A few words about nuclear weapons technology.. Fission weapons Nuclear weapons exploit two principle physical, or more specifically nuclear, properties of certain substances: fission and fusion. Fission is possible in a number of heavy elements, but in weapons it is principally confined to what is termed slow neutron fission in just two particular isotopes: 235U and 239Pu. These are termed fissile, and are the source of energy in atomic weapons. An explosive chain reaction can be started with relatively slight energy input (so-called slow neutrons) in such material. An actual 239Pu ingot, alloyed with gallium for improved physical properties Isotopes are 'varieties' of an element which differ only in their number of neutrons.
The Size of Our World
Physics 20b: Introduction to Cosmology - Spring 2010 - Download free content from UC Irvine on iTunesDescription Overview of modern scientific cosmology, including discussion of stars, the Milky Way galaxy, black holes, dark matter, the big bang, and evidence for our current understanding of the universe.
Relativity Tutorial Galilean Relativity Relativity can be described using space-time diagrams. Contrary to popular opinion, Einstein did not invent relativity. Galileo preceded him. Aristotle had proposed that moving objects (on the Earth) had a natural tendency to slow down and stop.
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First published Mon Aug 13, 2001; substantive revision Thu Aug 26, 2010 Quantum entanglement is a physical resource, like energy, associated with the peculiar nonclassical correlations that are possible between separated quantum systems. Entanglement can be measured, transformed, and purified. A pair of quantum systems in an entangled state can be used as a quantum information channel to perform computational and cryptographic tasks that are impossible for classical systems. The general study of the information-processing capabilities of quantum systems is the subject of quantum information theory. 1.
Open Course : Astronomy : Introduction : Lecture 1 : Science of Astronomy