The discussion centers around the size and age of the universe, exploring concepts related to cosmology, including the implications of the Big Bang, inflation, and the observable universe. Participants examine how measurements of distance and time relate to the universe's expansion and the challenges in extrapolating these values to determine age.
Participants express multiple competing views on the universe's size, age, and the implications of various cosmological models. No consensus is reached on these topics, and the discussion remains unresolved.
Limitations include the dependence on current measurements and models, which may not fully account for the complexities of cosmic expansion and the nature of the universe beyond the observable limits.
You should get the minimum radius of the curvature approx R=205 Gly. Is that what you have?GeorgeDishman said:I did a search of one of the forums a few weeks ago and found an old post (but I can't find it now of course) that gave the radius of the 3-sphere as:
##R = c / (H_0 sqrt(Ω_K))##
Plugging in the upper limit for ##Ω_K## from the Plank 2015 results then gives a minimum total volume. However, I've seen other sites that use that same argument but get very different numerical values from what I worked out.
Yes, for a Hubble Length of 14.4 Gly from Wikipedia: ##R = 14.4 / \sqrt(0.005) = 203 Gly## for the radius, which I think means ##2 \pi R = 1280 Gly## for the circumference (proper distance to return to your starting point) and ##2 \pi ^2 R^3 = 1.67*10^6 Gly^3## total volume. The Planck value is 95% confidence (from memory) so that would be 97.5% confidence minimum limits (50% chance of curvature < 0) assuming a 3-sphere rather than some other topology.Bandersnatch said:You should get the minimum radius of the curvature approx R=205 Gly. Is that what you have?
Thanks, I recognise those from the Lineweaver paper. The example I gave is outside our cosmological event horizon so the light will never reach us.Bandersnatch said:In the meantime, you could use these graphs:
Bill McKeeman said:I do not think we have any evidence of what an observer somewhere else in the Universe would see.
I'd say it's a reasonable assumption though, given that all of the Universe which we actually do see, is in fact isotropic and homogeneous at the large scaleBill McKeeman said:I do not think we have any evidence of what an observer somewhere else in the Universe would see. You must be applying the Cosmological Principal, which is an assumption, not a fact.