A Brief History of Time

by

Stephen Hawking

A quantum is a packet of energy that is always emitted in certain quantities. The rate at which hot bodies, such as stars, lose energy is finite. The higher the frequency of the wave, the greater the energy in each quantum.
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Quantum Term Timeline in A Brief History of Time

The timeline below shows where the term Quantum appears in A Brief History of Time. The colored dots and icons indicate which themes are associated with that appearance.
Chapter 4
Human Curiosity and Ingenuity Theme Icon
...Planck then suggested that light, and all waves, would be emitted in certain amounts, called quanta. Higher frequencies of light would be emitted in higher-energy quanta. This would make the energy... (full context)
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...it to see where it is. The higher the frequency of the light in the quantum, the more accurately you can see the particle, because the wavelengths of the light will... (full context)
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The Danger of Stubbornness  Theme Icon
Science and Religion Theme Icon
Heisenberg, Erwin Schrodinger, and Paul Dirac in the 1920s created quantum mechanics based on the uncertainty principle. This theory does not predict definite outcomes, but potential... (full context)
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The Danger of Stubbornness  Theme Icon
...that light, although a wave, could act as a particle, being emitted only in certain quanta. Heisenberg’s uncertainty principle made particles seem more like waves, with their movement spread out according... (full context)
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...electrons could only orbit at specific distances, which would balance it all out. According to quantum mechanics, the electrons would move as waves, and therefore would only form orbits where the... (full context)
The Search for a Unifying Theory of the Universe Theme Icon
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The Danger of Stubbornness  Theme Icon
Einstein’s general theory of relativity is considered a classical theory because it does not include quantum mechanics. This does not lead to inconsistency, though, as gravitational forces are so weak compared... (full context)
Chapter 12
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The Danger of Stubbornness  Theme Icon
Today, Laplace’s approach is defunct because of the uncertainty principle of quantum mechanics, which introduces a minimum level of randomness. Quantum theory gives particles less well-defined positions... (full context)
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Introducing quantum mechanics, however, leads to ideas of a finite, four-dimensional space with no boundaries. This could... (full context)