All Questions
25
questions
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
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
1
vote
1
answer
89
views
Cosmological Constant Problem calculations involving energy densities
I am following Timo Weigand lecutre notes on QFT, on page 28, he breifly touches on the Cosmological Constant Problem.
But I am a little confused.
He begins with a Lagrangian and include a nonzero $V_{...
- 489
1
vote
2
answers
152
views
Whether vacuum energy gravitate?
What is the relationship between vacuum energy and gravity, particularly in terms of gravitational effects and its contribution to the overall cosmological constant? Does vacuum energy possess ...
3
votes
1
answer
276
views
Can we just use the uncertainty principle to explain something from nothing? [closed]
I have been following the argument related to the early universe and the emergence of matter-energy from nothing.
They often refer to the notion of quantum fluctuations.
But I wonder if a simple ...
- 489
3
votes
1
answer
99
views
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.
7
votes
0
answers
132
views
Is GR the only theory in physics which cares about absolute energy?
In my QFT course, they justify dropping the vacuum energy as 'physics only cares about relative energies except for GR in the stress-energy tensor'.
Is this strictly true?
- 2,604
1
vote
1
answer
1k
views
What is time till false vacuum decay? (Which source is in error?)
https://arxiv.org/abs/1308.4686 says that the time till false vacuum collapse is just about the age of the universe:
ΛCDM ... can be achieved if the top quark pole mass is approximately 178 GeV
That ...
- 375
4
votes
1
answer
79
views
Is the value of the scalar components of the Higgs field known?
As I understand the relevant popular sources (example), since the end of the Electroweak epoch, the Higgs field became fixed in the whole known Universe. Thus, we are somewhere on the deep blue part (...
- 8,247
3
votes
1
answer
518
views
Cut-off energy necessary to avoid vacuum catastrophe
My understanding is that to obtain a finite vacuum energy density prediction from QFT, one must choose a cut-off point for the maximum allowed energy of a photon. Two seemingly natural choices are the ...
- 153
1
vote
3
answers
104
views
Vacuum energy density with respect to what reference frame?
Wikipedia quotes the observed vacuum energy density to be around $10^{-9}\frac{J}{m^3}$. Whatever the real energy density is, my question is, with respect to what reference frame is this being quoted?
- 13
5
votes
2
answers
301
views
Is the cosmological constant problem real? [duplicate]
The cosmological constant problem assumes that the cosmological constant (determined experimentally) can be identified with the vacuum energy density. Theroretical arguments from quantum gravity ...
- 191
0
votes
0
answers
96
views
How come the universe is considered flat if zero point energy is infinite?
If quantum field theory calculates that the vacuum energy is infinite and Einstein's theory of gravity implies this energy should produce a curvature of space-time then why shouldn't the universe be ...
1
vote
1
answer
932
views
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
0
votes
2
answers
130
views
Does the Uncertainty Principle imply a linear cosmology?
If the uncertainty in the age of the Universe is $\Delta t$ then the Uncertainty Principle implies that it has an uncertainty in its energy $\Delta E$ given by
$$\Delta E \ \Delta t \sim h.\tag{1}$$
...
- 5,925