In 1895, Wilhelm Röntgen studied cathode radiation, which occurs when an electrical charge is applied to two metal plates inside a glass tube filled with rarefied gas. Although the apparatus was screened off, he noticed a faint light on light-sensitive screens that happened to be close by. Further investigations revealed that this was caused by a penetrating, previously unknown type of radiation. X-ray radiation became a powerful tool for physical experiments and examining the body's interior. He received a Nobel Peace prize for his work with atomic physics and x-rays.
In 1896, his previous work was overshadowed by his discovery of the phenomenon of natural radioactivity. When Henri Becquerel investigated the newly discovered X-rays in 1896, it led to studies of how uranium salts are affected by light. By accident, he discovered that uranium salts spontaneously emit a penetrating radiation that can be registered on a photographic plate. Further studies made it clear that this radiation was something new and not X-ray radiation: he had discovered a new phenomenon, radioactivity.
The 1896 discovery of radioactivity by Henri Becquerel inspired Marie and Pierre Curie to further investigate this phenomenon. They examined many substances and minerals for signs of radioactivity. They found that the mineral pitchblende was more radioactive than uranium and concluded that it must contain other radioactive substances. From it they managed to extract two previously unknown elements, polonium and radium, both more radioactive than uranium.
She was a Polish and Naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the first woman to win a Nobel Prize and the first person and only woman to win twice. She discovered that uranium rays caused the air around a sample to conduct electricity. She helped disprove that ancient assumption that atoms were indivisible.
He is known as the co-inventor of the detector component of the Geiger counter and for the Geiger–Marsden experiment which discovered the atomic nucleus. In 1911 Geiger and John Mitchell Nuttall discovered the Geiger–Nuttall law (or rule) and performed experiments that led to Rutherford's atomic model
When Herbert Becker and Walter Bothe directed alpha particles (helium nuclei) at beryllium in 1930, a strong, penetrating radiation was emitted. One hypothesis was that this could be high-energy electromagnetic radiation. In 1932, however, James Chadwick proved that it consisted of a neutral particle with about the same mass as a proton. Ernest Rutherford had earlier proposed that such a particle might exist in atomic nuclei. Its existence now proven, it was called a "neutron".
He conceived the nuclear chain reaction in 1933, patented the idea of a nuclear reactor with Enrico Fermi, and in late 1939 wrote the letter for Albert Einstein's signature that resulted in the Manhattan Project that built the atomic bomb. He also helped to discover a means of isotope separation. This method became known as the Szilard–Chalmers effect, and was widely used in the preparation of medical isotopes.
In 1934, he evolved the ß-decay theory, coalescing previous work on radiation theory with Pauli's idea of the neutrino. He demonstrated that nuclear transformation occurs in almost every element subjected to neutron bombardment. This work resulted in the discovery of slow neutrons that same year, leading to the discovery of nuclear fission and the production of elements lying beyond what was until then the Periodic Table. He helped direct the first controlled nuclear chain reaction.
Oppenheimer was among those credited with being the "father of the atomic bomb" for their role in the Manhattan Project, the World War II undertaking that developed the first nuclear weapons used in the atomic bombings of Hiroshima and Nagasaki. As a scientist, Oppenheimer is remembered by his students and colleagues as being a brilliant researcher and engaging teacher who was the founder of modern theoretical physics in the United States.
Carbon is a fundamental component in all living material. In nature there are two variants, or isotopes: carbon-12, which is stable, and carbon-14, which is radioactive. Carbon-14 forms in the atmosphere when acted upon by cosmic radiation and then deteriorates. When an organism dies and the supply of carbon from the atmosphere ceases, the content of carbon-14 declines through radioactive decay at a fixed rate. In 1949 Willard Libby developed a method for applying this to determine the age of fossils and archeological relics. He also received a Nobel Peace Prize for his work in nuclear chemistry.
The Teller–Ulam design is the technical concept behind modern thermonuclear weapons, also known as hydrogen bombs. The Teller–Ulam design was for many years considered one of the top nuclear secrets, and even today it is not discussed in any detail by official publications with origins "behind the fence" of classification.
Opportunities to investigate our world's smallest components were revolutionized by C.T.R. Wilson's invention of the cloud chamber and Donald Glaser's invention of the bubble chamber. In these devices electrically charged particles leave trails behind them. In the latter part of the 1950s, Luis Alvarez further developed the bubble chamber by using liquid hydrogen. He also developed new measurement systems and computer-based methods for analyzing large quantities of data. This has led to the discovery of a number of previously unknown particles.