Where does the extra space come from as the universe expands? and if it’s just stretching, does that mean it somehow is getting thinned out?
In: 47
I think this is just a problem with how people talk about expansion. It’s useful to think about it as objects in the universe are getting farther apart as opposed to the universe expanding. If the things are just getting further apart the question of “what is the universe expanding into” goes away.
So if space is expanding then wouldn’t that mean space isn’t infinite? Is there some kind of space wall we cant get past should we be able to travel however many light years?
many wrong answers here.
yes, space is a *thing*, we don’t know how or why it is expanding, and no, it doesn’t thin out, it remains the same density.
dark energy is super mysterious
Q1, you’ve stumbled onto an unknowable answer. No one knows what is beyond the edge of the universe. It expands so fast that it outpaces the fastest we could possibly go with any sort of technology. Teleporting to it wouldn’t even work, it was be gone before you could look at it.
Q1-ELY5: IT JUST DOES, GO TO SLEEP.
Q2, yes. The universe is being stretched out. The amount of matter in the universe is always the same, and gravity keeps that matter together, but the distance between it constantly getting farther apart.
Q2-ELY5: You’re eating Cheerios. There’s only enough cereal to float on top of the milk, and it only covers have the surface. Those pieces tend to form a few clumps that seem to stick together. If you poured that milk into a wider bowl the cereal will still clump together even though the surface is larger. The clumps will be farther apart. Same matter, same clumps, bigger gaps.
The expansion of space isn’t really accurately represented when we try to conceptualize it as an expanding 2D plane or even an expanding 3D bubble. It doesn’t get thinned out and “extra space” isn’t being added in. Looking at the functions we use to model the expansion gives you a more intuitive understanding than trying to visually conceptualize it.
Considering its all theories, my theory is its like a giant anus, tunnel shaped and being stretched by the Bing Bang Buttplug, so some parts are stretching massively while others hardly are, but the more relaxed the universe gets, the more enjoyable the stretching can be.
I believe that it appears that space is expanding in 3 dimensions. When we consider other dimensions we don’t know what’s really happening. The only way I could understand additional dimensions is to imagine living in a 2d space. All you can see left right and forward. Someone living in a 2d plane can’t see the third dimension since they can only see left right and forward and back but not up or down.
Follow up – is Gravity able to counteract the ‘stretching’ by keeping things together? That seems counter-intuitive if the amount of distance is increasing – wouldn’t the distance between atoms increase, even if they were held together by gravity, in the same way that the distance between two stars would increase, despite whatever minute amount of gravity they affect one another with?
It feels like if gravity is able to counteract this process, then this force is relatively weak.
As a biologist, I enjoy the resulting schadenfreude of questioners asking physicists basic fundamental physics questions on Reddit. Zero agreement. LOL.
“Can we define space-time?”
“Yes!” MIT engineers.
“No!” Harvard physicists.
Fight!
Lol.
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