German physicist who found a new way to formulate quantum mechanics.
His theory was based only on what can be observed, for example, on the radiation emitted by the atom.
He maintained that we cannot always know the position of an electron in space at a given time.
Mechanical quantities, such as position, velocity, etc. should be represented,
not by ordinary numbers, but by abstract mathematical structures, or matrix equations.
Later Heisenberg stated his famous 'principle of uncertainty' - for that see Biography below.
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Biography + Nobel lecture