Questions tagged [big-bang]

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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Hypothetically, according to the Standard Model, if the universe were not expanding, could we not cut out the Big Bang and inflation?

Hypothetically, according to the Standard Model, if the universe were not expanding, could we not cut out the Big Bang and inflation and begin the universe in an expanded state and still get the same ...
2 votes
2 answers
77 views

Did electric charge not exist in the early universe?

I ask this question based on something Don Lincoln said in a video about leptogenesis over at the Fermilab Youtube channel. Video for reference: https://www.youtube.com/watch?v=PsqEcGMjEfo Here is his ...
-2 votes
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Was space created prior to the Higgs field during the Big Bang? [closed]

I am trying to understand what created physical space and what caused the creation of space during the BB. If something preceded space for example the Higgs field does this mean that the Higgs is ...
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Does the Higgs particle constitute the physical vacuum space? [closed]

If there was no Higgs particle besides of matter not being possible does this mean that there would be no physical space also?
3 votes
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Confused about size of the universe in the past

From Wikipedia, I got that the photons of the cosmic microwave background radiation originated when the spherical volume of space which will become the observable universe was 42 million light-years ...
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Standard resources outlining the Planck Epoch in detail?

The Wikipedia page on the Planck Epoch links to the universeadventure.org website, from UC Berkeley, which I so happened to have worked on (for a semester or so) when I was an undergraduate there. But ...
4 votes
1 answer
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Why don't we see the big bang?

excuse my understanding, my brain is melting. So I understand that pictures of far away objects is like viewing the past. and I think I pretty much get that the big bang was in every direction since ...
6 votes
3 answers
2k 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?
5 votes
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Are there primordial populations of neutron stars and white dwarfs?

There is a well-known prediction that density fluctuations in the first moments of the Big Bang produced primordial black holes. Black holes from stellar collapse have their masses constrained by ...
4 votes
1 answer
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How is it possible that we see light from shortly after the big bang?

How can astronomers see light from shortly after the big bang? How did we get "here" before the light that emanated from our "creation"?
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1 answer
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Implications of the axis of evil in Big Bang theory and cosmological inflation?

According the the axis of evil feature of the CMB map verified twice by space missions our home location is on this center axis of the CMB map! Making our home location sort of the center of the ...
3 votes
1 answer
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How can we still see the CMB? [duplicate]

May seem stupid but i cant wrap my head around it. if a star explodes we eventually see it when the light gets here. but once its got here we see the event and the star is now gone, we cant see it ...
2 votes
2 answers
784 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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1 answer
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Is HD1 Galaxy a potential Big Bang theory killer?

I have heard some first explanations of why the farthest ever galaxy discovered about 13.27 Bly away the HD1 appears so UV active and about the population III stars inside this galaxy made only from ...
2 votes
1 answer
85 views

Why can we see all the way back to 600 million years after the Big Bang?

I apologise that what I'm about to ask has probably in some format been discussed before on the site. Like many recent questions here, this is motivated by the James Webb telescope: a relative of mine ...
1 vote
1 answer
318 views

What is meant by "spontaneous creation" in this paper?

I have some questions in regard to the paper "Spontaneous creation of the universe from nothing". If I am not mistaken it is akin to Alexander Vilenkin's proposed cosmological model that has the ...
1 vote
2 answers
74 views

How is there energy and charge in the universe? [closed]

According law of conservation of charge "the total electric charge in the universe is constant and charge can neither be created nor be destroyed" so how did the existing charge came. I f it ...
1 vote
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Is Eddington-Lemaître universe relevant to current cosmology?

The "Modern Cosmology" article in Scholarpedia.org mentions the Eddington-Lemaître universe as an example for "an emergence from a static state" as a possible start of the universe....
-1 votes
2 answers
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Why the outer rim of our observable Universe is the oldest in age?

I don't get it. They telling us that the Webb space telescope will look far away from our home position deep into our observable Universe towards its outer rim about 13 Billion lyrs away where the ...
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2 answers
50 views

If there was an infinite amount of matter at big bang to form an infinite universe how it was possible for a so huge amount of matter to expand?

If there was an infinite amount of matter at big bang to form an infinite universe how it was possible for a so huge amount of matter to expand? Is it better to think that the universe is spatially ...
11 votes
3 answers
366 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 ...
1 vote
1 answer
46 views

Higher order terms in Big Bang derivation

You can easilty proof that an SEC fluid gives a big bang by looking at the second Friedmann equation: $$ \frac{\ddot{a}}{a} = -\frac{4\pi G}{3}(\rho + 3P) \le 0 $$ This implies that $\ddot{a} \le 0$ ...
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If KE of galaxies is negligible compared to dark energy of space expansion why then we should think matter at Big bang had high KE?

If KE of galaxies is negligible compared to dark energy of space expansion is then correct think that matter particles at Big bang had high KE while moving away from each other? Is reasonable think ...
2 votes
2 answers
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If CMB came from the big bang, how come we got to where we are before the CMB arrived? [duplicate]

I have read that the cosmic background radiation was formed 380,000 years after the big bang, when stuff changed from being opaque to light, because of free electrons, to becoming transparent. However,...
4 votes
2 answers
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Why is the baryon to photon ratio assumed to be constant?

For standard BBN calculations, we use the baryon to photon ratio $$ \eta=\frac{n_b}{n_\gamma} $$ that we get from CMB. Now, this clearly assumes that $$ \eta_{BBN}=\eta_{CMB}. $$ There are around ...
1 vote
3 answers
401 views

Right after the Big Bang, how did particles overcome extreme gravity and other forces and manage to fly apart?

I have read this question: Why did the universe not collapse to a black hole shortly after the big bang? where Lubos Motl says: This matter has no center - it is almost uniform throughout space - and ...
18 votes
4 answers
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How long will the Universe's hydrogen reserves last for?

I recently became really interested in learning about physics and cosmology, but I still know very little. Hopefully someone with more knowledge will be able to shed some light on my questions. Here ...
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1 answer
412 views

Is there a theory which suggests a cyclic Universe with a decreasing density parameter?

If the density of the Universe is less than the critical density it will expand forever If the density of the Universe is greater than the critical density, then gravity will cause to collapse back on ...
18 votes
4 answers
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How can the universe be hot or dense in the first moments after the big bang when it has no matter?

From the CERN website: In the first moments after the Big Bang, the universe was extremely hot and dense. I've always heard this about the big bang but I've never thought about it before now. If &...
1 vote
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Why is the Hubble law so accurate at scales smaller than galactic voids?

It's possible to derive the Hubble law: $$v = H_0 d$$ from the FRW metric by differentiation. Experimentally the Hubble law appears to hold for relatively small distances, say 20 Mpc and smaller. ...
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1 answer
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How does the scale of a cataclysm determine if we can look beyond it?

The textbook I am referring to (Physics for Scientists and Engineers ($9e$), page $1 469$, section $46.11$), has the following paragraph regading the Big Bang: ... This theory of cosmology states ...
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1 answer
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Matter-antimatter annihilation and CMBR [duplicate]

Does this intensity of microwave background radiation correspond to the huge amount of gamma photons that could be released during the theoretical annihilation of matter and antimatter at the time of ...
4 votes
2 answers
297 views

Hints of pre Big-Bang physics and how to detect them?

The Big Bang model is the current large-scale accepted and tested theory. However, several new physics models or theories propose that there could be a previous Universe. To what extent can be test ...
11 votes
2 answers
785 views

If we could build a telescope to view the cosmic neutrino background, what would we see?

If we could build a neutrino telescope capable of viewing relic neutrinos that decoupled after the big bang, with a similar angular and spectral resolution that is possible now for the CMB (e.g. with ...
101 votes
7 answers
19k views

Why is there a scarcity of lithium?

One of the major impediments to the widespread adoption of electric cars is a shortage of lithium for the batteries. I read an article a while back that says that there is simply not enough lithium ...
1 vote
1 answer
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Based on structure formation and the lifetime of the universe why is there an upper bound on the cosmological constant?

I understand that significantly greater values than the cosmological constant would result in difficulty for the formation of large gravitationally bound structures within the lifetime of the universe....
18 votes
5 answers
6k views

How does it make sense for the universe to have started from a big bang?

It has been said that the Big Bang started from a singularity. Think about a balloon radially growing over time. Fix a time $t_0, t_1 > 0$, and let $M_0, M_1$ be two balloons at time $t_0, t_1$ ...
2 votes
1 answer
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What implications to cosmology would it have if Webb Telescope probing the far end of our observable Universe finds out a large number of galaxies?

Since it is predicted that Cosmos is no less than 250 times that of the observable Universe (13.8 Blyrs) in size: MIT Technology Review I wondering how you can calculate any age of matter creation (...
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1 answer
238 views

Did gravity exist before the Big Bang?

Gravity is one of the biggest mysteries. It is the weakest of the 4 fundamental forces but we have no clue how it works. Einstein never was able to figure it out in his lifetime. There is evidence ...
1 vote
1 answer
68 views

How is the Big Bang compatible with the preservation of quantum information?

As detailed at https://en.wikipedia.org/wiki/No-hiding_theorem , in the quantum world, information cannot be created or destroyed. The Bekenstein bound limits the amount of information that can be ...
1 vote
2 answers
184 views

${}$Hawking radiation and Einstein-Cartan theory

As I understand it, Einstein-Cartan theory predicts that inside every black hole, there is an einstein rosenbridge connecting to a new universe that forms due to a white hole. Where does hawking ...
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1 answer
357 views

What is the difference between a quantum fluctuation and a singularity in the beginning universe?

I am sure this is a naive question that shows my lack of sophistication in physics but I keep reading "the early universe was a "singularity", on the other hand ..... I also see quantum fluctuation ...
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2 answers
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What is there at a point the universe hasn't expanded past yet? [duplicate]

(Please don't mark as a duplicate) If the universe is constantly expanding that means that there is a point the univese hasn't expanded past, with that what would be past that point? This isn't about ...
3 votes
1 answer
92 views

Deriving the age of the universe

I am trying to work out the solution to exercise 8.4 from An Introduction to Modern Cosmology by Andrew Liddle. I could derive the Friedmann equation as below, $$\dot{a}^2 = H_0^2 \left[\Omega_0a^{-1} ...
2 votes
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Do the apparent infinities at the center of black holes disappear if instead a phase-change takes the place of its singularity?

When I watch physics documentaries that discuss black holes, they talk of impossible infinities in the singularity at a black hole's centre. I was wondering about the bubbles of water vapour in ...
9 votes
1 answer
1k views

Why did the quark epoch occur earlier than the lepton epoch?

I don't understand the reason and hypothesis behind why the quarks appeared first—as per the big bang cosmology—shortly after the strong and electroweak force separated. We don't know what the quarks ...
1 vote
0 answers
32 views

Does photon-photon scattering influence classical vacuum E&M dynamics?

At a purely classical level, Maxwell's equations are completely linear, and associated with a linear coupling to a conserved current in the electrodynamical Lagrangian. When this Lagrangian is ...
1 vote
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Why is the age of the universe $=D/v$, despite that $v$ is not constant with time?

I am watching a series of lectures by the Noble prize laureate Brian Schmidt and Paul Francis and in this episode (at 4:20) they make the simple assumption that a galaxy receding from us due to the ...
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What if cosmological inflation never stopped?

If inflantionary theory is correct, the universe ceased to expand after just $10^{−32}$ seconds. Imagine a scenario where cosmic inflation never actually stopped. At the extremely accelerated ...
2 votes
2 answers
2k views

What caused the expansion of the universe to slow down after the inflationary epoch?

As everyone knows, when the big bang happened, the universe expanded at an unbelievable rate and this was called the inflationary epoch (or more popularly cosmological inflation) which lasted for ...

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