All Questions
12
questions
6
votes
3
answers
503
views
Inflation and gravitational interaction
In a new article, Cosmological constraints on slow-roll inflation, the authors write: "Notice that this
theory is said to be “minimal coupled to gravity” because there is not a direct coupling ...
- 576
11
votes
3
answers
2k
views
What would the wavelength of the Cosmic Background Gravitational Wave radiation be?
Considering electromagnetic CMB can only see light as old as 380,000 years after the Big Bang, whilst theoretically those being gravitational should be formed from the beginning, what would their ...
- 441
1
vote
1
answer
128
views
At which point in the universe history will inflation prevent galaxies feeding from intergalactic matter?
It's my understanding that galaxies formed from accretion of intergalactic matter around supermassive black holes. As the universe expands the amount of matter entering a galaxy decreases, until at ...
3
votes
2
answers
238
views
Is Einstein’s general relativity applicable to early universe?
The Lagrangian of general relativity is linear (first order) in Riemann curvature. The cosmological term, if included, is zero order in Riemann curvature.
From an effective field theory point of ...
- 4,452
5
votes
1
answer
420
views
How much uncertainty has the relic graviton background?
In the paper [1], it is mentioned that inflation predicts that a relic graviton background is about 0.9 K (cf. cosmic neutrino background, 1.945 K, and cosmic microwave background, 2.73 K). How much ...
- 6,611
0
votes
1
answer
144
views
According to Newton's Law of Universal Gravitation, why isn't the universe shrinking? [duplicate]
Every point mass is attracted to each other with a force $F= \frac{GMm}{r^2}$.
I know nothing about theories behind expanding universes but, why wouldn't the universe eventually shrink down to a ...
- 113
1
vote
0
answers
140
views
Repulsive domain walls in gravity - current status of the field?
I know that in gravity domain-wall solutions are known to be repulsive. See e.g. this paper. Does anybody know anything about the current state of this field? It seems natural and appealing to try to ...
- 2,921
4
votes
2
answers
1k
views
Attractive gravity has negative energy, what about repulsive gravity in the inflation phase?
Alan Guth's cosmic inflation theory posits that about 10^-38 second before the Big Bang which led to our particular universe, a tiny patch of space doubled in size more than 100 times, from sub-atomic ...
4
votes
1
answer
1k
views
Negative Energy in Inflation Theory (Low/Zero Energy Universe)
I've been reading Max Tegmark's book: Our Mathematical Universe. It's very interesting, but I wanted to know more about one particular thing. The book simplifies things and I know inflation theories ...
- 143
5
votes
2
answers
446
views
gravitational waves and inflation theory
I am not a technical guy and I have no scientific knowloedge in physics but I have been reading books, watching videos in order to understand our cosmology and ...
- 185
2
votes
1
answer
113
views
Object that causes spacetime to expand?
Is there any thing that will cause spacetime to expand, so that particles are pushed away from them rather than pulled towards it. I know things such as black holes and planets causes dips and curve ...
- 123
-1
votes
1
answer
153
views
Is gravity reversed during inflation?
I am not clear on that.
Is gravity repulsive during inflation?
- 821