47 votes
Accepted

Could liquid water have existed in open space 15 million years after the Big Bang?

Let's interpret your question to be about whether the conditions would permit blobs of water to remain liquid, whether or not water existed yet. And the answer is No, because the pressure was by then ...
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  • 2,525
38 votes
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Why didn't the Big Bang produce heavier elements?

I think that your thought process is flawed in that you assume that by drastically increasing the temperature you are guaranteed to get heavy elements. As odd as this may sound, this isn't the case (...
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38 votes

Why do galaxies collide?

The universe is expanding on a large scale. But locally things are always messy. Locally, galaxies are not set in stone, they move relative to each other, and the directions are random. If they're ...
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37 votes
Accepted

At the Big Bang, when everything was close together, why did it not "collide", violating Planck length or Pauli Exclusion Principle?

The Pauli Exclusion Principle forbids two indistinguishable fermions occupying the same quantum state. It does not prevent them getting arbitrarily close together so long as they have very different ...
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  • 118k
27 votes

Why did the big bang not just produce a big black hole?

Your problem essentially arises from trying to apply Schwarzschild black hole logic, the assumptions of which are pretty much maximally violated at the big bang. The following were true at the big ...
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25 votes
Accepted

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

The CMB is produced as the ionisation fraction of hydrogen falls from a high value to a very small value. Contrary to what is written in the Quora answer you may have been misled by, this happens at a ...
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  • 118k
21 votes

Could liquid water have existed in open space 15 million years after the Big Bang?

As others have mentioned in the comments, there wouldn't have been any oxygen to form water. Soon after the Big Bang, the protons were hot or dense enough to fuse up to helium and some lithium but ...
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  • 2,692
19 votes

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

It is. They're called galaxies and stars and we see them against the cosmic microwave background. However, they aren't (all) cooling because of the energy sources they contain. But perhaps that isn't ...
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  • 118k
18 votes
Accepted

Is any consensus forming on the solution to the "Lithium Problem"?

There is no absolute consensus and nothing proven beyond doubt, but there are favourite explanations. The discrepancy between the predicted big bang nucleosynthetic abundance of Lithium 7 and the ...
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  • 118k
13 votes
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What created the big bang's singularity?

No one knows what came before the Big Bang if, indeed, anything did. Theories include: The Ekpyrotic universe theory where the BB was the result of the collision of branes. Various oscillating ...
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  • 7,390
12 votes
Accepted

Can we see the Big Bang happen if we look far enough?

No. The furthest we can see is the cosmic microwave background radiation (CMB). Early on (after the big bang), matter was fully ionised and the electrons frequently interacted with the photons. That ...
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  • 5,276
11 votes

How can the universe be infinite?

I think the source of confusion between the two concepts - the Big Bang singularity and an infinite universe - is the misconception that the universe began as a finite expanse originally. This ...
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  • 408
10 votes

Why did the big bang not just produce a big black hole?

A black hole is a region of spacetime separated by an event horizon, which means no signals from the interior can propagate outward, no matter how long one waits. Locally, there is nothing special ...
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  • 7,684
10 votes
Accepted

BIg Bang Happened everywhere

Okay, I think I know what Max Tegmark is talking about in the video. He is referring to the fact that, when you observe the cosmic microwave background radiation (CMB) — i.e. the radiation that was "...
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  • 33.8k
10 votes

How do we know so many details about Big Bang, but we do not know if Universe is finite/infinite?

By observing the observable universe we can gather a lot of data about the constituents of the universe now and in previous epochs, right back to the cosmic microwave background. This data places ...
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  • 637
9 votes

Why can we still see 10 billion year old galaxies?

Those galaxies were 10 billion light years away from Earth. So light would take much more time to reach here and that light which is now 10 billion years older can be seen now. Even light from the Sun ...
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  • 211
9 votes

Are there heavenly bodies between galaxies?

The Big-Bang was not an explosion in empty space. Inter-galactic space is not empty, there is an inter-galactic medium, gas clouds and material ejected from galaxies, including stars and possibly ...
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9 votes
Accepted

What made cooler temperatures suitable for atom formation?

The temperature of a gas is a measure of the kinetic energy of the particles. For molecules you can have rotational and vibrational energy, while for single atoms you just have translational energy, ...
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  • 33.8k
9 votes

Amount of energy of the Big Bang

Let's start by making some points clear: 1. We don't know what the Big Bang was. Rather, we know that the Universe is expanding. If you extrapolate backwards, you'd expect the Universe to be denser ...
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9 votes

Why do galaxies collide?

The galaxies don't really get "off track" - it's not impossible, but that kind of thing probably doesn't happen anymore (as space continues to expand). What actually happens is that galaxies form ...
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  • 478
9 votes

Why do galaxies collide?

I'm not sure that anyone has answered the question asked. The root cause is indeed that gravitationally bound structures with freefall timescales that are much shorter than the age of the universe are ...
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  • 118k
9 votes

Are there only a set number of atoms in the whole universe?

There are several processes at work: Fission (of unstable elements) increases the number of atoms. Fusion (occurs in stars and supernovae) decreases the number of atoms. you could claim the formation ...
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  • 2,956
9 votes

Did Einstein supported Big Bang Theory cosmological model?

Einstein's opinions were not static, and he lived at a time when there were several competing theories and not much observational evidence. Einstein introduced a cosmological constant $\Lambda$ into ...
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  • 91.5k
9 votes
Accepted

What is meant by "vastness of space, which now filled a volume of a hundred million light years"?

I think this is at best a weird typo, but more likely a confusion by the authors (who are not cosmologists or astronomers, but a biologist and a geologist). The book is 10 years old, but our view of ...
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  • 33.8k
8 votes

What is in the center of the universe?

The universe doesn't expand away from any centre perse. All the distances are expanding uniformly throughout the universe. This causes such an effect that for each individual observer, it looks as if ...
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8 votes
Accepted

Outside of a Universe and its origin

You are making the mistake of thinking that there was a single spot in space that everything expanded from. Rather, the expansion was not of things in space, it was space that expanded. It was an ...
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  • 3,214
8 votes

How can the 13.8 billion years old universe have a radius of 46 billion light years?

You assumption is wrong. Universe can( and is ) expand faster than the speed of light. The photon emitted towards our planet in the early universe, had to traverse a universe that is expanding. That ...
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  • 427
8 votes

What was "space" like before big bang?

This is a common question that comes up - one I've (at least tried to) answer a few times. Let's try to understand what the Big Bang is. The Big Bang Theory is a model, and scientists came up with it ...
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  • 499
8 votes
Accepted

Why is the Cosmic Microwave Background evidence of for a hotter, denser early Universe?

By request: Beyond the fact that the cosmic microwave background (CMB) is a direct prediction of the big bang model, there is the question of how you would produce it in any other way. It is ...
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  • 118k
8 votes
Accepted

Why can't we point the centre of the universe from inflation graph we see?

That diagram does not depict the entire universe. At most, it depicts the history of what is now our observable universe (specifically, a 2D slice through it), with us at the center only because we're ...
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