According to the current cosmological theories, it's the model that explains the early life of the universe, starting from a rapid expansion of hot and dense matter.

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If nothing can travel faster than speed of light then how the Universe is only 13.7 billion years old? [duplicate]

The light would take 93 billion years to reach the edge of universe but nothing can travel faster than the speed of light not even the big bang?
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What does it mean to have infinite negative conformal time?

In the context of Inflationary Cosmology, it is postulated that there was a period of shrinking Hubble Sphere radius $(aH)^{-1}$. $$ \frac{d}{dt} (aH)^{-1} < 0 $$ Then the regions of the ...
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40 views

Primordial flunctuation gave rise to cosmic structures?

I'm not a physicist, not even a physics student. I'm just reading Lawrence Krauss's book A Universe From Nothing and I got stuck understanding a concept. In his book, Lawrence says: Quantum ...
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74 views

Probability of spontaneous Boltzmann brain formation

I was reading through: http://www.scottaaronson.com/papers/giqtm3.pdf But I can't make sense of page 61 discussing Boltzmann brains. Specifically the fact that it says: But the problem is worse. ...
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30 views

Was the mass of the universe the same when it first began as it is now? [duplicate]

I've heard that the big bang began in all places at once, but my physics teacher told my class that the universe was all once compressed into a single dense piece of matter. If my physics teacher is ...
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53 views

What would be the speed of a hypothethetical object created during the big bang

What would be the speed of a hypothethetical object created during the big bang, and that has been moving around in the universe and that is now close to the earth, so the time elapsed (from the ...
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32 views

Will it ever be possible to observe the cosmic neutrino background?

Is there any foreseeable technology which would facilitate the direct observation of the cosmic neutrino background? Would the ability to warp spacetime have any application here?
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61 views

Hot Big Bang vs. Big Bang

This should hopefully be a quick one. Is there any difference between the Big Bang Theory and the Hot Big Bang Theory? Around Cambridge I hear everyone using "Hot Big Bang Theory", for example ther ...
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41 views

Experimental evidence for the relic neutrinos

What are the experimental (indirect) evidence for the cosmic neutrino background? Where can I read more about this? The discussion on the wikipedia page about the C$\nu$B seems to me to be more ...
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222 views

gravitational waves

Now that scientists found the primordial gravitational waves that formed shortly after the big bang,and we all now that just after the bang the 4 fundamental forces were unified can we consider that ...
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123 views

Matter vs. Antimatter shortly after Big Bang

I am not a physicist or astronomer in training at all, so this might be a dumb question with an obvious answer, but as I watched something the other day on matter & anti-matter, and the discussion ...
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41 views

Qualtitative explanation for the link between low magnitude of high z supernova and accelerated expansion

Is there any explanation on a qualitative level why we can see in the observed magnitude vs. redshift z plot that the universe is expanding accelerated? See for example here: ...
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57 views

Could the universe be a series of Big Bangs? [closed]

Imagine an eruption of energy/mass $E$ from a singularity $O$, as in a Big Bang. After the energy/mass $E$ is all at more than a distance $d$ from $O$, is it for some value of $d$ possible that there ...
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46 views

Which big bang theory has more assumptions?

I'm trying to compare the two most popular big bang theories, the big freeze and the big crunch or big bounce theory, and apply Occam's razor, which says the more assumptions a solution has, the more ...
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62 views

Open Big Bang-less universe?

This came up in discussion around a class I'm taking. For a Universe with $\Lambda$ and matter contributions to energy density (and implicitly curvature, but no radiation), can you have a universe ...
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1answer
70 views

Is redshift the only way by which we can tell that space is expanding?

There's another question on physics.SE whose answer, if I have understood it correctly, explains that the farther the points are in space the faster they are moving away from each other. Actually, ...
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1answer
137 views

The first $10^{-35}$ seconds [closed]

I am a rank amateur, so please forgive me if the answer to this is well-known. The following quote can in a weekly update for an EdX course I am following in astrophysics: "And what a week it's ...
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2answers
263 views

When did the first carbon atom in the Universe come into existence?

I am a chemist with a passion for astrophysics and particle physics, and one of the most marvellous things I have learned in my life is the process of stellar nucleosynthesis. It saddens me how my ...
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136 views

How does the Cosmic Microwave Background give us information about the Big Bang?

I was reading about CMB after this new breakthrough last week and I could not figure this out. The CMB did not exist before the epoch of Last Scattering. They were just photons which were formed at ...
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1answer
118 views

Immediately after the Big Bang, was the universe in a state of extremely low or extremely high entropy?

Phase space theory suggests that the largest course-graining region, $p$, in a phase space, $P$, is the point in the phase space with the highest entropy. As such, it is in thermal equilibrium with ...
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342 views

Light takes too long to get here

When looking at the night sky, we see lots of stars. Several places tell you that the light of those stars has traveled to many light years to reach Earth and there may be others where light has not ...
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2answers
1k views

Inflation and the Meaning of Time

I'm not quite sure how to ask this so that it can be answered in layman's terms, but I have lately seen, in several places, that with cosmological inflation, there was a point where the universe ...
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195 views

If nothing can travel faster than the speed of light, how can there be parts of the universe we can't see? [duplicate]

Assuming we originated from a single infinitely dense point in space time in the big bang, how can there be parts of the universe that we can't see as the light has not reached us yet, if nothing can ...
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1answer
128 views

Many times speed of light [duplicate]

http://www.huffingtonpost.com/2014/03/24/theory-of-everything-big-bang-discovery_n_5019126.html What does "many times speed of light" really mean in this context? For a layman it's easy to draw wrong ...
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84 views

The gravity waves from the big bang? How can we know?

The latest news says that scientists detected gravitational waves from the Big Bang. My question is how do they know the waves originated in the big bang verses any number of supernovae and or ...
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35 views

How mass being distributed after an explosion

Consider an explosion which is taking place in a vacuum, The exploding object is very small with a huge amount of energy and high density (like a big bang explosion) and the object explodes from the ...
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The age of the universe

Many times I have read statements like, "the age of the universe is 14 billion years" . For example this wikipedia page Big Bang. Now, my question is, which observers' are these time intervals? ...
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Is Space conserved [closed]

Can space be created or destroyed? Is space conserved? I am not asking for matter,energy and time. Its just a question about conservation of space PS: I am asking for what was there before big bang. ...
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Connection between BAO und CMB Spectrum

I have a problem understanding the connection between the accoustic peaks in the CMB spectrum and the baryon oscillation picture. On the one hand it is stated, that the odd accoustic peaks (1,3,5..) ...
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288 views

If the universe didn't expand faster than light, would our nights brighter like day?

There's a common QnA which has amused and inspired many kids: There are billions of Stars in the sky. If we combine lights received from all stars, wouldn't it beat Sun? Why is night dark really? ...
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2answers
271 views

Did the singularity really existed in the begining of the universe?

I read in Hawking's brief history of time the following: The final result was a joint paper by Penrose and myself in 1970, which at last proved that there must have been a big bang ...
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1answer
162 views

Can we have a static point in the universe? [closed]

Big bang theory states that the universe began from a single point (which we may consider as a central frame of reference for the objects in the Universe). In 1929, Edwin Hubble confirmed that the ...
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57 views

According to Penrose, Weyl Tensor=0 is the start/end of the Universe. Must it =0?

If I understand Roger Penrose's theory, as the Universe expands and cools, matter is consumed by black holes. Eventually the black holes collide and evaporate so that there is only energy and the Weyl ...
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322 views

Was Einstein wrong when he said nothing can go faster than the speed of light? [duplicate]

If the universe is constantly expanding faster than the speed of light, how could Einstein be right?
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129 views

Initial conditions of the origin of the universe [duplicate]

I'm not quite sure this question fits the format of this site but I try to word it the best I can to comply the rules. The question is simple: How far can we go talking about the origin of the ...
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2answers
50 views

Approximation of the energy for low $T$ in the early universe

In Perkins `Particle Physics', to compute the baryon-antibaryon-ratio, he uses that for $Mc^2\gg kT$: $$E= Mc^2 + \frac{p^2c^2}{2m}.$$ I realize that the approximation comes from $E^2=M^2c^4 + p^2c^2$ ...
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315 views

What is happening as our Universe is expanding? Is entropy increasing or decreasing?

Scientists say that entropy of our universe is increasing as it is expanding and our universe is cooling down gradually from the time of it's birth.If something is getting cooler and cooler then how ...
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80 views

A way to determine the exact location of the Big Bang?

See What is our location relative to the Big Bang?, which contains the following: The conclusion is that the Big Bang happened everywhere, all at once. Phys.SE users Ali and WernerCD reached this ...
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698 views

Does the uncertainity principle violate the law of conservation of energy?

What is the scientific view of the beginning of universe? Quantum fluctuation seems to contradict with the law of conservation of energy. Uncertainity Principle does seem to violate the Law of ...
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2answers
128 views

How could mass exist before Big Bang?

I heard that before Big Bang the temperatures were so high that mass and energy constantly converted to each other. After big bang the temperature became less and the conversion stopped that is what ...
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1answer
74 views

Is this a possible big-bang scenario? [closed]

Assume an universe with a single black hole that contains all the universe's mass and then let's wait for quite some time. What happens if by Heisenberg's uncertainty principle a virtual ...
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1answer
53 views

branes-collision -> big-bang -> 2nd Universe?

If the cosmological model of the Ekpyrotic universe is correct should there not always a 2nd universe be created on the 2nd brane? Pictures and articles I found speak only of one universe. Why is ...
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98 views

Is there there is another universe which is made up of antimatter, in large amounts like ours is made up of matter?

Can it be possible that in the big bang, not one, but two universes were formed, one formed of matter, and the other formed of antimatter? It seems logical to me that since our universe is formed of ...
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1answer
73 views

What is actually universe? only matter or both matter and space? [duplicate]

I have googled for the "meaning of universe" where I found the following: "all existing matter and space considered as a whole; the cosmos. The universe is believed to be at least 10 billion light ...
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1answer
117 views

How to reconcile these two principles?

Quantum mechanics says that the entropy of an unobserved system remains constant. As such, the apparent growth of entropy is a subjective illusion. If we consider the wave function of the universe, ...
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1answer
76 views

A well-defined quantum probability in the beginning of the universe?

In mathematics or statistics, a well defined probability requires a large sample space. However, in the beginning of the universe, when the first quantum collapse happened, the sample space contains ...
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1answer
61 views

Speed of light's relation with the expansion of the universe [duplicate]

If nothing can travel at the speed of light and light cannot escape the universe, then the rate of expansion of the universe should be equal to the speed of light, why it is not?
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1answer
122 views

Would time dilation be too great for the early universe to expand?

I read that one second after the big bang the universe was composed of photons electrons and neutrinos. Wouldn't the density of energy/matter have caused such extreme time dilation that the universe ...
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1answer
193 views

Equation for Hubble Value as a function of time

I am trying to write the equation for the situation where the Hubble parameter $H$ would be changing over time. In other words, it would represent an accelerated expansion of the Universe. That is, ...
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2answers
573 views

Is there a center of the Universe if the Universe is finite?

Ok, let me make myself clear. I saw all the other questions related to the question, but none of them actually asks the question the way I would put it and therefore no one answers it the way I want ...