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Period: 460 BCE to 370 BCE
Democritus
Democritus and his mentor, Leucippus, were the first to envision atomic theory, or that the physical world was made up of minuscule, invisible particles. He hypothesized that all things existed within an infinite empty space he termed the Void. Within this Void was an equally infinite amount of indivisible and eternal particles, that were so small that they could not be any smaller. And that an object's properties were only a result of its shape. -
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Antoine Lavoisier
Antoine Lavoisier influenced the history of chemistry and biology greatly over the course of his life. Itis generally accepted that Lavoisier's great accomplishments in chemistry stem largely from his changing the science from a qualitative to a quantitative one. His most notable studies include his opposition to the phlogiston theory and his contribution to the creation of the metric system. -
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Joseph Proust
Joseph Proust is known mainly for his discovery of the law of definite proportions in 1794, stating that chemical compounds always combine in constant proportions. The law of definite proportions, quote: “sometimes called Proust's law, or law of constant composition states that a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation.” -
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William Tompson
William Tompson Pioneered the unitary continuum theory version of the Vortex Atom theory, originally made between 1870 and 1890, which prompted about 60 scientific papers to be written on the subject soon after. -
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J.J Thomson
J.J. Thomson's experiments with cathode-ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson's plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged mass. Tomson won many awards for his expertise in experimental physics. -
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Robert Millikan
Robert Millikan was the inventor of the oil-drop experiment, starting in 1909 with a prototype experiment involving water and ending with the full version just a year later. This experiment measured the elementary charge of an electron. This experiment, along with others involving space radiation, earned him a Nobel Prize in physics in 1923. -
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Ernest Rutherford
Ernest Rutherford devised a method of accurately detecting alpha particles, and by using radium and a thin gold foil, concluded that most of an atom’s mass resided within the center of the atom, and that it was positively charged. -
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Niels Bohr
Niels Bohr founded the institute of Theoretical Physics in 1920, as well as discovered the element hafnium and mentored other physicists such as Hans Kramers, Oskar Klein, George de Hevesy and Werner Heisenburg. The element Bohrium was named after him in 1976. -
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James Chadwick
”In 1932, Chadwick made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons – elementary particles devoid of any electrical charge. In contrast with the helium nuclei (alpha rays) which are charged, and therefore repelled by the considerable electrical forces present in the nuclei of heavy atoms.” -
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Wolfgang Pauli
Wolfgang Pauli was a theoretical physicist and one of the pioneers of quantum physics. Pauli was nominated for a Nobel Prize by Albert Einstein because of his "decisive contribution through his discovery of a new law of Nature, the exclusion principle or Pauli principle". Although he rarely published papers on his research his experiments and research have greatly influenced physics as a whole. -
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Sheldon Lee Glashow and James Bjorken
Sheldon Lee Glashow, not long after the publication of Zweig and Gell-Mann, predicted the existence of the fourth type of quark, as this would fit with observations of the weak interaction. This type of quark was named Charm. -
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George Zweig and Murray Gell-Mann
George Zweig and Murray Gell-Mann independently theorised that all hadrons (including protons and neutrons) were made up of even smaller particles. Gell-Mann named these particles quarks, and proposed that there were three types, Up, Down, and Strange, which had differing properties, such as charge. This was confirmed in 1968 by a series of experiments at the Stanford Linear Accelerator Center.
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