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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What would be the first compound formed in the early universe?

This may sound like a chemistry problem, but I suspect this would have lot to do with primordial nucleosynthesis. After all physics underlies everything. It is believed that several elements were ...
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Where does the number “380,000 years for electrons to be trapped in orbits around nuclei” come from?

How does this number get calculated? About 380,000 years after the Big Bang the temperature of the universe fell to the point where nuclei could combine with electrons to create neutral atoms. ...
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843 views

Is the cosmic horizon related to the Big Bang event?

The Universe expands according to the Hubble's law: velocity is proportional to distance. There must be some distance, therefore, at which the velocity reaches the speed of light. This defines the ...
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222 views

When was the cosmic background radiation in the visible spectrum?

From what I understand about the Cosmic Microwave Background Radiation is that it was from the big bang, and since space has streched and become bigger since then the wavelength of the CMBR has ...
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699 views

Alternative theories to the big bang?

Hey all, are there any theories out there on the origins (or infinite existence of) the universe beside the big bang that actually adhere to current scientific knowledge and fact?
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324 views

What really is Spacetime?

What is a good definition on Space, Time and the most specific topic "Spacetime"? Because someone told me that spacetime is the foundation of the entire universe? And also, Is it possible to create ...
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Why the red-shift of distant galaxies is considered to be the effect of expanding spacetime?

Why it's not explained just by Doppler redshift caused by faster movement of those galaxies billions of years ago when that light was emitted? Would the speeds of the galaxies necessary for Doppler ...
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on causality and The Big Bang Theory

With the notion of causality, firmly fixed by GR, we derived the concept of a singular point from where space-time begun. Causality alone gives us the possibility to talk about a known past (i.e. ...
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350 views

LHC Big Bang Temperatures

It's been claimed that the LHC's 14 TeV energy produces temperatures comparable to that which occurred very soon after the Big Bang. The well-known $E=1.5kT$ formula from classical statistical ...
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639 views

The Big Bang in an infinite universe

If the universe is spatially infinite (and assuming, if it makes a difference, that we don't have eternal inflation), what actually happened 13.7 billion years ago? Was the energy density infinite (or ...
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Physical laws prior the big bang (quantum fluctuations)

A theory among scientists says that quantum fluctuations caused the big bang and created the universe. This seems plausible to me. What I can't grasp yet is how a quantum fluctuation can even start ...
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818 views

Does (it make sense to say that ) the universe has a center?

I was reading this page: http://www.guardian.co.uk/science/2011/oct/23/brian-cox-jeff-forshaw-answers and I found this sentence by Brian Cox: That seems to imply that everything is flying away ...
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262 views

Why is there still radiation left from the Big Bang now? [duplicate]

Possible Duplicate: Why can we see the cosmic microwave background (CMB)? We all have seen evidence of radiation left from the Big Bang, but how is it still detectable? Why didn't it ...
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How can something happen when time does not exist?

I saw this documentary hosted by Stephen Hawkins. And if I didn't get it wrong, it says that there was no time before the big bang, time was created there. So how can anything happen when there is ...
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How do we know the size of the universe?

Ok, from astronomical observations we can tell that the observable matter is separating - so rewind the clock about 13.7 billion years and it was all at a single point. However, how do we distinguish ...
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562 views

Doesn't dating the universe violate the concept of spacetime's inseparability?

It would seem that measuring an age of the universe from the big bang requires separating spacetime into a 3D coordinate system and a time track. I fail to understand why it is appropriate to take ...
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424 views

Do all the forces become one?

Were the forces of nature combined in one unifying force at the time of the Big Bang? By which symmetry is this unification governed? Are there any evidence for such unification of forces? Has ever ...
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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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90 views

Why doesn't the light from galaxies appear stretched? [duplicate]

Maybe it's my ignorance of astrophysics/cosmology, but I have been wondering this: Why do galaxies not appear stretched when we observe them? Assuming a galaxy that we observe is 100,000 light years ...
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70 views

What would the universe look like if it started out without any irregularities?

(Warning! Newbie question coming up!) Background As seen on this picture of the cosmic microwave background (take from the Wikipedia entry on the very same topic) there exists irregularities in the ...
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Abundances of the light element of the Big Bang Nucleosynthesis

This question is related to the Big Bang Nucleosynthesis of light elements, more concretely I do not understand some features of the graph Why do the $^3$He and D abundances go down with ...
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384 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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4answers
837 views

Do new universes form on the other side of black holes?

I have four questions about black holes and universe formations. Do new universes form on the other side of black holes? Was our own universe formed by this process? Was our big bang a black hole ...
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654 views

Big bang and time

I heard Carl Sagan talking about the Universe 15 Billion years ago, and the Big Bang. He made the statement that it was the biggest explosion of all time (at first I thought this a subtle pun). This ...
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Do atoms get created or are they recycled?

Basically, are the atoms that make up my body right now something that has existed since the big bang?
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Looking for review articles on big bang nucleosynthesis

Can someone point to a good review article covering contemporary developments in big bang nucleosynthesis, beyond what's covered in Kolb and Turner's The Early Universe? Thanks.
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Why does the homogeneity of the universe require inflation?

They say inflation must have occured because the universe is very homogeneous. Otherwise, how could one part of the universe reach the same temperature as another when the distance between the parts ...
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563 views

Additional merits to Wetterich's “Universe without expansion” compared to standard cosmological redshift interpretation?

A recent news item in Nature promotes Wetterich's preprint "A Universe without expansion". All sounds very exciting but hard to judge for non-experts. As I understand from the Nature's article, the ...
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176 views

Which came first, movement or heat?

According to my measly understanding of the universe, when particles hit one another, some of their kinetic energy is transformed into heat. But when we heat particles (for instance, putting a bucket ...
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90 views

Quantum entanglement and the big bang

Prior to the Big Bang all matter was compressed into a point of high density. Why isn't all matter already entangled?
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If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?

I'm presuming that the scientific community pretty much agrees that randomness doesn't exits, and that everything has a cause. Please correct me if I'm wrong, I've heard of quantum mechanics, but as ...
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220 views

Is the universe expanding at a speed of almost $2c$?

I've been told nothing can travel faster than the speed of light. Therefore, from my vantage point the diameter of the universe is increasing at a rate of $2c$. Are there any flaws in my thinking?
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Is the observable universe enclosed by an infinitely dense shell?

In modern cosmology, it is commonly stated to the public that as we look deeper and deeper into space, we are seeing further into the past. CMB is the relic of the big bang after photon decoupling ...
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349 views

Age of the universe and the singularity at the Big Bang

Using the standard model of cosmology we calculate the Hubble time to obtain an estimate of the age of the universe. This model assumes a beginning of time in the past. But that point is a true ...
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486 views

Before the Big Bang

I've heard this saying before I don't know about anyone else. It says, "What ever was before the big bang is something physics can't explain..! Is this saying true (accurate)?
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Shouldn't LHC have used $p\bar{p}$ collisions, instead of $pp$ collisions, to study baryogenesis?

Baryogenesis is the physical process(es) that produced baryon antibaryon asymmetry in the early universe. That means, the laws that governed the bigbang was baryon-antibaryon symmetric. On the other ...
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660 views

Creation of matter in the big bang

I appreciate your patience to my neophyte question. I am working on my dissertation in philosophy (which has nothing or little to do with physics) about the "problem of naming." Briefly what I am ...
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284 views

Is there an exact formal definition of the Universe?

I've read several articles about observable Universe, Universe and Hubble volume, including Wikipedia article and references on it, and I wondered: Is there a formal, rigorous definition in physics of ...
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237 views

What was the density of the universe when it was only the size of our solar system?

What was the density of the universe when it was only the size of our solar system? Did it approach neutron star density? Is it physically correct to even ask such a question?
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114 views

Infinite number of galaxies?

I understand that the current estimate for the number of galaxies in the observable universe is about 100-200 billion. Is there anything in our understanding of physics and the evolution of the ...
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112 views

Hydrogen cloud at the universe's beginning?

What prevented all of the hydrogen at the universe's start from coalescing into one gigantic star?
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170 views

If the universe started again with exactly the same conditions… would it be the same?

Sorry if this is a basic question but I can't find anywhere to ask else to ask it: If the universe was created again and exactly the same conditions where in place at the beginning, would everything ...
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Question regarding the validity of the big bounce

I have several questions regarding the "big bounce" theory. It appears to be popular among LQG researchers. My questions are as as follows. 1) How one reconciles it with the fact that it is now ...
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157 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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148 views

Proportion of dark matter/energy to other matters/energy at the beginning of the universe?

What was the proportion of dark matter/energy to other matters/energy at the moments after the beginning of the universe (standard Big Bang model)?
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Could there be more universes?

In the documentary: "Curiosity - Did God Create the Universe (on YouTube)", theoretical physicist and cosmologist Stephen Hawking states that time did not exist before the big bang. The first ...
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285 views

Was the singularity at Big Bang perfectly uniform and if so, why did the universe lose its uniformity?

Am I right in understanding that current theory states that Big Bang originated from a single point of singularity? If so, would this mean that this was a uniform point? If so, as the universe ...
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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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975 views

Is “A Brief History of Time” still up to date?

I have recently found my copy of Hawkings' A Brief History of Time which I have never finished. This time I'm determined to read it all the way through. However, the book is now almost 25 years old. ...
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Light years and redshift from our point of view. How can we see it?

So I was reading about GN-108036 this morning and for some reason I thought of something which I can't quite wrap my head around and make sense of. It's early morning so maybe coffee hasn't kicked in ...