The most famous science experiments

Whether you’re just curious or if you want to win the next pub quizz / trivia night, this article is for you !

I had the idea for it last week while watching TV, when “the Milgram experiment” was mentioned. Scientists are usually aware of those well-known studies, but not everyone is. So get ready for a recap of the most famous science experiments that ever happened !

1) Pavlov’s dogs

Ivan Pavlov was a Russian experimental neurologist and physiologist who lived from 1849 to 1936. He gained fame for his research on classical conditioning, which he discovered through his experiments on dogs.

Pavlov was one of the first scientists to demonstrate the relationship between environmental stimuli and behavioral responses.

He was working on the gastric function of dogs at the time. During his experiment, he noticed that dogs began to salivate when they saw the technician that normally fed them, not when they saw food. He later experimented with different stimulus : sounds, electric shocks (that’s not very nice Ivan) and the infamous bell. Pavlov concluded that if a particular stimulus in the dog’s surroundings was present when the dog was given food, then that stimulus could become associated with food and cause salivation on its own. And voilà !

He got a Nobel Prize for his discovery. What’s interesting and the reason of his fame is that the fundamentals of classical conditioning have been examined across many different organisms, including humans. The basic principles of Pavlov’s theory have extended to a variety of settings, such as classrooms and learning environments. Our brains constantly create links between external stimuli and our behavior, an effect of “Pavlovian conditioning”.

2) Lavoisier and the conservation of mass

Antoine-Laurent Lavoisier was a French chemist who was central to the 18th-century chemical revolution and who had a huge influence on both the history of chemistry and biology.

He revolutionized the field of chemistry by introducing a new approach to laboratory analyses (which replaced the previously disorganized methods). His groundbreaking work in establishing the foundational principles of modern chemistry earned him recognition as one of the pioneers of the science.

His most famous experiment was the one that culminated in the Law of the Conservation of Mass discovery. Basically, Lavoisier stated in 1789 that mass is neither created nor destroyed in chemical reactions. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.

The concept of mass conservation is widely used in many fields such as chemistry, mechanics, and fluid dynamics, although it had to be modified a bit in order to “comply with the laws of quantum mechanics and special relativity under the principle of mass–energy equivalence” according to Wikipedia (don’t come at me, quantum physics is not my area of expertise).

3) Mendel and his pea plants

Gregor Johann Mendel was a nineteenth-century Czech monk (yes, monks can also be scientists) who discovered the basics of genetics through pea plants experiments in his monastery’s garden (yes, you really can make science anywhere).

Mendel played around with several characteristics of pea plants like plant height, pod shape and color and conducted simple hybridization experiments. The results were the foundations of what we now call “Mendelian inheritance or Mendelism“.

He was the one that discovered that some alleles are dominant while others are recessive and that an organism with at least one dominant allele will display the effect of the dominant allele. That is why he is believed to be “the father of modern genetics” (which is pretty impressive for someone playing with pea plants in his garden).

Subsequently, we now call “mendelian trait” a characteristic whose inheritance follows Mendel’s principles, meaning that the trait depends only on a single locus, whose alleles are either dominant or recessive.

4) Milgram’s experiment

Stanley Milgram was an American psychologist, born in 1933. His most noted work is his controversial experiments on obedience, conducted in the 1960s when he was a professor at Yale.

His inspiration for the experiment comes from the Nazi war criminals trials that took place after WW2. At that time, many criminals defended themselves by saying that they “just followed orders“. Milgram got curious and decided to test the depth of this defense.

The goal was to measure the willingness of study participants to obey an authority figure, especially when this figure instructed them to perform acts conflicting with their personal conscience. When you think about it, it really is an incredibly interesting psychosocial question.

The experiment was designed with 3 participants :

• The Experimenter was in charge
• The Teacher was a volunteer believing to be assisting (but “teachers” were actually the subjects)
• The Learner was an actor who pretended to be a volunteer

The procedure was simple : the experimenter, acting as figure of authority, asked the teacher to deliver (fake) electric shocks to the learner when he gave wrong answers.

The teacher could not see the learner but could hear him, and the shock generator included verbal markings that vary from “Slight Shock” to “Danger: Severe Shock”. They had sounds corresponding to the various shock levels, with screams and audible protests. The experimenter had a script to follow in case of reluctance, answering like “It is absolutely essential that you continue” or “You have no other choice; you must go on”.

Every psychologists that Milgram consulted before the experiments said the same thing : only a small percentage of participants would go until the final level. I mean, you cannot force ordinary people to willingly hurt a stranger, right ? Right ?

No. A majority of participants carried on the experiments until the end. Although all of them paused the experiment at least once to question it, most continued after being reassured by the experimenter.

In Milgram’s own words :

“The extreme willingness of adults to go to almost any lengths on the command of an authority constitutes the chief finding of the study and the fact most urgently demanding explanation. Ordinary people, simply doing their jobs, and without any particular hostility on their part, can become agents in a terrible destructive process. Moreover, even when the destructive effects of their work become patently clear, and they are asked to carry out actions incompatible with fundamental standards of morality, relatively few people have the resources needed to resist authority.“

Makes you think, eh ?

5) Newton’s apple

Isaac Newton was an incredibly talented scientist that lived from 1643 to 1727. He made quantity of contributions to science, whether it was in maths, chemistry or physics.

However, he is commonly associated to a simpler thing : watching an apple fall.

In 1666, Newton was peacefully in his garden in Linconlnshire, England. He saw an apple fall from one of his trees, which prompted him to think about a theory he actually had in mind for a long time : what is gravity, and how far it expands ?

That is where his theory of gravitation comes from. Newton’s law of universal gravitation says that “every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers”.

It’s still a law widely used today. In science, never overlook the little things !

6) Fleming and Penicillin

Sir Alexander Fleming is perhaps one of the most important scientist of the 20th century. He shaped the future of biology and medecine by being the one to discover the first ever antibiotic. And it was by accident ! He also was the one to discover lysozyme and also by accident. Talk about luck (and more importantly : intelligence to investigate the accidental findings).

Fleming is a great example for all scientists for 2 reasons :

• He is proof that every results, even unexpected or negative, are useful information and should be taken into consideration
• He is also a great example for those of you that are incapable of keeping a clean bench during your experiments : if Fleming was tidy, he would not have discovered Penicillin ! Yup.

So, back to Fleming : as I said, Fleming was not a tidy researcher and usually expected unusual bacterial growths in his culture plates. In 1928, he was working on the bacteria Staphylococcus aureus and inoculated several agar plates.

He then just… left on vacation while leaving everything in his bench ? Obviously history proved me wrong, but damn as a Lab Manager I am perplex.

When returning to the lab afterwards, Fleming saw that one of his agar plates had been contaminated by a fungus. As he inspected it more closely, he noted that the bacteria directly around the fungus had been destroyed.

He investigated the fungus and its anti-bacterial effect on many organisms, and noticed that it affected bacteria such as staphylococci and many other pathogens. Thus, Penicillin was discovered, and modern medicine was forever changed.

As much as it pains to say that as a Lab Manager : a messy bench ended up being the start of one of the world’s greatest scientific discovery, and saved millions of lives (please don’t remind my lab members of that fact).

7) Jenner and the first vaccine

Edward Jenner was an English scientist who discovered the concept of vaccines and created the smallpox vaccine, the world’s first vaccine, in 1796. He is basically the founder of the concept of immunology, and through his work participated in saving countless of lives.

Inoculation was already known at the time, but it was dangerous and inconsistent. Jenner’s idea was to try to induce immunization with a close, but less virulent organism than the lethal one. In the case of smallpox, it was cowpox.

His experience was pretty simple : he infected his gardener’s son with cowpox, which just gave him a small fever and some uneasiness. He afterwards confronted the boy with smallpox material, and no disease followed.

Thus, the first vaccine was born ! Fortunately, otherwise it would have been awkward with Jenner’s gardener…

8) Pasteur(ization)

After the father of modern genetics, let’s talk about one of the “fathers of microbiology” (with Robert Koch), aka Louis Pasteur. He was a French scientist born in 1822, renowned for his incredible discoveries of the principles of vaccination and pasteurization (yeah, just that).

• Vaccination : another story of lucky (or accidental) findings ! Pasteur was researching chicken cholera disease. He advised his assistant to inject chicken with fresh bacteria, before going on holidays. His assistant forgot, and used an old bacterial broth instead. After noticing that the chicken were less sick, he injected them with fresh bacteria and saw that this time, they did not get sick at tall. Conclusion : weakened bacteria caused the chickens to become immune to the disease.
• Pasteurization : as he noticed that micro-organisms were responsible for spoiled beverages, Pasteur invented the pasteurization technique : heating a liquid to a temperature between 60°C and 100°C will kill most bacteria and fungi already present in them. This method is still used to this day for beer, milk and countless other products.

The difference between smallpox vaccination by Jenner and chicken cholera vaccination was that the latter organism had been artificially weakened, so a naturally weak form of the disease organism did not need to be found.

This discovery revolutionized work in infectious diseases, and Pasteur changed the medicine world by laying the foundations of hygiene with his understanding of the causes and preventions of diseases.

9) Galileo (Galilei)

Galileo revolutionized the concept of astronomy by being one of the first to use the telescope for scientific observations of celestial objects.

In 1615, Galileo’s observations made him notice that our universe consisted in Copernican heliocentrism (Earth rotating daily and revolving around the Sun), instead of the Earth being at the center of the universe.

The Catholic Church was not happy about that, and 15 years later, Galileo was convicted as he refused to revoke his theory, and spent the rest of his life on house arrest.

We do not have a lot of benefits as scientists, but at least we’re (usually) not at risk of being arrested for our findings now.

10) The Stanford Prison Experiment

I included this one as it is pretty well-known, however it is controversial and some people have stated that the results were influenced.

The Stanford Prison Experiment is an experiment conducted by Stanford University psychology professor Philip Zimbardo in 1971. Zimbardo’s primary reason for conducting the experiment was to focus on the power of roles, rules, symbols, group identity and situational validation of behavior that generally would repulse ordinary individuals (kinda similar to Milgram’s experiment).

The plan was to hire young men and to put them in a prison setting, meaning they were divided into “prisoners” and “guards” and left in a prison-like place.

Those volunteers selected to be “guards” were instructed to prevent prisoners from escaping. Over the following five days, psychological abuse of the prisoners by the “guards” became increasingly brutal. The “prisoners” were very quickly humiliated and abused. After another psychologist came to evaluate the conditions, Zimbardo was confronted and he ended the experiment on the sixth day.

Afterwards, the results were disputed as participants may have been receiving encouragement from researchers.

However, I do believe that Milgram’s and Zimbardo’s experiments, even flawed, were right in stating that we all have the capacity for to be evil, given the right circumstances. It has unfortunately been proved by history, countless of times…

Conclusion

All of those brilliant (for the most part) scientists paved the way to modern science and experiments. Thanks to them, we saw immense improvement in the fields of psychology, immunology, hygiene, astronomy and science in general.

So the lessons of these famous science experiments are : keep on being curious, investigating unexpected results, questioning findings and having a messy bench ! No please, don’t do the last one, your lab manager’s mental health will thank you !

If you liked this article, be sure to check my other science stories !