1thebigbangtheory


 * The Universe **


 * A group of galaxies that have come together from some mutual gravity**
 * The Big Bang Theory **

**The Big Bang Theory seeks to explain what happened at or soon after the beginning**
 * of the Universe . **

Quick Facts **


 * **The overall framework of the big bang theory came out of solutions to Einstein's general relativity field equations and remains unchanged, but various details of the theory are still being modified today.**
 * **After Einstein's work of 1917, several scientists, including the abbé Georges Lemaître in Belgium, Willem de Sitter in Holland, and Alexander Friedmann in Russia, succeeded in finding solutions to Einstein's field equations.**








 * **In the 1940s George Gamow was joined by his students Ralph Alpher and Robert Herman in working out details of Friedmann's solutions to Einstein's theory. They expanded on Gamow's idea that the universe expanded from a primordial state of matter called ylem consisting of protons, neutrons, and electrons in a sea of radiation**.
 * **The students theorized the universe was very hot at the time of the big bang (the point at which the universe explosively expanded from its primordial state), since elements heavier than hydrogen can be formed only at a high temperature.**
 * **Alpher and Hermann predicted that radiation from the big bang should still exist.**
 * **Cosmic background radiation roughly corresponding to the temperature predicted by Gamow's team was detected in the 1960s, further supporting the big bang theory, though the work of Alpher, Herman, and Gamow had been forgotten.**
 * **Evidence indicates that the matter that scientists detect in the universe is only a small fraction of all the matter that exists.**
 * **Cosmologists now think that much of the universe - perhaps 99 percent - is dark matter, or matter that has gravity but that we cannot see or otherwise detect**.
 * **Scientists develop theoretical models to show how the universe's structures, such as clusters of galaxies, have formed. Their models invoke hot dark matter, cold dark matter, or a mixture of the two.**
 * **The theories continue to match the observations, though there is no consensus on the type or types of dark matter that must be included. Supercomputers are important for making such models.**
 * **Astronomers are making new observations that are interpreted within the framework of the big bang theory. Scientists have not found any major problems with the big bang theory, but the theory is being constantly adjusted to match the observed universe.**

Web Links **

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**Other Interesting Facts**




 * vocabulary on the big bang and universe **


 * Baryons- common particles including photons and neutrinos created at approximately 10^-33 seconds after the Big Bang**
 * Deuterium- a heavy isotope of hyrogen containing on proton and one neutron**
 * Hadrons- composite particles such as protons and neutrons forming after the temperature drops to 300 MeV**
 * Leptons- light particles existing with hadros including electrons, neutrinos and photons**
 * Red Shift- shift toward the red in the spectra of light reaching us from the stars in distant galaxies**
 * Tritium- transitional element between deuterium and the formation of a helium nucleus**