Nine famous scientific experiments in history

We conduct scientific experiments almost every day, such as trying a slightly different commute route, or heating food in a microwave oven for tens of seconds. Of course there are more advanced experiments, such as making a genetic variant, or finding the best key that might be the solution to a problem. In the final analysis, it is this spirit of search that has enabled mankind to make all the discoveries so far. The willingness to keep experimenting and exploring will help us to explore the essence of things more deeply through scientific recourse.

In showing the desire of human exploration, some experiments have completely withstood the test of time. Whether complex or rough, these often personal attempts with luck have brought human insights that can change our perception of ourselves and the universe. Here are nine very important scientific experiments in history, with a glorious failure.

Eratosthenes measure the earth
The experimental results measure the circumference of the earth for the first time

The end of the 3rd century BC

Eratosthenes measured the earth.

How big is the earth? Ancient cultures have many answers to this, and Eratosthenes ’amazingly accurate measurements in this area have influenced for centuries. Eratosthenes, born in Cyrene (an ancient Greek settlement on the coast of Libya today) around 276 BC, eventually became a polymath, which made him both admirable and dissent . According to the second letter of the Greek alphabet, some people refer to Eratosthenes as β (the meaning of “second child”). They think he jumps from one field to another faster than anyone in his generation, but his “shallow taste” makes him only the second child in every field he has been involved in. Some people also praised Eratosthenes as the all-around champion according to the ranking of the pentathlon in the ancient Greek Olympic Games.

Eratosthenes is undoubtedly a genius, he used to be the curator of the famous Alexander Library in Alexandria, Egypt. He heard that there is a well in the city of Seini (now the Egyptian city of Aswan) on the south side of the Nile because the sun at noon on the summer solstice in the northern hemisphere will not cast any shadows. Driven by curiosity, Eratosthenes measured the shadow cast by a vertical pole at noon on the summer solstice in Alexandria. He measured the angle of sunlight there as 7.2 °, which is 1/50 of 360 ° of the circumference. Many educated ancient Greeks knew that the earth was a sphere, and Eratosthenes was one of them. He thought: If he can know the distance between the two cities of Seini and Alexandria, then multiplying this distance by 50 should be the circumference of the earth. Knowing the distance between the two cities, he calculated that the circumference of the earth is 250,000 stades (the unit of length in ancient Greece and Rome, 1 stades is approximately equal to 182.9 meters), which is about 45,700 kilometers It falls within today’s accurate value-the allowable error range of 40,100 kilometers.

Eratosthenes’ motive for measuring the size of the earth was his love for geography. In fact, the subject of geography was named by him. Modern people call him “the father of geography”.

Harvey measures the pulse of nature
Experimental results found blood circulation

Published theory in 1628

Harvey measures blood circulation.

The blood flow model proposed by the ancient Greek medical scientist and philosopher Galin in the 2nd century AD is not correct, but it has been popular for nearly 1500 years. He proposed in this model: the liver continues to make blood with the food we eat; blood flows through the body through two separate pipes, one of which passes through the lungs, and the blood in this pipe carries the “Aura of Heaven”, while the human body The blood absorbed by the tissue will never flow back to the heart.

After a series of arguably horrifying experiments, this dogma was finally overthrown. Harvey, a British scientist born in 1578, later became the medical doctor of King James I of England, which gave him time and money to pursue his interest-anatomy. In order to verify whether Galin’s blood circulation model is correct, Harvey first bleeds small animals such as sheep. He realized that if Galin ’s model was correct, the blood flow pumped by the heart per hour would exceed the volume of the animal itself, which is simply impossible.

To make him understand his challenge to Galin, Harvey dissected live animals in public and showed that there was not much blood flow in them. He also gripped the main vein of a snake tightly with his fingers, preventing blood flow into the snake’s exposed heart. As a result, the snake’s heart contracted and became pale, and only a small amount of blood spurted out of the snake’s heart. Conversely, blocking the cardiovascular system to prevent blood from flowing out causes the heart to swell. By studying the slowing of the heartbeat of reptiles and other animals when they are dying, Harvey discovered the contraction of the heart, inferring that the heart transports blood to the whole body through a circuit. You know, Harvey’s inference is quite simple-if you observe the normal beating of the heart in a normal environment, it is difficult to directly see the function of the heart.

Experiments with volunteers that temporarily blocked the blood flow to the limbs further proved Harvey’s breakthrough concept of a blood circulation model. In 1628, he published his theory of blood circulation in his book “Heart Exercise”. His research method of speaking with evidence greatly promoted the development of medicine. Today, Harvey is regarded as the father of modern medicine and physiology.

Mendel lays the foundation for genetics
Experimental results Basic principles of genetic inheritance

1855 to 1865

Mendel Pea Experiment (Write Intent)

The children look more or less like one or both of their parents. Is this accidental or inevitable? The major mystery behind the inheritance of this physiological characteristic was not cracked until more than 150 years ago. Mendel, who was born in today’s Czech Republic in 1822, has no distinguished background (he was born in a farmer’s family), and he has no money for formal education, but he is uniquely talented in physiology. At the suggestion of a professor, he joined the Austin Conference which advocates research and study in 1843. Mendel, who was invisible in a monastery, soon began to stay in the garden for a long time. The plants of the fuchsia (also called lantern begonia) were particularly noticed by him, because their exquisiteness hinted at a remarkable design of nature. It is likely that the Fuchsia Advent gave birth to Mendel’s famous series of experiments. He crossed different varieties of fuchsia to try to obtain a new single color or color combination. His repeated results show that the genetic law is working.

As Mendel cultivated pea plants, these rules became clear. He used a paintbrush to gently lighten the pollen of one pea plant on another pea plant. In this way, he accurately matched thousands of pea plants with certain traits in about 7 years. He carefully records how yellow peas and green peas are paired to always produce information such as yellow pea plants. Pairing these yellow offspring, 1/4 of their offspring are green peas. This ratio led Mendel to invent the terms “dominant trait” (take yellow as an example) and “recessive trait”, and these traits are controlled by the genes called today.

Mendel is a man who walks ahead of the times. His research was not noticed in his time, but decades later, when other scientists discovered and repeated Mendel’s series of experiments, these experiments were finally admitted to be breakthrough. The innovation of Mendel’s series of experiments is that the simple hypothesis he formed can explain some phenomena well, rather than explain all the complexity of genetics at once. In other words, Mendel’s excellence is that he put everything he can to a research project.

Newton pioneered optics
Experimental results The essence of color and light

1665 to 1666

Newton (left) prism experiment.

Before becoming the inventor and distinguished scientist of the laws of motion, calculus and the law of gravity, the “ordinary” Englishman Newton found that he needed to pass the time. In order to escape the deadly plague that broke out at Cambridge University (Newton’s school), Newton spent all day at his childhood home in the English countryside, playing with a “children’s toy”-a prism he picked up at the local market.

By letting sunlight penetrate a prism, you get a rainbow (color separation spectrum). In the Newtonian era, the popular view was that the color of light came from the medium through which the light traversed, just as sunlight penetrated stained glass. Because he did not believe this point of view, Newton conducted a prism experiment to prove that color is an inherent characteristic of light itself. This breakthrough understanding created an optical discipline that is important to modern science and technology.

The Newton Prism experiment is not simple, but Newton is very skilled in the design and execution of this experiment. He drilled a hole in a blind, allowing a beam of sunlight to penetrate two prisms in sequence. By preventing the color formed by sunlight from penetrating the first prism from reaching the second prism, he proved that different colors refract through the prism in different ways. Then, he picked out and let only one color from the first prism pass through the second prism. As a result, this color did not change after the second prism was drilled. That is, the medium has no effect on the color of light, or the light itself has color.

Perhaps it is because the conditions of Newton’s prism experiment are too characteristic of his family, plus his incomplete introduction of his prism experiment in a 1672 paper, so his contemporaries just started to have difficulty replicating his prism Experimental results. In fact, the technical complexity of the Newton Prism experiment is quite high, but the experimental results are very convincing.

Newton’s talents and weirdness in his experimental methods played an important role in his achievement of his name. He once stared at the sun for a long time, almost blinding him. Another time, he put a long, thick needle under his eyelids to see how this would affect his vision. Newton also fell into the myth of mysticism. However, these did not prevent his fame. (The above attempts readers must not imitate)

Michael Sun, Morey and Ether
Experimental results

Time 1887

Michelson (left) and Molly’s ether experiment.

You say “Hi!” And the sound wave travels through the air into the listener’s ear. Ocean waves also move in their own medium-seawater, with the exception of light waves-in a vacuum without medium, light can propagate from here to there. Why is this happening? According to the popular saying in the physics community at the end of the 19th century, the answer is a ubiquitous invisible medium (so-called “luminous ether”). At that time, at the site of Case Western Reserve University in Ohio, USA, physicists Michael Sun and Morey set out to prove the existence of the ether. This led to what some scientists consider to be the most famous failed experiment in history.

At that time, scientists assumed that as the earth orbits the sun, the earth often travels through the ether, and ether wind is generated. If the beam travels in the same direction as the ether wind, then the beam will move faster than if the beam deviates from the direction of the ether wind. To test this conjecture, despite being tested on a micro scale, Michael Sun was at the right time. In the early 1980s he invented an interferometer. It can combine multiple light sources together to create an interference pattern like ripples on the surface of a pond. The Michael Sun interferometer passes a beam of light through a one-way mirror (also called a single-sided mirror). The beam is divided into two and travels at a certain angle. After a certain distance, the two beams of light reflect from the different mirrors they reach and head towards a central meeting point. If a certain displacement in the process of traveling (such as traveling in the ether wind) is different, then the time for the two beams to reach the confluence point will be different, which will form a unique interference pattern.

To avoid vibrations, Michael Sun and Morey placed their interferometer devices on a solid sandstone slab. The slate and interferometer device floated almost frictionlessly in a mercury tank, and the entire experimental device was placed in the basement of a campus building. They slowly rotate the stone slabs, expecting to observe interference patterns that occur as the beam enters and leaves the direction of the ether wind simultaneously, however, they do not observe such patterns. In other words, the speed of light has not changed.

Neither Michael Sun nor Morey fully grasped the importance of this “no result” experimental result. They attributed the result to an error in the experiment, after which they gave up the experiment and went on to other projects. In 1907, Michael Sun became the first Nobel Prize winner in the United States because of research results based on optical instruments. Michael Sun and Morey’s unintentional blow to the ether theory triggered a series of more in-depth experiments and theories, which eventually led to the breakthrough new paradigm of light proposed by Einstein in 1905, the special theory of relativity. This theory excludes the possibility of static ether.

Madame Curie explores matter
Experimental results define radioactivity

Time 1898

Madam Curie.

There are really not many women entering the chronicle of the legendary scientific experiment, which reflects the historical exclusion of women in scientific research, but Mary Curie broke this model. Mary was born in Warsaw, Poland in 1867. At the age of 24, she moved to Paris, France in order to get the opportunity to further study mathematics and physics. Here, she met and eventually married in the home of physics. As an intimate intellectual partner of Mary (Mrs. Curie), her husband Curie helped Mary’s pioneering ideas to gain a foothold in the male-dominated scientific field. It can be said that without Curie, Mary would never be accepted by the scientific society. We must admit that all the basic hypotheses that guide the future investigation of the nature of radioactivity were proposed by Mary.

Most of the time, Curie and Mary were buried in an improved shed on the campus where Curie worked. For the doctoral thesis in 1897, Mary began investigating a new type of radiation similar to X-rays that was discovered only a year ago. Using an electrometer developed by Curie and his brothers, Mary measured the mysterious rays emitted by thallium and uranium, and finally concluded that the radiation emission had nothing to do with the molecular structure of the substance. In contrast, radioactivity (the term proposed by Mary) is an inherent characteristic of a single atom, and radioactivity is emitted from the internal structure of the atom. Before Mary made this inference, scientists had always thought that atoms were the most basic and indivisible entities. Mary knocked on the door to the path to understanding matter at a more basic subatomic level.

Mary became the first female winner of the Nobel Prize in 1903. She was also one of the very few women who won the Nobel Prize twice in 1911 due to the discovery of elemental radium and elemental plutonium. Scientists say that Mary used her life and achievements to become a female role model who intends to start a scientific career.

Pavlov subverts tradition
Experimental results found conditioned reflex

Time from the 1990s to the 20th century

Pavlov and his experimental scenario.

The Soviet physiologist Pavlov won the Nobel Prize in Physiology or Medicine in 1904 because he used dogs to study how saliva and gastric juice digest food. Although his scientific heritage will always be linked to the dog’s haraz (saliva), the fact that made him so famous so far is his research on the mental functioning of dogs, humans, and other animals.

Measuring gastric secretions is not easy. Pavlov and his students collected secretions from the digestive organs of dogs by hanging test tubes over the mouths of some dogs to collect saliva. They noticed that once the feeding time came, even if they hadn’t tasted a bite of food, the dogs put into the test began to saliva. Like many other bodily functions, the production of saliva is considered to be a reflex of the time, that is, an unconscious action that occurs in the presence of food, and Pavlov ’s dogs learned to associate the appearance of the experimenter with The delicious food is linked, which means that the dog’s experience will affect their physiological response.

Prior to this study by Pavlov, animal reflexes were considered to be static, but Pavlov’s research proved that animal reflexes can be altered by animal experiences. The Pavlovian team then taught the dog to associate food with various neutral stimuli such as buzzers, metronome, spinners, black squares, whistle, flashing lights and electric shock. The results of their research form the conceptual foundation of classical reflection (ie Pavlovian conditional reflection). Scientists point out that Pavlov’s conditioned reflex has always existed in humans, and our brain has been connecting all kinds of things we experience. Cracking these conditioned reflexes is the strategy behind modern treatments for addiction and PTSD.

Millikan catches the charge
Experimental results Determination of single electron charge

Time 1909

Millikan and his oil drop experimental device.

By most standards, Millikan did a beautiful job. He was born in Millikan, a small town in Illinois, USA in 1868, and obtained degrees from Oberlin University and Columbia University. He then studied physics in Germany with European masters of science. He then joined the Department of Physics at the University of Chicago, and he even wrote several very successful textbooks.

His colleagues are prettier than he is. The turn of the 19th and 20th centuries was the golden age of physics: in less than 10 years, concepts such as quantum mechanics, special theory of relativity, and electrons appeared. For the first time, electrons are known, and they provide the first evidence that atoms can be subdivided. The discovery of electrons also provides scientists with an opportunity. A question that scientists had been puzzled at the time was: Does the electron represent a basic unit of charge? To develop particle physics, it is important to determine the answer to this question. Millikan found an opportunity to show his talents.

In his laboratory at the University of Chicago, Millikan began to study multiple containers (so-called “aerosol chambers”) containing dense water vapor. The electric field strength in each aerosol chamber was different. The droplets formed around charged atoms and molecules form an aerosol, which then falls. By adjusting the strength of the electric field, Millikan can use electricity to counteract the gravitational force, thereby slowing or even preventing the landing of a single droplet. Finding the exact balance of force between electricity and gravity, and assuming this force is constant, can reveal the amount of charge.

Because water evaporates too quickly, Millikan and his students (they are often behind the scenes of science) switch to another substance that can last longer: oil. They use a perfume atomizer to allow oil to enter the aerosol chamber. More and more complicated oil drop experiments finally proved that electrons do indeed represent charge units. Their estimate of the meta-charge (basic electricity) is almost the same as the currently identified meta-charge-1.602 × 10-19 library. For Millikan, this is a major contribution to particle physics.

Millikan’s oil drop experiment is undoubtedly an outstanding experiment. His experimental results undoubtedly proved the existence of electrons, and quantified the elementary charge. The journey of thousands of miles after particle physics is precisely at the foot of Millikan’s meta-charge.

Yang, Davidson and Jemer have the same work
Experimental results found that the wave-particle duality of light

Time 1801 and 1927

Thomas Young and the double-slit experiment.

Is light a particle or a wave? Many physicists who have been troubled by this problem for a long time tend to think that light is a particle after Newton ’s optical experiments, but a basic but powerful experiment by British scientist Thomas Young overturned this traditional understanding.

From Egyptology to medicine to optics, Yang’s interests are broad. To explore the nature of light, Yang designed this experiment in 1801. He made two thin slits in an opaque object, and let sunlight pass through the slits, observing the series of light and dark lines that the light beam cast on a screen. Yang speculates that this pattern originates from the light spreading out like a wave, just like the ripples passing through the pond, the peaks and troughs of different light waves are amplified or canceled each other.

Although physicists at the same time completely denied Yang’s discovery at the beginning, a large number of repeated double-slit interference experiments proved that the particles of light really moved like waves. The double-slit interference experiment is relatively easy to perform, which provides objective conditions to prove the seemingly difficult conclusion of the wave-particle duality of light. More than 100 years later, experiments by American physicists Davidson and Jemer showed that the wave-particle duality of light is of great significance. In what is now called the Nokia Bell Labs in New Jersey, the two physicists let electrical particles bounce off a nickel crystal, and the pattern generated by the interaction of scattered electrons is only when these particles behave like waves Only under the formation. Later, double-slit experiments using electrons proved that each particle and light particle behaves like particles and waves. This contradictory idea is precisely the core of quantum physics, and in the era of Davidson and Jammer, quantum mechanics has just begun to explain the behavior of matter at a basic level.

Scientists point out that these experiments prove that, fundamentally, the matter in the world, whether it is radiation or seeming entities, has certain wave-like characteristics that cannot be reduced and are inevitable. No matter how amazing or counterintuitive this may seem, physicists must incorporate this “ripple” into their thinking.

Payne and Starfish
Experimental results The key species have an important impact on the ecosystem

Time 1966

Payne and his starfish experiment.

By the 1960s, ecologists began to reach a consensus: the prosperity of biological habitats is mainly achieved through diversity. Observations of large and small animal interaction networks suggest that this is indeed the case, but American biologist Payne has a unique way to explore the truth. He was curious about this: what would happen if he intervened in an ecological environment? He set his starfish exile experiment site in a tidal pool on the rugged coast of Washington State, USA. His experiments have shown that even removing only the starfish species from the pond may leave the entire pond ecosystem unbalanced. Without the starfish control, the starfish’s prey, barnacles, breeds wildly, but then it is swallowed up by the mussels waiting for the opportunity. The mussels then began to drive away the limpets and seaweed species. As a result, the food chain was broken, leaving only ponds dominated by mussels.

Payne called the starfish a key species. This innovative concept means that not all species contribute equally in a particular ecosystem. Payne ’s discovery is of great significance for species conservation—the narrow approach of protecting a single species to protect a single species was eventually abandoned and replaced with a management strategy based on the entire ecosystem.

Jane, a marine ecologist at the University of Oregon, commented that Payne ’s influence is absolutely subversive. Fifty years ago, Jane and a professor at the University of Oregon (Jane’s husband) were Payne graduate students in the University of Washington laboratory. Jane served as the Director of the United States Atmospheric and Oceanic Administration from 2009 to 2013, during which time Payne ’s key concepts influenced fisheries management policies. Both Jane and her husband believe that Payne’s persevering search and curious personality have brought great changes to ecology. Payne has died in 2016. His later work is to explore the profound impact of human beings as a super key species, changing the earth ’s ecosystem through climate change and uncontrolled hunting and killing of animals.

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