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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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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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 = { } ...
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3answers
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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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85 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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174 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
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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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 ...
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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 ...
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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 ...
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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? ...
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225 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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40 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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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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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 ...
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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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5answers
192 views

Is the universe bounded?

As I understand it nobody can pinpoint an objective "center" of the universe nor "where" the Big Bang happened. It seems the observable universe is limited by our event horizon at some 14 billion ...
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2answers
434 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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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 ...
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2answers
120 views

How can we say time began at big bang?

I have seen many times scientists refer to time when Big Bang took place and space and time born out of singularity. 'Beginning of Time' is a very misleading statement,because process of beginning ...
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0answers
24 views

Rate of expansion of universe during big bang [duplicate]

We say big bang was the explosion not in the space but of the space itself that took place in a fraction of seconds. Speaking practically, we say the universe has no edge and is infinite. If the ...
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4answers
218 views

Is it possible that dark-matter is composed of a large number of neutrinos from the big bang? [duplicate]

They seem to have all the properties of dark-matter (massive, with no electromagnetic interaction). Could it be that many of the neutrinos produced since the big bang have formed massive neutrino ...
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1answer
87 views

Is it possible that there are still gravitational waves of the big bang?

We already discovered the cosmic background radiation what are the 'leftovers' of electromagnetic radiation of the big bang. Probably gravitational waves of the big bang (if they exists) would be to ...
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3answers
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Can space expand with unlimited speed?

According to this article on the European Space Agency web site just after the Big Bang and before inflation the currently observable universe was the size of a coin. One millionth of a second later ...
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2answers
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Gravitational wave of Big bang? [duplicate]

Questions about the g-wave caused by the big bang: 1)was there a g-wave produced? 2) when will it reach us? 3) will it be too weak for us to detect(atleast now?)?
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Did the strong force trigger inflation?

I understand there can only be speculative theories regarding this epoch, but it would be great to know if this theory has some level of acceptance in the physics community. If the strong force is ...
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1answer
68 views

Is there a truly stationary frame of reference? (part deux) [duplicate]

I wonder if the belief that there is no truly stationary frame of reference is really true. Here's my thinking, please poke holes in it and/or mock me :) As we understand it, before the big bang the ...
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1answer
37 views

How is the potential infinitude of the universe compatible with the Big Bang?

I know no physics, but I read that while the observable universe is finite, for all physicists know the universe is infinite. How is this compatible with the Big Bang hypothesis? Does it mean that it'...
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323 views

Is there a “CGBR”?

The recent discovery by the LIGO made me wonder about this. We know that there exists a CMBR, Cosmic Microwave Background Radiation, a blanket of electromagnetic energy covering the universe, made by ...
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0answers
20 views

Light from the big bang [duplicate]

Considering that the Big Bang all started from a single point in space time, and the light emitted from it has been spreading outwards in all directions ever since, how do we, from earth, see the ...
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42 views

Precise definition of “Observable Universe” and its alternatives

The Observable Universe is generally said to contain all space that could "in principle" have had a causal impact on Earth, but the exact limits of the "in principle" causal interaction go unspecified....
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3answers
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Could there have been two “Big Bangs”?

A couple of years ago, I remember seeing a documentary on the big bang theory. The theory presented was that to explain the cosmic microwave background radiation, there needed to have been two big ...
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1answer
105 views

Big Bang Quarks Travelling at Light Speed [closed]

When I think of an explosion it lasts a fraction of second. When the entire mass of the universe explodes how much time passes before the perfect sphere slows from traveling at/near the speed of light ...
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1answer
148 views

The naive idea of the big bang

Many people think that according to big bang cosmology, first there was empty space, then there was an explosion in the middle of the emptiness, and now all the galaxies are flying away from that ...
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Interpretation of a singular metric

I'm interested to find out if we can say anything useful about spacetime at the singularity in the FLRW metric that occurs at $t = 0$. If I understand correctly, the FLRW spacetime is a combination ...
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3answers
110 views

Observing a point 13.82b ly away, 1b years ago

I understand that we can observe far away galaxies to get an idea how the universe looked like in the past. Assuming the universe is 13.82b years old, would it be correct to say that if we looked at ...
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3answers
566 views

Age of the universe versus absolute time [duplicate]

In Wikipedia, the age of the universe is defined as the "time elapsed since the Big Bang" while "time" links to "the cosmological time parameter of comoving coordinates" which itself links to "the ...
3
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1answer
94 views

Why is the gravitational constant.. constant? [duplicate]

Many scientists have now come to the conclusion that a big bang might not explain the 'start' of the universe and are coming up with alternatives. Could it be that gravity is dependent on the ...
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Where does all the energy in the universe come from? [duplicate]

The principle of conservation of energy says that all energy in a system will remain the same. It can just be transformed. The universe contains a huge amount of energy, but where did it come from? ...
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1answer
109 views

What effects would a finding of Gravitational Repulsion Between Matter and Anti-Matter in the ALPHA Experiment have on Mainstream Theory? [closed]

The actual nature of the gravitational force between matter and anti-matter (attractive or repulsive) remains unsettled: See Are there experiments taking place right now that might show evidence for ...
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1answer
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Does all hydrogen originate from the Big Bang?

I was wondering, if every single hydrogen in the universe originate from the time about ~3 min after the Big Bang. I know there are nuclear fusion processes going on in stars like the pp-chain ...
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6answers
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What came first, the Universe or the Physical laws that govern the Universe? [closed]

This sounds like the Egg and the Hen question but I am curious about this. If universe came first and created physical laws for itself, then what created the law or the principle as a consequence of ...
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57 views

Could the Big Bang be the result of a decrease in entropy?

In my freshman engineering physics class I learned that a decrease in entropy, though hypothetically possible, is less statistically likely than either any or almost any other possible single ...
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What would we observe as background on the sky if the big bang had never occurred?

The data we've received so far from satellites such as WMAP paints a near uniform distribution in intensity of the background radiation that we take as evidence that our universe had an origin, and ...
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1answer
108 views

Hawking in A Brief History of Time: No beginning or end of the Universe

I am reading Stephen Hawking's book - A Brief History of Time. I haven't studied cosmology and the related sciences. Nevertheless, I am interested to know few things regarding the extract taken from ...
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138 views

What was outside the singularity during the Big Bang? [closed]

What was outside the proposed singularity during big bang?What was the size of singularity?
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15 views

How is the Lyman alpha forest and Gunn-Peterson trough evidence for Reionization? [duplicate]

I'm trying to understand how the Lyman alpha forest and Gunn-Peterson trough are evidence for Reionization. From what I've read, the Lyman alpha forest tells us how much neutral hydrogen is in the ...
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3answers
110 views

How big bang could produce later collisions

The Milky Way and the Andromeda galaxies are supposed to "collide" in 4 billion years (collide in the sense of overlapping space, but nothing is really supposed to contact anything else). Assuming: ...
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Is there any possible evidence that can give us insight into what happened exactly at the Big Bang/why it happened?

It's mostly well accepted today that the Big Bang was the reason for today's universe, mostly due to the expansion, the cosmic microwave background etc. and mathematically the FLRW metric supports it. ...