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10 Scientific Discoveries That Changed The World

Dna, gravity, and germ theory are a few of the key findings in history that forever shifted the course of human civilization. learn how these scientific discoveries changed the world..

The only constant is change. At least, that’s what the Greek philosopher Heraclitus is credited to have said. And while science and philosophy don’t always go hand in hand, there is some truth to Heraclitus’ notion. Change is inevitable and, in some cases, necessary for our species to evolve . While some change happens automatically, like the tides going in and out, some changes bloomed from scientific discoveries. 

Using fire to cook food and keep warm propelled our ancestors toward the foundations of early settlements and continued the growth of civilization. Using fire to shape metals for weapons and building materials led to more and more discoveries and more and more advancements. While many advances shaped humanity, we’ve focused on ten significant scientific discoveries that changed the world.

The discovery of DNA didn’t so much change the world as it did our understanding of it — more so, our understanding of life. DNA is a term we’ve only started using in the 20th century, though its initial discovery dates back decades into the 19th century.

What Is DNA?

DNA is the molecule that encodes genetic information for all living things. It plays a key role in passing traits from parents to offspring and is the primary component of chromosomes in the cell nuclei of complex organisms.

Who Discovered DNA?

Many people think scientists James Watson and Francis Crick discovered DNA in the 1950s. Nope, not so fast. DNA was actually first discovered in 1869 by Swiss physician Friedrich Miescher . He identified what he referred to as “nuclein” in blood cells. Several other researchers have worked on projects around identifying DNA up until Watson and Crick. 

What Does DNA Stand For?

The term nuclein eventually evolved into what we know as DNA, the shorthand for deoxyribonucleic acid. German biochemist Albrecht Kossel , who would later go on to win the Nobel Prize, is often credited with the name.

Levene’s Polynucleotide Model

Other scientists, such as Phoebus Levene , built on Miescher’s work over the years. Levene didn't know how DNA's nucleotide components were arranged. He proposed the polynucleotide model, correctly suggesting that nucleic acids are chains of nucleotides, each with a base, a sugar, and a phosphate group. 

Watson and Crick's Double-Stranded Helix

Watson and Crick and “their” groundbreaking discovery in the field of genetics accurately identified DNA’s double-stranded helix structure, connected by hydrogen bonds. For their discovery, Watson and Crick won a Nobel Prize in 1962 and worldwide acclaim. 

Though Watson and Crick won a Nobel Prize, years later, we’ve learned that the duo likely took research without permission from chemist Rosalind Franklin . Thanks to her research, the double helix structure was realized, though her Nobel Prize was not. 

In 2014, Watson auctioned off his Nobel Prize medal for over $4 million. The buyer was a Russian billionaire who returned it to Watson a year later. In 2019, Watson was stripped of his honorary titles because of racist comments.

Read More: DNA in Unlikely Places Helps Piece Together Ancient Humans' Family Trees

2. Earth in Motion

While it may be common knowledge that Earth spins on an axis and revolves around the sun, at one point, this idea was extremely outlandish. How could the planet move and we not feel it? Thanks to a few clever scientists, the Earth in Motion theory became more than a wild idea.

What Is Earth in Motion?

Earth in motion refers to the understanding that Earth is not stationary but moves in different ways. Earth rotates on an axis and revolves around a star. 

Earth’s Rotation

Earth rotates on its axis , which is an imaginary line running from the North Pole to the South Pole. This rotation is responsible for the day-night cycle, with one complete rotation taking about 24 hours.

Earth’s Revolution

Earth revolves around the Sun, completing one orbit approximately every 365 days. This revolution, combined with the tilt of the Earth's axis, leads to the changing seasons.

Who Discovered Earth's Motion?

The discovery and acceptance of Earth's motion was a gradual process involving several key figures in the history of science.

Aristarchus Hypothesis of Earth’s Motion

An ancient Greek astronomer, Aristarchus of Samos, was one of the first to suggest that Earth orbits the Sun . This view was not widely accepted in his time as it was believed Earth was the center of the Universe, and stars, planets, and the sun all revolved around our planet.

Copernicus Creates the First Model of Earth’s Motion

Mathematician and astronomer Nicolaus Copernicus is often credited with proposing the first heliocentric model of the universe. In 1543, he published his great work, On the Revolutions of the Heavenly Spheres , which explained his theories. 

Among them was that day and night was created by the Earth spinning on its axis. Copernican heliocentrism replaced the conventionally accepted Ptolemaic theory , which asserted that the Earth was stationary. Copernicus’ work was largely unknown during his lifetime but later gained support.

Galileo Galilei’s Telescopic Observations

Galileo Galilei agreed with Copernicus’ theory and proved it through his telescopic observations. In 1610, he observed phases of Venus and the moons of Jupiter, which were strong evidence against the Earth-centered model of the universe.

Galileo agreed with Copernicus’ theory and proved it by using a telescope to confirm that the different phases Venus went through resulted from orbiting around the sun.

Johannes Kepler’s Planetary Laws

German mathematician Johannes Kepler formulated a series of laws detailing the orbits of planets around the Sun. These laws, which remain relevant today, provided mathematical equations for accurately predicting planetary movements in line with the Copernican theory.

Why Don’t We Feel Earth Spinning? 

According to researchers at the California Institute of Technology (CalTech), Earth spins smoothly and at a consistent speed. If Earth were to change speeds at any time, we’d feel it. 

Read More: Earth's Rotation Has Slowed Down Over Billions of Years

3. Electricity

Did benjamin franklin discover electricity.

It’s a common misconception that Ben Franklin discovered electricity with his famous kite experiment. But his 1752 experiment, which used a key and kite, instead demonstrated that lightning is a form of electricity . Another myth is that Franklin was struck by lightning. He wasn’t, but the storm did charge the kite. 

Who First Observed Electricity?

Back in 600 B.C.E., it was the ancient Greek philosopher Thales of Miletus who first observed static electricity when fur was rubbed against fossilized tree resin, known as amber. 

Who Invented Electricity?

British scientist and doctor William Gilbert coined the word “electric,” derived from the Greek word for amber. Regarded as the “father of electricity,” Gilbert was also the first person to use the terms magnetic pole, electric force, and electric attraction. In 1600, his six-volume book set, De Magnete , was published. Among other ideas, it included the hypothesis that Earth itself is a magnet.

Read More: Ben Franklin: Founding Father, Citizen Scientist

4. Germ Theory of Disease

What is the germ theory of disease.

Germ theory is a scientific principle in medicine that attributes the cause of many diseases to microorganisms, such as bacteria and viruses, that invade and multiply within the human body. This theory was a significant shift from previous beliefs about disease causation.

Who Invented the Germ Theory?

Louis Pasteur discovered germ theory when he demonstrated that living microorganisms caused fermentation , which could make milk and wine turn sour. From there, his experiments revealed that these microbes could be destroyed by heating them — a process we now know as pasteurization. 

This advance was a game changer, saving people from getting sick from the bacteria in unpasteurized foods , such as eggs, milk, and cheeses. Before Pasteur, everyday people and scientists alike believed that disease came from inside the body. 

Pasteur’s work proved that germ theory was true and that disease was the result of microorganisms attacking the body. Because of Pasteur, attitudes changed, and became more accepting of germ theory.

How Did Koch’s Postulates Contribute to Germ Theory?

The German physician and microbiologist Robert Koch played a crucial role in establishing a systematic methodology for proving the causal relationship between microbes and diseases .

He formulated Koch's postulates and applied these principles to identify the bacteria responsible for tuberculosis and cholera, among other diseases.

Together, Pasteur and Koch laid the foundation for bacteriology as a science and dramatically shifted the medical community's understanding of infectious diseases. Their work led to improved hygiene, the development of vaccines, and the advancement of public health measures.

Read More: Why Do Some People Get Sick All the Time, While Others Stay in Freakishly Good Health?

Who Discovered Gravity?

Isaac Newton didn’t really get hit on the head with an apple, as far as we know. But seeing an apple fall from a tree did spark an idea that would lead the mathematician and physicist to discover gravity at the age of just 23. 

He pondered about how the force pulls objects straight to the ground, as opposed to following a curved path, like a fired cannonball. Gravity was the answer — a force that pulls objects toward each other. 

How Does Gravity Work?

The greater the mass an object has, the greater the force or gravitational pull. When objects are farther apart, the weaker the force. Newton’s work and his understanding of gravity are used to explain everything from the trajectory of a baseball to the Earth’s orbit around the sun. But Newton’s discoveries didn’t stop there. 

Newton’s Laws of Motion

In 1687, Newton published his book Principia , which expanded on his laws of universal gravitation and his three laws of motion. His work laid the foundation for modern physics. 

Building on the discovery, advancements in the field of electricity continued. 

In 1800, Italian physicist Alessandro Volta created the first voltaic pile , an early form of an electric battery.

Einstein’s Theory of General Relativity

In 1915, Einstein proposed the theory of general relativity . This theory redefined gravity not as a force but as a curvature of spacetime caused by the presence of mass and energy.

According to Einstein, massive objects cause a distortion in the fabric of space and time, similar to how a heavy ball placed on a trampoline causes it to warp. Other objects move along the curves in spacetime created by this distortion.

Both Newton and Einstein significantly advanced our understanding of gravity. Their theories marked critical milestones in the field of physics and have had far-reaching implications in science and technology.

Read More: 5 Eccentric Facts About Isaac Newton

6. Antibiotics

Much like Germ Theory revolutionized modern medicine, so too did the invention of antibiotics. This discovery would go on to save countless lives.  

When Were Antibiotics Invented?

According to the Microbiology Society , humans have been using some form of antibiotics for millennia. It was only in recent history that humans realized that bacteria caused certain infections and that we could now provide readily available treatment. 

In 1909, German physician Paul Ehrlich noticed that certain chemical dyes did not color certain bacteria cells as it did for others. Because of this, he believed that it would be possible to kill certain bacteria without killing the other cells around it. Ehrlich went on to discover the cure for syphilis, which many in the scientific community refer to as the first antibiotic. However, Ehrlich referred to his discovery as chemotherapy because it used chemicals to treat a disease. Ehrlich is referred to as the “Father of Immunology” for his discoveries. 

Ukrainian-American microbiologist Selman Waksman coined the term “antibiotic” about 30 years later, according to the Microbiology Society.

Who Discovered Penicillin? 

One of the most recognizable antibiotics known today is penicillin. Health professionals prescribe millions of patients with this antibiotic each year. However, one of the most well-known antibiotics was discovered by accident. 

In 1928, after some time away from the lab, Alexander Fleming — a Scottish microbiologist — discovered that a fungus Penicillium notatum had contaminated a culture plate with Staph bacteria. Fleming noticed that the fungus had created bacteria-free areas on the plate. After multiple trials, Fleming was able to successfully prove that P. notatum prevented the growth of Staph. Soon the antibiotic was ready for mass production and helped save many lives during World War Two. 

What Is Penicillin Used For? 

Penicillin is used to treat infections caused by bacteria. The medication works by stopping and preventing the growth of bacteria. 

Read More: Antibiotic-Resistant Bacteria: What They Are and How Scientists Are Combating Them

7. The Big Bang Theory

The Big Bang Theory is one of the most widely accepted theories on the beginning of the universe. The theory claims that about 13.7 billion years ago, all matter of the universe was condensed into one small point. After a massive explosion, the contents of the universe burst forth and expanded and continue to expand today. 

Who Came Up With the Big Bang Theory?

This first mention of the Big Bang came from Georges Lemaître, a Belgian cosmologist and Catholic priest. Initially, in 1927, Lemaître published a paper about General Relativity and solutions to the equations around it. Though it mostly went unnoticed. 

Though many scientists didn’t believe that the universe was expanding, a group of cosmologists was beginning to go against the grain. After Edwin Hubble noticed that galaxies further away from our own seemed to be pulling away faster than those closer to us, the idea of the universe expanding seemed to make more sense. Lemaître’s 1927 paper was recognized, and the term Big Bang appeared in Lemaître’s 1931 paper on the subject. 

What Is the Hubble Space Telescope?

Edwin Hubble’s discovery that galaxies are moving away from our own, dubbed Hubble’s Law, is on a long list of his many discoveries. Though this discovery helped add evidence to the Big Bang Theory, this discovery was hindered by the same thing that had been distributing telescopes since their inception: Earth’s atmosphere. According to NASA , Earth’s atmosphere distorts light, limiting how far a telescope can see, even on a clear night. 

Because of this, researchers, specifically Lyman Spitzer , suggested putting a telescope in space, just beyond Earth’s atmosphere and into its orbit. After a few attempts in the 1960s and 70s, NASA, along with contributions from the European Space Agency (ESA), launched a space telescope on April 24, 1990 . The Hubble Space Telescope, named for the pioneering cosmologist, became the strongest telescope known to humankind until the 2021 launch of the James Webb Space Telescope . 

What Is The Cosmic Microwave Background?

The Big Bang emitted large amounts of primeval light , according to the ESA. Over time, this light “cooled” and was no longer visible. However, researchers are able to detect what is known as Cosmic Microwave Background (CMB), which is, according to the ESA, the cooled remnant of the first light to travel through the universe. Some researchers even refer to CMB as an echo of the Big Bang. 

Read More: Did the Big Bang Happen More Than Once?

8. Vaccines

“An ounce of prevention is worth a pound of cure,” Benjamin Franklin once said. A statement that, at the time, applied to making towns safer against fires. However, the same statement can  be true for health and wellness. The advent of vaccines has helped prevent several serious diseases and keep people safe. Thanks to vaccines, people rarely get diseases like polio, and smallpox has been eradicated . 

What Is a Vaccine?

According to the Centers for Disease Control (CDC), a vaccine is a method of protection that introduces a small amount of disease to the human body so that the body can form an immune response should that disease try to enter the body again. 

Basically, through a vaccine, the human body is exposed to a small out of a disease so that the immune system can build a defense against it. 

When Was the First Vaccine Created?

According to the World Health Organization (WHO), Dr. Edward Jenner created the first vaccine in 1796 by using infected material from a cowpox sore — a disease similar to smallpox. He inoculated an 8-year-old boy named James Phipps with the matter and found that the boy, though he didn’t feel well at first, recovered from the illness. 

A few months later, Jenner tested Phipps with material from a smallpox sore and found that Phipps did not get ill at all. From there, the smallpox vaccine prevented countless deaths in the centuries to come. 

When Was the Polio Vaccine Invented?

From 1796 to 1945, doctors and scientists worked hard to create vaccines for other serious illnesses like the Spanish Flu, yellow fever, and influenza. One of these doctors was Jonas Salk. After Salk helped develop an influenza vaccine in 1945, he began working on the Polio vaccine. Between 1952 and 1955, Salk finished the vaccine, and clinical trials began. Salk’s vacation method required a needle and syringe, though, by 1960, Albert Sabin had created a different delivery method for the polio vaccine. Sabin’s version could be administered by drops or on a sugar cube.

Read More: The History of the Polio Vaccine

9. Evolution

What is evolution .

Evolution is a theory that suggests that organisms change and adapt to their environment on a genetic level from one generation to the next. This can take millions of years through methods such as natural selection. An animal’s color or beak may alter over time depending on the changes in their environment, helping them hide from predators or better capture prey. 

Who Is the Father of Evolution? 

After studying animals in the Galapagos , particularly the finches, a naturalist named Charles Darwin determined that the birds — who all resided on different Galapagos islands — were the same or similar species but had distinct characteristics. Darwin noted that the finches from each island had different beaks. These beaks helped the finches forage for their main food source on their specific island. Some had larger beaks for cracking open nuts and seeds, while others had smaller and more narrow beaks for finding insects. 

These observations earned Charles Darwin the title of the Father of Evolution. Though the theory of evolution has changed since Darwin published On the Origin of Species in 1859, he helped lay the framework for modern scientists. 

Is Evolution a Theory or Fact? 

The long-held belief for thousands of years was that the world and all of its organisms were created by one power. But, as science has advanced, there is clear evidence to argue against that. 

The answer to this question is complicated because evolution is both fact and theory. According to the National Center for Science Education , scientific understanding needs both theories and facts. There is proof that organisms have changed or evolved over time, and scientists now have the means to study and identify how those changes happen. 

Read More : 7 Things You May Not Know About Charles Darwin

What Does CRISPR Stand For? 

According to the National Human Genome Research Institute, CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. Researchers use this technology to modify the DNA of a living organism. 

Who Discovered CRISPR? 

There are several people involved and decades of research into the discovery of CRISPR . These researchers include Yoshizumi Ishino, Francisco Mojica, and the duo who recently won the Nobel Prize in Chemistry for CRISPR, Jennifer Doudna and Emmanuelle Charpentier. 

What Is CRISPR?

CRISPR is a technology that can edit genes or even turn a gene “on” or “off.” Researchers have described CRISPR as a molecular scissors that clips apart DNA, then replaces, deletes, or modifies genes. According to a 2018 study, scientists can use this technology to help replace certain genes that may cause diseases such as cancer or heritable diseases like Duchenne muscular dystrophy — a degenerative disorder that can cause premature death.   

How Does CRISPR Work?

In short, scientists use CRISPR technology to find specific pieces of DNA inside of a cell. Scientists then alter that piece of DNA or replace it with a different DNA sequence. CRISPR technology also ensures that the changed gene passes on to the next offspring through gene drive. 

Read More: CRISPR Gene-Editing Technology Enters the Body — and Space

This article was originally published on Oct. 22, 2021 and has since been updated with new information from the Discover staff.

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12 experiments that changed the world

by Charlie Evans · 10/09/2018

Cavendish weighs the world

N ot only did the solitary and eccentric Henry Cavendish discover hydrogen, but he also successfully measured the weight of the world. His ambitious experiment used a special piece of equipment called a torsion balance, and in 1798 he reported his results. By measuring the gravitational attraction between two different sized lead spheres, he calculated the Earth’s density. The apparatus consisted of a 1.8-metre wooden rod that had a 0.73-kilogram lead sphere attached to each end, suspended from a wire. A separate system of two larger 159-kilogram lead balls were placed close to the smaller balls. This exerted enough gravitational force so that when the weights were tugged slightly the rod twists (a telescope was used to observe this). Cavendish performed his experiments in a dark and wind-proof to prevent any external air currents and temperature differences affecting his results. He was able to calculate the Earth’s density by using the ratios of the forces between the spheres and the gravitational attraction of the Earth to the spheres. Incredibly, his results were very accurate, and his great experiment meant we could also calculate the mass of the Sun and the Moon and even other planets in our Solar System.

Galileo Galilei and the Leaning Tower of Pisa Experiment

Imagine you drop a bowling ball from one hand and a feather from the other. Which will fall faster? It is obviously the bowling ball, but this doesn’t reflect the nature of the force of gravity. Greek philosopher Aristotle had proposed that objects fell at different rates because gravity would act more strongly on heavier objects, but it turns out that the feather falls slower only because of air resistance. If you could perform the same experiment in a vacuum, the feather and ball will hit the ground at exactly the same time. It is difficult to separate fact from legend, but the story goes that Aristotle’s theory of gravity went unchallenged until Italian polymath Galileo Galilei disproved it. Though he spent the last years of his life imprisoned for going against the popular beliefs of the time, his work on speed, velocity, gravity and free fall provided the foundations of the understanding of how the planets and Solar System moved. Hundreds of years after his death his experiment was repeated on the Moon – unsurprisingly, Galileo was right

Mendel’s peas

How do we inherit our genes from our parents? The answer was actually discovered not by studying humans but peas. Gregor Johann Mendel, an Augustinian friar, crossbred peas with differing characteristics in order to evaluate how different features were inherited in their offspring. His work focused on pea plants and their seven observable traits: the shapes of the pods and seeds; plant height; flower position; and seed, pod and flower colour.

The study took around eight years, in which time he observed some 28,000 pea plants. When looking at the colour of peas produced, Mendel found that different generations of plants expressed different ratios of green and yellow peas, with yellow being the dominant colour. He discovered that genes are paired and the mathematical pattern seen throughout generations caused their dominant and recessive expression. This pattern can also apply to the genetics that code for our eye and hair colour.

Fleming’s accidental discovery of penicillin

1928, at St Mary’s Hospital in London, Alexander Fleming was busy investigating the bacterium, Staphylococcus aureus. The bacteria had been wreaking havoc, causing fatal infections, and there was no medicine at the time to treat them. On one occasion, Fleming forgot to put one of his Petri dishes into an incubator.

 He noticed that a mould had a clear zone around it. He investigated and found that the mould had contaminated the dish, inhibiting the growth of the bacteria. England, 20th century While he was away on a two-week holiday the bacteria multiplied, and on his return he noticed something unusual in the rogue Petri dish. There was an area where the bacteria could not grow and instead left a ‘mould juice’ to form a clear Penicillium notatum. By the late 1930s, scientists Howard Florey and Ernst Boris Chain had managed to isolate and purify penicillin, and the antibiotic was available as an injection by 1941. It is estimated that this discovery has saved up to 200 million lives to date.

Pasteur uncovers the origin of cells

Back in the 1800s, people thought food spoiled and diseases were caused by ‘bad air’ or life spontaneously generating. Louis Pasteur didn’t – he rejected the idea that mice could be randomly created from rotting wheat and old cloth over a few weeks. After noticing that his own vats of beer were turning sour, Pasteur started analysing them only to discover they were swarming with bacteria. This convinced him that the spoiling of his brew was caused by these tiny microorganisms. He designed a simple experiment to prove his revolutionary germ theory, and as a result, disproved the idea that cells could come from nothing. So crucial was his work in the food and medicine industry that we even named a process after him – pasteurisation; the process of heat-treating something for a short time and cooling it down quickly to make it safe from bacteria.

Fermi’s nuclear reactor

After the atom was split and the term ‘nuclear fission’ was coined, physicist Enrico Fermi applied the principle to create the first self-sustaining nuclear chain reaction in a human-made reactor: Chicago Pile-1. Scientists were aware that a nuclear reactor would allow for the production of a weapon like nothing seen before. The outbreak of WWII meant that weapon production was a priority, a consequence of which was the birth of both the Manhattan Project and Fermi’s reactor. Once uranium-235 is hit with a neutron, the nucleus splits to form two smaller nuclei and more neutrons, which then go on to split other uranium atoms, thus forming a chain reaction. The reactor was made from stacks of graphite blocks to slow down fast uranium neutrons, increasing the likelihood of nuclear fission. This reaction needed to be controlled in order for it to be safe. Control rods made from cadmium were used to absorb the excess neutrons created from the nuclear fission. Adding or removing the rods could control the longevity of the chain reaction. This reaction produced large amounts of energy, which could then be harnessed for warfare.

Rutherford strikes gold

It was previously believed that the structure of the atom was a sphere of positive charge housing smaller negatively charged electrons within it, like plums within a pudding. To test the accuracy of this ‘plum pudding’ model — under the direction of Ernest Rutherford — Hans Geiger and Ernest Marsden performed a series of experiments between 1908–1913 to prove Rutherford’s theory of an atomic model, which resembled planets orbiting the Sun.

The physicists used a radioactive substance to bombard a thin piece of gold foil with positively charged alpha particles. The majority of particles passed through the foil without any deflection, suggesting that atoms had a great deal of open space.

However, some were deflected o the gold foil at different angles, which meant that those particular particles had hit something with the same charge. This meant that rather than a positive charge engulfing electrons, a smaller positive charge was held in the dense middle, thus heralding the discovery of the atomic nucleus.

Lavoisier and the conservation of mass

It was a French chemist named Antoine Lavoisier who formulated the concept of the conservation of mass – the idea that matter can neither be created nor destroyed, only rearranged. He did so by measuring the mass of reactants and products during chemical reactions. One of Lavoisier’s experiments entailed placing a burning candle inside a sealed glass jar. As the wick burned down and the candle melted, the weight of the jar and its contents remained the same, thereby proving his pioneering theory. At the time, chemists were exploring the formation of calx (an oxide), predicting that metals lost mass as they were burnt. Lavoisier countered this with the idea that calx was the result of atmospheric gas interacting with the metal. Rather than the metal losing mass, he found it gained weight by combining with oxygen from the air.

Lind cures sailors’ scurvy

Bleeding gums, your teeth dropping out, weak limbs, swollen legs and nasty patches of blood under your skin – a pirate’s life probably wouldn’t have been ideal for most of us. Scurvy was one of the diseases that plagued pirates and sailors in the early days of seafaring. We know today that the disease is caused by a serious lack of vitamin C, something we need to form collagen, a vital component in structural and supportive connective tissue. Without enough collagen, the blood vessels and bones of those with scurvy break down until they suer a slow and painful death. But in the time of Scottish physician James Lind, there was no knowledge about these tiny nutrients. People thought that scurvy might be contagious or caused by madness. In 1747, Lind started one of the world’s first clinical trials. He suspected that acids could help stop the putrefaction of the body, and he devised a trial to test dierent ways of introducing certain acids into people’s diets. He divided a group of 12 scurvy-ridden sailors into six groups of two, all of which were to eat the same diet as one another but with the addition of an acidic supplement. Each group was treated with either a quart of cider, 25 drops of elixir of vitriol, two spoonfuls of vinegar, half a pint of seawater, two oranges and one lemon, or a spice paste, every day. After six days most of the sailors eating the fruit had made an almost complete recovery. While Lind was on the wrong track about the cause of the disease, he had found the cure.

Scientific explanations in theoretical physics often remain just that, theoretical – but not all of them do. Albert Einstein published his general theory of relativity back in 1915, a criterion of which was that light bends near a massive gravitational force. However, Einstein was aware that should this or any of the other criteria required to support his revolutionary idea be disproven, then bang went the theory.

Einstein’s pioneering work remained a theory until an astronomer named Sir Arthur Eddington used an eclipse to prove light could be bent by gravitational forces. In order for Einstein’s theory to be correct, Eddington had to prove that the light had been bent by a source of intense gravity, such as the Sun.

A total solar eclipse in 1919 presented Eddington with a unique opportunity to witness the night sky during the daytime. After setting sail to Príncipe Island to get the best view of a predicted solar eclipse and test out Einstein’s theory, Eddington observed the locations of stars at night and then again under the false night of an eclipse. This meant that he could observe if the gravity of the Sun had altered the stars’ apparent positions, which in fact it had. This proved that light had been bent on its journey to Earth by way of the Sun’s gravity, meaning Einstein was correct.

The creation of graphene

From theory to reality

In 1964, particle physicist Peter Higgs proposed a theory as to how particles have mass. He suggested that empty space is occupied by a field termed the Higgs field, where particles pass through it and either collect mass, like an electron or don’t interact with it at all and remain massless, such as a photon.

An analogy would be a person moving through a crowd of strangers versus a crowd of friends.

Moving through of crowd of strangers, you would pass easily without stopping, whereas surrounded by friends you might stop to talk, taking you longer to make your way through. In this case, your friends would be the Higgs boson. The Large Hadron Collider fires two beams of protons in opposite directions and accelerates them to near the speed of light so they collide to release the boson and other subatomic particles. This became a reality on 4 July 2012.

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by Chris Woodford . Last updated: January 6, 2023.

Photo: There are always new theories to test and experiments to try. Even when we've completely nailed how Earth works, there's still the rest of the Universe to explore! Fourier telescope experiment photo by courtesy of NASA .

1: Galileo demonstrates that objects fall at the same speed (1589)

Photo: Galileo proved that different things fall at the same speed.

2: Isaac Newton splits white light into colors (1672)

Artwork: A glass prism splits white light into a spectrum. Nature recreates Newton's famous experiment whenever you see a rainbow!

3: Henry Cavendish weighs the world (1798)

Artwork: Henry Cavendish's experiment seen from above. 1) Two small balls, connected by a stick, are suspended by a thread so they're free to rotate. 2) The balls are attracted by two much larger (more massive) balls, fixed in place. 3) A light beam shines from the side at a mirror (green), mounted so it moves with the small balls. The beam is reflected back onto a measuring scale. 4) As the two sets of balls attract, the mirror pivots, shifting the reflected beam along the scale, so allowing the movement to be measured.

4: Thomas Young proves light is a wave... or does he? (1803)

Artwork: Thomas Young's famous double-slit experiment proved that light behaved like a wave—at least, some of the time. Left: A laser (1) produces coherent (regular, in-step) light (2) that passes through a pair of slits (3) onto a screen (4). If Newton were completely correct, we'd expect to see a single bright area on the screen and darkness either side. What we actually see is shown on the right. Light appears to ripple out in waves from the two slits (5), producing a distinctive interference pattern of light and dark areas (6).

5: James Prescott Joule demonstrates the conservation of energy (1840)

Artwork: The "Mechanical Equivalent of Heat"—James Prescott Joule's famous experiment proving the law now known as the conservation of energy.

6: Hippolyte Fizeau measures the speed of light (1851)

Artwork: How Fizeau measured the speed of light.

7: Robert Millikan measures the charge on the electron (1909)

Artwork: How Millikan measured the charge on the electron. 1) Oil drops (yellow) are squirted into the experimental apparatus, which has a large positive plate (blue) on top and a large negative plate (red) beneath. 2) X rays (green) are fired in. 3) The X rays give the oil drops a negative electrical charge. 4) The negatively charged drops can be made to "float" in between the two plates so their weight (red) is exactly balanced by the upward electrical pull of the positive plate (blue). When these two forces are equal, we can easily calculate the charge on the drops, which is always a whole number multiple of the basic charge on the electron.

8: Ernest Rutherford (and associates) split the atom (1897–1932)

Artwork: Transmutation: When Rutherford fired alpha particles (helium nuclei) at nitrogen, he produced oxygen. As he later wrote: "We must conclude that the nitrogen atom is disintegrated under the intense forces developed in a close collision with a swift alpha particle, and that the hydrogen atom which is liberated formed a constituent part of the nitrogen nucleus." In other words, he had split one atom apart to make another one.

Artwork: In Rutherford's gold-foil experiment (also known as the Geiger-Marsden experiment), atoms in a sheet of gold foil (1) allow positively charged alpha particles to pass through them (2) as long as the particles are traveling clear of the nucleus. Any particles fired at the nucleus are deflected by its positive charge (3). Fired at exactly the right angle, they will bounce right back! While this experiment is not splitting any atoms, as such, it was a key part of the decades-long effort to understand what atoms are made of—and in that sense, it did help physicists to "split" (venture inside) the atom.

9: Enrico Fermi demonstrates the nuclear chain reaction (1942)

Artwork: The nuclear chain reaction that turns uranium-235 into uranium-236 with a huge release of energy.

10: Rosalind Franklin photographs DNA with X rays (1953)

Artwork: The double-helix structure of DNA. Photographed with X rays, these intertwined curves appear as an X shape. Studying the X pattern in one of Franklin's photos was an important clue that tipped off Crick and Watson about the double helix.

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Don't want to read our articles try listening instead, find out more, on this website.

• Six Easy Pieces by Richard Feynman. Basic Books, 2011. This book isn't half as "easy" as the title suggests, but it does contain interesting introductions to some of the topics covered here, including the conservation of energy, the double-slit experiment, and quantum theory.
• The Oxford Handbook of the History of Physics by Jed Z. Buchwald and Robert Fox (eds). Oxford University Press, 2013/2017. A collection of twenty nine scholarly essays charting the history of physics from Galileo's gravity to the age of silicon chips.
• Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein Edited by Maurice Shamos. Dover, 1959/1987. This is one of my favorite science books, ever. It's a great compilation of some classic physics experiments (including four of those listed here—the experiments by Henry Cavendish, Thomas Young, James Joule, and Robert Millikan) written by the experimenters themselves. A rare opportunity to read firsthand accounts of first-rate science!

Text copyright © Chris Woodford 2012, 2023. All rights reserved. Full copyright notice and terms of use .

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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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