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Questions tagged [big-bang-theory]

Questions regarding the currently prevalent cosmological model for the origin of the universe.

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Is there a good Big Bang visualization (similar level of precision as the one they did for a proton)?

I watched a video visualising the proton. Is there something similar for the Big Bang? So far I've seen only those, where the bright explosion kind of happens (and dies out) at a single spot, instead ...
Andrey Lebedenko's user avatar
-2 votes
1 answer
167 views

Why no Big Bang are happening now?

Why we are not able to see any Big Bang now? There is a possibility, I think. Is it that Universe is so large that the probability of it's happening in the observable universe is almost zero, or is ...
KeShAw's user avatar
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2 answers
308 views

Big bang cosmology [closed]

What is the main evidence that the Big Bang is real. Why can we know that the big bang exists. In a short summary, the evidence? In your owns words?
Brendan Darrer's user avatar
4 votes
2 answers
345 views

Was the Big Bang an event within a preexisting Universe, or did it mark the beginning of the entire Universe, beyond just the observable Universe?

Could it be that the Universe is truly infinite, and the Big Bang was merely a singular, specific event that resulted in the birth of a 'bubble,' i.e. what we perceive as 'the observable universe'? ...
impact's user avatar
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2 votes
1 answer
142 views

Big Bang vs movements within a supercluster

Hubble measured the velocity of galaxies relative to Earth and determined that the galaxies were moving away from Earth. Speed increased with distance to Earth. This correlates well with the Big Bang ...
Peter's user avatar
  • 381
0 votes
1 answer
195 views

Are we really 13.8 billion light years from the big bang

Scientists tell us that the rate of expansion was once up to six times the speed of light. It then slowed down, by how much I am not sure. Now it is increasing again. The big bang happened 13.8 ...
Michael Mcgarry's user avatar
3 votes
1 answer
2k views

Could the Methuselah star be evidence that there was a universe before this one?

If the Methuselah star proved to be older than the universe could it be from a previous big bang big crunch cycle in which not everything was crunched? What would be the smallest radius the universe ...
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-1 votes
1 answer
119 views

Could vacuum expansion arising from the Big Bang be a consequence of entanglement?

The model assumed here is that the vacuum is a coherent 4-d manifold, embedded in a background of quantum spacetime “foam”, or bulk. It is further assumed the bulk is itself disentangled, possessing ...
RalphW's user avatar
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2 answers
163 views

Is dark matter made from the particles that had charge but no mass in the early part of the Big Bang

It is assumed that massless charged particles acquired mass after the early phase of the Big Bang. But could most charged particles be massless now as dark matter. They wouldn't interact with photons ...
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3 votes
1 answer
234 views

Could macroscopic primordial black holes have created metals shortly after the big bang?

After seeing articles about the JWST like these two: https://news.cornell.edu/stories/2023/02/astronomers-discover-metal-rich-galaxies-early-universe https://www.livescience.com/james-webb-space-...
Nathan Stanton's user avatar
3 votes
1 answer
103 views

If the energy density during inflation were lower, how would the CMB look in comparison to the observed CMB today?

I am assuming that a big bang followed by inflation is still theoretically possible with a different starting density. Would the CMB look the same but just colder?
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Does the other side of the Big Bang factor into JWST observations?

Our (roughly) 13.6 billion light year view to the point of origin (big bang) is just along a radial axis. Assuming most matter ejected in a (roughly) spherical pattern, the diameter of the universe is ...
TonyG's user avatar
  • 109
24 votes
3 answers
7k views

Is the Big Bang a theory or a model?

I ask this because someone mentioned ‘it isn't a theory, it's a model’ in the comments in an old question of mine: Is the expansion of the universe proof of the big bang? I guess defining terms is ...
Kilise's user avatar
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0 answers
97 views

Why is it assumed that the universe started out with a size equal to the Planck length?

What if the Planck length is the distance between particles when the universe was very small . For a spherical ball of 10^ 78 protons that would give the universe a radius of 10^26 X 10^-35 = 10^-9 ...
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17 votes
1 answer
3k views

Why do cosmologists assume that inflation began shortly after the Big Bang, rather than at the exact start?

Somehow, I have never come across an explanation of why cosmologists claim that the alleged inflation of the very early universe occurred not at the Big Bang, but very shortly afterwards (~10^-36 to ...
Kurt Hikes's user avatar
  • 5,177
2 votes
0 answers
69 views

Cosmic background radiation - what frequency tells us?

I understand that cosmic microwave background radiation is remnant of the universe after 380,000y of the origin. To me, this radiation is still a wave which has a microwave frequency and I also ...
Giorgi Lagidze's user avatar
0 votes
1 answer
127 views

why couldn't atoms form in the early big bang?

I'm asking about the time when temperature was super high, but at that time we already had proton, neutron, electrons. It seems they were moving super fast due to temperature being so high. What I'm ...
Giorgi Lagidze's user avatar
1 vote
1 answer
77 views

Could inhomogeneities or topological defects break the fundamental symmetries of the Universe?

I have heard that some types of inhomogeneities and topological defects in cosmology have been proposed to be able to break fundamental symmetries of nature such as the Poincaré, Lorentz, ...
vengaq's user avatar
  • 1,017
2 votes
3 answers
264 views

Why is it Cosmic microwave background not Cosmic gamma ray background [duplicate]

If the universe was at so much heat at the singularity point at big bang , Then the light of CMB must be gamma rays (high energy photons) but how did they transfer into microwaves?
Naveen V's user avatar
  • 171
5 votes
1 answer
281 views

What is the elemental composition of the universe?

What is the current distribution of elements in the observable universe? Wikipedia lists the composition of the Milky Way, but I'm not sure how the values would change if intergalactic medium were ...
WaveInPlace's user avatar
3 votes
1 answer
316 views

Redshift distance proportionality at high Z and need for "mighty mouse" galaxies?

Allegedly supported by some evidence from the new James Webb space telescope physicist Eric Lerner has written an article that have garnered some attention. He writes that: "Put another way, the ...
Agerhell's user avatar
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6 votes
1 answer
457 views

What parameters of the Big Bang model will have to be adjusted to account for JWST's observations of highly redshifted galaxies?

There are a lot of claims, on YouTube at least, that the James Webb space telescope have found too many to old/highly redshifted normal looking galaxies to fit easily into the Big Bang model. One such ...
Agerhell's user avatar
  • 457
2 votes
1 answer
106 views

Can the JWST track element abundances throughout time? Would this be of any interest at all?

Now that the JWST is peering further and further back into the cosmos, I came to a few questions that I would love to see answered. We know that models of the big bang nucleosynthesis result in ...
Maximal Ideal's user avatar
3 votes
0 answers
59 views

Can we determine our orientation in the universe relative to the origin point of the big bang? [duplicate]

Based on our knowledge of the expansion of the universe, can we trace galaxy movement backwards in order to determine the approximate relative location of the point where the big bang occurred? The ...
Michael Hall's user avatar
1 vote
0 answers
54 views

Does cosmic inflation spawn from empty space, or vice versa?

In the eternal inflation model supported by Sean Carroll and others, the basic premise is that inflation is continuous in places across an infinite cosmos, and that bubble universes (like our own) are ...
DouglasPhillips's user avatar
2 votes
2 answers
240 views

Expansion rate of an infinite universe at the Big Bang

If the universe is infinitely large, then any two arbitrarily distant points must have been arbitrarily close together at some earlier point in time. Doesn't that mean that the expansion rate of the ...
T Scherer's user avatar
  • 123
3 votes
1 answer
108 views

Does the Cosmic microwave background (CMB) have an amplitude? Does it vary, like the 'temperature' (wavel./freq.) and the polarization?

Somehow, I have never read about this or thought about, until now... Does the number of photons from the CMB hitting us from all directions vary at all?
Kurt Hikes's user avatar
  • 5,177
2 votes
1 answer
146 views

Strange plot in Max Tegmark book, Our Mathematical Universe

In Max Tegmark's book, Our Mathematical Universe, we can find (in chapter 5, figure 5.3) the following (horrible and poor quality) plot that is supposed to highlight the extreme sensitivity of the ...
Vincent ISOZ's user avatar
2 votes
1 answer
216 views

How is it possible that a Big Bang happened instead of becoming trapped as a Kugelblitz? [duplicate]

I was reading about Kugelblitz on Wikipedia, and it says that if enough energy gets concentrated it leads to a black hole (from where nothing can escape - supposedly). So, if during the Big-Bang, when ...
Joako's user avatar
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1 vote
0 answers
74 views

How did cosmic inflation even occur?

I wanted to ask this question that which inflation model shall i believe? Following below will be MY UNDERSTANDING (MAY NOT BE CORRECT) OF IT: I read "A Brief History of Time" and in chapter ...
Aveer's user avatar
  • 191
8 votes
1 answer
2k views

Why was the Cosmic Microwave Background (CMB) released at a blackbody temperature of 3000K rather than 30,000K?

If the ionization (or reionization, or Recombination) energy of atomic hydrogen is 13.6 EV, which corresponds to a black body temperature of 30,000K, why did the CMB not begin to appear then? Why did ...
Kurt Hikes's user avatar
  • 5,177
9 votes
1 answer
931 views

Why isn't the CMB blurred by the blackbodies emitted in the time after atoms first formed?

I am confused about why the light released from the moment when gas first formed was so dominant in comparison to the light released afterwards. Why isn't the CMB in interference with a series of ...
Daniel Turon's user avatar
1 vote
0 answers
140 views

How did the Universe climb out of its own Big Bang black hole?

The Big Bang started as a singularity. That means small. All the matter in the universe was in a volume smaller than its own Schwarzchild radius. The universe was inside a black hole. At present, the ...
Woody's user avatar
  • 1,040
1 vote
0 answers
32 views

How can scientists deduce the number of types of neutrinos, or 'effective number', from Planck satellite data?

Is it related to the way they deduce the Hubble constant from Planck data? Would more types of oscillating and mixing neutrinos mean faster or slower expansion of the universe? Would a fourth mass ...
Kurt Hikes's user avatar
  • 5,177
2 votes
1 answer
352 views

Because the Universe is expanding, what is it taking up?

It is my understanding that the universe is expanding and that matter takes up space. While the universe only contains small percent of matter, wouldn't expansion indicate that the universe is ...
depperm's user avatar
  • 129
1 vote
1 answer
40 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 ...
Aryan Arya's user avatar
2 votes
0 answers
77 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 ...
Astroturf's user avatar
  • 1,111
8 votes
1 answer
186 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 ...
Mark Foskey's user avatar
  • 3,916
4 votes
0 answers
55 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....
B--rian's user avatar
  • 5,626
30 votes
3 answers
6k 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 ...
Cerelic's user avatar
  • 403
1 vote
1 answer
110 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. ...
Kurt Hikes's user avatar
  • 5,177
5 votes
0 answers
84 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 ...
Radoslaw Garbacz's user avatar
1 vote
0 answers
91 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 ...
B--rian's user avatar
  • 5,626
1 vote
0 answers
56 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, ...
reginald Bengtson's user avatar
1 vote
0 answers
71 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 ...
Stilez's user avatar
  • 1,022
0 votes
0 answers
91 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 ...
Jack the Ranger's user avatar
0 votes
1 answer
73 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.
Jack the Ranger's user avatar
4 votes
0 answers
101 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 ...
bandybabboon's user avatar
  • 4,250
3 votes
1 answer
178 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 ...
Astroguy1234's user avatar
2 votes
1 answer
842 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, ${\...
Kurt Hikes's user avatar
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