A Brief History of Time

A Brief History of Time

by

Stephen Hawking

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Quantum mechanics Term Analysis

A theory of how small particles are formed and act based on the quantum principle (by which energy is emitted in certain packets, or quanta) and the uncertainty principle.

Quantum mechanics Quotes in A Brief History of Time

The A Brief History of Time quotes below are all either spoken by Quantum mechanics or refer to Quantum mechanics. For each quote, you can also see the other terms and themes related to it (each theme is indicated by its own dot and icon, like this one:
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). Note: all page numbers and citation info for the quotes below refer to the Bantam edition of A Brief History of Time published in 1988.
Chapter 8 Quotes

We don’t yet have a complete and consistent theory that combines quantum mechanics and gravity. However, we are fairly certain of some features that such a unified theory should have.

Page Number: 138
Explanation and Analysis:
Quotes explanation long mobile
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Quantum mechanics Term Timeline in A Brief History of Time

The timeline below shows where the term Quantum mechanics appears in A Brief History of Time. The colored dots and icons indicate which themes are associated with that appearance.
Chapter 1
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Scientists now describe the universe in terms of the general theory of relativity and quantum mechanics —both great achievements of the first half of the 20th century. The first relates to... (full context)
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...the ultimate theory becomes hard to justify. Then again,  people argued this about relativity and quantum mechanics , which eventually gave us nuclear power and microelectronics. Thus, the search for a theory... (full context)
Chapter 3
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...curved, like the surface of the earth. When combining the general theory of relativity with quantum mechanics (as discussed later), space and time can be finite without a boundary. But this doesn't... (full context)
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...there was a big bang. However, Hawking himself has since changed his mind, when taking quantum mechanics into account. (full context)
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...down at the beginning of the universe. When the universe was squeezed into infinite density, quantum mechanics comes into play. As such, their focus turned from the massive to the miniscule. (full context)
Chapter 4
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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 outcomes.... (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)
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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 5
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...the first to propose a theory consistent with both the general theory of relativity and quantum mechanics . He showed mathematically how spin ½ works and predicted that electrons should have partners,... (full context)
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...same way as our own. Any theory that obeys the general theory of relativity and quantum mechanics must follow the symmetry of CPT. J. W. Cronin and Val Fitch proved the universe... (full context)
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...happens in that time, when they become a black hole, that draws general relativity and quantum mechanics together. (full context)
Chapter 6
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...light was a particle or a wave, and how gravity would therefore affect it. Under quantum mechanics , scientists know it is both. Gravity will affect light the same way it does... (full context)
Chapter 7
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...people up the wrong way, and was the first significant example of general relativity and quantum theory combining. John G. Taylor opposed Hawking when he announced these discoveries. But in the end,... (full context)
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...emissions. But is seems when a black hole becomes really small, it will simply disappear. Quantum theory seemed to undermine the idea of singularities, and Hawking’s work turned in that direction in... (full context)
Chapter 8
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...collapses back in on itself, or in localized singularities in black holes. But when applying quantum mechanics , it is clear that black holes re-emit mass and energy into the universe, eventually... (full context)
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...would also account for why there is so much matter in the universe. According to quantum theory , particles can be created by energy, which raises the question of where the energy... (full context)
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...becomes so strong that we need to return to the quantum level, and use a quantum theory of gravity. (full context)
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There is no consistent theory that combines quantum theory and gravity. If there were, it should involve Feynmann’s sum over histories proposal, which states... (full context)
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Another feature of the unified theory of quantum mechanics and general relativity is that gravity is represented in a curved space-time. Applying the sum... (full context)
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...to be so powerful at these points that it had to be considered on the quantum theory scale. Singularities will only appear as such in real time, but one could equally say... (full context)
Chapter 9
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To unify gravity with quantum mechanics , one must apply imaginary time. Imaginary time is no different from the dimensions of... (full context)
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...way from the cosmological arrow, but that is not what we observe. One requires a quantum theory of gravity to know how it all began, rather than guess. (full context)
Chapter 10
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Quantum theory allows a negative energy balance in certain areas as long as the universe’s overall balance... (full context)
Chapter 11
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...about nuclear science at the time, but also because of his own refusal to accept quantum theory despite his own input into its creation. The uncertainty principle, on which quantum theory is... (full context)
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...into GUTs is that it does not take into account the uncertainty principle that defines quantum mechanics . (full context)
Chapter 12
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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)