Questions tagged [cosmological-inflation]

Cosmological inflation refers to an era of expansion that lasted for approximately $10^{-34}$ seconds, during which the universe expanded by a factor of approximately $10^{26}$ in every direction. This is different from ordinary space expansion and from the acceleration in expansion we experience now and questions tagged by inflation should pertain to this era and not be about the expansion of the universe in general.

Filter by
Sorted by
Tagged with
-1
votes
1answer
117 views

Is there any other explanation for the expansion of the universe other than dark energy?

Why did the universe expand from the Big Bang singularity? If gravity was a separate force and in its current form by 1 Plank time, would not have gravity prevented expansion, unless there was some ...
-3
votes
0answers
38 views

Inflation is the only scientific proof of multiverse [closed]

How the inflation theory of the big bang proposed by Alan Guth has it's correspondence with the theory of multiple universes?
0
votes
0answers
19 views

Does eternal inflation predate big bang and big bang is only where it partially stops OR does big bang start it and inflation only stops partially?

I am aware eternal inflation could also be infinite to the past, but if it had a beginning, is that beginning the big bang we observe using the cosmic microwave background? Did the big bang start the ...
2
votes
1answer
64 views

How did the Universe thermalize to the same temperature before inflation?

Inflation is speculated to take place at about $10^{-35}$ seconds after BigBang. The idea is that at that moment the universe was small enough so that photons could thermalize to reach the same ...
0
votes
0answers
15 views

The nature of cosmological inflation — unfolding dimensions?

While the paradigm of cosmological inflation is well established, the nature of the inflation is not known and is tackled by introduction of a hypothetical "inflaton" field. I was wondering if there ...
1
vote
3answers
59 views

What is meant by “Big Bang” in expressions like “$10^{-36}$ seconds after the Big Bang”?

Sometimes I find expressions like "The inflationary epoch lasted from $10^{−36}$ seconds after the conjectured Big Bang singularity [...]". What is meant by "the Big Bang" in this context? I ...
2
votes
1answer
100 views

The inflaton field exists in a superposition of energies. How does that affect the rate of cosmological expansion?

The inflaton field is a scalar field that each field value corresponds to different rates of expansion. The field exists in a superposition of energies, that is, the wave function hasn’t collapsed. ...
1
vote
0answers
22 views

Could the matter-antimatter equivilance paradox be solved by inflation?

At the moment of the Big Bang, matter and antimatter should have been produced in the same amounts. However, we observe only matter and no antimatter leftover from that time. I was thinking that this ...
1
vote
1answer
39 views

If the Universe were a white hole, how would inflation fit in

So, I was thinking about white holes and one theory in particular about white holes, and that is that white holes, the theoretical opposite of black holes, are each "Big Bangs". That is to say on the ...
0
votes
0answers
9 views

Is there work done when light is cosmological redshifted?

I heard an analogy using gas molecules trap inside a container, when the gas is heated up it gains kinetic energy and slam harder at the wall of the container creating a push. So it argues that ...
3
votes
0answers
44 views

Would other parts of the universe have a different rest frame for their own Cosmic Background Radiation?

The CMB, once the Doppler shift from the Earth's motion is subtracted, is fairly uniform, which seems to imply that all the matter that emitted it moved at more or less the same velocity when it did. ...
0
votes
0answers
35 views

String Landscape and Extremal / SUSY Black Holes

I should preface this question that I am new to understanding the string landscape and swampland program and F-theory, so I apologize if my question is obvious / unclear! Recently I was reading some ...
0
votes
0answers
30 views

Geometry of Tegmark's Level I multiverse

Consider Tegmark's Level I spatially infinite multiverse: it has the usual gravity, and each local copy of some material configuration has the same gravity. But how does the geometry of the Level I ...
0
votes
1answer
48 views

Why don't galaxies have larger peculiar velocities?

I am trying to reconcile two facts: That galaxies' comoving velocities are generally close to zero, and That the universe has no preferred reference frame. Galaxies seem to move very little relative ...
0
votes
0answers
27 views

How the variation of Gauss Bonnet term is done?

I am trying to do the variation of Gauss Bonnet Invariant which is $G=R^2+R_{abcd}R^{abcd}-4R_{ab}R^{ab}$ and having problem in doing the variation of $δ(R_{abcd}R^{abcd})$. Can anyone please give ...
2
votes
1answer
54 views

Does the homogeneity of space imply that the expansion of the universe is uniform?

Obviously, homogeneity implies that the density is the same everywhere at any time. However, does this imply that the expansion is uniform? By uniformity, I mean that if I pick three galaxies to form ...
0
votes
0answers
37 views

Inflation to extract information from black holes

Suppose inflation were to occur for some brief period of time within the Schwarzschild radius such that the Schwarzschild radius reduces in size. Wouldn't this mean we can get information from the ...
1
vote
1answer
42 views

Did the big bang start at ONE infinitely curved point (or a 4D curved ball shrunk to a point) with an infinite density of energy?

I'm confused. In this question it is said: The simple answer is that no, the Big Bang did not happen at a point. Instead, it happened everywhere in the universe at the same time. How could it have ...
2
votes
1answer
65 views

What is the expected size of primordial black holes?

I often see it implied that primordial black holes tend to be small compared to stellar masses; Since primordial black holes did not form from stellar gravitational collapse, their masses can be ...
0
votes
1answer
68 views

A thought experiment related to the age of the universe

Okay, So, this thought experiment starts with the movie, Interstellar. In which humans went through a wormhole to a system consisting of a Black Hole. They landed on a planet (I don't remember its ...
4
votes
0answers
41 views

Quantum tunneling of dark energy from black holes

There was an article posted recently suggesting there is a very deep connection between dark energy and black holes. https://phys.org/news/2019-09-black-holes-dark-energy.html I was thinking this ...
1
vote
1answer
41 views

Vacuum decay and Coleman-de Luccia bubbles

Can someone suggest me some good and detailed books (or notes) on the problem of vacuum decay and Coleman-de Luccia bubbles?
0
votes
0answers
28 views

Energy equivalence of the Universe? [duplicate]

Let us have the following constants: speed of light $c$, gravitational constant $G$, mass of the Universe $M$ and the Hubble's radius $R$. Firstly, is it just a silly coincidence that we have the ...
2
votes
0answers
45 views

Exact solution for (simple) Reheating Boltzmann equations?

Let's say we have the Universe which is exiting Inflation, with the inflaton field $\phi$ decaying into relativistic particles (radiation $R$). Without any other assumption, the equations describing ...
0
votes
0answers
13 views

Gravitational contribution to the action for Coleman-de Luccia instanton?

In the Coleman-de Luccia calculation of the transition rate from one de Sitter minimum to another, the action for the scalar field $\phi(\xi)$ and Euclidean radius $\rho(\xi)$ is $S_E = 2\pi^2 \int \...
2
votes
1answer
71 views

If inflation is an exponential expansion, is the exponent known?

Inflation is often called exponential expansion. I can't seem to find what that exponent is. Is it 2, or 20, or completely unknown?
0
votes
0answers
35 views

'My question is about' …the size of the Universe after Inflation [duplicate]

Hitherto, I had assumed, on account of Inflation, "boom" the Universe was "out there" and it has taken light 13.6 BY to get here. However... Quoting the aerospace engineer: In my thinking if the ...
1
vote
4answers
109 views

Flat yet finite Universe

I would like to ask you this question: Let's assume that the universe is perfectly flat and big bang happened as described by our theories some 14 billion years ago. Shouldn´t, therefore, the radius ...
0
votes
0answers
29 views

World line of a photon from a distant galaxy in the $\Lambda$CDM model

The title is pretty much explaining the question: I am used to the graphs of Einstein-De Sitter model horizons: But then I don't understand 1) Are we using this kind of diagrams also now to ...
0
votes
1answer
100 views

What is the relation between comoving particle horizon $d_{hor}^c(t)$ and comoving Hubble radius $1/(aH)$ for arbitrary expansion laws?

I was learning Inflation by reading Hannu's lecture. But on page 4 of this lecture (Chapter 7 Inflation, 7.2.1 Accelerated expansion), there are some things I don't understand. The content is shown in ...
1
vote
0answers
19 views

How do we know that Dark Energy has homogeneous energy density? [duplicate]

I’ve read places that the density of Dark Energy is the same throughout the universe. If the expansion density of dark energy were the same throughout the universe, why don’t all galaxies have the ...
0
votes
0answers
23 views

Intergalactic medium and cosmic expansion

Presumably, the intergalactic medium (IGM) should get less dense as the universe expands. Also presumably, There should be a Hubble redshift to absorption lines due to the IGM. Could this provide ...
1
vote
1answer
96 views

Why is the measure problem an issue if the universe is always finite?

As a follow-up from this question, I was wondering how the measure problem applies to the idea of eternal inflation. First, why is it even a problem? As time progresses, more universes are created in ...
0
votes
2answers
119 views

How necessary is inflation given the laws of physics?

How deeply is cosmic inflation required for the laws of physics? Is inflation required for a universe remotely like ours, or is it simply a contingent on the starting conditions of the universe? For ...
3
votes
1answer
112 views

Inflation v.s. Big Bang

It is said that that transition or certain quantum rotor field, and “rolling” down into the valley (of some quantum potential), is what causes inflation to come to an end, and create the hot Big Bang. ...
0
votes
0answers
11 views

How does the cosmological constant dominate cold matter perturbations?

I have been studying inhomogeneous universe in physical cosmology, whereupon I arrive at cold matter perturbations which are dominated by various background fluids. I understood the solutions for the ...
6
votes
2answers
168 views

What exactly is the problem that Inflation solves?

There's copious documents about how Inflation solves the problem that General Relativity predicts a lumpy CMB. That influation 'smooths' out the curvature fluctuations and, so, predicts a CMB at ...
0
votes
3answers
166 views

How inflation creates a universe from nothing?

I have a basic, mostly purely conceptual understanding of Quantum Field Theory, and after lots of Youtube (thanks PBS Spacetime!) I have an idea of how inflation works to turn the vacuum into a ...
1
vote
1answer
48 views

How can an inflaton field let spacetime expand?

Whatever the Nature of an inflaton-field, how did it make spacetime grow at an incredible rate? A little speck of spacetime was inflated to the entire observable Universe and everything beyond in very ...
0
votes
0answers
39 views

Why is momentum divergence from energy release not considered in Big Bang models?

From the formation of subatomic particles to the formation of atoms to the nuclear fusion in stars to the explosions of supernovae, the process of conversion of rest-mass energy from fields into ...
0
votes
0answers
77 views

Higgs Field before or after Cosmological Inflation?

Question: When exactly did the Higgs Field begin to exist (before cosmological inflation or after cosmological inflation)?
1
vote
0answers
54 views

Does an expanding universe assume a space within which the expansion is happening? [duplicate]

When I read about the expanding universe and inflation I often see pictures like this: (Source: https://en.wikipedia.org/wiki/Inflation_(cosmology)) or explanation like this: For getting an idea ...
-1
votes
1answer
86 views

Multiverse and the anthropic principle? [closed]

In this paper (https://arxiv.org/abs/hep-th/0211048) by physicist Andrei Linde, the multiverse concept, the anthropic principle, quantum cosmology and inflationary cosmology are analyzed. In the ...
2
votes
2answers
130 views

Why physical / cosmological models that have been falsified weren't abandoned? [closed]

Before anything, I'd like to say that I'm a layman (non physicist) and english is not my main language; I apologize if my choice of words make me sound rude / arrogant, that is not my intent. I often ...
0
votes
1answer
70 views

Are there other theories (apart from string theory) that combined with inflation, would produce universes with different laws?

In chaotic inflation, space would stop expanding in some points, creating hubble volumes that could experience different spontaneous symmetry breaking, which would result in different properties, such ...
5
votes
3answers
129 views

Cosmological Inflation: If Photon expands, why not other matter?

I keep repeatedly reading in many Stack Exchange and Quora questions that space of universe expands but particles (matter) don't, see e.g. this Phys.SE post. The reason given is that particles are ...
-3
votes
1answer
44 views

Could gravitational waves be the cause of inflation? [closed]

Ok, crazy idea time. Context: https://www.livescience.com/65441-gravitational-wave-memory.html Quick lay summary: Apparently gravitational waves alter the structure of the space they pass through. ...
0
votes
0answers
49 views

Tests of inflation theory

So I'm following a course in Early Universe Cosmology right now. For the next lecture we have to solve a few questions about inflation, just as preparation. I read some closely related lecture notes ...
1
vote
1answer
50 views

Is it possible that black holes generate space? [closed]

Suppose that there is a limit to the strength of a gravitational field. Then, if the mass is added to a black hole, the gravity term in the EFE will not increase, so the spatial expansion term must ...
0
votes
0answers
10 views

Regarding the initial curvature conditions in simple single scalar field slow roll inflation models

So while learning about modelling inflation using a single scalar field slow roll, most authors seem to use the Friedmann equation with the spatial curvature taken to be 0. Now one of the precursors ...