this post was submitted on 02 Oct 2023
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Everything not gravitationally bound is moving away from everything else. Every single point in space is growing larger. That means that things farther away from you are moving away from you faster then things closer to you. That's true no matter where in the universe you are.
There's not really an "away" from the big bang. That's something science communicators fail to explain - the big bang happened everywhere. Space may have been infinite in size (we don't know) and it still happened everywhere.
I'd recommend looking up the YouTube channel for FermiLab. They've got some excellent videos on the subject.
So I'm getting bigger? How much per year?
No. Local attractive forces, like gravity, especially those at the atomic level, overpower the expansion for tightly coupled systems. So the earth isn't expanding, and neither are the people on it. I don't recall exactly what scale it kicks in at, but there is a good chance it's not even affecting the distance between planets in a system. Most likely it only plays a role in inter-planetary-systems and larger. Ie, stars get further apart from each other.
Edit. This explains it better https://www.astronomy.com/science/does-the-space-inside-an-atom-expand-with-the-universe/
That says that the expansion really only applies to the space between galaxies. In anything smaller than that, gravity still overpowers the expensive forces. Making it far weaker than I initially thought.
It's at a much, much larger scale** than that
our local group is collapsing in on itself, and it's ~10M lightyears in diameter.
** talking about length scales only makes sense in reference to the specifics
two bananas separated by 10M lightyears, with no other matter nearby, would (I'm guessing) be expanded away, but a cluster of galaxies will not.
Using a banana for scale really made this so much better. :)
Yeah, finally I can imagine the vastness of space. Thank you, bananas!