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Bethe Maxwell Geiger
Becquerel Plucker Newton
Mendeleev Fermi Roentgen
Leucippus Broglie Moseley
Dalton Rutherford Faraday
Millikan Thomson The Curies
Soddy Einstein Bohr
Planck Schrodinger Chadwick
Heisenberg Democritus Crookes
Lavosier Gassendi Zeno

500 B.C.Leucippus

Leucippus, born in the Greek province of Miletus around 500 B.C., is the man credited with developing, and later refining, the first theory of the atom. Leucippus was not a particularly well-known or prolific author during his time period, but one of the few works he did publish, The Great World System, provided the incorporation of his theories on atoms and the concept of the void. Many of Leucippus’ theories were actually crafted in retaliation to another theory of the time, the Theory of Eleatics, first proposed by Parmenides and Zeno, two popular Greek philosophers. The Eleatics described the Universe as having one gigantic, all-encompassing, stagnant mass that contained absolutely no void. Leucippus’ theory stood in contrast of such beliefs, as it upheld the notion that void was absolutely necessary for motion to occur, and that all things were comprised of an infinite number of atoms, known as atomos by the Greeks, all which are too small to be seen by a normal human eye. Although Leucippus is recognized as the first man to postulate a theory concerning atoms, his ideas were considerably advanced and widely spread not by Leucippus himself, but rather by his pupil, Democritus.

480 B.C.Zeno

Zeno, pupil of Parmenides, was a widely read Greek philosopher who, along with his mentor, first proposed the Theory of Eleactics. This theory, which was actually preferred to the atomic theory first proposed by Leucippus and Democritus, viewed the universe as a single entity. Therefore, the universe was solid, infinite, without motion, and possessing of no empty space, otherwise known as void. Obviously, this theory is now viewed as incorrect, and actually goes against much of the basic knowledge provided by the human senses, but it was favored by many of the philosophers at the time.

460 B.C.Democritus

Democritus, born around 460 B.C. in the small Greek city-state of Abdera, is the man most commonly recognized as the greatest advocate of Atomistic theory in the ancient world. Known as the “Laughing Philosopher” due to his genial attitude and great appreciation of life, Democritus was a much more widely known writer than his mentor, Leucippus. Over the course of his life, Democritus would dedicate himself to refining and advancing the Atomistic theory that Leucippus had created. Although these ancient theories were frequently primitive and incorrect, they were instrumental in the creation of modern atomic theory and the discovery of the atom. Democritus believed that all matter was composed of atoms, and that each atom was separated by a distinctive amount of space. Democritus also described atoms as solid, possessing no clear internal structure and varying greatly in terms of size, shape, and weight. Unfortunately, the dominant Greek philosopher of the era, Aristotle, vehemently opposed all ideas concerning atomic theory, and refused to believe that anything such as an atom could even exist; this Aristotelian mindset was commonplace in Ancient Greece, and as a result, ideas concerning atoms eventually faded away, largely ignored throughout the majority of the centuries following the end of the Greco-Roman period.

1640 A.D.Pierre Gassendi

Pierre Gassendi, an Renaissance era philosopher born in France in 1592 A.D., was the man who finally revived Atomistic ideas, which had remained on the fringes of known science since the Ancient Greek period. Gassendi was a politically influential figure, and as a result he was able to communicate his ideas, despite the fact that many of them broke with the conventionally acceptable Aristotelian views, to a wide variety of people. Gassendi basically reaffirmed the Greek atomistic ideals; he believed that although atoms differ in size, shape, and weight, all are solid and lacking in internal structures. However, Gassendi’s atomic theories differed slightly with those of Ancient Greece; Gassendi not only believed that atoms could form into groups known as moleculae, but also that they had not existed since the Earth’s creation, having instead been handed down by God at a certain point.

1704 A.D.Isaac Newton

Sir Isaac Newton had little to do with the actual scientific processes used to discover the atom; however, his accomplishments as a scientist in eighteenth-century England not only established him as one of the greatest scientific minds in human history, but also paved the way for the development of the scientific outlooks and methodology used by those who would eventually discover the atom. It would be Newton who would irrevocably smash the Aristotelian view of the universe, a view which, significantly, did not include any ideas concerning atoms. Be reaffirming the ideas of Copernicus and Galileo, and by developing his infinitely famous Laws of Universal Gravitation and Motion, as described in his Philosophiae naturalis principia mathematic, Newton developed the concept of a mechanical universe; others would later come to understand that this mechanical universe was, in fact, driven by the atom.

1789 A.D.Antoine Lavosier

Antoine Lavosier is often described as the father of Modern Chemistry. Although many of his scientific breakthroughs proved to be pivotally important in the discovery of the atom, Lavosier himself believed that the existence of atoms was philosophically impossible. Lavosier developed the Law of Conservation of Mass in 1789; this law described elements as pure substances that are unable to be broken down. This breakthrough, along with many others, helped Lavosier to regiment and organize the various sections of chemistry into one cohesive science; this chemical revolution would later set the stage for many of the important discoveries which furthered human understanding of the atom. Unfortunately, Lavosier and many other Enlightenment philosophes were persecuted during the French Revolution, particularly the Reign of Terror (1793-1794), and Antoine Lavosier was executed at the guillotine in 1794.

1803 A.D.John Dalton

John Dalton is an enormously important figure in any timeline created to explore the discovery of the atom, for it was he who first postulated an actual “atomic theory,” one which dealt specifically with solid atoms, all of which were spherical in shape and governed by a property known as the atomic mass, a measurement created by Dalton himself. Dalton’s ideas are extremely complex, but can be broken down to several simple points. Firstly, he believed that elements are made of atoms, which is basically the same thing we believe today; Dalton’s atoms were blank slates in description, although Dalton was slightly aware of the existence of atomic structures. Secondly, Dalton believed that the atoms of an element are equal in their masses. This is now known to be incorrect, due to the existence of isotopes, which would not be properly discovered until 100 years after Dalton first proposed his theory. Thirdly, Dalton believed that atoms of different elements have different masses; this was a refinement to an idea originally developed by the Greeks. Finally, Dalton proposed that the combination of atoms could be measured in simplistic, whole number ratios. John Dalton would go on to contribute to science in many different ways, including his first successful identification of human color-blindness, but his work with atoms ranks among his most important.

1832 A.D. Michael Faraday

It is interesting to note that although Michael Faraday’s studies into magnetism and the effect of electricity on different solutions and elements were pivotal to the discovery of the atom, Faraday himself was not a supporter of atomic theory. Faraday, who was born in England in 1791, is regarded by many as the greatest experimentalist who has ever lived. Among his accomplishments in the field of science is the discovery of an effect that he named electrolysis, which he described as the splitting of molecules through the use of electricity; he would later go on to outline the Laws of Electrolysis which govern this effect. Faraday also came to believe that a magnetic field could carry an electric current, and he first demonstrated this concept, which he called induction, in 1831, thereby advancing the field of electromagnetism greatly. Many of Faraday’s discoveries and scientific breakthroughs have become staples of modern physics and chemistry.

1859 A.D.J. Plucker

Born in Bonn, Germany in 1801, Julius Plucker, a German mathematician, physicist, and chemist, was the first to identify and experiment with what were actually electron rays produced in a vacuum; Plucker, unknowing of the electron’s existence upon his discovery in 1859, christened them cathode rays. Later, he discovered the fact that such cathode rays were deflected by magnets. Plucker’s research into cathode rays actually stimulated further research into atomic theory, as is evidenced by the works of J. J. Thomson, who finally was able to unravel the mystery of Plucker’s cathode rays with his discovery of electrons in 1897. Plucker died in 1868.

1869 A.D. - Dmitri Mendeleev

Dmitiri Mendeleev, who was born in Tobolsk, Siberia in 1834, contributed greatly to atomistic theory through his discoveries concerning elements. Mendeleev was the first to organize elements into a Periodic Table, the elemental organizational system which is still used today. Although Mendeleev’s table consisted of only 63 elements (his table excluded all of the Noble Gases, which had not yet been discovered), his Periodic Table demonstrated that alternate organizational systems could be applied to atoms and elements, rather than the conventionally accepted atomic weight system which had been originally proposed by the ancient Greeks. He also developed a series of laws, known as the Laws of Period, which determined that the properties of elements were actually functions of their atomic weights. Ultimately, Mendeleev’s advances concerning elements and periodic organization opened up new possibilities for atomistic theory and shed new light on many aspects of chemical elements.

1873 A.D.James Clark Maxwell

James Clark Maxwell, who was born in Scotland in 1841, was a mathematician and physicist by trade, rather than a chemist, and yet his work constitutes some of the most important in the atomistic field, in the same vein as men such as Dmitri Mendeleev and Michael Faraday who were not directly involved in atom research, yet whose works greatly influenced and shaped the atom’s timeline. Maxwell was actually heavily influenced by the works of Michael Faraday, and many of his theories and publications are actually improvements or refinements of concepts that Faraday introduced. Basically, Maxwell proposed that electric waves, as well as magnetic waves, filled what had been described by the ancient Greeks as the “void,” the area in which no matter exists. Maxwell also managed to translate many of Michael Faraday’s theories into a mathematical format of equations; these equations became known as the Maxwell equations, and are still used today to apply formulas to electricity and magnetism.

1879 A.D. Sir William Crookes

William Crookes was born in London, England during the summer of 1832. As a youth, Crookes was very much so interested in his education, particularly concerning the areas of mathematics and science. Crookes later attended the Royal College of Chemistry in London, earning his degree in 1854. After seven years of post-graduate labor, Crookes finally achieved a discovery; he was responsible for the identification and isolation of the element thallium in 1861. Although Crookes was a brilliant scientist, he had one flaw; he was actually interested in too many areas of science to be able to focus in on one specific area, and between 1854 and 1900 he studied extensively in the fields of chemistry, physics, mathematics, and even economics. Crookes’ main contribution to the advancement of the atomic theory, however, is his identification of many properties of cathode rays; Crookes discovered that these rays move in a straight line, cause glass to glow, carry negative charges, and are capable of being deflected by electric fields. Crookes’ discoveries would directly influence the work of J. J. Thomson, the man who finally identified the electron. Crookes was knighted in 1897, and died in 1916.

1895 A.D. Wilhelm Roentgen

Wilhelm Roentgen was performing an experiment on November 8th, 1895, that seemed mundane to him, and yet it would be this seemingly routine experiment which would revolutionize not only the fields of medicine and physics, but would also shape the future of the atom, as well. Roentgen was attempting to futher study cathode rays using a partially evacuated Hittorf-Crookes tube when he was attracted to an odd glowing, which he later determined was the result of invisible rays emanating from within the tube. These rays were actually so powerful that they were able to penetrate the dark black paper which surrounded the tube itself. Little did he know it at first, but Roentgen had just discovered X-rays, and unlike many discoveries, which are deemed insignificant at first, the discovery of X-rays almost instantaneously changed the way humans looked at medicine and physics. Roentgen spent many years of his life further investigating X-rays; further studies yielded the fact that X-rays were not deflected by magnetic fields. Roentgen was awarded the Nobel Prize in Physics in 1901 for his discovery, but he experienced a great deal of hardships in his life, and upon his death following the First World War, he was almost completely penniless.

1896 A.D.Henri Becquerel

Henri Becquerel, born in France in the year 1852, had very view ambitions in his life other than his ambition of becoming a scientist; he was born into an affluent family of French chemists and physicists, and inherited their shared interest in science nearly from birth. Becquerel’s own research was profoundly influenced by the discovery of X-rays by Wilhelm Roentgen, and one year after that fateful discovery, in 1896, Becquerel was able to garner a sufficient supply of fluorescent materials to mount his own studies into that incredible discovery. Becquerel created a mixture of uranium and potassium that he exposed to sunlight for a length of time, and then placed on a photographic plate wrapped in black paper similar to the type of paper that had been permeated by the X-rays Roentgen had observed nearly a year earlier. After developing these photographic plates and noticing that they exhibited an image of the uranium crystals that had been placed upon them, Becquerel concluded that the uranium had absorbed the sun’s energy and had then proceeded to transform that energy into X-rays. This was not correct, and Henri Becquerel would soon be the one to discover that. The experiment was repeated once again, with similar results expected; however, cloudy skies on the date of the repeated experiment blocked the sun’s rays, and when Becquerel developed his photographic plates, he expected them to show nothing. In stark contrast to his expectations, the image of the uranium crystals was extremely clear upon the plate. Henri Becquerel had just discovered radioactivity, later defined as the spontaneous emission of radiation by a certain material due to decomposition. For his discovery, which increased the understanding of X-rays almost immeasurably and opened up new possibilities for radioactive studies, Becquerel was awarded the Nobel Prize for Physics in 1903.

1897 A.D.J. J. Thomson

J. J. Thomson, an unassuming, mild-mannered English physicist, can possibly be described as a man whose accomplishments did more to shape the human understanding of the atom than any other in history. It was Thomson’s discoveries that finally shattered the preordained concept of the heavy, solid, absolutely indivisible atom and replaced it with the concept that the atom was in fact itself comprised of smaller particles, a concept that we still study to this day. Thomson’s breakthroughs began with his studies what was known as the cathode ray, which was created using a strange device known as a cathode ray tube, which had first been invented more than thirty years earlier. Cathode rays were not widely understood in Thomson’s time, and eventually, Thomson’s experiments led him to make a brash, and, in some cases, shocking scientific claim; Thomson proposed that cathode rays were made up of particles much smaller in size than an atom that were in fact fractions (or, as he called them, “corpuscles”) of an atom; these particles, Thomson claimed, were roughly 1000 times smaller than an actual atom in size. He further suggested that these corpuscles might even comprise all matter within at atom. For the scientific community of the time, which regarded the atom as a fundamental and indivisible unit of matter, this was truly a shocking claim, and Thomson’s colleagues regarded his theories with doubt. By 1899, however, others had also adopted Thomson’s theories, and history would soon prove Thomson correct; the extremely small particles which had discovered and referred to as corpuscles were actually electrons, negatively charged particles that stand as one of the primary components of the atom, and for possessing the courage to break with conventional thinking J.J. Thomson is remembered as the discoverer, and perhaps even the “father,” of the electron. Thomson died in 1940.

1898 A.D.The Curies

Maria Sklodowska, a mathematician and scientist born in Poland in 1867, along with her husband Pierre Curie, a French professor of physics, represent two of the greatest and best known scientific minds of the early 20th century. Although the couples’ early researches were focused on other areas of physics, the discovery of radioactivity by Henri Becquerel in 1896 came to dominate their research in the years afterwards. Although Becquerel was the first to notice radioactivity and studies it thoroughly throughout his lifetime, it was the research conducted by the Curies that would come to define modern knowledge of the radioactive process. The Curies were the first to actually create the term “radioactivity,” and were the first to identify, isolate, and study the properties of two important radioactive elements: radium and polonium. Following the premature death of her husband in 1906, Marie Curie took over his position as Professor of Physics at the Sorbonne in France, and was later bestowed with many awards for her breakthroughs in the areas of physics, chemistry, and medicine. It is interesting to note that the Curies were also the first to develop the cure for rabies, a serious and quite often deadly disease of the early 20th century. After a short bout with a serious illness, Marie Curie died in Savoy, France, in 1934.

1900 A.D.Max Planck

Max Planck was born in Kiel, Germany in 1858, the son of a prosperous law professor. Planck attended and successfully graduated from the University of Munich, where he received his doctorate degree. In 1879, Planck became a respected professor at the University of Berlin, a post he remained at until he retired in 1926. Throughout his long scientific career, Planck focused on many different fields of science, including thermodynamics. However, by 1898, Planck had focused on the gaps that were still present in the understanding of the radioactive processes, particularly in the distribution of energy during such radioactive processes. In a series of papers published in 1900, Planck revealed that he had successfully uncovered the relationship between the energy and the frequency of radiation. Furthermore, Planck had successfully developed the idea of the quanta, which he defined as a discrete unit of energy, which later figured importantly in the area of quantum physics.. Unfortunately, Planck suffered many tragedies in his later years; he lost his home and one of his sons to the brutality of the Second World War, and he died after the war’s end in Gottingen, Germany, in 1947.

1905 A.D. Albert Einstein

The man who would eventually become one of the influential scientists of the 20th century was born in 1879 near Ulm, Germany, and was, for the early parts of his life, described as a soft-spoken, shy child; his parents actually began to fear that he had some sort of disorder due to his hesitancy in speaking. After graduating from the Eidgenössische Technische Hochschule in Zurich, Einstein pursued many different jobs, first working as a teacher at a German high school, than as a patent clerk. While working as a patent clerk, Einstein published a series of works between 1905 and 1909. His most famous theory, first published in 1905, was the theory of relatively, which was not actually confirmed until many years after its initial publication. In this theory, Einstein had discovered the relationship between energy and mass, expressed as E=mc², in which E stands for energy, M represents mass, and C² represents the square of the speed of light. Einstein continued to be an active researcher, lecturer, and teacher for the rest of his life, advising the Navy Ordinance Bureau during World War 2 and acting as a mentor to many of the key figures involved with the Manhatten Project. He died in 1955.

1908 A.D.Hans Geiger

Born in 1882 in Germany, Hans Geiger attended the University of Munich, where he earned a doctorate degree in physics; many of his professors remarked that Geiger possessed a remarkable aptitude for physics in particular. Geiger became particularly interested atomic physics, and formed the majority of his research around his quest to obtain more accurate measurements of atomic events. After leaving Munich, Geiger traveled to Manchester to work alongside Ernest Rutherford, one of the most prominent scientists of the time period. For their experiments, an accurate measurement of emanation from radium was necessary; therefore, in 1908, Geiger devised his most famous invention, one that is still used in many different applications today. This was the Geiger counter, a device which was able to accurately count alpha particles through the use of an electric spark, which produced a distinct clicking noise when it came in contact with alpha particles. Although the first Geiger counter was a simplistic device consisting of a tube filled with inert gas, argon and a piece of wire, the device was markedly improved over the years, and is still used by many scientists, government agencies, and even the U.S. Military. Later in his life, during World War II, Geiger was actually a part of the German government’s failed plan to develop an atomic bomb. He died in Berlin, Germany, in 1945.

1909 A.D. Robert Andrew Millikan

Robert A. Millikan was born in Illinois in 1868, and he led a relatively normal life in rural Illinois before he attended Oberlin College in Ohio in 1886. Initially, Millikan’s major was mathematics, but he soon changed it to physics after his interest in that area of science began to increase. After his graduation in 1893, Millikan spent a great deal of time as a teacher and a text-book author, but after becoming an associate professor at Columbia University, Millikan became determined to a pursue a singular line of research; the discovery of the fundamental unit of the electric charge. In order to facilitate this, Millikan used his famous oil-drop experiment, which was actually inspired by other similar experiments which had been conducted earlier, although none had been nearly as successful as Millikan’s would prove to be. Other scientists had tried to observe the effect of electric fields on large quantities of water, but Millikan instead used single drops; when these singular drops of water began to evaporate, Millikan switched to oil. By observing the effects of an electric field on the oil, Millikan was able to determine not only the charge of an electron (1.602 x 10-19 coulomb), but also the mass of an electron (9.11 x 10-28 gram). This very accurate representation later figured importantly in the development of Bohr’s quantum theory of the atom. Millikan moved to California in the 1930s and remained there until his death in 1953. He won the Nobel Prize for Physics in 1923.

1911 A.D.Ernest Rutherford

Ernest Rutherford, like John Dalton and J. J. Thomson before him, stands as one of the giants in atomic research; it was this English scientist, originally hailing from New Zealand, who discovered not only the positively charged particle that we now know of as the proton, but also the fact that the atom actually possesses a nucleus, a discovery which practically revolutionized previous concepts of the atom, which had viewed the atom as solid and possessing of no internal structures. Born in 1871 in the town of Nelson, New Zealand, Rutherford traveled to England as a young man to pursue his scientific studies. He specialized in physics, and is probably best known for his creation of a classification system used to organize different types of rays; Rutherford christened particle rays as alpha or beta, and created a different category for gamma rays, which derive from high energy electromagnetic radiation. After observing the fact that radioactivity halves over time, an effect that Frederick Soddy had called “half life,” Rutherford was then awarded the Nobel Prize in Chemistry in 1908 for proposing that the atom was, in fact, nuclear. By 1914, Rutherford had realized that in order for simple rays to be created, a positively charged particle must exist; Rutherford named this positively charged particle the proton. But Ernest Rutherford’s most enduring fame came from his discovery of the nucleus of an atom; he achieved this through his gold foil experiment. By using alpha particles almost as projectiles, Rutherford was able to reflect some of the alpha rays backwards, even with the use of only an extremely thin piece of gold foil. Thus, Rutherford came to the conclusion that nearly all of the atom’s mass was concentrated in an area that was actually a thousand times smaller than an actual atom; Rutherford called this area the nucleus, and with its discovery, the nuclear model of the atom had originated. Unfortunately, Ernest Rutherford’s life was cut short due to complications from hernia surgery, and he died in October of 1937.

1913 A.D.Frederick Soddy

Frederick Soddy, the son of a London businessman, was born in Sussex, England in 1877. He graduated from Oxford University with honors in chemistry, and later traveled to Montreal, Canada, where he worked extensively with Ernest Rutherford, the man who had identified electrons and nuclei in atoms. He and Rutherford were responsible for a variety of studies into atomic disintegration and the formation of new matter, as well as the gaseous emanation related to radium. However, it was not until 1913 that Soddy achieved his most famous scientific breakthrough in relation to atoms; he devised the concept that certain specific elements could possibly exist in two or more forms, each possessing a different atomic weight, but otherwise indistinguishable. He called such elements isotopes, the study of which has become an important part of modern atomistic knowledge. Soddy also recognized that many isotopes were created due to the spontaneous decomposition that was a characteristic of radioactivity; Soddy’s further studies led him to discover “half life,” the halving time of the intensity of radioactivity. Soddy continually returned to Oxford to study and lecture until his death in 1956.

1914 A.D.H. G. J. Moseley

Everyone who uses a periodic table in present times has something to owe to H. G. J. Moseley, a brilliant physicist who became a British lieutenant in the First World War, a war which he later became a victim of. Moseley became a part of Ernest Rutherford’s research group at Cambridge University in 1910, and together with Rutherford and other’s Moseley was instrumental in sorting out and uncovering much of the structure of the atom. Moseley’s breakthroughs involved the use of X-rays; he used cathode rays to bombard elemental samples, and was then able to photograph the X-rays that resulted. This allowed Moseley to postulate that an atom could be identified by the charge on its nucleus; by observing that the paths of certain lines in the x-ray spectrum moved when the atomic number was increased, Moseley also discovered that the atomic number can be used to supply the number of protons within the nucleus of an atom. Moseley then went on the reorganize the periodic table, which had previously been based upon atomic number, rather than atomic mass. Unfortunately, he was killed at Gallipoli by Turkish forces in 1915, only a short time after joining the British army to serve in World War I.

1922 A.D. - Niels Bohr

Niels Bohr, born in Copenhagen, Denmark in 1885, was a world-class physicist who made numerous contributions to the scientific study and understanding of atomic structure and quantum physics. Bohr received a doctorate degree from the University of Copenhagen in 1911, and like many other promising physicists of the period, he soon found himself in Manchester, England, studying with the prominent Ernest Rutherford. Rutherford’s research had proven that the atom possessed a positively charged nucleus, with a group of negatively charged electrons circling it in orbit. Bohr elaborated upon this; he suggested that the electrons could travel only in successively expanding orbits. He also suggested that the outer orbits, including what we now know of as the “valance shell,” could hold more electrons than inner orbits, and thus determined many of the atom’s properties. Bohr’s research also yielded discoveries on the way atoms emit radiation (when an electron on an outer orbit jumps to an inner one, it emits light – other scientists expanded upon Bohr’s theory, which eventually became a basis for quantum mechanics). During World War II, Bohr advised scientists such as Enrico Fermi and J. Robert Oppenheimer, who were heavily involved with the secretive Manhattan Project. He died in his hometown of Copenhagen in 1962.

1923 A.D. - Louis de Broglie

Louis de Broglie was born in France in 1892, and as a young man became interested in mathematics and physics. He had just graduated from the Sorbonne University in France when World War I broke out, and de Broglie became a senior non-commissioned officer in the French Army’s signal corps. After the war, de Broglie, along with his brother Maurice, returned to France to begin studying experimental physics. Heavily influenced by his brother’s work on X-rays, de Broglie, in 1923, postulated the theory which he is probably best known for: the theory of particle-wave duality. Basically, de Broglie believed that electrons possessed a dual nature, with properties representative of both particles and waves. This theory was later confirmed by scientists in the United States and Britain, and afterwards figured heavily in the work of Albert Einstein, and man whom de Broglie supported. Louis de Broglie died in Paris, France, in 1987, at the age of 95.

1927 A.D.Werner Heisenberg

Werner Heisenberg was born in December, 1901, in Bavaria, which at the time was a German state. He showed an interest in the sciences from a young age, and entered into the University of Munich in 1920; while at Munich, he pursued a doctorate in physics, but soon found that he had almost no interest in experimental physics. Rather, Heisenberg’s interests lay primarily in theoretical physics, which he would study for the majority of his life. Heisenberg’s breakthroughs include the foundation of quantum mechanics, which he is primarily responsible for, and the advancement of quantum theory. Of particular note is Heisenberg’s famous Uncertainty Principle, in which Heisenberg revealed that it is an impossibility to know a particle’s position and velocity. Heisenberg was also involved in a measure of controversy during World War II, as he was a chief researcher behind the Nazi nuclear reactor projects that occurred during the war. After the war, Heisenberg became an active lecturer and scholar in West Berlin and the United States. He died of cancer in 1976.

1930 A.D. Erwin Schrodinger

Erwin Schrodinger was born in Vienna, Austra in 1887. After attending and graduating from the University of Vienna with a doctorate in 1910, Schrodinger entered into experimental physics, rather than theoretical physics, which was becoming a popular area of science in the early 1900s. After a stint as an artillery officer in the German Army during World War I, during which time Schrodinger actually continued with his experiments despite serving at the front lines, Schrodinger began studying and publishing works on quantum physics. All of Schrodinger’s research efforts came to fruition in 1930, when he finally published works proposing that wave mechanics was the actual mathematical model of the atom; these works were heavily influenced by the work of Heisenberg and Einstein, and also dealt with the theory of relativity. Schrodinger continued to work with quantum physics and mechanics until his death in 1961.

1932 A.D. James Chadwick

Like Ernest Rutherford and J. J. Thomson before him, Sir James Chadwick stands as one of the most influential researchers in the field of atomic theory, as his discoveries did much to advance the burgeoning human understanding of the atom’s structure. Born in England in 1891, Chadwick attended the University of Manchester, which he graduated with a degree in physics in 1911. Afterwards, Chadwick studied under Lord Ernest Rutherford at the University of Cambridge; it was while at Cambridge that he made his most important breakthrough; the discovery of the nucleus. Before 1932, the atom was believed to be essentially comprised of the positively charged nucleus, which contained nearly all of the mass of the atom, and which was surrounded by orbital tracts containing varying numbers of electrons. However, with Chadwick’s discovery came knowledge of the third basic component of the atom, which was capable of increasing an atom’s mass while providing no electrical charge. For his work, Chadwick was awarded the Nobel Prize for Physics in 1935, and was knighted a decade later. He also served as a British advisor to the Manhattan project during the Second World War. He died in 1974.

1935 A.D. Hans Bethe

Hans Bethe was born in 1906, in a town known as Strasbourg, located in the territory of Alsace-Lorraine. After studying at the Universities of Frankfurt and Munich, Bethe earned a doctorate degree and soon after, fearful of the rising Nazi government in Germany, he emigrated first to Great Britain, then to the United States, where he remained for the rest of his life. Once settled in a new position at Cornell University, Bethe delved into his work in the fields of experimental and theoretical physics. Bethe’s most recognized work is in the field of nuclear reactions, including the carbon-nitrogen reaction, which Bethe discovered to be the reaction that provides power for stars and some other celestial bodies. Bethe also published in depth works on collision theory and refined many previous theories concerning the nuclei of atoms; it was Bethe who, in 1935, developed the theory of the deuteron. Bethe, like many other contemporary physicists working in the time period, also served as an advisor to the Manhattan project, spending nearly 3 years in the deserts of New Mexico working on the secretive government project. Bethe became a full citizen of the U.S. in 1941 and still lives in Ithaca, New York.

1942 A. D. Enrico Fermi

Enrico Fermi was born in Rome, Italy in 1901. After achieving a scholarship to the University of Pisa, he went on to graduate with a doctorate in 1922. By the time Fermi had settled into his career as a scientist, quantum mechanics was settling into its full development, and as a result Fermi was presented with many different opportunities relating to atomic theory. In 1938, after winning the Nobel Prize for physics and accepting a position at Columbia University, Fermi learned of the discovery of fission, and began to experiment on atomic chain reactions. However, it would be war, rather than study, which would allow Fermi to achieve his greatest breakthroughs. In December, 1942, under secrecy imposed by the United States War Department, Fermi achieved success in creating the chain reaction necessary for an atomic bomb to be built, thus conducting the first chain reaction to release energy from an atoms’ nucleus under controlled circumstances. Fermi was instrumental in the building of the first atomic bomb at Los Alamos, New Mexico, and took on a position at the Institute of Nuclear Studies in Chicago after the war’s end. He died in 1954.