Top 10 Greatest Scientific Discoveries in History

Nicolaus Copernicus's De Revolutionibus (1543), placing the Sun rather than Earth at the centre of the solar system, launched the Scientific Revolution by displacing humanity from the cosmic centre. Copernicus, Galileo, and Kepler's work overturned 1,400 years of Ptolemaic geocentrism, challenged Church authority over natural knowledge, and established the principle that empirical observation can override received wisdom — however ancient and authoritative.

Einstein's General Theory of Relativity (1915) replaced Newton's concept of gravity with a geometric theory of curved spacetime, explaining the precession of Mercury's orbit that Newtonian physics could not account for. Confirmed by Eddington's 1919 solar eclipse observations, it predicted black holes (observed 2019), gravitational waves (detected 2015), and the Big Bang — the origin and evolution of the universe itself.

Louis Pasteur's experiments disproving spontaneous generation and demonstrating that specific microorganisms cause specific diseases in the 1860s, confirmed and extended by Robert Koch's work identifying the bacteria causing tuberculosis, anthrax, and cholera, gave medicine its first causal understanding of infectious disease. Before germ theory, illness was explained by miasma ("bad air"). After it, rational treatments, vaccines, sanitation, and antibiotics became possible.

Charles Darwin and Alfred Russel Wallace's simultaneous development of the theory of evolution by natural selection provided for the first time a coherent, evidence-based, non-supernatural account of biological diversity. Darwin's On the Origin of Species (1859) fundamentally altered biology, anthropology, psychology, economics, and philosophy, establishing a secular framework for understanding the place of humanity in the natural world.

Quantum mechanics — developed by Planck, Einstein, Bohr, Heisenberg, and Schrodinger between 1900 and 1927 — revealed that at the subatomic level, nature behaves in ways completely unlike everyday experience: particles exist in superpositions, measurement changes the thing measured, and certain pairs of properties cannot simultaneously be known precisely. It is the most successfully tested theory in science and the foundation of transistors, lasers, MRI machines, and computing.

Georges Lemaitre's 1927 proposal that the universe was expanding from an initial singularity — confirmed by Hubble's 1929 observations of receding galaxies and the 1964 discovery of cosmic microwave background radiation by Penzias and Wilson — gave humanity its first scientific account of the origin of the universe. The Big Bang is now supported by convergent evidence from four independent observational methods and is the foundation of modern cosmology.

Dmitri Mendeleev's Periodic Table (1869) organised the chemical elements by atomic weight and properties in a way that revealed regularities allowing him to predict the existence and properties of elements not yet discovered. His predictions of gallium, scandium, and germanium were vindicated within 15 years. The periodic table is the most elegant organising principle in chemistry and the foundation of all materials science and chemical engineering.

Frederick Banting and Charles Best's isolation of insulin at the University of Toronto in 1921 transformed Type 1 diabetes from a death sentence — patients typically died within years of diagnosis — to a manageable chronic condition. Before insulin, the only treatment was a near-starvation diet that might extend life by a year. The first human recipient in January 1922 was a 14-year-old boy in a diabetic coma who made a complete recovery.

Jennifer Doudna and Emmanuelle Charpentier's adaptation of the CRISPR-Cas9 bacterial immune system into a programmable gene-editing tool in 2012 (for which they won the 2020 Nobel Prize in Chemistry) has the potential to be the most consequential biological discovery since DNA's structure. CRISPR enables precise editing of any genome in any living cell, making it the foundational tool of the genomic medicine era: treating genetic diseases, developing disease-resistant crops, and potentially reversing hereditary conditions.

Nicolaus Copernicus's De Revolutionibus (1543), placing the Sun rather than Earth at the centre of the solar system, launched the Scientific Revolution by displacing humanity from the cosmic centre. Copernicus, Galileo, and Kepler's work overturned 1,400 years of Ptolemaic geocentrism, challenged Church authority over natural knowledge, and established the principle that empirical observation can override received wisdom — however ancient and authoritative.

Einstein's General Theory of Relativity (1915) replaced Newton's concept of gravity with a geometric theory of curved spacetime, explaining the precession of Mercury's orbit that Newtonian physics could not account for. Confirmed by Eddington's 1919 solar eclipse observations, it predicted black holes (observed 2019), gravitational waves (detected 2015), and the Big Bang — the origin and evolution of the universe itself.

Louis Pasteur's experiments disproving spontaneous generation and demonstrating that specific microorganisms cause specific diseases in the 1860s, confirmed and extended by Robert Koch's work identifying the bacteria causing tuberculosis, anthrax, and cholera, gave medicine its first causal understanding of infectious disease. Before germ theory, illness was explained by miasma ("bad air"). After it, rational treatments, vaccines, sanitation, and antibiotics became possible.

Charles Darwin and Alfred Russel Wallace's simultaneous development of the theory of evolution by natural selection provided for the first time a coherent, evidence-based, non-supernatural account of biological diversity. Darwin's On the Origin of Species (1859) fundamentally altered biology, anthropology, psychology, economics, and philosophy, establishing a secular framework for understanding the place of humanity in the natural world.

Quantum mechanics — developed by Planck, Einstein, Bohr, Heisenberg, and Schrodinger between 1900 and 1927 — revealed that at the subatomic level, nature behaves in ways completely unlike everyday experience: particles exist in superpositions, measurement changes the thing measured, and certain pairs of properties cannot simultaneously be known precisely. It is the most successfully tested theory in science and the foundation of transistors, lasers, MRI machines, and computing.

Georges Lemaitre's 1927 proposal that the universe was expanding from an initial singularity — confirmed by Hubble's 1929 observations of receding galaxies and the 1964 discovery of cosmic microwave background radiation by Penzias and Wilson — gave humanity its first scientific account of the origin of the universe. The Big Bang is now supported by convergent evidence from four independent observational methods and is the foundation of modern cosmology.

Dmitri Mendeleev's Periodic Table (1869) organised the chemical elements by atomic weight and properties in a way that revealed regularities allowing him to predict the existence and properties of elements not yet discovered. His predictions of gallium, scandium, and germanium were vindicated within 15 years. The periodic table is the most elegant organising principle in chemistry and the foundation of all materials science and chemical engineering.

Frederick Banting and Charles Best's isolation of insulin at the University of Toronto in 1921 transformed Type 1 diabetes from a death sentence — patients typically died within years of diagnosis — to a manageable chronic condition. Before insulin, the only treatment was a near-starvation diet that might extend life by a year. The first human recipient in January 1922 was a 14-year-old boy in a diabetic coma who made a complete recovery.

Jennifer Doudna and Emmanuelle Charpentier's adaptation of the CRISPR-Cas9 bacterial immune system into a programmable gene-editing tool in 2012 (for which they won the 2020 Nobel Prize in Chemistry) has the potential to be the most consequential biological discovery since DNA's structure. CRISPR enables precise editing of any genome in any living cell, making it the foundational tool of the genomic medicine era: treating genetic diseases, developing disease-resistant crops, and potentially reversing hereditary conditions.