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Do cosmologists know for sure that the Big Bang is propelling all matter away? (lemm.ee)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]

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Is it at all possible that instead of being pushed away, we are instead getting pulled toward something huuuuuge via gravity? As if we are falling into something way greater than ourselves? I thought this was a wild idea but after I Googled it I found out that there is such a thing as a “Great Attractor”. Something 150 million light-years away is literally pulling all nearby galaxies towards it but no one knows exactly what it is.

So how do we know there aren’t any other Great Attractors, Greater Attractors, ad infinitum?

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[–] [email protected] 1 points 1 year ago (1 children)

Wouldn't it cause some sort of force locally at the atomic level all the same even for tightly coupled systems? They shouldn't feel the expansion as it is not a force from my understanding but just growth of space itself. But for example wouldn't the orbit around an atom be off just so slightly that it would need to expend some level of energy to correct for lack of better word.

Or do we think this does happen but the amount is so small that we can not measure it experimentally in any way.

[–] [email protected] 1 points 1 year ago

My understanding is that it does exert a force everywhere, even locally. It's just so incredibly weak that other local forces dominate and overpower it. Take the classic example of expansion as ants on a balloon as it's inflated. The expansion wants to pull them apart, but if they were tied to each other by thread, the thread would be stronger and they would stay together. The thread represents the inter molecular forces. Also remember that the expansion force is in every direction, without an origin, so from an atom's perspective the force seems to push outward,not from the side, so there would be no "offset".