A scientific theory is a well-tested, comprehensive explanation of an important feature of nature supported by evidence and facts gathered over time (Oregon State). These theories are typically proposed by one scientist or researcher and then retested and reexamined over time by other scientists and researchers, who will either agree with and add onto the original theory or will find evidence against it and eventually debunk it.
Debunked scientific theories are these theories that were once widely accepted within the mainstream scientific community but nowadays are considered to be inaccurate descriptions of nature. Often times, these debunked scientific theories are only disproven when scientists and researchers work to retest the original theory and another theory emerges from this research to replace it as the norm. In this anthology, a series of famous debunked scientific theories, such as the Flat Earth Theory or the idea of Geocentrism, are given an in-depth look.
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Phrenology was a scientific movement that was founded in 1796 as neuroscience became more popular. One of the theories about the brain was that, every function that can be attributed to the brain such as personality traits like self-esteem and caution could be localized to a particular part of the brain. It was believed that these areas of the brain were dedicated to that single function alone. Because of this in an effort to understand the brain scientists tried identifying which pieces were responsible for which functions. This hypothesis was initially proposed in 1796 by Austrian physician Franz Joseph Gall, as part of his new theory of phrenology. Gall and soon other phrenologists believed that the parts of the brain which corresponded to functions that an individual used a great deal would grow larger, while those functions which were neglected would shrink. This lead to the idea that the brain was muscle. The idea was that because of this the brain was a bumpy surface and certain areas would be larger and others smaller. This lead to the idea that bumpy parts of the skull would correlate to bumpy parts of the brain and thus phrenology was born. People began studying and measuring the size of bumps on the skull to determine a person’s characteristics and personality. (Stanford ) This theory fell out of fashion in the 1840s and was disproven when x rays were discovered seeing the structure of the brain and it was determined it is not a muscle. Also the brain is responsible more for fundamental actions like breathing rather than personality. However, phrenologists were correct that areas of the brain are compartmentalized and certain areas are responsible for certain things (Stanford ).
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The Geocentric theory was a popular theory which was that stars and planets rotated around the Earth. This was a popular belief during up until the Renaissance when it began to fall out of fashion. This belief was so popular in part because of the Bible and Christianity which proclaimed that because of God the Earth was the center of the universe. Part of the reason it was so popular was because to the untrained eye and without advanced telescopes and satellites it appears that everything in the sky rotates around the Earth. The Renaissance became a key point for the Geocentric theory as science and scientific thinkers became more important. This video describes how we transitioned from the geocentric model to the heliocentric model. It was because of scientists like Copernicus and later Kepler and Galileo who began to use rudimentary scientific techniques and telescopes to being calculating orbits of the planets. Despite evidence which was produced by these scientists the heliocentric model was banned by the Church until 1758 (Khan Academy). While the heliocentric model is incorrect because the sun is not the center of the universe it successfully debunked the geocentric model.
The theory of phlogiston was developed in 1667 by Johann Becher in an attempt to discover why things burned. The theory attempted to explain burning processes such as combustion and rusting. However since he was unaware that oxygen existed he tried to explain the process through phlogiston. As seen in the diagram below phlogiston was a chemical that was present in all things and was released into the air when things burned. In his theory, some things would be more phlogiston-rich than others which explained why some things burned better than others.
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This theory was later expanded on by Georg Ernst Stahl. Stahl believed that the corrosion of metals in air was also a form of combustion. When a metal was converted to its calx, or metallic ash the phlogiston in it was lost. Therefore, metals were composed of metallic ash and phlogiston. He felt that the function of air was merely to carry away the liberated phlogiston (Encyclopedia Britannica). The phlogiston theory was discredited by Antoine Lavoisier between 1770 and 1790. He studied the gain or loss of weight when tin, lead, phosphorus, and sulfur underwent reactions of oxidation or reduction (deoxidation); and he showed that the newly discovered element oxygen was always involved (Encyclopedia Britannica).
The flat earth theory was the idea held by many early people that the Earth was a flat plane or disk. This belief was held that the sky was a dome which touched the sides of the world like the picture below.
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The idea of a spherical Earth appeared in Greek philosophy. Aristotle provided evidence for the spherical shape of the Earth on empirical grounds by around 330 BC. Knowledge of the spherical Earth gradually began to spread beyond the Greeks from that point in time. However, one of the main reasons the Flat Earth theory is so famous is that even today when images from the International Space Station can prove the Earth is Round there is a large group of people who still believe the world is flat (Huffington Post ). The Flat Earth Society was founded in 1956 by Samuel Shelton. This shows the importance of scientific theories because even with the ability to google images of the round Earth taken from space, people still believe the Earth is flat. This increases the importance of making people aware of the Flat Earth Theory and why it's false.
The Planet Vulcan was the idea that there was another planet between Mercury and the sun which was causing irregularities in Mercury's orbit. The main proponent of the existence of the planet was Urbain Le Verrier. Verrier was a French mathematician who had discovered Neptune. In 1846, Verrier and other astronomers had quite a bit of data they could work with because Uranus had completed one full rotation around the sun since it had been discovered in 1781. Using the information they used to find Neptune they tried to discover what was causing Mercury's odd orbit (Encyclopedia Britannica). As Mercury travels around the Sun its perihelion (the point at which it is closest to the Sun) advances a little bit shown in the gif.
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Le Verrier speculated that a planet was causing this irregularity. He called this hypothetical planet Vulcan, after the Roman god of fire because of the proximity to the sun (Encyclopedia Britannica). The planet was debunked when a number of reputable investigators became involved in the search for Vulcan, but no such planet was ever found. The peculiarities in Mercury's orbit are now explained by Albert Einstein's theory of general relativity. Overall while the theory was proven wrong and there is no planet the science behind it was later expanded upon giving us the answer.
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According to the Blank Slate Theory, all humans are born into the world with blank slates, or Tabula Rasa, meaning that they have no genetic or biological predisposition and are morally neutral. This theory states that, rather, each individual becomes who he or she is through social experiences and through the world around him or her. We are nurtured into the people that we are today and that personality and language skills come into being in humans through the environment. Advocates of this theory, such as philosopher John Locke (pictured above), stated that biology and genetics play no role in the acquisition of these whatsoever (University of Michigan). Because of this, it was also believed that children could be molded by their parents into whoever and whatever the parents wanted the child to be. However, over time, the Tabula Rasa theory was proven to be false due to heaps of evidence against it. For example, it’s been noticed that no two kids are born with the same temperaments. Some children are very easy as newborns whereas others are very difficult, proving the idea that before the environment and caregivers have the chance to imprint on a child, genetics and biology have to play a role (Ted Talk). Nowadays, it is believed that nature and nurture both play a role in the development of children. Children have a set of genes that give them a predisposition into deciding who they are but they are also heavily impacted by the environment around them.
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The Four Humors of the Body was a system of medicine accepted by the ancient Greeks and Romans in which four physical qualities existed. These four physical entities helped to determine the behavior of all created things, including the human body (U.S National Library of Medicine). These four humors were black bile, yellow bile, blood, and phlegm and each of these, likewise, corresponded to a temperament of the human being: melancholia (depression), choleric (irritability), sanguine (optimism), and phlegmatic (tranquility). In the body, the interaction, excess, and/or deficiency of these four humors explained differences of temperament, age, gender, emotion, and disposition in different human beings. It was believed that the humors changed with the seasons, times of day, and with the human lifespan. Every individual had their own combination of these four humors, thus resulting in a unique being (U.S National Library of Medicine). Despite dominating the medical world for almost two thousand years, in the 19th century, this theory was discredited due to advancements in cellular pathology and chemistry.
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The Cosmic Ice Theory, otherwise known as Welteislehre in German, was a 20th-century theory created by Hanns Hoerbiger (pictured above), an Austrian engineer, in order to explain what the world was made out of and how it was created. This theory stated that ice was the basic substance of all cosmic processes and that ice moons and ice planets determined the entire development of the universe. In the mid 1920’s, in primarily German speaking countries, this theory gain a huge following despite it not having any true, hard, scientific evidence behind it. According to FWF Der Wissenchaftsfonds, an Austrian scientific magazine, the reason this theory had such a huge backing was due to the way that Hoerbiger communicated his world view; this view of the world was a very simple one, in the form of a story. The common man could easily understand it and it seemed to make a lot more sense than the scientifically based, complex theories. After the Second World War in Germany, the Cosmic Ice Theory was discredited by several different researchers and astronomists and thus has since been labeled as “pseudoscience,” an idea which tries to gain legitimacy in the scientific world and is mistakenly regarded to as being based on scientific method.
In 1877, Italian astronomer Schiaparelli began to map and name areas on planet Mars through the use of new refractor telescope technology (map pictured below). While doing this, he came across deep trenches along the surface, which he called “canali” in Italian which translated to “canals” in English (NASA). The connotation of “canals” implied that there was water on Mars, supposedly filling these canals, and that, then. there must be intelligent life on this planet living off of this water source.
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Years later, American astronomer Percival Lowell picked up on Schiaparelli’s work with Mars and was very, very intrigued. He decided to build his own observatory for the exact purpose of studying these supposed canals on Mars. Lowell went on to “discover” and to map thousands of these canals very enthusiastically, eventually even publishing a book of his findings. Lowell stated that these canals were artificial canals created by intelligent life forms and that they were built in order to carry water. He also stated that Mars might be in an advanced stage of evolution compared to Earth, suggesting that the supposed life-forms on Mars are smarter than human beings (Popular Mechanics). Eventually, it was discovered that the lines seen through the telescope while observing Mars are nothing more than the tendency of the human eye to find patterns. According to (NASA), “when looking at a faint group of dark smudges, the eye tends to connect them with straight lines” and that this is exactly what happened with Martian Canals.
In the early to mid-nineteenth century, a cholera epidemic (depicted below) in an urban and industrialized England forced scientists to try to pinpoint the cause of such diseases.
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One of the most popular theories on how diseases were caused and spread at this time was the Miasmic theory of diseases. This theory states that cholera and other diseases were caused by a type of “bad air” called Miasmas, which arose from decayed, organic matter (UCLA). It was believed that this bad air was evident due to the foul odors the organic matter gave off. In 19th century England, a time of urbanization, when the city was overcrowded and polluted, this theory seemed to make perfect sense. Several poor and filthy neighborhoods tended to be the focal points of disease and when sanitation improved in these areas, disease decreased, thus providing more ample support for the idea of Miasmas (Science Museum). Eventually, in the late 19th century, the Miasmic theory of disease was replaced with the germ theory, the idea that diseases are caused by a type of germ foreign to the human body.
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The idea of the spontaneous generation first came around during the time of the ancient Romans, and continued all the way through to the late nineteenth century. During that time, it was commonly accepted belief that some life forms arose spontaneously from non-living matter. It was suggested that this came from decaying matter, such as placing sweaty underwear and husks of wheat in a jar and in around 21 days, the combination would create a mouse (NC State). The idea was first attacked in 1668 when Italian physician Francesco Redi tested where maggots came from by putting rolled meat in a variety of flasks both open and closed, and noticed that maggots only appeared in the open flasks, where flies could get to and lay their eggs (NC State). The debate still continued for centuries, with the 1745 experiment by john Needham boiling chicken broth and microorganism appeared. Then an Italian priest Spallanzini then modified this experiment to where he sealed the flask of chicken broth off from air, and no microorganisms appeared (NC State). The idea was eventually put to rest in 1859 when a chemist Louis Pasteur used methods from both Needham and Spallazini, and showed what happened when air could reach the broth and when it could not, and showed that microorganisms are everywhere, in the air. This bust was important to science because it showed that microorganism are everywhere, but also need air to survive (NC State).
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An Idea that came up during the age of exploration, in hopes to achieve financial gain, the idea of a warm open polar sea was created in the 1500’s in a hope of an easy way for sailors to get from Europe to Asia. In the 16th Century, many theorists believed that the summers would create enough energy to melt the ice, and British explorer john Davis proposed that Ice could only be formed in fresh water, and that the north pole was far from fresh water. Explorer Robert Thorne proposed the King Henry the VIII to finance a voyage to go and search for it in hopes of a sea advantage. In 1527, he set out on a voyage, and this yielded no success, with many ships being lost and damaged (Gizmodo). "This continued for decades, all proving failure. Hopes of a sea died in 1879 when an expedition led by American Naval Officer George Washington de Long led a crew to their deaths after being trapped in the ice in the Bering Strait for around 14 months" (Gizmodo). This theory today has been completely disproven with the use of satellites showing that even though ice does melt and the frozen sea does subside during the warmer months, it does not do it enough to create an open polar sea.
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There was a popular theory that humans only use about 10 percent of their brain power all the time. It is not clearly known when this theory was developed but is was believed the have been created in the early 1800’s by theorists that believed that brain function could be localized to particular regions of the brain and those who believed the brain acted as a whole. One theorist Karl Spencer Lashley proposed that memory was not dependent on any specific portion of the brain, and was showed by him by putting lesions on rats brains and were still able to complete tasks (Brain Connection). This helped lead to the popular 10% theory. This theory has been debunked by many factors. Clinical evidence has shown that many parts of the brain are active during many different tasks, being at a lower level then the ones being used, but still active. If humans would not be able to use 90 percent of their brain function at all, then many neurons would be damaged and degenerate. Overall, we do use a lot of our brain, especially more than 10 percent (Brain Connection).
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It’s hard to think now that California was once considered an island. But it used to be believed so. The theory of the island of California first cam about it 1533 when it was first discovered by a European voyage led by Hernan Cortes, the Spanish conqueror of Mexico. They actually found Baja Peninsula (Magazine Pomona). So that led to them believe that California was in fact an island, with a tale of riches. This enchantment had kept map makers from possibly trying to draw something else or to fully investigating. This was also not helped with the voyage of Sir Francis Drake’s claim of being at the pacific coast. The theory was eventually put to rest interestingly when in 1747, Ferdinand VI of Spain issued a royal proclamation that California was in fact not an island (Magazine Pomona). This can also be credited to exploration by American frontiersman, better land surveying, and the development of satellites.
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For a long time, we have believed that 65 million years ago, there was a massive asteroid that crashed onto Earth and single-handedly caused the extinction of the dinosaurs. From recent studies, this theory might actually be debunked. This theory was recently put to the test by scientists from Exeter University where in a lab they held an experiment that tried to replicate the heat wave that the asteroid would have created. They used four powerful halogen lamps to recreate the blast of the asteroid to how it affected different parts of the world (International Business Times). What they found was that this could not have started any wild fires because it would have lasted only a few seconds, but in another blast in New Zealand lasted a few minutes, and could have caused fires (International Business Times). This ruled out the global hypothesis, and could not have done a world wide extinction. Another factor is the apparent huge volcanic episode in India in the late Crustaceous period. This would have also affected the climate of the Earth at the time (International Business Times). While this theory is not fully debunked, it certainly looks like it will be.
A scientific theory is a well-tested, comprehensive explanation of an important feature of nature supported by evidence and facts gathered over time. Some of these theories can be as old as the beginning of curiosity, and for a while held as truth, while others only last for a matter of years until one or anther group of people come along and debunk it. In debunking a theory, many times scientists offer an alternate explanation for natural phenomena. For example, the Miasmic Theory of Disease was replaced when the Germ Theory was discovered and this theory is still used today. The discovering and debunking of diseases is an endless cycle and it will continue in the future.
In this anthology, we have learned so much as to why some of these debunked theories were regarded as fact, and how future thinkers and scientists were able to eventually disprove them. From alchemy all the way planet Vulcan, being able to find a new truth helps us advance our minds and advance our understanding of how science actually does work, in all it’s presumed ways.