There are very few instances where an entire scientific field has completely collapsed but there are cases where once-prominent fields were either abandoned, replaced, or significantly redefined due to paradigm shifts. It would have taken me 2 weeks to compile this list while chatGPT could do that in seconds (and denies to have used Wikipedia). Here are some examples:
1. Phlogiston Theory (18th Century) – Replaced by Modern Chemistry
- What it was: A widely accepted theory that explained combustion and rusting as the release of an invisible substance called “phlogiston.”
- Why it collapsed: Antoine Lavoisier’s discovery of oxygen in the late 18th century showed that combustion was actually a reaction with oxygen, not the loss of phlogiston. This led to the rise of modern chemistry and the fall of phlogiston theory.
2. Geocentrism (Ptolemaic Model) – Replaced by Heliocentrism
- What it was: The belief that Earth was the center of the universe, with the Sun and planets orbiting it.
- Why it collapsed: Observations by Copernicus, Galileo, and Kepler provided overwhelming evidence for a heliocentric solar system, where planets orbit the Sun.
3. Vitalism – Replaced by Biochemistry and Molecular Biology
- What it was: The idea that living organisms were fundamentally different from non-living things because they contained a “vital force” beyond physical and chemical processes.
- Why it collapsed: Discoveries in biochemistry and molecular biology, such as the synthesis of urea (Wöhler, 1828) and the discovery of DNA’s structure, showed that life can be explained through chemistry and physics alone.
4. Catastrophism (Pre-Darwinian Geology) – Replaced by Uniformitarianism
- What it was: The belief that Earth’s geological features were shaped primarily by sudden, short-lived catastrophic events (like Noah’s flood).
- Why it collapsed: Charles Lyell’s uniformitarianism argued that slow, gradual processes (like erosion and sedimentation) shaped the Earth over millions of years. This view became the foundation for modern geology.
5. Alchemy – Replaced by Modern Chemistry
- What it was: A mix of mystical, philosophical, and proto-scientific ideas aimed at transforming base metals into gold and discovering the “elixir of life.”
- Why it collapsed: The development of systematic chemical experimentation and the discovery of elements through atomic theory rendered alchemy obsolete.
6. Ether Theory – Replaced by Relativity and Quantum Mechanics
- What it was: The idea that light waves needed a medium called “luminiferous ether” to propagate through space.
- Why it collapsed: The Michelson-Morley experiment (1887) failed to detect ether, and Einstein’s theory of relativity (1905) showed that light does not need a medium to travel.
7. Spontaneous Generation – Replaced by Germ Theory
- What it was: The belief that living organisms could arise spontaneously from non-living matter (e.g., maggots appearing from rotting meat).
- Why it collapsed: Louis Pasteur’s experiments in the 19th century proved that life comes from pre-existing life, leading to the acceptance of germ theory.
While complete collapses of scientific fields are rare, history shows that many dominant ideas have been overturned or refined as new evidence and methods emerge.