All Questions
95
questions
-2
votes
0
answers
29
views
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 "...
- 2,462
0
votes
0
answers
68
views
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
0
votes
1
answer
78
views
Could cosmic rays induce a vacuum decay in the future?
I've been told that very energetic cosmic rays could cause a vacuum phase transition or vacuum decay (and even could cause a true vacuum level to go "uphill" to a false vacuum) due to their ...
- 2,462
0
votes
1
answer
47
views
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
3
votes
2
answers
153
views
What would an inter-universal medium be like?
I don't really believe in the Multiverse Theory, but hypothetically, if universes were like soap bubbles in a foam, what might that foam be like? I know this seems like an opinion-based question but ...
- 143
1
vote
0
answers
55
views
Angular momentum, black holes and up-tunneling events in the vacuum
To give some context on the matter, I found these interesting articles (https://arxiv.org/abs/2007.11428 & https://arxiv.org/abs/2003.04927) where the authors analyzed, among other things, the ...
- 2,462
0
votes
0
answers
42
views
Up-tunneling of vacuum with high-energy events?
I was reading these papers by Sean Carroll (https://arxiv.org/abs/1405.0298 ; https://arxiv.org/abs/1505.02780) in which, among other things, he argues against vacuum up-tunneling occurring in the ...
- 2,462
1
vote
0
answers
62
views
Bunch-Davies initial condition
I have the Mukhanov-Sasaki equation in terms of $Q(t)$
\begin{align*}
Q''(t)+3HQ'(t)+k^2Q/a^2+\left(3\phi'(t)^2-\phi'(t)^4/2H^2+2\phi'(t)V_\phi/H+V_{\phi\phi}\right)Q=0,\ u=aQ
\end{align*}
and also ...
-1
votes
1
answer
79
views
Is the equation of state of the cosmological vacuum $P=-(1/3)\rho$?
I understand that the equation of state of the vacuum is assumed to be $P = -\rho$ due to the Lorentz invariance of its stress-energy tensor. But this argument assumes flat spacetime. We know at ...
- 5,925
0
votes
0
answers
52
views
False Vacuum State (QFT)
I am wondering if someone can refer me to a proof that the false vacuum state is a natural consequence of scalar field theories? I see that being said in a lot of texts on cosmology when discussing ...
- 1
0
votes
0
answers
60
views
How to select proper values to solve Bunch-Davies initial condition?
I am trying to solve the Mukhanov-Sasaki equation for a Starobinsky potential $V(\phi(t))=3/4m^2M_P^2(1-e^{-\sqrt{2/3}\phi(t)})^2$. I could change the equations so that $m^2$ does not appear and chose ...
3
votes
1
answer
500
views
Does energy exist on its own? [closed]
So to my understanding as a layman is that energy transfers from one material to another (I guess that's why there's potential and kinetic energy), for example photons to solar panels. Now my question ...
- 149
-4
votes
1
answer
78
views
The background of the universe [closed]
Mass(-energy-momentum) curves space(-time).
However - what is space-time?
Is it (the background) necessarily flat(without something in it) ?
If there were an empty universe - is there still spacetime ...
- 63
0
votes
0
answers
71
views
What mathematics indicate that the vacuum of the universe is metastable?
As I understand it, the meta stability of the universe's vacuum depends on the electroweak force, which depends on the mass of the top quark and the Higgs boson. But I don't understand this fully. Can ...
- 11
0
votes
1
answer
190
views
What would the universe look like if it had undergone a false vacuum decay in the past?
Inspired by "if a metastable de Sitter space lasting for cosmological durations really is impossible in string theory, then dark energy needs to be explained in some other way, e.g. via ...
- 21.4k