10 most important experiments that changed our world

What scientists and researchers have not done for the good of science. What crazy experiments they didn’t set to discover something new. All this can now cause a smile or, on the contrary, bewilderment due to the strangeness of what was happening, but then it was really important, and nobody knew that it would be strange. Nevertheless, we owe many of these experiments to what we now have. In this article, you are offered a selection of the strangest, most unusual, cool, and very important studies that have ever been conducted. Perhaps they led to the discovery of what you use in everyday life.

Scientific experiments

Even we, ordinary people, carry out experiments every day, the result of which affects our lives. For example, what will happen if you heat the cutlets in the microwave, not 40, but 50 seconds? Or what will happen if you go home wrong, but like that, will it be faster? Oddly enough, these are also experiments that help us understand the world. Scientists are doing about the same thing.

The most successful experiments change a lot and remain in history. We can say that this is a miraculous monument to our inquiring mind and the desire of mankind to move forward and conquer new scientific peaks.

Below I will give examples of successful experiments and even one scientific failure, which will show that not everything always goes as planned, even if the experiment was initially very cool.

Dimension of the World by Eratosthenes

This study was conducted at the end of the third century BC by an enthusiast – a scientist named Eratosthenes, born in 276 BC. in Cyrene (Greek settlement on the territory of modern Libya).


Eratosthenes constantly switched from one to another, as he was very addicted to people. At the same time, he worked as a librarian in the famous Alexandria Library. It was there that he conducted his famous experiment. He heard that in the city of Siena on the Nile River (modern-day Aswan), the midday sun shone directly, without casting a shadow, on the summer solstice. Intrigued, Eratosthenes measured the shadow cast by a vertical stick in Alexandria on the same day and time. He determined that the angle of sunlight there is 7.2 degrees or 1/50 of a 360-degree circle.

The Greeks knew that the Earth was spherical. Eratosthenes decided that knowing the distance between the two cities and the fact that the shadow angle is 1/50 of the full circle, we can multiply these two values ​​and get the circumference of the Earth. As a result, he got a figure of 45,700 kilometers. The actual circumference is approximately 40,000 kilometers.

Reading the accuracy of measuring instruments of that time and the fact that the distance between cities was determined with an error, we can say that its conclusion turned out to be very accurate, and the deviation is not so big. It was he who, carried away by such measurements, invented the science of geography, of which he is still considered the father.

Who discovered the pulse and blood flow

Many people spoke about blood and how it flows inside living organisms, including Galen, a Greek physician-philosopher, whose theory existed for about one and a half thousand years. But it wasn’t until 1628 that a different theory was published that changed everything.


It was published by William Harvey, who was the royal physician at the court of James I. Such work gave him time and money for research, which he enjoyed doing, sometimes performing very strange and even creepy experiments.

For example, Harvey publicly slashed animals to show that there was very little blood inside them. He also conducted experiments on snakes, showing that if you clamp the vessels that lead to the heart, then it shrinks and turns white, and if those that come out of it, then it swells. So he proved the flow of blood through the heart.

He also performed experiments on volunteers. In particular, blocking the flow of blood to the limbs in order to understand how it circulates through the human body.

As a result of his research, he concluded that blood flows in two circles, is formed in the liver from the food that people eat, and necessarily passes through the lungs, saturated with “spirit”. But in any case, it moves throughout the body, going into even the most remote corners of it.

He published his theory in 1628 in the book De Motu Cordis (Movement of the Heart). His evidence-based approach changed medical science and is today recognized as the father of modern medicine and physiology.

Who discovered genetics

A child always looks like his parents – from a slight resemblance to a full copy. Many people at all times wondered why this is necessary.


The answers to these questions began to appear about 150 years ago from a scientist who was born in the territory of the present Czech Republic in 1822. The parents of Gregor Mendel did not have money for the education of children and in 1843 he joined the August Order, a monastic group that emphasized research and education.

Hiding in a monastery in Brno, the shy Gregor immediately became interested in science. First, he tried to cross flowers, getting new shades and petal shapes. He was especially attracted by fuchsias. Then he switched to peas, carefully documenting his experiments and proving that when crossing green and yellow peas, yellow always turns out. However, crossing these two yellow “offspring” periodically produced green peas again.

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

The brilliance of Mendel’s experiments was that he formulated simple hypotheses that explain some things very well, instead of immediately solving all the difficulties of heredity. So he laid the foundations of genetics and gave modern scientists an excellent foundation for development.

How the color spectra of light were discovered
Isaac Newton during an outbreak of plague on his campus was waiting for an epidemic elsewhere and often went to the local market, where he got a children’s toy in the form of a prism. She just showed that light enters into it, and the output is a rainbow. That was all she could give, but Newton began to study her more closely and made an important discovery.

He proved that ordinary light breaks down into color spectra. This discovery made it possible to create a science called optics, which is an integral part of modern physics.

To prove that it was not a prism, he passed light through one prism, and one of the selected color streams through another. It did not change its color, so it was not a matter of the prism, and it could not change the light passing through it, coloring it.

In an original article in 1672, Newton did not fully describe the installation with which he worked, so his contemporaries tried their best to repeat the experiment, but they did not succeed. However, no one questioned the results, since they were very convincing.

Newton did many strange things, including delving into biblical numerology, the occult, and sticking needles in his eyelids, but all this did not stop him from making many important discoveries and immortalizing his name in history.

How light waves propagate

If you say something, then due to air vibration, sound is transmitted to the ears of the listener. If you throw a stone, then waves go through the water, but they always have an environment in which they move. Light travels through air, water, and even a vacuum.

This is what caused questions at the end of the 19th century. Nobody understood why there is no medium, but there is a movement of light. The only explanation was the existence of the luminiferous ether.

Working together at Western Case University in Ohio, Albert Michelson and Edward Morley set out to prove the existence of this ether. What they do is arguably the most famous failed experiment in history.

prism of light

The hypothesis of scientists was as follows: when the Earth revolves around the Sun, it constantly passes through the ether, creating the etheric wind. When the path of the light beam is moving in the same direction as the wind, the light should move slightly faster compared to going “against the wind”.

In the early 1880s, Michelson invented a type of interferometer, an instrument that combines light sources. A Michelson interferometer emits light through a one-way mirror. The light is split in two and the resulting rays move at right angles to each other. After some time, they are reflected from the mirrors back to the central meeting place. If light rays come at different times due to some kind of distortion (say, from the ether wind), they create a characteristic interference pattern.

The researchers protected their device from vibration by placing it on a solid sandstone slab and insulating it in the basement of the campus building. Michelson and Morley slowly turned the slab, expecting to see interference patterns when the light beams synchronized with the direction of the ether, but the speed of light did not change.

As a result, the experiment failed, but the scientists did not give up and in 1907 Michelson became the first American to receive the Nobel Prize for research based on optical devices. And doubts about the theory of ether laid the foundation for the research of many other scientists. Including this, it indirectly led to the discovery of the theory of relativity by Albert Einstein.

The Marie Curie experiment

Marie Curie is one of the few women whose names have been noted in large experiments.

Marie Curie

Born in Warsaw in 1867, she immigrated to Paris at the age of 24 in order to be able to continue studying mathematics and physics. There she met and married physicist, Pierre Curie. For all her talent and abilities, she most likely would not have established herself in academia if not for him. Moreover, it was she who put forward the main ideas in the area in which they made discoveries.

For her doctoral dissertation in 1897, Marie began researching a newfangled form of radiation, similar to X-rays, discovered just a year earlier. Using an instrument called an electrometer, created by Pierre and his brother, Marie measured the mysterious rays emitted by thorium and uranium. Regardless of the mineralogical composition of the elements (one was a yellow crystal, and the other was a black powder), the radiation intensity varied exclusively depending on the amount of the element itself.

Curie concluded that radioactivity – the term she coined – was an intrinsic property of individual atoms, resulting from their internal structure. Up to this point, scientists considered atoms elementary and indivisible. Marie opened the door to understanding matter on a more fundamental, subatomic level.

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

What is a Pavlov’s dog

Probably, this experiment is the most common noun and the word “Pavlov’s dog” is often used when talking about a habit.

Pavlov dog

Russian physiologist Ivan Pavlov even won the Nobel Prize in 1904 for his work with dogs, researching how saliva and gastric juices digest food. The study may seem strange and insignificant, but it was it that answered many questions related to digestion.

Pavlov and his students conducted an experiment with a group of dogs. First, they showed food, and then fed them, and the second group joined at a later stage of the experiment. As a result, it turned out that those dogs who knew that after they saw food, they would receive it, began to produce saliva and gastric juice in advance. The second group did not show such a result.

Later, the experiment was repeated with symbols that the dogs saw before feeding. For example, an illuminated light. As a result, it was found that the production of saliva and gastric juice is reflex and does not depend on conscious action.

The experiment also showed that reflexes can be conditioned and unconditioned. That is, not all reflexes are “sewn” into the body from the very beginning and can be acquired as it develops. An attempt to abandon such acquired reflexes now underlies many types of therapy.

Is an electron a particle of charge

The twentieth century was a tumultuous time for physics: in just over ten years, the world became familiar with quantum physics, special relativity, and electrons – the first proof that atoms have divisible parts.

It was necessary to understand whether the electrons are charge carriers. Then Robert Millikan joined the case, who before that had not achieved special heights in physics.

In his laboratory at the University of Chicago, he began working with containers of thick water vapor, called cloud chambers, and altering the strength of the electric field inside them. Clouds of water droplets formed around charged atoms and molecules before descending by gravity. By adjusting the strength of the electric field, he could slow down or even stop the droplets from falling by counteracting gravity with electricity.

Later, Millikan and his students realized that it was difficult to work with water, as it evaporates quickly. In the end, they switched to oil, which was sprayed with a perfume spray.

Increasingly sophisticated experiments with oil droplets ultimately determined that the electron is indeed a unit of charge. They appreciated its significance with great precision. It was a revolution for particle physics

How particles form waves

Do you think light is a particle or a wave? Many scientists have emphasized that light is a particle-based on Newton’s experiments with prisms. But Thomas Young’s evidence destroyed that belief.

Young was interested in everything from Egyptology (he helped decipher the Rosetta Stone) to medicine and optics. To investigate the essence of light, Young prepared an experiment in 1801. He made two thin slits in an opaque object, passed sunlight through them, and watched the rays cast a series of bright and dark stripes on the screen. Young explained the different sections by the fact that the light propagates in waves, like ripples on a pond, with ridges and hollows from different light waves, amplifying and compensating each other.

Although modern physicists at the beginning rejected Young’s conclusions, the repetition of his experiments with two slots showed that light particles really move like waves. Further experiments proved that such a propagation of light is possible only if the particles move like waves. This discovery and its features, among other things, underlie quantum physics.

Proof of the Prosperity of Species

By the 1960s, environmentalists had come to an agreement that habitats thrive mainly on the basis of the diversity of species in them. It was believed that a change in the ratio of representatives of these species does not lead to a change in the entire habitat. But Robert Payne did not agree with this.

Payne conducted his experiments with the exclusion of starfish from tidal basins along the coast of Washington. It turned out that the destruction of this single species can destabilize the whole ecosystem.


Without starfish, mussels began to absorb their prey, greatly increasing their population. This led to the fact that they began to displace algae and take their place. As a result, the entire ecosystem has simply turned into a hotbed of mussels.

Payne’s discovery had a great impact on the conservation of species of living organisms, proving that it is necessary to preserve not individual species, but entire ecosystems.

So Payne’s discovery turned his eyes on the whole system of interaction of living organisms. He died in 2016 and in recent years has worked hard to study the influence of humans on the extinction of species, including due to global warming.

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Author: Julia Harris
Graduated from Stanford University. Previously, he worked in various free news media. Currently, it is a columnist of the economy section in the Free News editors.
Function: Reporter

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