The most important scientific discoveries of all time
The top 3 according to 48 votes from people: The laws of motion and universal gravitation · Germ theory of disease · Evolution by natural selection. (Updated Nov 18, 2025.)
The discoveries that most changed how we understand the universe, life and ourselves, as ranked again and again by science magazines and popular-science sites. Discoveries, not inventions.
Top 20
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1
The laws of motion and universal gravitation
Isaac Newton's Principia (1687) explained falling apples and orbiting planets with the same laws.
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2
Germ theory of disease
Louis Pasteur and Robert Koch showed in the 1860s-1880s that microbes cause disease.
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3
Evolution by natural selection
Charles Darwin's On the Origin of Species (1859), independently matched by Alfred Russel Wallace.
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4
Plate tectonics
Wegener's continental drift (1912), confirmed in the 1960s: the continents move.
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5
The Big Bang and the expanding universe
Edwin Hubble showed in 1929 that galaxies are moving apart; the cosmic microwave background confirmed it in 1965.
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6
The structure of DNA
The double helix, published by Watson and Crick in 1953 using Rosalind Franklin's X-ray images.
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7
Quantum mechanics
From Planck (1900) to Heisenberg and Schrödinger (1920s): the physics of the very small.
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8
Electromagnetism
Faraday's induction (1831) and Maxwell's equations (1860s) unified electricity, magnetism and light.
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9
Laws of heredity
Gregor Mendel's pea experiments (1866), rediscovered in 1900, founded genetics.
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10
Vaccination
Edward Jenner's 1796 smallpox vaccine showed immunity could be trained.
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11
Gravitational waves
Predicted by Einstein in 1916 and first detected by LIGO in 2015.
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12
Conservation of mass
Antoine Lavoisier (1789): in a chemical reaction nothing is lost, nothing is created.
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13
Heliocentrism
Copernicus put the Sun at the centre (1543); Galileo and Kepler proved him right.
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14
Penicillin
Alexander Fleming noticed in 1928 that a mould killed bacteria: the first antibiotic.
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15
The periodic table
Dmitri Mendeleev ordered the elements in 1869 and predicted ones not yet found.
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16
The circulation of the blood
William Harvey showed in 1628 that the heart pumps blood round the body.
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17
Cells
Robert Hooke named cells in 1665; cell theory (1838-39) said all living things are made of them.
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18
X-rays
Wilhelm Röntgen discovered them in 1895 and won the first Nobel Prize in Physics.
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19
The theory of relativity
Einstein's special (1905) and general (1915) relativity: space and time bend, and E = mc².
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20
Radioactivity
Discovered by Henri Becquerel in 1896 and explored by Marie and Pierre Curie.
Candidates
They don't make it into the top 20… yet. Vote for them to move them up.
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21
The Higgs boson
Found at CERN's Large Hadron Collider in 2012, completing the Standard Model.
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22
Atomic theory
John Dalton (1808) and then Rutherford's nucleus (1911): matter is made of atoms.
How is this ranking ordered? By people's votes: each ▲ adds a point and each ▼ takes one away. Anyone can vote and add what is missing.
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Comments (1)
Penicillin should be in the top 5, saved hundreds of millions.