All Questions
Tagged with cosmology quantum-mechanics
132
questions
16
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Question on Roger Penrose's argument on using particles as clocks
In Roger Penrose's book Cycles of Time under section 2.3 (space-time, null cones, metrics, conformal geometry), Penrose makes the following argument which states that only particles with mass can be ...
- 498
12
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5
answers
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Quantum entanglement versus inflation in the early universe
Quantum entanglement is one of the most fascinating and mysterious phenomena in nature. It needs no interactions, or any sort of exchange for it to take place. It is possible, not against any rules of ...
- 3,860
12
votes
2
answers
253
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Is quantum uncertainty a function of how matter is distributed in the universe?
As an outcome of his PhD thesis work, Richard Feynman and John Wheeler wrote a series of papers on how the kickback on an electron as it emits a photon can be modeled accurately as the result of an "...
- 22.1k
10
votes
2
answers
386
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What does QM say about the past rather than the future?
In QM, the wave function (in the Copenhagen interpretation) is not an actual physical wave but a device to derive probabilities about the outcomes of experiments. The wave function encodes all the ...
- 5,034
9
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4
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Is heat death reversible by thermal or quantum fluctuations given an infinite time?
I'm new here, so apologies if the question doesn't sound meaningful considering what physics is supposed to answer. I don't have a physics or mathematics background, but I did learn a few things about ...
- 452
9
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1
answer
299
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How deep is the region near an event horizon where Hawking radiation is generated?
In other words, how strong does gravity have to be to cause Hawking radiation to occur?
- 223
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2
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Does the uncertainty principle violate the law of conservation of energy?
What is the scientific view of the beginning of universe? Quantum fluctuation seems to contradict with the law of conservation of energy.
Uncertainty Principle does seem to violate the Law of ...
- 465
7
votes
1
answer
511
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Does zero point energy really contribute to the cosmological constant?
The zero point energy is usually supposed to contribute to the cosmological constant. And the mismatch between the small cosmological constant compared with the huge zero point energy is deemed as one ...
- 4,452
7
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0
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116
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How many apparent horizons could the universe have?
I was reading a paper written by Nobel laureate George Smoot, Go with the Flow, Average Holographic Universe, which assumes the holographic principle as true and conjectures that our universe would be ...
- 2,462
6
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2
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334
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How can we differentiate between matter and antimatter? [duplicate]
For instance if there was a galaxy, assume it to be made up of antimatter (isolated from other "normal" galaxies), how would we, or rather, would we be able to distinguish if it was made up of matter ...
- 7,319
5
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Bargmann–Wigner equations in NP formalism
Bargmann-Wigner equations describe free particles of arbitrary spin $j$, namely
$$(-\gamma^{\mu}\partial_{\mu}+m)_{\alpha_r \alpha_{r���}}\Psi_{\alpha_1,..,\alpha_{r’},...,\alpha_{2j}}=0$$
where we have ...
- 341
4
votes
1
answer
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Particles entangled after the big bang
Is that true that the big bang caused the quantum entanglement of all the particles of the universe so every particle is entangled to each other particle of the universe?
- 145
4
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4
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548
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Could dark energy be powered by force particles that obey quantum mechanics?
From what (little) I know about physics, I understand that the universe is expanding due to dark energy, and I understand that no one quite understands it yet. I also understand that the cosmic ...
- 143
4
votes
1
answer
374
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Can the entropy of a subsystem exceed the maximum entropy of the system in quantum mechanics?
Quantum mechanics has a peculiar feature, entanglement entropy, allowing the total entropy of a system to be less than the sum of the entropies of the individual subsystems comprising it. Can the ...
- 41
4
votes
1
answer
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Knowable and Unknowable Hidden Variable theories
Following a recent interesting question about the collapse of the wave function (link at the bottom).
It seems that the wave function is just a mathematical way to give predictions of various outcomes ...
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