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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How to calculate temperature of the universe from cosmic microwave background radiation?

Two scientists detected the cosmic microwave background radiation at a frequency of 160 GHz. What is the temperature of the universe? So I used the following two equations. peak wavelength x ...
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2answers
3k views

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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1answer
31 views

Is matter infinite? [on hold]

This may be a sophomoric question so please lay into me...but I can't find a straight answer. Many theories (multiverses on the mind), assume an infinite amount of mass/energy. Have read for every ten ...
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2answers
50 views

Did Hawking radiation flood into the small true vacuum of the early universe? [closed]

If a black holes density and temperature is inversely proportional to its mass then was this what existed before the Big Bang, an infinitely large black hole and so did Hawking radiation flood into ...
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1answer
52 views

Qualitative picture or reference for a Lemaître's Cold Big Bang theory

Warning: please, consider this question to be motivated by historical curiosity or as an exercise in model-building. I believe this cannot be considered non-mainstream physics as it was very much ...
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3answers
273 views

Reference request for low entropy big bang

There is a somewhat widely accepted argument that the second law of thermodynamics exists because the universe began in a low-entropy state. I'm writing a paper that mentions this (and must be ...
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4answers
113 views

Why is acceleration of expansion of space unexplained?

I didn't know how to better phrase the question so here we go. It says that the farther we see from our galaxy the faster the other object seems to be going away (accelerating). My common sense ...
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2answers
66 views

In the classical inflation and big bang theory how can the universe grow to infinity?

Some astronomers make the conjecture that the universe is actually infinite in extent (which is a bad manner of expressing, I know). If so, how could it grow to this size in the classical theory of ...
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1answer
74 views

Should entropy define order rather than disorder? [closed]

Disorder, as I understand it, is basically a measure of entropy. This does not seem correct to me, and appears to be a result of our macroscopic bias. Not only does the beginning of the universe ...
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1answer
53 views

What is Hawking's, “No Boundary Conditions”? [closed]

In his "No Boundary Conditions", is Hawking stating that time is eternal? And what is the difference between Real Time and Imaginary Time? Is he saying there are two different arrows of time, and ...
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1answer
46 views

What other particles don't participate in BBN?

This is a follow up to an earlier question. Of the responses I got back, the general sense is that Dark Matter (DM) is a "thermal relic" from an earlier epoch of the universe when temperatures were ...
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1answer
42 views

How do we filter out radiation from galaxies from the cosmic background radiation?

When a whole sky view is done to get a picture of the cosmic background radiation the radiation from our Galaxy is filtered out, and we are left with a picture which show radiation coming, more or ...
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1answer
191 views

Is the Universe infinite or it's just expanding to infinity?

According to the WMAP data in the past years we can say that our universe is considered flat or at least nearly flat and we also know that flat universe is allowed to be both infinite or finite in ...
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1answer
70 views

Hubble's constant measured by observer approaching light speed

I recently read about expansion of the universe and I can't figure out if Hubble's law (and other models of expansion of the universe) is compatible with the theory of relativity. My question is: In ...
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2answers
208 views

Is entropy absolute (as in absolute temperature)?

Following this question on the Entropy at the Big Bang where I asked: Since Entropy always increases (in general); its expected that the entropy at the beginning of the universe should be the ...
111
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5answers
14k views

Did the Big Bang happen at a point?

TV documentaries invariably show the Big Bang as an exploding ball of fire expanding outwards. Did the Big Bang really explode outwards from a point like this? If not, what did happen?
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Can we see the past view of our galaxy while observing in the sky because of the homogeneous structure of our universe?

As a sense, we think that simple speed addition should work ($V_1+V_2$) for all references but we know today that universe does not match our this sense. We cannot exceed the speed of light in any ...
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1answer
53 views

Why does the flatness problem (of the universe) present a fine tuning problem?

The Friedmann equation can be written $$|\Omega-1|=\frac{|k|}{a^2H^2}$$ In a period where the universe is decelerated $a^2H^2$ becomes bigger as we extrapolate into the past. We know $|\Omega-1|$ ...
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32 views

Logical Explanation as to how exactly did Space and Time originated with the Big Bang [duplicate]

I've read a couple of answers to this question but somehow I'm unable to find a chain of causalities that would prove that space and both time originated from Big Bang, besides I don't quite ...
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37 views

Gravitational entropy [duplicate]

In the beginning (big bang), mass was evenly distributed (if you consider an elementary particle as an extended object, like a circle on a very thin cylinder, with a radius near the Planck length, but ...
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1answer
253 views

What is the difference between the Big Bang Model and the Λ-CDM Model?

If I'm going to write about "The Consensus Model of Cosmology" should I include Big Bang Model or should I go with just the $\Lambda$-CDM Model?
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1answer
108 views

How can Big Bang happen without time?

I had recently watched a video and he says big bang could have happen by the slow collision rather than a fast collision. But I know that there was no time before the big bang and fast and slow are ...
0
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1answer
63 views

Big Bang not really the beginning of a completely new universe? [closed]

From what I know about the origins of the universe and the big bang, it is stated that it all started from an intensely hot and dense mass. This sounds like a singularity to me, which means a black ...
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1answer
101 views

How did gravity exist before mass?

I'm brushing up on my Big Bang, and I noticed that, apparently, although gravity is the first force to split from the original "superforce", mass does not appear on the scene until after the second ...
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1answer
340 views

In the big crunch theory, when the big crunch singularity forms, can the resulting black hole decay through hawking's radiation?

I've been pondering about this and I couldn't really find the answer for this. The big crunch theory postulates that the universe will eventually stop expanding and reverse back in on its self into a ...
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4answers
669 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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Did time also began from big bang?

Did time began from big bang? If not then what existed before big bang? If time had a beginning, then does it have a end, or pause because if time had a pause then we would not have known about it, ...
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32 views

What if a black hole of normal matter and a black hole of antimatter collided? [duplicate]

This is a curiosity question. Considering same mass black holes. As nothing can come out of either black hole, would the annihilation result into a black hole of energy? Assuming the two black holes ...
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3answers
69 views

What evidence is there that universe will not shrink again?

There are theory that universe eternally expanding and shrinking, so that every event and our lives will repeated again. At the other hand some scientists thinks that it will not shrink again because ...
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24 views

The big bang singularity and entanglement [duplicate]

Since our universe began as a singularity would that mean that everything in the universe is entangled with itself? I am not sure that makes sense, but hopefully some one can figure out what I am ...
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0answers
27 views

quantum fluctuation to explain the big bang

I have seen on this site a few times the following picture but the big bang was supposedly the beginning of time also so how can quantum fluctuations which are functions in time (like all our known ...
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2answers
108 views

Scanning the universe - edit: expanding or shrinking

I know that this may sound as a very basic question, but how come that we can detect CMB radiation, light or gravitational waves from the big-bang era? Shouldn't this radiation has overtaken us a ...
7
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1answer
209 views

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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49 views

When did the universe become lighter than water at 1 g/cm3 [closed]

Did the universe become lighter than water before light could travel through it? What temperature was it at the time where matter was roughly 1g/cm3?
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1answer
72 views

Creating something from nothing [closed]

Space is NOT NOTHING this is space in Cantorial Set Theory: S = {(x, y, z) | r² = x² + y² + z² } But NOTHING in set theory has a special symbol and it is written like this: Ø = { } ...
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3answers
84 views

Baryonic acoustic oscillations: Why are there standing waves in the CMB?

On page three of the following http://www.quantumfieldtheory.info/CMB.pdf, Klauber talks about the formation of standing waves from acoustic vibrations in the early universe. He claims that they form ...
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1answer
84 views

Does Big Bang Cosmology imply/require infinite space?

The reason I am asking this question is because if all points in space observe recession of galaxies the same as we do from Earth, the universe would have to be infinite (or a closed sphere in 4D or ...
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1answer
165 views

Could the uncertainty principle create matter in the Universe?

According to quantum mechanics we have the uncertainty principle: $$\Delta E \ \Delta t \geq \frac{\hbar}{2}$$ Near the beginning of the Universe $\Delta t$ is very small and therefore $\Delta E$ is ...
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2answers
50 views

How Can a Singularity contain different things? [closed]

According to the Big Bang model, space and everything in it was squeezed into a infinitely small point which subsequently expanded. But if everything is squeezed into a point of zero size than there ...
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1answer
72 views

Wouldn't it take an infinite amount of time to create an infinite universe? [duplicate]

I have heard many people say that the universe is possible infinite. But, if it takes time and energy to create bodies such as planets and stars and the universe has only existed for 13.7 billion ...
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5answers
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Did time exist before the creation of matter in the universe?

Does time stretch all the way back for infinity or was there a point when time appears to start in the universe? I remember reading long ago somewhere that according to one theory time began shortly ...
3
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32 views

Disappearing galaxies [duplicate]

According to the cosmological model of the expanding universe, the distant (diametrally opposite) galaxies have bigger and bigger relative comoving speed, and this speed (which is not a relative speed ...
3
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1answer
2k views

Obtaining a copy of Hawking's Ph.D thesis - Properties of Expanding Universes

Due to its popularity, I am interested to know the 4 chapter titles and topics covered in S.W. Hawking Ph.D, Properties of Expanding Universes. I also ask this because that thesis is hardly available.
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68 views

Black Holes and the Multiverse [closed]

Are there any peer-reviewed theories which explore the idea that black holes in our universe may spawn other universes - or that our universe came from a black-hole-like event in another universe? ...
7
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1answer
210 views

Restoration of spontaneously broken symmetry at high energy

It is common to find books saying that above a certain energy, a certain symmetry in particle physics is restored, e.g. the $SU(2)\times U(1)$ electroweak symmetry was unbroken between $10^{-36}$ to $...
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1answer
38 views

Were the known laws of physics valid at the Big Bang?

Did the currently known laws of physics also come into existence at the time of the big bang? What about the various constants such as mass of electron or speed of light? Did these also come into ...
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0answers
77 views

What started the Big Bang? [duplicate]

If the Big Bang started everything, including time, what EVENT could ever occur outside time unless all events are non-temporal prior to and during the big bang?
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25 views

Time in the early universe [duplicate]

When it is said, for example, that grand unification took place "Between 10−43 second and 10−36 second after the Big Bang", how are these figures of time derived? Moreover, do these figures have any ...
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What would happen if another big bang occurred at the centre of the current universe? [duplicate]

If another Big Bang occurred now, at the centre of our universe, what would happen? As the rate of expansion is increasing, the two "layers" (if there were any) would never meet, in which case, would ...