All Questions
Tagged with cosmology quantum-mechanics
132
questions
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Can Poincaré recurrences happen eventually in a universe with zero vacuum energy?
I am interested in the topic of possible vacuum up-tunneling and down-tunneling events in cosmology. One popular instance of this is a vacuum decay from a metastable vacuum energy level to a "...
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68
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Are vacuum "up-tunneling" phase transition in AdS and Minkowski spaces impossible?
I am interested in the topic of vacuum phase transitions in models of the universe. One popular instance of this is a vacuum decay from a metastable vacuum energy level to a "true" one (in ...
- 2,462
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3
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73
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Are there universes where "symmetry breaking" went differently? [closed]
What have happened with other possible variants of asymmetry?
Are there other universes being run in parallel to our universe where the ball is not at C, but at B?
Stephen Wolfram told
I have found ...
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38
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How can baryonic CP violation contribute to the explanation of the large matter-antimatter asymmetry in our universe?
I have been doing baryonic CPV experimental search in the past few years. However, I never really get a good clue on this fundamental question.
The thing is that CPV has only been found in the meson ...
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2
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85
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If a laser is bounced off two mirrors repeatedly for several years, will it g et red-shifted?
I understand that red shift is what shows how far away the star light came from, or how far back in time the light was emitted? If so, should we not see red-shift if a laser is bounced repeatedly off ...
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1
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47
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Electrons keeping dynamical quantum fluctuations?
I was thinking about this paper (https://arxiv.org/abs/1405.0298) where the authors argue that there wouldn't be dynamical quantum fluctuations in a De Sitter space as fluctuations would be static ...
- 2,462
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3
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126
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Does science have evidence that the simulation hypothesis is true? [closed]
It is often written that the simulation hypothesis cannot be proven or disproved.
There is also a lot of talk about the fact that the simulation hypothesis is not science.
But the people also write ...
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How fast would a hypothetical microscopic quantum black hole evaporate with an effective mass of two protons?
According to the analysis shown in this research here, see link the evaporation time can be calculated in seconds using this equation:
$$
\begin{array}{l}
t_{\text {evap }}=\left(\frac{5120 \pi G^2}{\...
- 4,170
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40
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How would have electron and muon fields been identified as distinct in the electroweak era?
During the Electroweak era, the Higgs mechanism had not yet distinguished particles such as electrons and muons by mass. Is there a conceivable experiment, or a hypothetical cosmological observation ...
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3
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1
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132
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How was the universe once small enough to be subject to quantum mechanical effects?
I have often read that our universe was once small enough to be subjected to quantum mechanical effects, potentially altering how our universe turned out. This is a large theme in Laura Mersini-...
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2
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122
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Quantum fluctuations and symmetries?
While reading this piece about symmetry breaking, in section 3 I came across the term "anomalous symmetry breaking", which happens when a symmetry is broken by quantum fluctuations:
Let us ...
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2
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102
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What is the role of an observer in "consciousness causes collapse"? [duplicate]
If a "conscious observer" is part of a theory of physics (e.g. some versions of QM, cosmology), then how (according to what theories) did the universe evolve before the existence of ...
- 203
2
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112
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Toy example of superdeterminism using Rule 30
From what I understand of Bell's Theorem, it requires giving up local realism or embracing superdeterminism. I still haven't been able to understand why superdeterminism gets such a bad rap, so I've ...
- 204
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1
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132
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Cosmological perturbations and energy in an expanding universe?
I was reading an interesting book from cosmomogist Viatcheslav Mukhanov Physical Foundations of Cosmology and I had a specific question about it:
It is usually said that energy conservation is ...
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2
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229
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If entropy increases with time, are humans' thoughts becoming more random as time increases? [closed]
If entropy increases with time, are humans' thoughts becoming more random as time increases? What effect would entropy have on the brain over generations from the absolute space-time coordinate? Are ...
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2
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112
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Can there be some kind of photon emission caused by cosmological expansion?
Are there any kind of observed and experimentally verified processes or mechanisms where photon emission occurs and which are directly cause by spacetime expansion in some way?
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96
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From a true vacuum to a false vacuum in expanding space?
It is known that spacetime expansion affects many aspects in the universe. For instance, due to this, a global definition of energy conservation is difficult to define.
Could this expansion affect the ...
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1
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92
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Can we observe two galaxies (other then ours) to be receding from each other faster then the speed of light?
There are a lot of questions and answers on this site that deal with galaxies receding from us faster then the speed of light like this one:
In summary, Hubble Law: v=H(t)D, where v is recession ...
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2
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155
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If you knew perfectly knew the initial state of everything, could you predict everything? [closed]
Due to the Heisenberg Uncertainty Principle, one cannot know the complete state of a system, or particle. And so, unable to know fully certainly the state of a system, it is impossible to perfectly ...
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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 ...
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75
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Conservation of information in expanding universe
As the observable universe expands the amount of information is increasing, at least locally. How is this compatible with the conservation of information in quantum mechanics?
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106
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All matter will turn into Fe-56?
from what I understand, fe-56 is the most stable configuration of matter and therefore over time, so Dyson in "Time without end: Physics and biology in an open universe", thanks to quantum ...
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1
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625
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Why Superfluid Vacuum Theory has not proved yet that Vacuum space is possible a superfluid?
Our Universe and subatomic world being defects of an omnipresent type of superfluid we call "Vacuum Space" therefore a medium, unknown phase of matter is an intriguing idea expressed by SVT.
...
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2
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90
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Rydberg energy and Hubble constant
Although they are of different dimensions, the value of the Rydberg energy is very close to that of the Hubble constant.
Rydberg energy (R): $2.179 \times 10^{-18}$ [Joule] = 13.6 [eV]
Hubble ...
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108
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Could one, in principle, make any predictions using the wavefunction of the universe? [closed]
Do physicists talk about the wavefunction of the universe? What does that wavefunction even mean? Usually, wavefunctions describe probabilities of measurements of a system. But in this case, every ...
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58
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Is the set of reachable arrangements of an indeterministic universe (of a given material substrate) sensitive to its initial arrangement?
Suppose two equally massive universes have an identical material substrate of the same fundamental particles. Suppose then that these two universes initially have different arrangements of these same ...
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1
answer
98
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Is the set of reachable states of an indeterministic universe sensitive to its initial conditions?
Suppose two universes with the same amount of mass-energy and evolving according to the same natural laws, but having different initial conditions. Is the set of states that are reachable by the ...
4
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109
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What is the best way to describe a classical field in quantum field theory (coherent state)?
In quantum field theory, we have the following expansion on a scalar field (I follow the convention of Schwarz's book)
$$\phi(\vec{x},t)=\int d^3 p \frac{a_p exp(-ip_\mu x^\mu)+a_p^{\dagger}exp(ip_\mu ...
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3
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183
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Are most reals fake? Does it make a difference?
There are uncountably many reals. However, there are only countably many definable numbers. Thus, almost all reals are undefinable. Undefinable means that the shortest representation of that number ...
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99
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Which of these 2 ideas is correct about a "bubble" of false vacuum decay?
The whole volume of the bubble is true vacuum.
Only the surface layer of the bubble is true vacuum while the interior has turned back to false vacuum.
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2
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304
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If there's a small probability particles may teleport anywhere in an infinite Universe, shouldn't stars pop up in existence close to us ever so often?
I've been having a question on the top of my mind for a while, and didn't really manage to get it solved, so I'm asking it here:
Assuming that particles may "teleport" (or superposition, or ...
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77
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Does quantum physics always determine a particle's past state?
I have been studying black holes lately. One complaint I hear often is that information is lost when a particle enters a black hole. Supposedly, this never happens outside a black hole. It is ...
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1
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62
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What are $δ$ and $ε$ in the list of Dirac's five 'fundamental constants', concerning his 'Large number hypothesis'?
From Jean-Philippe Uzan's Varying Constants, Gravitation and Cosmology:
Dirac formed five dimensionless ratios among which1 δ ≡ H0ħ/mpc2 ∼ 2h × 10−42 and equation M1 and asked the question of which of ...
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187
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Could the rotating superfluid halo around a galaxy form a regular Abrikosov vortex lattice and serve as a naturally generated Quantum Matrix?
Spherical halo (shown in blue) surrounding galaxies could be a superfluid [Bose-Einstein condensate] according to Prof. Justin Khoury's hypothesis and may help to understand dark matter and galactic ...
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120
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Time Crystals in the Early Universe?
There is an extremely exciting footnote/remark from Prof. Frank Wilczek during the subsequent Question and Answer (Q&A) session (starting from 01 h 03 min 42 sec) of his recently held presentation:...
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1
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142
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If the universe is infinite, would QM allow the existence of "weird" zones? [closed]
If we suppose that the universe is spatially infinite and extends more or less homogenously in all directions without end (having similar galaxies, stars etc.), then we can assume that there is a more ...
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1
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493
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What is the 'effective number of neutrino species'? And how does that, rather than the total number of them, affect the universe?
As stated above...
How can the the physics of early cosmology (articles about which are where I usually come across mentions of such) be affected by an 'effective' number of neutrino types, rather ...
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0
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73
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Are singularities formed only of bosons? [duplicate]
my thinking is that, due to the Pauli exclusion principle, singularities must be formed of bosons (if anything), and not fermions since fermions may not occupy the same quantum state as one another. ...
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3
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1
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199
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Will the ever accelerating space expansion (like at the level of inflation) eventually break causality?
I have read this question:
requires that "for an action at one point to have an influence at another point, something in the space between the points, such as a field, must mediate the action&...
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29
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Quantum tunneling wave function derivation
In Vilenkin's paper Quantum cosmology and the initial state of the Universe, We find the tunneling wave function to be $ \psi _{T}=\frac{Ai(-z)+iBi(-z)}{Ai(-z_{0})+iBi(-z_{0})}$ (4.27 in the original ...
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84
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How to understand the Wheeler-de Witt equation correctly?
I am a student and for me it is still quite difficult to understand the Wheeler-de Witt equation for the wave function of the Universe. This is a kind of analogue of the Schrödinger equation, which ...
- 956
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1
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306
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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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1
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77
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Am I correct in understanding that in the many-worlds interpretation the Universe is considered as a single quantum object?
Among the tags there is also a topic of interpretation, so I hope that the question will not be closed. In the many-worlds interpretation, the wave function acquires an onotological meaning, that is, ...
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35
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Does the history of the universe change when the initial conditions change in superdeterministic theories?
In quantum mechanics, superdeterminism is a loophole in Bell's theorem, that allows one to evade it by postulating that all systems being measured are causally correlated with the choices of which ...
- 956
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0
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52
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Histories of the Universe under Different Initial Conditions
The history of the evolution of the Universe (we are talking about the observable part) on ultra-large scales (larger than the scale of galactic superclusters) under any initial conditions would be ...
- 956
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6
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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 ...
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2
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163
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Uncertainty of the past
If the future today can be described as a complex set of probabilistic wave functions which collapse to form our reality, is it possible that the past history of the universe could also be ...
- 533
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1
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77
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Does kinetic energy qualify as negative energy in the wormhole of Kip Thorne and Mike Morris?
Referring to Lagrangian methods if potential energy of gravity is considered as positive energy, then kinetic energy should be considered negative.
Recent publications on frame dragging could suggest ...
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153
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Does the 'No-Superdeterminism' assumption of the 2020 Wigner's friend experiment excl backwards/block-wise/holistic consistency & limited nonlocality?
In "A strong no-go theorem on the Wigner’s friend paradox" authors conclude that one of three possible options is necessary for reconciling quantum physics with more classical physical ...
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1
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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 ...
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