Gregor Mendel: Laws of Inheritance and the Birth of GeneticsFor centuries, heredity was explained by the flawed concept of blending inheritance, where offspring were thought to be a simple mix of parental traits. The true mechanism of inheritance was revealed by the meticulous, quantitative work of the Austrian monk Gregor Mendel (1822–1884). Working in obscurity in his monastery garden, Mendel performed thousands of controlled crossing experiments with pea plants, which led to the discovery ...

Gregor Mendel: Laws of Inheritance and the Birth of GeneticsFor centuries, heredity was explained by the flawed concept of blending inheritance, where offspring were thought to be a simple mix of parental traits. The true mechanism of inheritance was revealed by the meticulous, quantitative work of the Austrian monk Gregor Mendel (1822–1884). Working in obscurity in his monastery garden, Mendel performed thousands of controlled crossing experiments with pea plants, which led to the discovery ...

Thomas Young: The Double-Slit Experiment and the Wave Nature of LightAt the beginning of the 19th century, the nature of light was still hotly debated. Isaac Newton (Article 151) had strongly advocated the corpuscular (particle) theory of light, and his authority largely held sway in the scientific community. The English polymath Thomas Young (1773–1829)—a physician, physicist, and Egyptologist—challenged this view. In 1801, his ingenious Double-Slit Experiment provided undeniable visual evid...

Thomas Young: The Double-Slit Experiment and the Wave Nature of LightAt the beginning of the 19th century, the nature of light was still hotly debated. Isaac Newton (Article 151) had strongly advocated the corpuscular (particle) theory of light, and his authority largely held sway in the scientific community. The English polymath Thomas Young (1773–1829)—a physician, physicist, and Egyptologist—challenged this view. In 1801, his ingenious Double-Slit Experiment provided undeniable visual evid...

Karl Popper: Falsification and the Philosophy of ScienceSir Karl Raimund Popper (1902–1994) was an Austrian-British philosopher considered one of the most influential thinkers of the $20^\text{th}$ century in the philosophy of science. Popper’s most enduring contribution was solving the demarcation problem—the challenge of distinguishing genuine science from non-science (or pseudoscience). He argued that the true criterion of a scientific theory is not its ability to be proven (verification),...

Karl Popper: Falsification and the Philosophy of ScienceSir Karl Raimund Popper (1902–1994) was an Austrian-British philosopher considered one of the most influential thinkers of the $20^\text{th}$ century in the philosophy of science. Popper’s most enduring contribution was solving the demarcation problem—the challenge of distinguishing genuine science from non-science (or pseudoscience). He argued that the true criterion of a scientific theory is not its ability to be proven (verification),...

Max Planck: Quantum Theory and the Quantization of EnergyAt the close of the 19th century, physics seemed largely complete, defined by the robust frameworks of Newtonian mechanics and Maxwell's electromagnetism. However, a lingering problem known as the ultraviolet catastrophe resisted classical explanation. The German physicist Max Planck (1858–1947) reluctantly solved this problem in 1900 by introducing a revolutionary concept: that energy is not continuous but exists in discrete packets, o...

Max Planck: Quantum Theory and the Quantization of EnergyAt the close of the 19th century, physics seemed largely complete, defined by the robust frameworks of Newtonian mechanics and Maxwell's electromagnetism. However, a lingering problem known as the ultraviolet catastrophe resisted classical explanation. The German physicist Max Planck (1858–1947) reluctantly solved this problem in 1900 by introducing a revolutionary concept: that energy is not continuous but exists in discrete packets, o...

Max Born: The Probability Interpretation of Quantum MechanicsThe development of Quantum Mechanics (Articles 51, 52) provided a powerful mathematical framework for describing the behavior of atoms and subatomic particles. However, the physical meaning of the core mathematical function—the wave function ($\psi$)—was initially unclear. The German physicist Max Born (1882–1970), working with the initial wave equation developed by Erwin Schrödinger (Article 53), provided the critical step by propo...

Max Born: The Probability Interpretation of Quantum MechanicsThe development of Quantum Mechanics (Articles 51, 52) provided a powerful mathematical framework for describing the behavior of atoms and subatomic particles. However, the physical meaning of the core mathematical function—the wave function ($\psi$)—was initially unclear. The German physicist Max Born (1882–1970), working with the initial wave equation developed by Erwin Schrödinger (Article 53), provided the critical step by propo...

Nikola Tesla: Alternating Current (AC) and the War of the CurrentsNikola Tesla (1856–1943), a Serbian-American inventor, electrical engineer, and futurist, is one of the most brilliant and enigmatic figures in the history of technology. While his later life involved highly speculative projects, his foundational work in the late 19th century—specifically his invention of the Alternating Current (AC) electrical system—provided the blueprint for the global, long-distance power grid that sustains...

Nikola Tesla: Alternating Current (AC) and the War of the CurrentsNikola Tesla (1856–1943), a Serbian-American inventor, electrical engineer, and futurist, is one of the most brilliant and enigmatic figures in the history of technology. While his later life involved highly speculative projects, his foundational work in the late 19th century—specifically his invention of the Alternating Current (AC) electrical system—provided the blueprint for the global, long-distance power grid that sustains...

Ferdinand de Saussure: Structuralism and the Science of SemioticsFerdinand de Saussure (1857–1913) was a Swiss linguist whose posthumously published work, Course in General Linguistics (1916), laid the foundation for two critical 20th-century intellectual movements: Structuralism and Semiotics (the study of signs and symbols). Saussure shifted the study of language away from historical evolution and towards its internal organization, arguing that language is a self-contained system of interde...

Ferdinand de Saussure: Structuralism and the Science of SemioticsFerdinand de Saussure (1857–1913) was a Swiss linguist whose posthumously published work, Course in General Linguistics (1916), laid the foundation for two critical 20th-century intellectual movements: Structuralism and Semiotics (the study of signs and symbols). Saussure shifted the study of language away from historical evolution and towards its internal organization, arguing that language is a self-contained system of interde...

Svante Arrhenius and Jean Baptiste Fourier: The Greenhouse EffectThe mechanism by which Earth maintains a temperature suitable for life—the Greenhouse Effect—was discovered and mathematically quantified long before it became a subject of global concern. The initial concept was introduced by French mathematician Jean Baptiste Joseph Fourier (1768–1830), and the quantitative link between atmospheric carbon dioxide and global temperature was established by Swedish chemist Svante Arrhenius (1859–...

Svante Arrhenius and Jean Baptiste Fourier: The Greenhouse EffectThe mechanism by which Earth maintains a temperature suitable for life—the Greenhouse Effect—was discovered and mathematically quantified long before it became a subject of global concern. The initial concept was introduced by French mathematician Jean Baptiste Joseph Fourier (1768–1830), and the quantitative link between atmospheric carbon dioxide and global temperature was established by Swedish chemist Svante Arrhenius (1859–...

Otto Hahn and Fritz Strassmann: The Chemical Proof of FissionThe discovery of nuclear fission was one of the most consequential scientific breakthroughs of the $20^\text{th}$ century, leading directly to the atomic bomb and nuclear power. This discovery was the result of a crucial experiment performed by German chemists Otto Hahn (1879–1968) and Fritz Strassmann (1902–1980) in Berlin in late 1938. While Lise Meitner (Article 132) provided the theoretical physics explanation, it was Hahn and S...

Otto Hahn and Fritz Strassmann: The Chemical Proof of FissionThe discovery of nuclear fission was one of the most consequential scientific breakthroughs of the $20^\text{th}$ century, leading directly to the atomic bomb and nuclear power. This discovery was the result of a crucial experiment performed by German chemists Otto Hahn (1879–1968) and Fritz Strassmann (1902–1980) in Berlin in late 1938. While Lise Meitner (Article 132) provided the theoretical physics explanation, it was Hahn and S...

George Zweig and Murray Gell-Mann: The Quarks and the Eightfold WayBy the early 1960s, particle physics was grappling with a confusing proliferation of subatomic particles, collectively known as hadrons (including the proton and neutron). This collection was humorously dubbed the "particle zoo." The order underlying this chaos was independently discovered by American theoretical physicists Murray Gell-Mann (1929–2019) and George Zweig (b. 1937), who proposed that all hadrons were composed of ...

George Zweig and Murray Gell-Mann: The Quarks and the Eightfold WayBy the early 1960s, particle physics was grappling with a confusing proliferation of subatomic particles, collectively known as hadrons (including the proton and neutron). This collection was humorously dubbed the "particle zoo." The order underlying this chaos was independently discovered by American theoretical physicists Murray Gell-Mann (1929–2019) and George Zweig (b. 1937), who proposed that all hadrons were composed of ...