Questions tagged [big-bang-theory]
Questions regarding the currently prevalent cosmological model for the origin of the universe.
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Could the duration of some gamma ray bursts be information from outside our universe?
Could we be in a system where a large mass explodes dispersing matter in all directions until gravity pulls it together with matter from other explosions until the maximum mass limit is reached, ...
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in current models of the Big Bang, what happens to the products of baryon annihilation?
In current thinking about the Big Bang, the baryogenesis phase involves CP/CPT symmetry violation. There is an excess (says Wikipedia) of perhaps 1 in $10^{10}$ baryons over antibaryons, the majority ...
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Accuracy of the Inflation theory
In the Inflation theory, it said that the Inflationary epoch has happened $10^{-32} \,\mathrm{s}$ after the Big Bang, and I cannot find anything related to how this number was calculated and how ...
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1answer
47 views
Centre of the Universe [duplicate]
Why shouldn't the original singularity of the big bang happen to be the centre of the Universe? Assume that the universe is expanding isotropically with a constant speed.
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From what distances do the atoms in you come from?
If the atoms of a human come from stars, comets, nebulas and magnetrons, then what is the greatest distance that two atoms of a human can possibly have been away from each other previously? Perhaps ...
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1answer
67 views
Question on the singularity theorem
I have just started studying Cosmology and we have been asked to prove that in an expanding FRW Universe which obeys the strong energy condition: $$\rho + 3P >0$$
Then there must exist a Big Bang ...
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1answer
54 views
What is the 'scale factor' equation for a dark-matter dominated universe?
The Friedmann equations can be solved exactly in presence of a perfect fluid with equation of state
$${\displaystyle p=w\rho c^{2},}p=w\rho c^2$$,
where ${\displaystyle p}$ is the pressure, ${\...
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2answers
133 views
Why can't we point the centre of the universe from inflation graph we see?
This question is not about whether it makes sense to have a centre of the universe or not instead, it's about the inflation graph we used to see while describing the Big Bang. From the inflation graph ...
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2answers
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What powered the Big Bang?
According to the first law of thermodynamics, law of conservation of energy states,
The total energy of an isolated system is constant; energy can be transformed from one form to another, but can be ...
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63 views
Was universe spawn from nothing? [duplicate]
Was universe spawn from nothing?
Until now, scientists figured out that the Big Bang happened from a tiny particle which was infinitely energy densed and having infinite mass. If that is the case ...
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1answer
155 views
What happened before, Big Bang or inflation?
I always thought that the cosmic inflation happened after the big bang (10-36 sec) and lasted for a very tiny fraction of time).
Now, I recently came across a couple of articles (links below) claiming ...
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1answer
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Why is the Cosmic Microwave Background at the same distance no matter the direction we look?
I've read from different sources that:
The CMB is visible at a distance of 13.8 billion light years in all
directions from Earth, leading scientists to determine that this is
the true age of the ...
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2answers
577 views
What is meant by “vastness of space, which now filled a volume of a hundred million light years”?
I am reading the book Cosmic biology: How life could evolve on other worlds (citation below) and do not understand the meaning of the following paragraph from page 4 (emphasis mine):
It took 200,000 ...
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1answer
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How can something infinitely big have expanded from an infinitely small?
Please help me reconcile what I see as contradicting theories:
The universe began with the Big Bang and expanded from an infinitesimally small point.
The universe is infinite.
How can something ...
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1answer
151 views
How did matter first come into existence? [closed]
How did matter come to be?
Why is there matter if matter and antimatter cancel each other?
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1answer
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At the Big Bang, when everything was close together, why did it not “collide”, violating Planck length or Pauli Exclusion Principle?
How could so much matter, or "all" in fact, have been concentrated in a smaller universe without being in the actual same place? Why did this not result in undercutting the Planck Length or ...
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Does the cosmological principle apply to the entire universe?
Some cosmological models assume that the universe is isotropic and homogeneous and that is also flat and infinite. If the universe is infinite now it was infinite immediately after the big bang. If ...
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1answer
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Types of Multiverses [closed]
Can anyone recommend me books or other online resources on the concept of the Multiverse, it types, and about higher mathematical dimensions of space-time. I have been interested in such topics for a ...
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Is our universe a singularity?
According to the Big Bang theory our universe used to be a lot smaller in size.
It actually used to be so small that in the beginning it used to be a singularity.
And the universe started to expand ...
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How is the big bang a plausible theory? [duplicate]
In the Big Bang Theory, it is said that it started with a small speck of matter, yet we have an unimaginable mass of expanding universe which is assumed as immeasurable. If the theory of "Matter ...
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23 views
When did relatvistic effects take hold after the big bang? [duplicate]
As far as I understand it the universe did not become a black-hole at the big bang.
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Is there a place where one can see the beginning of the universe? [duplicate]
If the night sky Is dark because we’re seeing the world as it was a long time ago, when there wasn’t much to see, is there a place on the universe where we can see the universe at the beginning of ...
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1answer
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Why is CMB an evidence of hotter and denser early Universe?
In his book Gravitation and cosmology, Steven Weinberg says that CMB makes it "difficult to doubt that the universe has evolved from a hotter denser early stage".
In my understanding, CMB ...
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1answer
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Did Einstein supported Big Bang Theory cosmological model?
Einstein made many predictions, including gravitational waves and the possibility of black holes.
Relativity is taken into consideration for the Big Bang model, so did Einstein agree with it or did ...
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2answers
221 views
Is Olbers' Paradox Nonsense? [closed]
Ok, this is a bold question, I know. But, let me explain: After first hearing about Olbers' paradox, I found that something seemed 'off' about it, so I looked into the subject as much as my skills (...
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Must all galaxies in a galaxy cluster have the same expansion rate?
If we observe a distant galaxies cluster where all galaxies travel with the same speed away from us, except for one galaxy whose speed is significantly lower than of the neighboring galaxies. Does ...
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1answer
51 views
What reference frame do age-of-the-universe calculations assume?
I'm thinking, in particular, about general relativity. When we speak, for example, of neutrino decoupling, what do we mean when we say this happened in the first second after the Big Bang? Do we mean ...
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2answers
218 views
Are there only a set number of atoms in the whole universe?
As per the title, are there only a set number of atoms in the universe? Or does the universe make more atoms, and if so, how does it work?
I'm a high school student that just had a question during ...
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1answer
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Understanding The Fluctuations In The CMB Maps
If I'm understanding this correctly the fluctuations in CMB are a result of the "last scatter" of photons when electrons joined together with nuclei that before this formed plasma. CMB is among other ...
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1answer
165 views
How do we know so many details about Big Bang, but we do not know if Universe is finite/infinite?
I understand that this question may be too vague, but I am confused about the following:
On one hand we know a lot of "details" about Big Bang, like really precise details, evolution of universe, age ...
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2answers
421 views
If space is negative energy and matter is positive energy then does that mean the universe is finite?
I was reading a book by Stephen Hawking, it was written that universe is made up of 2 ingredients,i.e., space and energy and space was the negative energy, so they add up to 0. But since space is ...
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1answer
203 views
What does it mean for space to expand?
In this YT video Michelle Thaller says The Big Bang wasn’t an explosion but an expansion and as such there's no empty center where the explosion would've been.
To explain expansion she uses the ...
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Why do galaxies collide?
If the universe is expanding outward, what is the processes for one galaxy to get off track enough to collide with another?
Say, the Andromeda Galaxy and the Milky Way.
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1answer
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Have we measured or found evidence of a detectable origin point of the big bang? [duplicate]
Based on reading the wiki page of the big bang, a simple question with a probably not a simple answer came to mind.
The statement on the wikipedia page was.
Since Georges Lemaître first noted in ...
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Is it possible for 'pre-big bang' empty space to have the property of being able to spawn matter and/or energy into existence? [closed]
.. and if so, wouldn't this also mean that during this event, time would be created as a collateral, as a canvas for this property to manifest?
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Expansion of space - how do we end up with an unobservable region?
I've just been answering a question on this issue,in physics SE,and realised that my answer conceals a point I don't myself understand.
I understand that
The expansion of metric isn't affected by ...
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1answer
145 views
How much helium has been created since the Big Bang?
When I try to find figures for the amount of helium today and just after the Big Bang, I get similar figures. I was expecting that all of the stars since then would have created more helium. Is the ...
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How did the Big Bang occured if before that there was no time? [duplicate]
I am thinking, that if the Big Bang created time, it implies that before the Big Bang there was no time (correct me if I am wrong).
My question is that, if there was no time before the Big Bang, how ...
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1answer
118 views
How can you verify the theories presented on TV shows like “How the Universe Works” is current and/or valid? [closed]
There are many TV shows such as "How the Universe Works" that explain theories about the origin of the universe such as the Big-Bang Theory.
What resources can I access to verify the scientific ...
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2answers
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How does science knows what is the early universe?
I've read about Hubble seeing the brightest quasar in the early universe. Question is, how does science knows what is early and what is late?
Please correct me if I'm wondering, but after the big ...
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1answer
148 views
Why more matter still left after collision with anti-matter?
Question implies all, why is that? Why we exist even after equally creation of matter and anti-matter, any possible exception?
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Is there a theory about a collision between a shrinking universe and a new expanding universe?
I recently read a post on a discussion board about the creation of our current universe that stated, and I quote:
[T]he shrinkage activity of the old universe and the new Big Bang expansion ...
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3answers
355 views
How could time only have started with the Big Bang?
I understand that before the Big Bang time (as well as dimensions) didn't exist. But how could this be? If there was no time then nothing could change, and so time itself couldn't come into existence.
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1answer
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Is it possible that the Universe is expanding due to additional Big Bang events?
Is it theoretically possible that the Universe is expanding due to additional Big Bang events that have occurred at the same location that the original Big Bang occurred at?
Perhaps there has been an ...
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1answer
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How thick is the cosmic microwave background, including the part we cannot see within the observable universe?
What I want to know is how thick the observable universe is from the point of the cosmic microwave background and beyond.
It appears the thickness of the cosmic microwave background itself (the part ...
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3answers
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If the Higgs field only formed after the Big Bang, how was hydrogen formed?
These two statements seem to conflict, but since we're here they can't:
Electrically charged particles cannot be massless.
Hydrogen was created at the moment of the Big Bang.
However, the Higgs ...
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3answers
691 views
How did space start?
How did this 'black fabric' that we call space start? How was it made? How was the initial singularity formed? How did the first atom come into existence?
If it all started from a tiny particle that ...
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1answer
2k views
What created the big bang's singularity?
I have heard theories for the big bang like: of another universe existing before the Big Bang, or an unstable white hole that blew up, or our universe detaching from our mother universe, or our ...
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1answer
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Fundamental axioms in LCDM
What are the axioms (if any) behind the LCDM model of cosmology?
NB: axioms, not postulates (e.g., inflation)
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Just after the Big Bang, was the space, in its entirety, filled with Hot gas?
After the Big bang occurred, was the space filled with hot gas totally?
If there's any problem in my question please inform me. Thanks!
