize (twice) for her discoveries — making her the first woman to do so — and later trained doctors to use X-rays to image broken bones and bullet wounds. She died of aplastic pernicious anemia, a disease caused by radiation exposure, in 1934.

Expansion of the universe

While using the 100-inch Hooker telescope in California to study the light glimmering from distant galaxies in 1929, Edwin Hubble made a surprising observation: The light from the distant galaxies appeared to be shifted toward the red end of the spectrum — an indication that they were receding from Earth and each other. The farther away a galaxy was, the faster it was moving away.

Hubble's observation became a crucial piece of evidence for the Big Bang theory of our universe. Yet precise measurements for galaxies' recession, known as the Hubble constant, still confound scientists to this day .

Put simply, the universe is indeed expanding, but depending on where cosmologists look, it's doing so at different rates. In the past, the two best experiments to measure the expansion rate were the European Space Agency 's Planck satellite and the Hubble Space Telescope . The two observatories, each of which used a different method to measure the expansion rate, arrived at different results. These conflicting measurements have led to what some call a "cosmology crisis" that could reveal new physics or even replace the standard model of cosmology.

Ignition of nuclear fusion

In 2022, scientists at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in California used the world's most powerful laser to achieve something physicists have been dreaming about for nearly a century: the ignition of a pellet of fuel by nuclear fusion .

The demonstration marked the first time that the energy going out of the plasma in the nuclear reactor's fiery core exceeded the energy beamed in by the laser, and has been a rallying call for fusion scientists that the distant goal of near-limitless and clean power is, in fact, achievable.

However, scientists have cautioned that the energy from the plasma exceeds only that from the lasers, and not from the energy from the whole reactor. Additionally, the laser-confinement method used by the NIF reactor, built to test thermonuclear explosions for bomb development, will be difficult to scale up.

Measurement of Earth's circumference

By roughly 500 B.C., most ancient Greeks believed the world was round — citing evidence provided by Aristotle and guided by a suggestion from Pythagoras, who believed a sphere was the most aesthetically pleasing shape for our planet.

Then, around 245 B.C., Eratosthenes of Cyrene thought of a way to make the measurement directly. Eratosthenes hired a team of bematists (professional surveyors who measured distances by walking in equal-length steps called stadia) to walk from Syene to Alexandria. They found that the distance between the two cities was roughly 5,000 stadia.

Eratosthenes then visited a well in Syene that had been reported to have an interesting property: At noon on the summer solstice each year, the sun illuminated the well's bottom without casting any shadows. Eratosthenes went to Alexandria during the solstice, stuck a pole in the ground and measured the shadow from it to be about one-fiftieth of a complete circle. Pairing this with his measurement of the distance between the two cities, he determined that Earth's circumference was about 250,000 stadia, or 24,497 miles (39,424 km). Earth is now known to measure 24,901 miles (40,074 km) around the equator, making the ancient Greeks' measurements remarkably accurate.

Discovery of black holes

The acceptance of Einstein's theory of general relativity led to some startling predictions about our universe and the nature of reality. In 1915, Karl Schwarzschild's solutions to Einstein's field equations predicted that it was possible for mass to be compressed into such a small radius that it would collapse into a gravitational singularity from which not even light could escape — a black hole.

Schwarzschild's solution remained speculation until 1971, when Paul Murdin and Louise Webster used NASA's Uhuru X-ray Explorer Satellite to identify a bright X-ray source in the constellation Cygnus that they correctly contended was a black hole.

More conclusive evidence came in 2015, when the LIGO experiment detected gravitational waves from two of the colliding cosmic monsters. Then, in 2019, the Event Horizon Telescope captured the first image of the accretion disk of superheated matter surrounding the supermassive black hole at the center of the galaxy M87.

Discovery of X-rays

While testing whether the radiation produced by cathode rays could escape through glass in 1895, German physicist Wilhelm Conrad Röntgen saw that the radiation could not only do so, but it could also zip through very thick objects, leaving a shadow on a lead screen placed behind them. He quickly realized the medical potential of these rays — later known as X-rays — for imaging skeletons and organs. His observations gave birth to the field of radiology, enabling doctors to safely and noninvasively scan for tumors, broken bones and organ failure.

The Bell test

In 1964, physicist John Stewart Bell proposed a test to prove that quantum entanglement — the weird instantaneous connection between two far-apart particles that Einstein objected to as "spooky action at a distance" — was required by quantum theory.

The test has taken many experimental forms since Bell first proposed it, but the findings remain the same: Despite what our intuition tells us, what happens in one part of the universe can instantaneously affect what happens in another, provided the objects in each region are entangled.

Detection of the quark

In 1968, experiments at the Stanford Linear Accelerator Center found that electrons and their lepton cousins, muons, were scattering from protons in a distinct way that could only be explained by the protons being composed of smaller components. These findings matched predictions by physicist Murray Gell-Mann, who dubbed them "quarks" after a line in James Joyce's "Finnegans Wake."

Archimedes' naked leap from his bathtub

First recorded in the first century B.C. by Roman architect Vitruvius, Archimedes' discovery of buoyancy is one of the most famous stories in science. The prompting for Archimedes' finding came from King Hieron of Syracuse, who suspected that a pure-gold crown a blacksmith made for him actually contained silver. To get an answer, Hieron enlisted Archimedes' help.

The problem stumped Archimedes, but not long after, as the story goes, he filled up a bathtub with water and noticed that the water spilled out as he got in. This caused him to realize that the water displaced by his body was equal to his weight — and because gold weighed more than silver, he had found a method for judging the authenticity of the crown. "Eureka!" ("I've got it!") Archimedes is said to have cried, leaping from his bathtub to announce his discovery to the king.

Deepest and most detailed photo of the universe

In 2022, the James Webb Space Telescope unveiled the deepest and most detailed picture of the universe ever taken . Called "Webb's First Deep Field," the image captures light as it appeared when our universe was just a few hundred million years old, right when galaxies began to form and light from the first stars started flickering.

The image contains an overwhelmingly dense collection of galaxies, the light from which, on its way to us, was warped by the gravitational pull of a galaxy cluster. This process, known as gravitational lensing, brings the fainter light into focus. Despite the dizzying number of galaxies in view, the image represents just a tiny sliver of sky — the speck of sky blocked out by a grain of sand held on the tip of a finger at arm's length.

OSIRIS-REx asteroid-sampling mission

In 2023, NASA's OSIRIS-REx spacecraft came hurtling back through Earth's atmosphere after a years-long journey to Bennu, a " potentially hazardous asteroid " with a 1-in-2,700 chance of smashing cataclysmically into Earth — the highest odds of any identified space object.

The goal of the mission was to see whether the building blocks for life on Earth came from outer space. OSIRIS-REx circled the asteroid for 22 months to search for a landing spot, touching down to collect a 2-ounce (60 grams) sample from Bennu's surface that could contain the extraterrestrial precursors to life on our planet. Scientists have already found many surprising details that have the potential to rewrite the history of our solar system .

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Ben Turner is a U.K. based staff writer at Live Science. He covers physics and astronomy, among other topics like tech and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.

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Transform Science Classes with Free Virtual Labs

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A Historic Hydrogen Experiment

May 29, 2024  •  EPISODE 224

In this thrilling episode of Science LIVE, Roger Billings shares several unforgettable stories from his past featuring the first hydrogen car and his little brother Lewis. Discover how he and his brother conducted a daring hydrogen experiment that nearly ended in disaster.

Read more about DrB »  About the Roger Billings Scholarship Program »

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14 Comments

This so interesting, because I can know about the first hydrogen car inveted by Dr Roger Billings.

This is so Cool! Thank you Dr. Roger Billings!!

This is my fav

This is really neat! Dr. Billings really inspires me!

I just now found out about everything Dr.Billings has invented, this is so cool! 😊

I never knew a hydrogen car could be a thing!

Acellus helped me so much for my senior year!

Can we see more of Lewis 51?

Very cool how they named Bluetooth after Herald Bluetooth.

I like how they used the kings initials as the Bluetooth logo

So it that L-51 one now or…?

When can I have him make me a Hydrogen car?

Are there other ways to invent a hydrogen powered car?

THANK you for all of the teaching DR .B

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• Grades 6-12
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80 Best High School Science Experiments and Projects for Every Subject

Fire up the Bunsen burners!

For even more free science ideas and printables,  head to our science hub!  You’ll find resources in every science subject for middle and high school.

The cool thing about high school is that kids are old enough to tackle some pretty amazing science experiments and projects. Some science experiments for high school are just advanced versions of simpler projects they did when they were younger, with detailed calculations or fewer instructions. Other projects involve fire, chemicals, or other materials they weren’t old enough to use before.

Many of these projects can be used as classroom labs or science fair projects. Feel free to adapt them as needed for students’ individual projects, or use them as full-class activities. However you plan to use the projects, just consider variables that you can change up, like materials or other parameters.

To make it easier to find the right high school science experiment for you, we’ve rated all the projects by difficulty and the materials needed:

Difficulty:

• Easy: Low or no-prep experiments you can do pretty much anytime
• Medium: These take a little more setup or a longer time to complete
• Advanced: Experiments like these take a fairly big commitment of time or effort
• Basic: Simple items you probably already have around the house
• Medium: Items that you might not already have but are easy to get your hands on
• Advanced: These require specialized or more expensive supplies to complete
• Biology and Life Sciences High School Science Fair Projects
• Chemistry High School Science Fair Projects
• Physics High School Science Fair Projects
• Engineering High School STEM Fair Projects

Biology and Life Sciences High School Science Fair Projects and Experiments

Explore the living world with these biology science project ideas, learning more about plants, animals, the environment, and much more.

FEATURED PICK

Ward’s Science Engage Kit : Cell Cycles

Difficulty: Medium / Materials: Easy (Everything is provided for you!)

In this activity, your students will step into the shoes of an R&D intern at an agricultural biotech company. They’ll dig into a new plant crop virus and brainstorm solutions to tackle it.

Ward’s Science Engage Kits are an amazing way to bring more inquiry-based activities into your classroom. The kits come with everything you need to complete hands-on labs with your class. Your students will develop their critical questioning, research, and teamwork skills while working to solve problems that feel real and important.

Extract DNA from an onion

Difficulty: Medium / Materials: Medium

You don’t need a lot of supplies to perform this experiment, but it’s impressive nonetheless. Turn this into a science fair project by trying it with other fruits and vegetables too.

Make plants move with light

By this age, kids know that many plants move toward sunlight, a process known as phototropism. So high school science fair projects on this topic need to introduce variables into the process, like covering seedling parts with different materials to see the effects.

Test the 5-second rule

We’d all like to know the answer to this one: Is it really safe to eat food you’ve dropped on the floor? Design and conduct an experiment to find out (although we think we might already know the answer).

Find out if color affects taste

Just how interlinked are all our senses? Does the sight of food affect how it tastes? Find out with a fun food science fair project like this one!

See the effects of antibiotics on bacteria

Difficulty: Medium / Materials: Advanced

Bacteria can be divided into two groups: gram-positive and gram-negative. In this experiment, students first determine the two groups, then try the effects of various antibiotics on them.

Buy it: Get a gram stain kit , bacillus cereus and rhodospirillum rubrum cultures, and antibiotic discs from Home Science Tools.

Learn more: Antibiotics Project

Witness the carbon cycle in action

Experiment with the effects of light on the carbon cycle. Make this science fair project even more interesting by adding some small aquatic animals like snails or fish into the mix.

Learn more: Carbon Cycle

Look for cell mitosis in an onion

Cell mitosis (division) is actually easy to see in action when you look at onion root tips under a microscope. Students will be amazed to see science theory become science reality right before their eyes. Adapt this lab into a high school science fair project by applying the process to other organisms too.

Test the effects of disinfectants

Grow bacteria in a petri dish along with paper disks soaked in various antiseptics and disinfectants. You’ll be able to see which ones effectively inhibit bacteria growth.

Learn more: Effectiveness of Antiseptics and Disinfectants

Re-create Mendel’s pea plant experiment

Gregor Mendel’s pea plant experiments were some of the first to explore inherited traits and genetics. Try your own cross-pollination experiments with fast-growing plants like peas or beans.

Pit hydroponics against soil

Growing vegetables without soil (hydroponics) is a popular trend that allows people to garden just about anywhere.

Research soil erosion

Difficulty: Medium / Materials: Easy

Learn about the factors that contribute to soil erosion, and create a demonstration of how soil erosion does, and doesn’t occur. Make this more advanced by increasing the number of variables that students investigate and discuss.

Learn more: Soil erosion experiment

Difficulty: Easy / Materials: Medium

Growing mold is something that students may have done already, but increase the rigor of this experiment by adding in control variables and turning the experiment on its head to study what might prevent mold growth. Once students know where mold spores are, what should we do about it? How can we prevent mold growth?

Learn more: Growing mold experiment

More Life Sciences and Biology Science Fair Projects and Experiments for High School

Use these questions and ideas to design your own experiment:

• What are the most accurate methods of predicting various weather patterns?
• Try out various fertilization methods to find the best and safest way to increase crop yield.
• Does exposure to smoke or other air pollutants affect plant growth?
• Compare the chemical and/or bacterial content of various water sources (bottled, tap, spring, well water, etc.).
• Explore ways to clean up after an oil spill on land or water.
• Conduct a wildlife field survey in a given area and compare it to results from previous surveys.
• Find a new use for plastic bottles or bags to keep them out of landfills.
• Devise a way to desalinate seawater and make it safe to drink.

Chemistry High School Science Fair Projects and Experiments

Bunsen burners, beakers and test tubes, and the possibility of (controlled) explosions? No wonder chemistry experiments are such popular high school science fair projects!

Break apart covalent bonds

Break the covalent bond of H 2 O into H and O with this simple experiment. You only need simple supplies for this one. Turn it into a science fair project by changing up the variables—does the temperature of the water matter? What happens if you try this with other liquids?

Learn more: Covalent Bonds

Measure the calories in various foods

Are the calorie counts on your favorite snacks accurate? Build your own calorimeter and find out! This kit from Home Science Tools has all the supplies you’ll need.

Detect latent fingerprints

Forensic science is engrossing and can lead to important career opportunities too. Explore the chemistry needed to detect latent (invisible) fingerprints, just like they do for crime scenes!

Learn more: Fingerprints Project

Use Alka-Seltzer to explore reaction rate

Difficulty: Easy / Materials: Easy

Tweak this basic concept to create a variety of high school chemistry science fair projects. Change the temperature, surface area, pressure, and more to see how reaction rates change.

Determine whether sports drinks provide more electrolytes than OJ

Are those pricey sports drinks really worth it? Try this experiment to find out. You’ll need some special equipment for this one.

Buy it: electrolyte test kit at Home Science Tools

Turn flames into a rainbow

You’ll need to get your hands on a few different chemicals for this experiment, but the wow factor will make it worth the effort! Make it a science project by seeing if different materials, air temperature, or other factors change the results.

Discover the size of a mole

The mole is a key concept in chemistry, so it’s important to ensure students really understand it. This experiment uses simple materials like salt and chalk to make an abstract concept more concrete. Make it a project by applying the same procedure to a variety of substances, or determining whether outside variables have an effect on the results.

Learn more: How Big Is a Mole?

Cook up candy to learn molecule calculations

Students make rock candy while learning about chemical reactions and calculations. If they change any of the reactions or amounts, what happens?

Learn more: Rock candy experiment

Make soap to understand saponification

Take a closer look at an everyday item: soap! Use oils and other ingredients to make your own soap, learning about esters and saponification. Tinker with the formula to find one that fits a particular set of parameters.

Learn more: Soap making

Uncover the secrets of evaporation

Explore the factors that affect evaporation, then come up with ways to slow them down or speed them up for a simple science fair project.

Learn more: Evaporation

Dancing popcorn

Another way to show a chemical reaction is the dancing popcorn experiment. This video shows two ways to conduct the reaction, students can explain the science behind each.

Learn more: Dancing popcorn experiment

The Egg and Vinegar Experiment

Show how vinegar can take the shell off an egg with this experiment. Students can show this experiment in various stages, and talk about what’s happening at the molecular level.

Learn more: Egg and vinegar experiment

Make a lava lamp

Show a chemical reaction with a lava lamp. This is a great experiment to do at science fairs that have a lot of younger siblings who will be excited to see this experiment come to life.

Cabbage pH experiment

Explain pH using cabbage water and some other household items. Students can set up a pH demonstration and be ready to explain how pH works.

Learn more: Cabbage pH experiment

Buy it: pH test strips at Amazon

Split water

Show how water splits into hydrogen and water in this easy experiment. Make it more complicated by adding pH or adding snap circuits to focus on electricity.

Learn more: Electrolysis of water lab

More Chemistry Science Fair Projects and Experiments for High School

These questions and ideas can spark ideas for a unique experiment:

• Compare the properties of sugar and artificial sweeteners.
• Explore the impact of temperature, concentration, and seeding on crystal growth.
• Test various antacids on the market to find the most effective product.
• What is the optimum temperature for yeast production when baking bread from scratch?
• Compare the vitamin C content of various fruits and vegetables.
• How does temperature affect enzyme-catalyzed reactions?
• Investigate the effects of pH on an acid-base chemical reaction.
• What’s the best way to slow down metal oxidation (form of rust)?
• How do changes in ingredients and method affect the results of a baking recipe?

Physics High School Science Fair Projects and Experiments

When you think of physics science projects for high school, the first thing that comes to mind is probably the classic build-a-bridge. But there are plenty of other ways for teens to get hands-on with physics concepts. Here are high school science experiments some to try.

Remove the air in a DIY vacuum chamber

You can use a vacuum chamber to do lots of cool high school science fair projects, but a ready-made one can be expensive. Try this project to make your own with basic supplies.

Put together a mini Tesla coil

Looking for a simple but showy high school science fair project? Build your own mini Tesla coil and wow the crowd!

Boil water in a paper cup

Logic tells us we shouldn’t set a paper cup over a heat source, right? Yet it’s actually possible to boil water in a paper cup without burning the cup up! Learn about heat transfer and thermal conductivity with this experiment. Go deeper by trying other liquids like honey to see what happens.

Build a better light bulb

Emulate Thomas Edison and build your own simple light bulb. You can turn this into a science fair project by experimenting with different types of materials for filaments.

Measure the speed of light—with your microwave

Grab an egg and head to your microwave for this surprisingly simple experiment. By measuring the distance between cooked portions of egg whites, you’ll be able to calculate the wavelength of the microwaves in your oven and, in turn, the speed of light.

Generate a Lichtenberg figure

See electricity in action when you generate and capture a Lichtenberg figure with polyethylene sheets, wood, or even acrylic and toner. Change the electrical intensity and materials to see what types of patterns you can create.

Learn more: Lichtenberg Figure

Explore the power of friction with sticky-note pads

Difficulty: Medium / Materials: Basic

Ever try to pull a piece of paper out of the middle of a big stack? It’s harder than you’d think! That’s due to the power of friction. In this experiment, students interleave the sheets of two sticky-note pads, then measure how much weight it takes to pull them apart. The results are astonishing!

Build a cloud chamber to prove background radiation

Ready to dip your toe into particle physics? Learn about background radiation and build a cloud chamber to prove the existence of muons.

Measure the effect of temperature on resistance

This is a popular and classic science fair experiment in physics. You’ll need a few specialized supplies, but they’re pretty easy to find.

Learn more: Effect of Temperature on Resistance

Launch a bottle rocket

A basic bottle rocket is pretty easy to build, but it opens the door to lots of different science fair projects. Design a powerful launcher, alter the rocket so it flies higher or farther, or use only recycled materials for your flyer.

Make a solar oven

Model how solar heating works with a solar oven. Students can make this experiment high school-worthy by testing different type of oven designs, measuring the temperature inside, or determining how much more efficient the solar oven is than a microwave or oven.

Learn more: Solar oven experiment

Sound proof a box

Students experiment with acoustics and sound proofing to create a space that’s sound-proofed. This would be a major challenge for a high schooler who has to block out the sounds at a busy science fair.

Learn more: Soundproofing

More Physics Science Fair Projects and Experiments for High School

Design your own experiment in response to these questions and prompts.

• What’s the best way to eliminate friction between two objects?
• Explore the best methods of insulating an object against heat loss.
• What effect does temperature have on batteries when stored for long periods of time?
• Test the effects of magnets or electromagnetic fields on plants or other living organisms.
• Determine the best angle and speed of a bat swing in baseball.
• Explore methods for reducing air resistance in automotive design.
• Use the concepts of torque and rotation to perfect a golf swing.
• Compare the strength and durability of various building materials.

Engineering High School Science Fair Projects and Experiments

Many schools are changing up their science fairs to STEM fairs to encourage students with an interest in engineering to participate. Many great engineering science experiments for high school start with a STEM challenge, like those shown here. Use these ideas to spark a full-blown project to build something new and amazing!

Construct a model maglev train

Maglev trains may just be the future of mass transportation. Build a model at home, and explore ways to implement the technology on a wider basis.

Learn more: Maglev Model Train

Design a more efficient wind turbine

Wind energy is renewable, making it a good solution for the fossil fuel problem. For a smart science fair project, experiment to find the most efficient wind turbine design for a given situation.

Re-create Da Vinci’s flying machine

Da Vinci sketched several models of “flying machines” and hoped to soar through the sky. Do some research into his models and try to reconstruct one of your own.

Learn more: Da Vinci Flying Machine

Design a heart-rate monitor

Smartwatches are ubiquitous these days, so pretty much anyone can wear a heart-rate monitor on their wrist. But do they work any better than one you can build yourself? Get the specialized items you need like the Arduino LilyPad Board on Amazon.

Create cars and race them using balloons or this baking soda experiment. Add more complexity by having students create their cars using 3D printer technology.

Learn more: Balloon baking soda experiment

Grow veggies in a hydroponic garden

Hydroponics is the gardening wave of the future, making it easy to grow plants anywhere with minimal soil required. For a science fair STEM engineering challenge, design and construct your own hydroponic garden capable of growing vegetables to feed a family. This model is just one possible option.

Learn more: Vertical Hydroponic Farm

Grab items with a mechanical claw

Delve into robotics with this engineering project. This kit includes all the materials you need, with complete video instructions. Once you’ve built the basic structure, tinker around with the design to improve its strength, accuracy, or other traits.

Construct a crystal radio

Return to the good old days and build a radio from scratch. This makes a cool science fair project if you experiment with different types of materials for the antenna.

Learn more: Crystal Radio

Buy it: Crystal radio kit at Home Science Tools

Build a paper bridge

Bridge building is a fun STEM activity that can be made more or less challenging depending on the ultimate goal. The more functional the bridge has to be, the more difficult the project.

Learn more: Paper bridge project

Potato battery

Make, test, and showcase a potato battery. The process is simple enough, so students can figure out just how much power their potato has and what they can do with their battery.

Learn more: Potato battery

Marble roller coaster

Another fun project that high schoolers can revisit now that they know more about physics and engineering is the roller coaster. Students make a roller coaster for a small car or marble.

Learn more: Paper roller coaster

Looking for more science content? Check out the Best Science Websites for Middle and High School .

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• Biz & IT

How physics moves from wild ideas to actual experiments

Science often accommodates audacious proposals.

Neutrinos are some of nature’s most elusive particles . One hundred trillion fly through your body every second, but each one has only a tiny chance of jostling one of your atoms, a consequence of the incredible weakness of the weak nuclear force that governs neutrino interactions. That tiny chance means that reliably detecting neutrinos takes many more atoms than are in your body. To spot neutrinos colliding with atoms in the atmosphere, experiments have buried 1,000 tons of heavy water, woven cameras through a cubic kilometer of Antarctic ice, and planned to deploy 200,000 antennas .

In a field full of ambitious plans, a recent proposal by Steven Prohira , an assistant professor at the University of Kansas, is especially strange. Prohira suggests that instead of using antennas, we could detect the tell-tale signs of atmospheric neutrinos by wiring up a forest of trees . His suggestion may turn out to be impossible, but it could also be an important breakthrough. To find out which it is, he'll need to walk a long path, refining prototypes and demonstrating his idea’s merits.

Prohira’s goal is to detect so-called ultra-high-energy neutrinos. Each one of these tiny particles carries more than fifty million times the energy released by uranium during nuclear fission. Their origins are not fully understood, but they are expected to be produced by some of the most powerful events in the Universe, from collapsing stars and pulsars to the volatile environments around the massive black holes at the centers of galaxies. If we could detect these particles more reliably, we could learn more about these extreme astronomical events.

Other experiments, like a project called GRAND , plan to build antennas to detect these neutrinos, watching for radio signals that come from their reactions with our atmosphere. However, finding places to place these antennas can be a challenge. Motivated by this experiment, Prohira dug up old studies by the US Army that suggested an alternative: instead of antennas, use trees. By wrapping a wire around each tree, army researchers found that the trees were sensitive to radio waves, which they hoped to use to receive radio signals in the jungle. Prohira argues that the same trick could be useful for neutrino detection.

Crackpot or legit science?

People suggest wacky ideas every day. Should we trust this one?

At first, you might be a bit suspicious. Prohira’s paper is cautious on the science but extremely optimistic in other ways. He describes the proposal as a way to help conserve the Earth’s forests and even suggests that “a forest detector could also motivate the large-scale reforesting of land, to grow a neutrino detector for future generations.”

Prohira is not a crackpot, though. He has a track record of research in detecting neutrinos via radio waves in more conventional experiments, and he even received an $800,000 MacArthur genius grant a few years ago to support his work.

More generally, studying particles from outer space often demands audacious proposals, especially ones that make use of the natural world. Professor Albrecht Karle works on the IceCube experiment, an array of cameras that detect neutrinos whizzing through a cubic kilometer of Antarctic ice.

“In astroparticle physics, where we often cannot build the entire experiment in a laboratory, we have to resort to nature to help us, to provide an environment that can be used to build a detector. For example, in many parts of astroparticle physics, we are using the atmosphere as a medium, or the ocean, or the ice, or we go deep underground because we need a shield because we cannot construct an artificial shield. There are even ideas to go into space for extremely energetic neutrinos, to build detectors on Jupiter's moon Europa.”

Such uses of nature are common in the field. India’s GRAPES experiments were designed to measure muons, but they have to filter out anything that’s not a muon to do so. As Professor Sunil Gupta of the Tata Institute explained, the best way to do that was with dirt from a nearby hill.

"The only way we know you can make a muon detector work is by filtering out other radiation [...] so what we decided is that we'll make a civil structure, and we'll dump three meters of soil on top of that, so those three meters of soil could act as a filter," he said.

The long road to an experiment

While Prohira’s idea isn't ridiculous, it's still just an idea (and one among many). Prohira’s paper describing the idea was uploaded to arXiv.org , a pre-print server, in January. Physicists use pre-print servers to give access to their work before it's submitted to a scientific journal. That gives other physicists time to comment on the work and suggest revisions. In the meantime, the journal will send the work out to a few selected reviewers, who are asked to judge both whether the paper is likely to be correct and whether it is of sufficient interest to the community.

At this stage, reviewers may find problems with Prohira’s idea. These may take the form of actual mistakes, such as if he made an error in his estimates of the sensitivity of the detector. But reviewers can also ask for more detail. For example, they could request a more extensive analysis of possible errors in measurements caused by the different shapes and sizes of the trees.

If Prohira’s idea makes it through to publication, the next step toward building an actual forest detector would be convincing the larger community. This kind of legwork often takes place at conferences. The International Cosmic Ray Conference is the biggest stage for the astroparticle community, with conferences every two years—the next is scheduled for 2025 in Geneva. Other more specialized conferences, like ARENA , focus specifically on attempts to detect radio waves from high-energy neutrinos. These conferences can offer an opportunity to get other scientists on board and start building a team.

That team will be crucial for the next step: testing prototypes. No matter how good an idea sounds in theory, some problems only arise during a real experiment.

An early version of the GRAPES experiment detected muons by the light they emit passing through tanks of water. To find how much water was needed, the researchers did tests, putting a detector on top of a tank and on the bottom and keeping track of how often both detectors triggered for different heights of water based on the muons that came through randomly from the atmosphere. After finding that the tanks of water would have to be too tall to fit in their underground facility, they had to find wavelength-shifting chemicals that would allow them to use shorter tanks and novel ways of dissolving these chemicals without eroding the aluminum of the tank walls.

“When you try to do something, you run into all kinds of funny challenges,” said Gupta.

The IceCube experiment has a long history of prototypes going back to early concepts that were only distantly related to the final project. The earliest, like the proposed DUMAND project in Hawaii, planned to put detectors in the ocean rather than ice. BDUNT was an intermediate stage, a project that used the depths of Lake Baikal to detect atmospheric neutrinos. While the detectors were still in liquid water, the ability to drive on the lake’s frozen surface made BDUNT’s construction easier.

In a 1988 conference , Robert March, Francis Halzen, and John G. Learned envisioned a kind of “solid state DUMAND” that would use ice instead of water to detect neutrinos. While the idea was attractive, the researchers cautioned that it would require a fair bit of luck. “In summary, this is a detector that requires a number of happy accidents to make it feasible. But if these should come to pass, it may provide the least expensive route to a truly large neutrino telescope,” they said.

In the case of the AMANDA experiment, early tests in Greenland and later tests at the South Pole began to provide these happy accidents. “It was discovered that the ice was even more exceptionally clear and has no radioactivities—absolutely quiet, so it is the darkest and quietest and purest place on Earth,” said Karle.

AMANDA was much smaller than the IceCube experiment, and theorists had already argued that to see cosmic neutrinos, the experiment would need to cover a cubic kilometer of ice. Still, the original AMANDA experiment wasn't just a prototype; if neutrinos arrived at a sufficient rate, it would spot some. In this sense, it was like the original LIGO experiment , which ran for many years in the early 2000s with only a minimal chance of detecting gravitational waves, but it provided the information needed to perform an upgrade in the 2010s that led to repeated detections. Similarly, the hope of pioneers like Halzen was that AMANDA would be able to detect cosmic neutrinos despite its prototype status.

“There was the chance that, with the knowledge at the time, one might get lucky. He certainly tried," said Karle.

Prototype experiments often follow this pattern. They're set up in the hope that they could discover something new about the Universe, but they're built to at least discover any unexpected challenges that would stop a larger experiment.

Major facilities and the National Science Foundation

For experiments that don't need huge amounts of funding, these prototypes can lead to the real thing, with scientists ratcheting up their ambition at each stage. But for the biggest experiments, the governments that provide the funding tend to want a clearer plan.

Since Prohira is based in the US, let's consider the US government. The National Science Foundation has a procedure for its biggest projects, called the Major Research Equipment and Facilities Construction program. Since 2009, it has had a “no cost overrun” policy. In the past, if a project ended up costing more than expected, the NSF could try to find additional funding. Now, projects are supposed to estimate beforehand how the cost could increase and budget extra for the risk. If the budget goes too high anyway, projects should compensate by reducing scope, shrinking the experiment until it falls under costs again.

To make sure they can actually do this, the NSF has a thorough review process.

First, the NSF expects that the scientists proposing a project have done their homework and have already put time and money into prototyping the experiment. The general expectation is that about 20 percent of the experiment’s total budget should have been spent testing out the idea before the NSF even starts reviewing it.

With the prototypes tested and a team assembled, the scientists will get together to agree on a plan. This often means writing a report to hash out what they have in mind. The IceCube team is in the process of proposing a second generation of their experiment, an expansion that would cover more ice with detectors and achieve further scientific goals. The team recently finished the third part of a Technical Design Report , which details the technical case for the experiment.

After that, experiments go into the NSF’s official experiment design process. This has three phases, conceptual design, preliminary design, and final design. Each phase ends with a review document summarizing the current state of the plans as they firm up, going from a general scientific case to a specific plan to put an experiment in a specific place. Risks are estimated in detail and list estimates of how likely risks are and how much they will cost, a process that sometimes involves computer simulations. By the end of the process, the project has a fully detailed plan and construction can begin.

Over the next few years, Prohira will test out his proposal. He may get lucky, like the researchers who dug into Antarctic ice, and find a surprisingly clear signal. He may be unlucky instead and find that the complexities of trees, with different spacings and scatterings of leaves, makes the signals they generate unfit for neutrino science. He, and we, cannot know in advance which will happen.

That's what science is for, after all.

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