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In physics, nucleogenesis is the process that occurred a few minutes after the Big Bang when the atomic nuclei were created. The relative abundance of the different light nuclei - hydrogen, helium, lithium - calculated theoretically agrees with the observed abundance. This agreement provides us with circumstantial evidence of the Big Bang Theory.

The nucleogenesis of heavier elements is generally an exothermic process so that the binding energy of a nucleus declines on a per-proton/neutron basis as one goes up the chart of the nuclides or periodic table until one reaches iron at atomic number 55.

From iron up, the energy per nucleon increases suggesting that formation of heavier nuclei is a endothermic process. One place where heavier nuclei are formed in during the explosion of a supernova. The energy density and particle density during a supernova event create some very heavy nuclei including uranium and thorium. Heavier nuclei are surely formed but their shorter half-lives would make them unlikely to be present far away from a supernova in space and/or time.

In our own planetary system, the presence of significant quantities of uranium and thorium help date our planet and result in a net positive heat flux out into space. The Earth seems to emit 4% more energy into space than it receives in solar influx. That energy keeps the mantle semifluid. The convection currents in the mantle result in volcanoes and earthquakes from the movement of tectonic plates.

Those same species (uranium and thorium) have begun to be exploited as an energy source for mankind since the discovery of the fissioning of uranium-235 in the late 1930's. Estimates of exploitable uranium in the Earth's crust reachable by mines or extractable from seawater suggest a virtually inexhaustable source of power for future generations. While use of uranium as an energy source is a commonplace, future development of a thorium fuel cycle for reactors would provide even more fuel.

Nucleogenesis is also the name of two compositions of music by composer Vangelis on his 1976 album, Albedo 0.39.

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