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Does the fact that we are able to see CMBR implies that universe expanded faster than light?

Although another answer accurate points out that we don't see radiation from arbitrarily early times, we could in principle without violating relativity. For example, the possibility has been ...
Sten's user avatar
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1 vote

Does the fact that we are able to see CMBR implies that universe expanded faster than light?

No, the fact that we see the CMB simply means that the radius of the observervable universe is at least 13 billion light years. If you imagine the early universe as a 3D infinite sea of bright orange ...
RC_23's user avatar
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2 votes

Does the fact that we are able to see CMBR implies that universe expanded faster than light?

We do not detect any CMBR from the inflationary epoch. The CMBR originated about 370000 years later, at recombination. Before that time the universe was opaque, like a star or substantially hotter. ...
Dale's user avatar
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3 votes

Could Space and Time Be Decoupled Pre- Big Bang?

As pointed by gandalf61, all we can do here is mostly speculation. We are far from getting answers to these questions, both from theory and observation. I don't know any theoretical framework which ...
Léo Vacher's user avatar
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3 votes
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Could Space and Time Be Decoupled Pre- Big Bang?

We really don't know anything about space or time before the Big Bang - or even if the phrase "before the Big Bang" is at all meaningful. This is because General Relativity predicts a ...
gandalf61's user avatar
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0 votes

What does the plot of the universe's Entropy versus Time starting from the big bang look like?

I currently feel that information is third state of universe, at one "time" it was all potential, then all kinetic, then informational energy, then collapsing back to all potential and ...
Ron's user avatar
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1 vote

Is cosmic background radiation the same photons bouncing around?

Before the event in our universe's history called recombination, the universe was so hot and dense that protons and electrons were mostly separated, not combined into hydrogen atoms. This meant that ...
wollyben's user avatar
1 vote

Is cosmic background radiation the same photons bouncing around?

The very early universe was so hot that electrons and nuclei could not combine to form atoms. These free charges bounced photons around very well. Things were very hot, so there were a lot of photons ...
mmesser314's user avatar
2 votes

Is the matter-antimatter asymmetry a logical or a statistical problem?

The basics This answer first addresses the title question: Is the matter-antimatter asymmetry a logical or a statistical problem? Then, it puts that question into a larger context that gives the ...
ohwilleke's user avatar
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9 votes

If we consider the spacetime of the universe to be four-dimensional, does the Big Bang lie in its center?

Some other answers say the universe isn't embedded in a background space, but I think that misses the point; the universe doesn't have to be embedded in anything for this idea to make sense. If the ...
benrg's user avatar
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25 votes
Accepted

If we consider the spacetime of the universe to be four-dimensional, does the Big Bang lie in its center?

There are two important points in here. The first was raised in a previous answer (and I'll comment on it also), but there is another nuance. The Big Bang is not a point in spacetime Yeah, that's ...
Níckolas Alves's user avatar
2 votes

If we consider the spacetime of the universe to be four-dimensional, does the Big Bang lie in its center?

Differential topology allows us to describe a 4 dimensional (3spatial+1temporal) space expanding without needing to embed it in a higher dimensional space. The balloon is a common metaphor for an ...
Cort Ammon's user avatar
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-1 votes

What would one use a theory of quantum gravity for?

Has anyone mentioned the graviton? A QG would showcase this as a fundamental force. It would then be left to delineate the limit of GR as a geometry to the discreteness of this fundamental particle of ...
Mark Thomas's user avatar
2 votes

Are there any observations from the beginning of the universe until the CMB?

In astronomy there are broadly 4 ways you can "observe" or collect information about the universe (which is what I assume you mean by "observational evidence"). By receiving ...
ProfRob's user avatar
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2 votes
Accepted

Was the singularity a boson?

No. Within our best theories, this is incorrect. In general relativity, a singularity is a hole in spacetime (which is properly defined by means of geodesic incompleteness). It is not a particle and ...
Níckolas Alves's user avatar
0 votes

What would one use a theory of quantum gravity for?

A bunch of areas in which QG would be needed: Primordial Cosmology Black hole singularities Development (or finding a no-go theorem against) of time-machines and faster-than-light travel. ...
Rexcirus's user avatar
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1 vote

What would one use a theory of quantum gravity for?

I suggest you take a look at Oriti's discussion of the Bronstein hypercube of QG meta-thelries. The different vertices of the cube correspond to the target theory one gets based on the number of ...
starseed_trooper's user avatar
3 votes

What would one use a theory of quantum gravity for?

Others have answered in terms of theoretical achievements. But there also could be practical, technological benefits. What would they be? Who knows? Could the early researchers into quantum mechanics ...
Barmar's user avatar
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