Questions tagged [big-bang-theory]
Questions regarding the currently prevalent cosmological model for the origin of the universe.
168
questions
1
vote
1answer
28 views
Can two neighboring galaxies move apart at steady speed?
While I was trying to understand the three models that obey Friedmann's two assumptions of a non-static universe, I came across a line that says and I quote "It (referring to Big Bang) starts at ...
-1
votes
0answers
41 views
How did the infinitely dense point before the Big Bang exist? [duplicate]
I read that before the Big Bang, there was an infinitely dense point that was extremely hot. If the universe started there, where did that dense point start? What created or formed it?
2
votes
0answers
47 views
How do we know or predict which particles were present before Big Bang Nucleosynthesis occurred?
I'm reading Carroll and Ostlie's "An Introduction to Modern Astrophysics". In the BBN section, they describe that the universe contains a mixture of photons, electron-positron pairs, and ...
6
votes
0answers
55 views
What is the history of the average pressure, density, and temperature of the matter in the universe over time?
This question is inspired by this more specific question where Cerelic wanted to know if conditions were suitable for liquid water to exist during an epoch when the characteristic temperature of the ...
3
votes
0answers
35 views
Expanded element (and molecule) abundance graph?
There is the "classical" nucleosynthesis timeline chart where the $\log ({\rm mass \,fraction})$ is plotted as a function of $\log(t)$ where $t$ is in seconds after the big bang, looking e.g....
30
votes
3answers
5k views
Could liquid water have existed in open space 15 million years after the Big Bang?
Around 15 million years after the Big Bang, the ambient temperatures was about $24^\circ {\rm C}$, which is in a range where water could be liquid. Could liquid blobs of water be existent then?
PS: I ...
1
vote
1answer
54 views
Shouldn't the estimate of the universe's age be higher, not lower, after the attractive strength of gravity is taken into account?
From 'Fundamentals: Ten Keys to Reality', by Frank Wilczek :
"Running the movie of cosmic history backward in our minds, we found the galaxies all coming together to meet at a definite time. ...
5
votes
0answers
54 views
Early (high density) Universe's event horizon [duplicate]
Taking into consideration the big bang theory and the followed expansion of our Universe, was there a time when density of the Universe created an event horizon?
If so, then for how long and how is it ...
1
vote
0answers
60 views
Math for the “universe in a black hole” hypothesis?
There are various pop-science article entitled Are we living in a Black Hole? or Did A Black Hole Give Birth To Our Universe? which say things like
There’s a lot to like about the idea that there’s a ...
0
votes
0answers
51 views
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, ...
0
votes
0answers
56 views
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 ...
0
votes
0answers
73 views
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 ...
0
votes
1answer
58 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.
4
votes
0answers
93 views
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 ...
2
votes
1answer
95 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 ...
2
votes
1answer
143 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
$${\displaystyle p=w\rho c^{2}} \qquad p=w\rho c^2$$
where ${\displaystyle p}$ is the pressure, ${\...
0
votes
2answers
140 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 ...
2
votes
2answers
141 views
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 ...
0
votes
0answers
64 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 ...
3
votes
1answer
206 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 ...
1
vote
1answer
199 views
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 ...
4
votes
2answers
647 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 ...
0
votes
1answer
102 views
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 ...
1
vote
1answer
195 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?
12
votes
1answer
4k views
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 ...
4
votes
0answers
85 views
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 ...
2
votes
1answer
71 views
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 ...
-3
votes
1answer
85 views
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 ...
2
votes
0answers
50 views
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 ...
1
vote
0answers
28 views
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 ...
6
votes
1answer
147 views
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 ...
2
votes
1answer
112 views
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 ...
-2
votes
2answers
248 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 (...
0
votes
0answers
36 views
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 ...
1
vote
1answer
67 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 ...
8
votes
2answers
222 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 ...
7
votes
1answer
104 views
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 ...
8
votes
1answer
172 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 ...
0
votes
2answers
529 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 ...
-1
votes
1answer
213 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 ...
25
votes
6answers
8k views
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.
0
votes
1answer
75 views
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 ...
1
vote
0answers
71 views
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?
1
vote
0answers
71 views
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 ...
4
votes
1answer
194 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 ...
3
votes
0answers
48 views
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 ...
4
votes
1answer
121 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 ...
1
vote
2answers
175 views
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 ...
1
vote
1answer
153 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?
2
votes
0answers
81 views
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 ...
