All Questions
Tagged with quantum-field-theory cosmology
151
questions
2
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95
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How does the direction of time work with timeless wave functions?
In thermodynamical theory, if we have a set of states for example:
A) gas all in top left corner of box.
B) gas spread out near the left.
C) gas spread out to fill entire box.
We can give the ...
user84158
0
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0
answers
94
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Vanishing integral in deriving stress-energy tensor from action
In the derivation of the energy-stress tensor for a scalar field (context: Inflation Theory for Cosmology) by varying the action with respect to the metric, the integral over spacetime that is ...
- 548
2
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1
answer
73
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Guessing the temperature dependence of a decay rate $\Gamma(A\to B+B)$
For a two-body decay of the form $$A\to B+B$$ if the interaction strength controlling the decay is $\lambda$, the Feynman amplitude $\mathcal{M}$ will contain a factor of $\lambda$ from the vertex ...
- 26.8k
2
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98
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What's the difference, if any, between Soft Hair & Quantum Hair
In the early 90s, John Preskill, Sidney Coleman, Frank Wilzcek and Lawrence Krauss presented a series of papers [1][2][3] on Quantum Hair on Black Holes due to Cosmic strings in a number of ways ...
- 425
2
votes
1
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92
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Are there viable alternatives to the no boundary proposal?
As I understand it, quantum field theory can be described as the evolution of a wave function $\psi_t[\phi]$ depending on some fields, $\phi$. But when we include gravity and we admit that time is ...
user84158
1
vote
1
answer
933
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Can our universe be a true vacuum bubble?
The paper "Spontaneous creation of the universe from nothing" by Dongshan He, Dongfeng Gao and Qing-yu Cai
claims that our universe was created by the quantum fluctuations in the metastable false ...
- 29
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36
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Could I use this informal explanation for Hawking radiation?
I need to explain Hawking radiation to my classmates for a homework. Could I use this informal explanation? (unfortunately without math). Correct me if I need to change/add something:
Quantum ...
- 21
1
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0
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115
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In what ways is eternal inflation less certain than standard inflation? [closed]
Eternal inflation is the idea that inflation could be eternal due to the effect of quantum fluctuations of the inflaton field.
Why do some cosmologists accept inflation, but consider eternal ...
- 855
1
vote
1
answer
578
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Zero-energy universe - What is nothing?
I am a layman, so excuse me in advance for the stupidity of my questions, and I hope you can answer them in a way that I can understand.
I have read, here and there, that the Universe might have a ...
5
votes
0
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158
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Meaning of the simplest potential of quintessence models. Fields in denominator?
I am reading Sec. 1.12 of the Cosmology book by Weinberg.
In this section he explains the very simple model of quintessence which attempts to provide a dynamical explanation of the smallness of the ...
- 2,197
4
votes
1
answer
662
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Quantum fluctuations producing CMB fluctuations also cause inflation to be eternal?
It is believed that quantum fluctuations in the inflaton field caused inflation to end at different times in different places, which led to CMB fluctuations (1 part in 100,000).
Eternal inflation ...
- 855
2
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226
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Does Coleman-de Luccia instanton approach a Hawking-Moss instanton?
Suppose a Coleman-de Luccia instanton terminates in the basin with the true vacuum between the top of the potential barrier and the field value with potential energy equal to the potential energy of ...
- 395
1
vote
2
answers
213
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What type of fields existed in early universe?
In quantum field theory we associate field to every particle. So how many elementary fields exits in nature? Why are fields associated to particles different from fields associated to fundamental ...
- 165
3
votes
1
answer
95
views
Would the formulation of a theory of quantum gravity in the presence of a nonzero cosmological constant depend on the origin of the latter?
The cosmological constant is the coefficient of a term in the Einstein tensor for which there are no a priori reasons to assume it to be zero, so that it could be regarded as a fundamental constant of ...
- 9,304
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107
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Do quantum fields with energy stored in it usually exert pressure?
There are types of quantum fields in the universe like spinor, vector, tensor, scalar fields.
Do these fields with energy stored in it (as energy density) usually exert pressure, or be pressureless?
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- 855