# Tag Info

## Hot answers tagged big-bang-theory

47

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 far too low. Basically, space was already a vacuum, just not as hard a vacuum as intergalactic space is now. It is appealing to imagine an era when the universe ...

21

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 nothing heavier. Heavier elements were eventually fused in the first stars and partially dispersed in space by their winds and when they exploded as supernovae, ...

8

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 observing it. Someone at the furthest reaches of that portion of the universe would see us at the furthest reaches of their observable universe, and themselves ...

4

Attractive gravity means a shorter time since the Big Bang, for any given Hubble value. Here's a picture (from lecture notes by Sean Carroll): The averaged distances and speeds of nearby galaxies give us the slope of the curve at the horizontal position marked "now". If you assume they've always moved at that speed, you get the scale factor ...

2

This is a difficult question to answer. Physics really starts after the big bang. Scientist don't know about the laws, if any, before the first instance after the big bang. The time before and during the big bang is really the province of philosophy.

2

(I can't comment)- See https://physics.stackexchange.com/questions/136860/did-the-big-bang-happen-at-a-point TLDR, The big bang happened everywhere in the universe at the same time, because it was the universe. The top answer goes more in depth.

1

I find it helpful, when considering a universe that may be infinite, to think of everything within space getting smaller, rather than space itself getting "bigger". Rulers, planets, stars, galaxies. That allows visualisation of an expanding universe without having to worry about the "edges". Not very scientific as it assumes space itself ...

1

The key word here is "eventually." The strength of the gravitation felt between two objects is inversely proportional to the square of the distance between the two bodies. As a result of this, raising an object from a nonzero distance from object A to an infinite distance from object A requires a finite amount of energy. In a Keplerian/Newtonian ...

1

So, the big bang started 13.7 billion years ago, and for the next 380,000 years, the universe expanded and cooled, so atoms could start forming later on. 13,685,000,000 years ago, the early universe was too hot and dense for liquid water to form. So, the answer is NO, liquid water could not form about 15 million years after the big bang. Hoping this was ...

1

There are theories which suggest that the universe is like a giant spring, constantly expanding and collapsing. Its possible that pre-big-bang, there was another universe which collapsed, only to re-expand into the universe we know now. But in reality we have no idea

1

It does not have to start from the big bang. There are also different universe models such as the big bounce. Where the universe has an infinite past, such that it expands and then contract. See https://www.quantamagazine.org/big-bounce-models-reignite-big-bang-debate-20180131/ https://www.wired.com/story/what-if-the-big-bang-was-actually-a-big-bounce/ For ...

1

You answered your question actually. You have said Note that this solution is not valid for domination of the cosmological constant, which corresponds to an w=−1 then you are saying But if 'w' is negative-one then 'a' is proportional to tt The $w=-1$ does not apply to $a(t) \propto t^{2/3(1+w)}$

1

the expansion of the universe is relative to where it is being observed from. Much like dots on a balloon. Its easy to point to the center of the balloon (like what the picture shows) because it is only a 3d object. But for higher dimensions we don't have the spacial awareness to understand where than center of the universe is (if there even is one)

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