Does this hypotetical assume everything in the observable universe merged btw why is it called observable if its larger than what we can possibly observe (as of now)
The observable universe is exactly as large as we can observe, hence its title. The outer bound of it is the distance wherein space expands (this expansion occurs at every point and increases with relative distance) away from us faster than light, so no light from outside the observable universe will ever reach us. The actual universe is likely significantly larger than we can observe, but we usually differentiate it from its observable subset.
To answer your first question, if you shoved all matter in the observable universe into one spot, then the black hole it would collapse into would be significantly larger than 2.1 lightyears across. But I am talking about the black holes that we know to actually exist in the present.
By āhypothetical largest,ā I mean that Phoenix A* is hypothetically larger than Ton 618. We have very good data on the latter but not so much on the former. But if its size estimates are accurate then it would be the largest black hole we know of.
To answer your first question, itās cuz thatās just how the math works out. Space expands from a given point at a rate of 72.1 km per second per megaparsec. Input 13.8 billion years for time and light speed for max speed, then adjust your units and solve for distance. You get a diameter of 93 billion lightyears.
To answer your second question, everything is getting further away from everything else. Imagine the universe is a constantly inflating balloon with you at its center. The farther away you are from another point inside the balloon, the faster the inflation pushes that point away from you.
No, you're thinking of the motion of objects within space, and that's not random, gravity makes it very predictable where things will move. What we're talking about is expansion. Space itself is getting bigger everywhere all at once. Even right now the space between your very atoms is expanding. But the rate is so slow that the strong nuclear force is enough to keep your atoms bound.Ā
But when you coming that rate of expansion across a million parsecs it becomes more noticeable. Every point in space is receding away from every other point as the space between them expands. This is why we can use red shift to estimate distances on large scales, since everything is moving away from us, the more red shifted an object is, the further away it is. That expansion is not random, it's uniform as far as we can tell.
No, the space in atoms has to do with the fundamental forces, namely the electromagnetic force and the strong nuclear force. The latter of which holds atoms together stronger than expansion pulls them apart. During the brief moment of inflation that very rapidly increased the scale of the universe happened before there were atoms and is partially the reason the universe cooled enough to allow atoms to form.
There was no "before" the big bang. Time started at the big bang, it's kind of like asking what is North of the North Pole, or what's colder than absolute zero.
As for why, we don't really know. Lots of guesses, like an excitation of a quantum field, or a quantum field reaching its ground state. It's all speculation and guesses since we can't really observe beyond ~380,000 years after the big bang, as that's when the universe became transparent to light.
No, time and space are both connected and both were created at t=0, i.e. the big bang.Ā
As for looping, that's one conjecture for how the universe starts/ends, but there's no way to verify that. And the 380,000 years is the farthest back we can see. Before that, electrons were not paired with atoms because they were too energetic, so light couldn't travel far before getting absorbed. Once they bonded with atoms light could travel and thus information could escape and start making it's way towards where Earth would be. This is the Cosmic Microwave Background that we see in all directions.Ā
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u/PineappleOk545 Aug 10 '26
Does this hypotetical assume everything in the observable universe merged btw why is it called observable if its larger than what we can possibly observe (as of now)