Under Cosmic Expansion, everything beyond the Hubble Sphere is traveling away from Earth faster than the speed of light, which implies most of the Universe is traveling away from Earth faster than the speed of light, under a flat-space (or almost flat) assumption, and this condition seems to hold for every other location. Does Cosmic Expansion therefore cause everything to travel faster than light, relative to almost everything else?
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$\begingroup$ What's the question? Is it just the question in the title? $\endgroup$– AllureOct 21, 2021 at 3:34
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$\begingroup$ Yes, that is the question. Now edited to repeat question in the body. $\endgroup$– waveOct 21, 2021 at 3:36
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$\begingroup$ physics.stackexchange.com/questions/107748/… physics.stackexchange.com/questions/593083/… physics.stackexchange.com/questions/107748/… $\endgroup$– anna vOct 21, 2021 at 4:18
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$\begingroup$ Wikipedia as a "mainstream" source: "In cosmology, a Hubble volume or Hubble sphere, subluminal sphere, causal sphere and sphere of causality is a spherical region of the observable universe surrounding an observer beyond which objects recede from that observer at a rate greater than the speed of light due to the expansion of the Universe." Edward Robert Harrison (2003). Masks of the Universe. Cambridge University Press. p. 206. ISBN 978-0-521-77351-5. Physics SE- ""remote objects may indeed be becoming more remote faster than light." $\endgroup$– waveOct 21, 2021 at 4:41
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Does Cosmic Expansion therefore cause everything to travel faster than light, relative to almost everything else?
Yes, if you consider "almost everything else" as everything that's outside that something's Hubble sphere.
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