- How did Henri Becquerel discover radioactivity while trying to test something else entirely?
- What did the Curies have to do, physically, to prove radioactivity came from inside the atom rather than a chemical reaction?
- Why did the Nobel committee split the 1903 physics prize between Becquerel and the Curies rather than award it to one party?
Radioactivity and Radioactive Decay
The spontaneous emission of radiation from unstable nuclei.
- What clue told Marie Curie that pitchblende contained an undiscovered radioactive element?
- How much raw ore did the Curies have to process to isolate just one gram of radium?
- What working conditions did Marie and Pierre Curie endure while isolating radium?
- What later applications did radium's isolation make possible?
- Where did Ramsay find helium before he found it in the atmosphere?
- Which noble gas was still missing from the periodic table in 1904, and when did it turn up?
- How did Pierre Curie die on 19 April 1906?
- What position did Marie Curie take over at the Sorbonne after Pierre's death?
- How many more years did Marie Curie continue their radioactivity research alone after Pierre died?
- What did Rutherford demonstrate about how radioactive elements transform into other elements?
- How does Rutherford's demonstrated transmutation of elements compare to the alchemists' historical dream of transmutation?
- How does the gas-filled tube in a Geiger counter turn a single alpha particle into a measurable electrical pulse?
- Why did the Geiger counter make it possible to observe radioactive decay as discrete quantum events rather than bulk averages?
- What process did Marie Curie use to isolate pure radium metal from tonnes of pitchblende residue?
- Why was it significant that Curie won a second Nobel Prize in a different scientific field than her first?
- How did the French Academy of Sciences respond to Curie's candidacy in the same year she won the Chemistry Nobel?
- How did the radium standard Curie produced come to define the international unit for measuring radioactivity?
- What anomaly did Soddy notice in radioactive decay products that behaved chemically like known elements but had different atomic masses?
- Why did scientists before 1912 assume that atmospheric ionizing radiation came from the ground rather than from space?
- What clue in lead samples from different radioactive decay chains hinted at isotopes before the term existed?
- What problem in the periodic table led Frederick Soddy to propose the concept of isotopes?
- Why do isotopes of the same element share chemical behavior despite having different atomic weights?
- What did William Bragg's ionisation spectrometer let the pair measure that earlier diffraction images could not show precisely?
- What arithmetic problem with atomic mass and atomic number led Rutherford to propose a neutral nuclear particle?
- Why would a neutral particle be immune to the Coulomb repulsion that made packing protons together difficult?
- How many years passed between Rutherford's prediction of the neutron and Chadwick's experimental discovery of it?
- How did the discovery of the neutron eventually make nuclear fission possible?
- What did Frederick Soddy discover while studying radioactive transmutation with Ernest Rutherford?
- How did the isotope concept explain the bewildering variety of lead produced by uranium ore decay chains?
- Why is hafnium so effective at absorbing neutrons, and how did that property make it useful in nuclear reactors?
- How did Harold Urey use evaporating liquid hydrogen to concentrate a heavier isotope?
- Why does heavy water moderate neutrons in a nuclear reactor without absorbing them the way ordinary hydrogen does?
- Why did Rutherford predict as early as 1920 that the nucleus must contain a neutral particle?
- What result from the Joliot-Curies' beryllium experiment tipped Chadwick off that gamma rays weren't the real explanation?
- How did the energy balance of ejected protons reveal that a neutral, proton-mass particle was responsible?
- What later technologies, for better and worse, became possible once the neutron was understood?
- How did evaporating liquid hydrogen repeatedly allow Urey to concentrate the heavier isotope enough to detect it?
- Why is heavy water useful as a neutron moderator in nuclear reactors?
- How did Irène Joliot-Curie's Nobel Prize connect to her mother Marie Curie's earlier work on radioactivity?
- What caused the aplastic anaemia that killed Marie Curie in 1934?
- Why are Marie Curie's personal notebooks still too radioactive to handle without protection nearly a century later?
- What made Marie Curie the only person to win Nobel Prizes in two different sciences?
- How did bombarding beryllium with alpha particles reveal a new subatomic particle?
- Why can a neutron enter an atomic nucleus more easily than a proton can?
- What later technologies depended on the discovery of the neutron?
- How did Marie Curie's death the year before shape the significance of her daughter's prize?
- How does a single neutron striking a nucleus lead to a runaway multiplication of reactions?
- Why did Victor Hess expect ionising radiation to fade with altitude, and what did he find instead?
- Why did slowing down neutrons with paraffin or water make them more effective at triggering nuclear reactions?
- How did Fermi's slow-neutron findings become foundational to the design of the first nuclear reactor?
- Why does francium's short half-life mean only a tiny amount ever exists on Earth at once?
- Why did neptunium-238 need to decay before plutonium could be identified?
- Why was a disused squash court under Stagg Field chosen as the site for the first nuclear reactor?
- How did the control rods let Fermi start and stop a self-sustaining chain reaction on demand?
- What share of the world's electricity does nuclear power generate today, decades after Chicago Pile-1?
- Why was it chemically impossible to separate radium D from lead, and how did that failure lead de Hevesy to isotope tracing?
- How does a radioactive isotope let scientists track a molecule's path through a living plant or a human bloodstream?
- What did Hahn and Strassmann find when they bombarded uranium with slow neutrons that made no chemical sense at first?
- Where and how did Otto Hahn learn he had won the Nobel Prize, and what else happened during that same internment?
- How powerful was the Trinity detonation compared to conventional explosives, and how far did its effects reach?
- What is trinitite, and why is the ground at the Trinity site still radioactive today?
- What did Oppenheimer and Kenneth Bainbridge each say in the moments after the detonation, and how did their reactions differ?
- How much time passed between the Trinity test and the bombings of Hiroshima and Nagasaki?
- What is the half-life of carbon-14, and how is it used to calculate the age of organic remains?
- What was the yield of RDS-1 compared to the bomb dropped on Nagasaki?
- How did the United States detect that the Soviet Union had tested a nuclear weapon?
- What factors let the Soviet nuclear program reach this milestone faster than American analysts expected?
- What technologies trace their origin back to the first controlled nuclear reaction in 1932?
- How did Edwin McMillan discover neptunium by bombarding uranium with neutrons?
- Why did Hershey and Chase label phage DNA with radioactive phosphorus and protein with radioactive sulphur?
- How does a staged thermonuclear design use a fission explosion to ignite a secondary fusion stage?
- Why did Elugelab Island disappear entirely after the Ivy Mike test?
- Why was the Ivy Mike device impractical to deploy as an actual weapon?
- How quickly did the Soviet Union respond with its own thermonuclear test after Ivy Mike?
- What second Nobel Prize did Pauling win in 1962, and why did it make him unique among laureates?
- Why did the Castle Bravo test yield three times more explosive power than its designers calculated?
- How large an area of the Pacific did Castle Bravo's radioactive fallout contaminate, and who was affected?
- What happened to the crew of the fishing vessel Lucky Dragon No. 5 after Castle Bravo's fallout reached them?
- How much power did the Obninsk reactor supply when it connected to the Soviet grid in 1954, and how many homes could that light?
- How long did the Obninsk reactor operate before it was shut down, and what type of reactor design did it use?
- What propaganda contrast did Soviet engineers draw between Obninsk's civilian power and the American Castle Bravo test in the same year?
- What share of global electricity today is generated by the same nuclear physics Obninsk first proved out?
- How did Reines and Cowan's liquid-scintillator detector confirm antineutrinos near the Savannah River reactor in 1956?
- What happened on 17 October 1956 when Queen Elizabeth II connected Calder Hall to the UK National Grid?
- Why did Calder Hall's Magnox reactors serve both civilian electricity and Britain's weapons programme at the same time?
- How long did Calder Hall operate, and how did that compare to its intended design life?
- What did colleagues suspect caused von Neumann's fatal bone cancer?
- How did von Neumann react to learning that Klaus Fuchs had passed bomb designs to Moscow?
- What is the half-life of carbon-14, and why does that particular number make it useful for dating human history?
- Why is lawrencium's longest-lived isotope's half-life of about eleven hours significant for how much of the element can exist at any time?
- What did Pauling's 1958 petition to the United Nations demand, and how many scientists signed it?
- What did the 1963 Partial Nuclear Test Ban Treaty actually prohibit?
- How did the release of 'The China Syndrome' affect public perception of the accident?
- What long-term effect did Three Mile Island have on new nuclear plant orders in the US?
- What was the Chernobyl safety test on the night of 25-26 April 1986 actually trying to verify?
- What design flaw in the RBMK reactor allowed power to surge to roughly a hundred times its rated output in a fraction of a second?
- Why are X-rays poor at detecting light elements like hydrogen inside a crystal, and how do neutrons get around that blind spot?
- Why did it take roughly forty years between Shull and Brockhouse's foundational experiments and their Nobel Prize?
- How did Frederick Reines and Clyde Cowan manage to detect a particle that barely interacts with anything?
- Why did Jacques Chirac receive the Ig Nobel Peace Prize for resuming nuclear testing at Mururoa Atoll?
- What did Chirac do the following year that suggested the international objections had been heard?
- What is exponential decay, and what other natural phenomena does it also describe?
- How did Lefkowitz isolate and clone the adrenaline receptor using radioactive tracers?