10 Most Famous Scientific Theories That Were Later Debunked


The most genuine merit of science is probably its readiness to admit if it preaches or reveals something wrong. The therios in science are always being reconsidered and scrutinized. Modern research often rejects old ideas, hoaxes and myths.

Today’s post on our Science Blog will discuss ten of the most popular and influential scientific discoveries that were based on dubious data, and were consequently proven wrong, debunked and replaced with more reliable and logical modern theories.

1- Fleischmann–Pons’s Nuclear Fusion

Cold fusion is a supposed kind of nuclear reaction that would occur at relatively low temperatures compared with hot fusion. As a new type of nuclear reaction, it gained much popularity after reports in 1989 by famous electrochemists Stanley Pons and Martin Fleischmann. The craze about cold fusion became weaker as other scientists, after trying to repeat the experiment, failed to get similar results.

2- Phrenology

Now widely considered as a pseudoscience, phrenology was the study of the shape of skull as indicative of the strengths of different faculties. Modern scientific research wiped it out by proving that personality traits could not be traced to specific portions of the brain.

3- The Blank Slate

The Blank Slate theory (or Tabula rasa), widely popularized by John Locke in 1689, proposed that individuals are born without built-in mental content and that their knowledge comes from experience and perception. Modern research suggests that genes and other family traits inherited from birth, along with innate instincts of course, also play a very important role.

4- Luminiferous Aether

The aether (or ether) was a mysterious substance that was thought to transmit light through the universe. The idea of a luminiferous aether was debunked as experiments in the diffraction and refraction of light, and later Einstein’s special theory of relativity, came along and entirely revolutionized physics.

5- Einstein’s Static (or Stationary) Universe

A static universe, also called a “stationary” or “Einstein” universe, was a model proposed by Albert Einstein in 1917. It was problematic from the beginning. Edwin Hubble’s discovery of the relationship between red shift obliterated it by completely demonstrating that the universe is constantly expanding.

6- Martian Canals

The Martian canals were a network of gullies and ravines that some 19th century scientists erroneously thought to exist on Mars. First detected in 1877 by Italian astronomer Giovanni Schiaparelli, modern telescopes and imaging technology completely debunked the myth. The “canals” were actually found to be a mere optical illusion.

7- Phlogiston Theory

First postulated in 1667 by German physician Johann Joachim Becher, Phlogiston Theory is an obsolete scientific theory regarding the existence of “phlogiston”, a fire-like element, which was contained within combustible bodies and released during combustion. The theory tried to explain burning processes such as combustion and the rusting of metals, which are now jointly termed as “oxidation”.

8- The Expanding or Growing Earth

The Expanding Earth or Growing Earth is a hypothesis suggesting that the position and relative movement of continents is dependent on the volume of the Earth increasing. Modern science has turned down any expansion or contraction of the Earth.

9- Discovery of the Planet Vulcan

A small planet that was supposed to exist in an orbit between Mercury and the Sun, French mathematician Urbain Jean Joseph Le Verrier coined the name “Vulcan” while trying to explain the nature of Mercury’s orbit. No such planet was ever discovered, while the orbit of Mercury was explained in detail by Albert Einstein’s theory of general relativity.

10- Spontaneous (or Equivocal) Generation

Spontaneous generation or equivocal generation is an obsolete principle concerning the origin of life from inanimate matter. The hypothesis was brought out by Aristotle who advocated the work of earlier natural philosophers. It was proven wrong in the 19th century by the experiments of Louis Pasteur, drawing influence from Francesco Redi who was an early proponent of germ theory and cell theory.



  1. Forkpah Pewee says

    This is very wonderful. Science in its nature of existence is a circulating event in which its theories can be formulated and debunked. Thanks for the hard job done.

  2. Krystina Rae says

    Interesting piece. The only I have to point out it that the majorities of these were never widely held theories. Instead most of them were either hypothesis or were only believed to be true by a small percent of the scientific community. There is a big difference between hypothesis and scientific theory.

  3. says

    A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of knowledge that has been repeatedly confirmed through observation and experiment.[1][2] Scientists create scientific theories from hypotheses that have been corroborated through the scientific method, then gather evidence to test their accuracy. As with all forms of scientific knowledge, scientific theories are inductive in nature and do not make apodictic propositions; instead, they aim for predictive and explanatory force.[3][4]

    1 National Academy of Sciences, 1999
    2 AAAS Evolution Resources
    3 Schafersman, Steven D. “An Introduction to Science”.
    4 American Association for the Advancement of Science, Project 2061

  4. Peter J. King says

    Some of these are dubious at best. For example, the luminiferous aether wasn’t debunked; it was not needed in the new theories, and so it dropped out of physics, but that’s a very different matter. Locke’s objection to innate ideas, principles, knowledge, etc., not only wasn’t a scientific theory, but isn’t touched by genetic theory, or by any scientific theory. Moreover, he was happy to accept that we have innate capacities and abilities, which is all that science has attempted to explain in terms of genetics, etc. No-one, to the best of my knowledge, claimed to have discovered Vulcan, nor was its existence a theory, it was part of a hypothesis designed 9as you point out) to explain the ways in which Mercury’s orbit failed to accord with Newtonian physics.

  5. allon says

    neo-darwinism is largely debunked as explanation for increasing biological complexity. This theory, largely composed of population genetic concepts to understand how selection could bring change is still valid to explain variability within species.

    The major explanation for increase of organismal complexity, i.e. from prokaryotes to eukaryotes, from single cell to multicellular organisms, from primitive to complex species is not explained by neodarwinism.

    Horizontal gene transfer, Genome duplication (polyploidization and subsequent genome fragmentation) are largely singular events caused by drift rather than mutation and selection.

    It is hardly understood by lay people how the current genomic revolution is reshaping evolutionary concepts.

    And I have not even mentioned the revival of Lamarckism.

    I think this contemporary example is a much nicer example that outmoded phlogiston theories from times before modern sciences had its current rigour

  6. allon says

    In genetics the definition of the “GENE” has changed over and over since it was coined by Johansson in 1909.

    Gene as unit of function
    Gene as unit of recombination
    Gene as unit of mutation
    One gene one enzyme concept
    The central Dogma DNA->RNA->protein

    All these views have been revised by newer concepts.
    An overview of all outmoded definitions and the problematic attempts to offer a current defention that is valid now, was published in

  7. ritahead says

    I wished they would have mentioned the carbon dating and radioactive dating. One thing I did learn in science is that to prove your theory, you have to have a control. How can they prove that bones are millions of years old? My bible tells me the earth is not that old.

  8. Rex says

    I hope we can soon add the cholesterol theory of heart disease. It’s been debunked, but getting it to die is proving difficult.

  9. Elison says

    Scientists use Hubble Telescope to comment the entire universe would be expanding.

    How could Hubble Telescope work in reality? It simply works by collecting light from the sky through the use of primary mirror in this Telescope and then to reflect it upon a secondary mirror for analysis. However, the reflection of light by means of primary mirrors could result in obscure image in secondary mirror. The reason is simply lights could reflect in any directions and angles from any parts of primary mirror. As a result, overlapping of lights on secondary mirrors as a result of reflection from primary mirrors could be possible to the ultimate formation of obscure images. These collective obscure images could lead to false information that the entire universe could be expanding.

    Hubble Space Telescope uses the same technique as Hubble Telescope to collect lights from the sky for analysis. Thus, false images could be gathered too.

    Thus, fake images from the collection of lights from the sky through the reflective mirrors would cause information that would be gathered from Hubble Space or Hubble Telescope might not to be reliable.

  10. MrX says

    RITAHEAD, the bible is a BOOK. I could write a book that says the Earth is flat and the Moon is made of green cheese and would that make it true? Of course not! The Bible is wrong about many things. Including the value of the pi constant. Deal with it.