Carl Edward Sagan was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is his research on the possibility of extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space, the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued in favor of the hypothesis, accepted since, that the high surface temperatures of Venus are the result of the greenhouse effect.
Nuclear winter is a severe and prolonged global climatic cooling effect that is hypothesized to occur after widespread firestorms following a large-scale nuclear war. The hypothesis is based on the fact that such fires can inject soot into the stratosphere, where it can block some direct sunlight from reaching the surface of the Earth. It is speculated that the resulting cooling would lead to widespread crop failure and famine. When developing computer models of nuclear-winter scenarios, researchers use the conventional bombing of Hamburg, and the Hiroshima firestorm in World War II as example cases where soot might have been injected into the stratosphere, alongside modern observations of natural, large-area wildfire-firestorms.
Mutual assured destruction (MAD) is a doctrine of military strategy and national security policy which posits that a full-scale use of nuclear weapons by an attacker on a nuclear-armed defender with second-strike capabilities would cause the complete annihilation of both the attacker and the defender. It is based on the theory of rational deterrence, which holds that the threat of using strong weapons against the enemy prevents the enemy's use of those same weapons. The strategy is a form of Nash equilibrium in which, once armed, neither side has any incentive to initiate a conflict or to disarm.
Project A119, also known as A Study of Lunar Research Flights, was a top-secret plan developed in 1958 by the United States Air Force. The aim of the project was to detonate a nuclear bomb on the Moon, which would help in answering some of the mysteries in planetary astronomy and astrogeology. If the explosive device detonated on the surface, and not in a lunar crater, the flash of explosive light would have been faintly visible to people on Earth with their naked eye. This was meant as a show of force resulting in a possible boosting of domestic morale in the capabilities of the United States, a boost that was needed after the Soviet Union took an early lead in the Space Race and was also working on a similar project.
James Barney Pollack was an American astrophysicist who worked for NASA's Ames Research Center.
Human extinction is the hypothetical end of the human species due to either natural causes such as population decline from sub-replacement fertility, an asteroid impact, large-scale volcanism, or to anthropogenic (human) causes.
The faint young Sun paradox or faint young Sun problem describes the apparent contradiction between observations of liquid water early in Earth's history and the astrophysical expectation that the Sun's output would be only 70 percent as intense during that epoch as it is during the modern epoch. The paradox is this: with the young sun's output at only 70 percent of its current output, early Earth would be expected to be completely frozen – but early Earth seems to have had liquid water and supported life.
A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, though to date all fusion-based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device. Nuclear explosions are used in nuclear weapons and nuclear testing.
The terraforming of Venus or the terraformation of Venus is the hypothetical process of engineering the global environment of the planet Venus in such a way as to make it suitable for human habitation. Terraforming Venus was first proposed in a scholarly context by the astronomer Carl Sagan in 1961, although fictional treatments, such as The Big Rain of The Psychotechnic League by novelist Poul Anderson, preceded it. Adjustments to the existing environment of Venus to support human life would require at least three major changes to the planet's atmosphere:
- Reducing Venus's surface temperature of 737 K
- Eliminating most of the planet's dense 9.2 MPa (91 atm) carbon dioxide and sulfur dioxide atmosphere via removal or conversion to some other form
- The addition of breathable oxygen to the atmosphere.
Georgy Sergeyevich Golitsyn is a prominent Russian scientist in the field of Atmospheric Physics, full member of the Academy of Sciences of the USSR since 1987, Editor-in-Chief of Izvestiya, Atmospheric and Oceanic Physics, ISSN 0001-4338, member of the Academia Europaea since 2000. 1990-2009 - Director of the A.M. Obukhov Institute of Atmospheric Physics, RAS, Moscow, Russia. He is a member of the princely house of Golitsyn. His father is the Russian writer Sergei Mikhailovich Golitsyn.
Vladimir Valentinovich Alexandrov was a Soviet/Russian physicist who created a mathematical model for the nuclear winter theory. He disappeared while at the Second International Conference of Nuclear Free Zones Local Authorities in Cordoba, Spain on 31 March and his ultimate fate remains unknown, though speculation continues. One of his last papers was Man and Biosphere published in 1985; it is said to have charted the moving trend in the science of nuclear winter. It was co-authored with Nikita Moiseyev and A. M. Tarko.
William Welch Kellogg was an American meteorologist and climatologist. He served as Associate director and senior scientist at the National Center for Atmospheric Research (NCAR). His research included pioneering studies of the role that satellites could play in weather observation and prediction.
A nuclear holocaust, also known as a nuclear apocalypse,nuclear Armageddon, or atomic holocaust, is a theoretical scenario where the mass detonation of nuclear weapons causes globally widespread destruction and radioactive fallout. Such a scenario envisages large parts of the Earth becoming uninhabitable due to the effects of nuclear warfare, potentially causing the collapse of civilization and, in the worst case, extinction of humanity and/or termination of all biological life on Earth.
Owen Brian Toon is a professor of atmospheric and oceanic sciences. He is a fellow at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder. He received an A.B. in physics at the University of California, Berkeley in 1969 and a Ph.D. in physics at Cornell University in 1975 under Carl Sagan. His research interests are in cloud physics, atmospheric chemistry, and radiative transfer. He also works on comparing Earth and other planets such as Venus.
The Cold and the Dark: The World after Nuclear War is a 1984 book by Paul R. Ehrlich, Carl Sagan, Donald Kennedy, and Walter Orr Roberts.
Alan Robock is an American climatologist. He is currently a Distinguished Professor in the Department of Environmental Sciences at Rutgers University, New Jersey. He advocates nuclear disarmament and, in 2010 and 2011, met with Fidel Castro during lecture trips to Cuba to discuss the dangers of nuclear weapons. Alan Robock was a 2007 IPCC author, a member of the organisation when it was awarded the Nobel Peace Prize, "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change".
The Leo Szilard Lectureship Award is given annually by the American Physical Society (APS) for "outstanding accomplishments by physicists in promoting the use of physics for the benefit of society". It is given internationally in commemoration of physicist Leo Szilard.
"In the year's of Szilard's life and activity it became clearer than ever before how great the responsibility of scientists is to the society. And, to a large extent, it is due to Szilard that this awareness began to spread in the scientific community." - Andrei Sakharov
Nuclear famine is a hypothesized famine considered a potential threat following global or regional nuclear exchange. It is thought that even subtle cooling effects resulting from a regional nuclear exchange could have a substantial impact on agriculture production, triggering a food crisis amongst the world's survivors.
John W. Birks is an American atmospheric chemist and entrepreneur who is best known for co-discovery with Paul Crutzen of the potential atmospheric effects of nuclear war known as nuclear winter. His most recent awards include the 2019 Haagen-Smit Clean Air Award for his contributions to atmospheric chemistry and the 2022 Future of Life Award for discovery of the nuclear winter effect.
Elizabeth A. Barnes is an American climate scientist. Barnes is best known for her work and expertise on the use of statistical methods to understand the variability of Earth's short- and long-term climate. Her work is characterized by an integration of both physics and computer science approaches. She is a Fellow of the American Geophysical Union.
