Submitted by modsarebrainstems t3_1018gn0 in askscience
Krail t1_j2p4eko wrote
Reply to comment by ScootysDad in How do galaxies move? by modsarebrainstems
So, are you saying that past a certain magnitude threshold, the force of gravity effectively causes the expansion of space in that region to stop?
omgwtfbbqgrass t1_j2pb1nu wrote
It's not that gravity causes the expansion of space to stop, it's just that on relatively "small" scales we can safely ignore the expansion of space. Gravity still dominates even at the scale of galactic superclusters (for now). But increase the scale by comparing entities billions of light years away, and it's the expansion of space that dominates over gravity.
ScootysDad t1_j2pq816 wrote
Forces have an effective range. At the sub-atomic range, the Strong and Weak forces act on particles like quarks. Above that is is the electromagnetic force which works at the atomic level to the macroscopic level (normal everyday experiences). After that is the gravitational "force" which works at the normal everyday objects like apples, cars, rockets, and people to galaxies, local clusters, and superclusters. All of the above forces are orders of magnitude stronger than the dark force that caused the expansion of the universe.
So, the space between superclusters is vast and gravity no longer hold sways over the space fabric so it stretches.
One posit is that gravity is not a force but rather a time gradient around mass. The closer you are to the central mass the greater the time curvature so the differential time difference causes you to spiral downward through space instead of an actual field that interacts with a particle (like photon to the electromagnetic field or the Higgs boson with the Higgs field to give us mass).
[deleted] t1_j2wtzih wrote
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[deleted] t1_j3vfov1 wrote
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omgwtfbbqgrass t1_j2pb29x wrote
It's not that gravity causes the expansion of space to stop, it's just that on relatively "small" scales we can safely ignore the expansion of space. Gravity still dominates even at the scale of galactic superclusters (for now). But increase the scale by comparing entities billions of light years away, and it's the expansion of space that dominates over gravity.
[deleted] t1_j2pllwx wrote
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