Gravity Grinch / is on Nostr

observational cosmologist -- the particle horizon is the limit!
thegravitygrinch.blogspot.com

Last Notes

2024-08-09 09:59:11

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Olber's paradox is quite vaguely phrased, similar to the Cosmological Principle, so that refining the statement and analysing the possible scenarios can help to refute certain astrophysical or cosmological assumptions. 6/6

2024-08-09 09:58:59

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So, imho, there is a resolution to Olber's paradox in Einstein's static universe, if we refine the paradox to only hold on average (in space and time) and discard the idealised, mathematical infinities which will most likely not occur in nature, anyway. 5/6

2024-08-09 09:58:41

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mathematically, a countable set has zero measure, thus, the total night-sky wouldn't be inf bright. Moreover, if stars only have a finite lifetime and the number of stars stays the same on average, we even resolve the problem of inf brightness along these l.o.s. 4/6

2024-08-09 09:58:26

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assuming, like Einstein, that the universe was only hom+iso on average, he rather assumed a finite set of stars. Let them shine eternally again. Then, only a countable number of lines of sight end in stars and only those could be inf bright for us.
However... 3/6
https://cdn.masto.host/astrodonsocial/media_attachments/files/112/931/471/586/896/329/original/5ae74b1de584c36a.png

2024-08-09 09:57:55

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If the hom+isotropic matter density of this model consisted of inf many eternal stars, then, yes, we would see a bright sky. Light would have had inf much time to come from all directions to us and each line of sight would end in a star.
But... 2/6
https://cdn.masto.host/astrodonsocial/media_attachments/files/112/931/469/510/895/522/original/6df99f11a0a167d6.png

2024-08-09 09:57:27

Have you ever wondered what it may be like to live on the 3d-surface of a 4d-sphere that never changes?
Einstein did in 1917 and found it to be the only viable cosmology from his field equations at first.
But wouldn't that surface be infinitely bright? 🧶 1/6
#cosmology #astronomy #astrophysics
https://cdn.masto.host/astrodonsocial/media_attachments/files/112/931/461/510/933/098/original/9b07ffd1ec7d20c8.mp4

2024-07-24 22:22:13

Does anybody here happen to know if Einstein thought about obeying Olber's paradox (keep the number of stars finite to keep the sky dark) when writing his 1917-paper in which he developed his static (spatially spherical) universe?
#astronomy #astrophysics #history #cosmology

2024-07-24 22:22:13