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### Werner Heisenberg

Werner Karl Heisenberg (; German: [ˈvɛʁnɐ kaʁl ˈhaɪzn̩bɛʁk] ; 5 December 1901 – 1 February 1976) was a German theoretical physicist, one of the main pioneers of the theory of quantum mechanics, and a principal scientist in the Nazi nuclear weapons program during World War II. He published his Umdeutung paper in 1925, a major reinterpretation of old quantum theory. In the subsequent series of papers with Max Born and Pascual Jordan, during the same year, his matrix formulation of quantum mechanics was substantially elaborated. He is known for the uncertainty principle, which he published in 1927. Heisenberg was awarded the 1932 Nobel Prize in Physics "for the creation of quantum mechanics".
Heisenberg also made contributions to the theories of the hydrodynamics of turbulent flows, the atomic nucleus, ferromagnetism, cosmic rays, and subatomic particles. He was also instrumental in planning the first West German nuclear reactor at Karlsruhe, together with a research reactor in Munich, in 1957.
Following World War II, he was appointed director of the Kaiser Wilhelm Institute for Physics, which soon thereafter was renamed the Max Planck Institute for Physics. He was director of the institute...

Definition from Wikipedia – Werner Heisenberg

### Uncertainty principle

The uncertainty principle, also known as Heisenberg's indeterminacy principle, is a fundamental concept in quantum mechanics. It states that there is a limit to the precision with which certain pairs of physical properties, such as position and momentum, can be simultaneously known. In other words, the more accurately one property is measured, the less accurately the other property can be known.
More formally, the uncertainty principle is any of a variety of mathematical inequalities asserting a fundamental limit to the product of the accuracy of certain related pairs of measurements on a quantum system, such as position, x, and momentum, p. Such paired-variables are known as complementary variables or canonically conjugate variables.
First introduced in 1927 by German physicist Werner Heisenberg, the formal inequality relating the standard deviation of position σx and the standard deviation of momentum σp was derived by Earle Hesse Kennard later that year and by Hermann Weyl in 1928:
where
ℏ
=
h
2
π
{\displaystyle \hbar ={\frac...

Definition from Wikipedia – Uncertainty principle

### Walter Lewin

Walter Hendrik Gustav Lewin (born January 29, 1936) is a Dutch astrophysicist and retired professor of physics at the Massachusetts Institute of Technology. Lewin earned his doctorate in nuclear physics in 1965 at the Delft University of Technology and was a member of MIT's physics faculty for 43 years beginning in 1966 until his retirement in 2009.
Lewin's contributions in astrophysics include the first discovery of a rotating neutron star through all-sky balloon surveys and research in X-ray detection in investigations through satellites and observatories. Lewin has received awards for teaching and is known for his lectures on physics and their publication online via YouTube, MIT OpenCourseWare and edX.
In December 2014, MIT revoked Lewin's Professor Emeritus title after an MIT investigation determined that Lewin had violated university policy by sexually harassing an online student in a MITx course he taught in fall 2013.

Definition from Wikipedia – Walter Lewin