Changes

Einstein's statistical explanation of Brownian motion (the random movement of microscopic particles mixed in with pollen) is sometimes credited with helping to confirm the atomic theory at a time when some scientists argued against it.<ref>Cassidy, David (2004). [http://www.aip.org/history/einstein/essay-brownian.htm "Einstein on Brownian motion"].  [http://www.aip.org/history/einstein/great1.htm American Institute of Physics/AIP Center for History of Physics/Albert Einstein-Image and Impact/The Great Works I].  Retrieved on January 24, 2014.]</ref> Most scientists had accepted atomic theory a century earlier.

Einstein's statistical explanation of Brownian motion (the random movement of microscopic particles mixed in with pollen) is sometimes credited with helping to confirm the atomic theory at a time when some scientists argued against it.<ref>Cassidy, David (2004). [http://www.aip.org/history/einstein/essay-brownian.htm "Einstein on Brownian motion"].  [http://www.aip.org/history/einstein/great1.htm American Institute of Physics/AIP Center for History of Physics/Albert Einstein-Image and Impact/The Great Works I].  Retrieved on January 24, 2014.]</ref> Most scientists had accepted atomic theory a century earlier.

Einstein also published a heuristic explanation of the photoelectric effect in which light has particle like properties as well as wave like properties. According to Maxwell's equations, light is a wave so one might expect that increasing the intensity of light should increase the number of electrons emitted from metal. The German physicist Lénard did an experiment proving that this was not true. Einstein argued that the experiment was consistent with [[Max Planck]]'s hypothesis that light is quantized and different particles of light or photons have different frequencies. Therefore, increasing the intensity of low frequency photons has no effect, while using a higher (blue or ultra violet) frequency of light does cause more electrons to be emitted. The formula Einstein used to explain this was Planck's formula e = hf, where h is Planck's constant and f is the frequency.<ref>Davis, Warren, PhD. (2008 or before).  [http://www.physlink.com/Education/AskExperts/ae24.cfm?CFID=8792067&CFTOKEN=36662276 "What is the photoelectric effect?"]  PhysLink.com.  Retrieved on January 24, 2015.</ref>

Einstein also published a heuristic explanation of the photoelectric effect in which light has particle like properties as well as wave like properties. According to Maxwell's equations, light is a wave so one might expect that increasing the intensity of light should increase the number of electrons emitted from metal. The German physicist Lénard did an experiment proving that this was not true. Einstein argued that the experiment was consistent with [[Max Planck]]'s hypothesis that light is quantized and different particles of light or photons have different frequencies. Therefore, increasing the intensity of low frequency photons has no effect, while using a higher (blue or ultra violet) frequency of light does cause more electrons to be emitted. The formula Einstein used to explain this was Planck's formula ''e'' = ''hf'', where ''h'' is Planck's constant and ''f'' is the frequency.<ref>Davis, Warren, PhD. (2008 or before).  [http://www.physlink.com/Education/AskExperts/ae24.cfm?CFID=8792067&CFTOKEN=36662276 "What is the photoelectric effect?"]  PhysLink.com.  Retrieved on January 24, 2015.</ref>

Although Einstein won a Nobel Prize for explaining the photoelectric effect, Lénard was critical of his accomplishments.<ref>Evans, Richard J. (2005).  ''The Third Reich in Power'' (London:  Penguin Books), pp. 306-309.</ref> Planck and Lénard had already received Nobel Prizes for related work explaining the photoelectric effect.

Although Einstein won a Nobel Prize for explaining the photoelectric effect, Lénard was critical of his accomplishments.<ref>Evans, Richard J. (2005).  ''The Third Reich in Power'' (London:  Penguin Books), pp. 306-309.</ref> Planck and Lénard had already received Nobel Prizes for related work explaining the photoelectric effect.

===E=mc²===

===E=mc²===

Einstein’s famous formula ''E=mc''² says that mass and energy can turn into each other. It was first published by H. Poincare. Einstein published an alternate derivation that was corrected and improved by M. Planck. E stands for [[energy]], m is [[mass]], and c is the [[speed of light]]. So, if you increase the energy of a substance, for example by heating it, it gains a minute amount of mass. It was later realized that if you split an atom apart, as in a nuclear explosion, it loses a tiny amount of mass that is released in the form of [[energy]].   

Einstein’s famous formula ''E=mc''² says that mass and energy can turn into each other. It was first published by H. Poincare. Einstein published an alternate derivation that was corrected and improved by M. Planck. ''E'' stands for [[energy]], ''m'' is [[mass]], and ''c'' is the [[speed of light]]. So, if you increase the energy of a substance, for example by heating it, it gains a minute amount of mass. It was later realized that if you split an atom apart, as in a nuclear explosion, it loses a tiny amount of mass that is released in the form of [[energy]].   

The connection ''E=mc''² to nuclear energy is not as direct as pop culture sometimes represents. Einstein did not discover the huge energy available from nuclear reactions. Early workers in radioactivity, such as Ernest Rutherford, understood clearly that the natural radioactive decay of radium released quantities of energy that could not be explained by chemistry, and were much larger than those of chemical reactions. Neither did Einstein originate the key idea that made nuclear energy a possible weapon or a practical energy source. That was Leo Szilard, who acknowledged having been inspired by a 1914 [[H. G. Wells]] novel. Szilard discovered or invented the chain reaction (and patented it). However, other people recognized the relation between Einstein's interpretation of the ''E=mc''² formula and chain reactions. Einstein explained that matter releasing energy is also losing mass.

The connection ''E=mc''² to nuclear energy is not as direct as pop culture sometimes represents. Einstein did not discover the huge energy available from nuclear reactions. Early workers in radioactivity, such as Ernest Rutherford, understood clearly that the natural radioactive decay of radium released quantities of energy that could not be explained by chemistry, and were much larger than those of chemical reactions. Neither did Einstein originate the key idea that made nuclear energy a possible weapon or a practical energy source. That was Leo Szilard, who acknowledged having been inspired by a 1914 [[H. G. Wells]] novel. Szilard discovered or invented the chain reaction (and patented it). However, other people recognized the relation between Einstein's interpretation of the ''E=mc''² formula and chain reactions. Einstein explained that matter releasing energy is also losing mass.