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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Is this explanation for the Universe's low entropy at its origins plausible? [on hold]

I've been thinking about this, and it may sound very ludicrous (and it probably is), but I may have come up with a proto-explanation for it. I hope I won't come across as some misinformed perpetual ...
1
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0answers
15 views

Did the universe really start with a single point? [duplicate]

I read everywhere the famous, but offhand statement that "the universe began from a single point" and this bugs me because that surely isn't true. My understanding has always been that this was an ...
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2answers
81 views

Origin of time or origin of space-time? [on hold]

Are there alternate theories or models that contradicts the idea that big bang is the origin of time ?
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2answers
61 views

Why is the possibility of the universe having a centre around which everything orbits not considered feasible?

I'm sure there is some kind of reason as to why this isn't considered as a legitimate theory but upon giving it though it seemed to make sense to me. I figure if all gravitational orbits are ...
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1answer
44 views

Why is it said that photon-wavelengths have increased by a factor of 1000 since our universe became transparent to light?

After reading several explanations for the so-called "Hubble-radius", and still being confused, (as I reckon are some of the folks who tried to answer THAT question !!), I have a related question, ...
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52 views

Are the laws of physics and the properties of matter intrinisc to the universe? Could it have been different? [closed]

Are the specific laws and properties of all that exists within this universe intrinsic to what makes up the universe (whether it was in the state it was in before the Big Bang, how it is now, or how ...
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1answer
64 views

Is the universe actually formed according to the big bang theory? [closed]

Big-Bang pretty much explain the origin of universe, but still many people don't believe it. Isn't it possible that our universe come out of a white hole which have been pulled out from a black hole ...
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3answers
499 views

How would cold neutrinos get trapped by stars?

Continuing on from the cool physics Q&A'd on the threads Where are all the slow neutrinos?, Is it possible that all "spontaneous nuclear decay" is actually "slow neutrino" ...
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0answers
25 views

How do we know that the big bang happened everywhere, simultaneously? [duplicate]

If we can't see beyond the limits of the observable universe how do we know that the big bang happened everywhere, simultaneously?
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3answers
250 views

What does the cosmic neutrino background look like today, given that neutrinos possess mass?

This question is inspired by (or a follow-up to) the threads Where are all the slow neutrinos? and Is it possible that all “spontaneous nuclear decay” is actually “slow neutrino” induced? The cosmic ...
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1answer
62 views

Is it possible to dumb down the idea that “Time didn't exist until the big bang”? [duplicate]

So, I've asked questions before that have been met with "Time (and our laws of physics) didn't exist before the big bang" and other answers to that effect. This is massively confusing to me, for ...
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2answers
2k views

How do we know what happened during the Big Bang?

Any data that we have on the Big Bang comes from the cosmic microwave background (CMB) which was created about 380,000 years after the Big Bang. From there we have been able to calculate what the ...
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18 views

What is signifcance of density of the universe if it changes?

So theories of expansion of the universe (before dark matter and energy) said that the ultimate fate of the universe is based on the density of the universe and this being compared to the critical ...
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2answers
67 views

Big Crunch, then new Big Bang = exact same Universe? [closed]

If after a Big Crunch, the new singularity explodes in a Big Bang, would we get the same Universe all over again? Since black holes retain all the information they've stored, would we get an exact ...
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3answers
62 views

How can we look back at our Universe 13Billion years ago? [duplicate]

I read this article on Space.com and I quote "As far as we know, that's as far [back] as we can see — we get an image of the universe as it was when it was about 389,000 years old," So what I wanna ...
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0answers
41 views

The origin of the universe and its current movement [duplicate]

Our universe started with the big bang, which was not within our universe, since it didn't exist. Let's assume it was the result of a quantum fluctuation in time. I have 2 questions: The common ...
3
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2answers
51 views

Could a pocket universe be birthed out of the negative pressure in our universe?

I have just recently started learning about inflationary cosmology so I don't know much about it. But from my understanding, the theory says the big bang was started by the expansion of a small region ...
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2answers
74 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
58 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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4answers
114 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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1answer
77 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 ...
0
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1answer
58 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
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 ...
3
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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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0answers
43 views

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 ...
2
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1answer
55 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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0answers
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 ...
4
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1answer
281 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
113 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 ...
4
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1answer
105 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 ...
0
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1answer
68 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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3answers
70 views

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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0answers
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
71 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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0answers
27 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
32 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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1answer
50 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
75 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 = { } ...
2
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3answers
93 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
173 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 ...
0
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2answers
51 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
74 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 ...
3
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0answers
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 ...
7
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1answer
224 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 $...
1
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0answers
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? ...
1
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0answers
26 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 ...
0
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0answers
26 views

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 ...
3
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1answer
48 views

Hydrogen in a glass of water

One of the great Sagan quotes is that we are made of star stuff - meaning the atoms in our bodies were formed from stellar nucleosynthesis. However, what about the hydrogen in a glass of water? Would ...
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0answers
69 views

My question is about big bang theory [closed]

Oh srry my english is weak i am only 11 years old but i love physics my question was accourding to maxwell and enistien nothing can go faster than light and if we give an object enough energy to move ...