Changes

==History==

==History==

While the roots of quantum mechanics can be traced to experiments performed in the 19th century, the theory began to emerge when [[Max Planck]] proposed a "quantum hypothesis" to explain the energy spectrum of [[black body]] radiation in 1900. In 1905, [[Albert Einstein]] suggested that light is composed of discrete packets (''quanta'') in order to explain the [[photoelectric effect]].  A decade later, [[Niels Bohr]] proposed a model of the atom in which [[angular momentum]] is quantized.  Eventually, the mathematical formalism that became known as quantum mechanics was developed in the 1920s and 1930s by [[John von Neumann]], [[Hermann Weyl]], and others, after [[Erwin Schrodinger]]'s discovery of wave mechanics and [[Werner Heisenberg]]'s discovery of matrix mechanics.

While the roots of quantum mechanics can be traced to experiments performed in the 19th century, the theory began to emerge when [[Max Planck]] proposed a "[[quantum hypothesis]]" to explain the energy spectrum of [[black body]] radiation in 1900. In 1905, [[Albert Einstein]] suggested that light is composed of discrete packets (''quanta'') in order to explain the [[photoelectric effect]].  A decade later, [[Niels Bohr]] proposed a model of the atom in which [[angular momentum]] is quantized.  Eventually, the mathematical formalism that became known as quantum mechanics was developed in the 1920s and 1930s by [[John von Neumann]], [[Hermann Weyl]], and others, after [[Erwin Schrodinger]]'s discovery of wave mechanics and [[Werner Heisenberg]]'s discovery of matrix mechanics.

==The uncertainty principle==

==The uncertainty principle==