Talk:Hubble volume

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[edit] Factual inaccuracies?

Cosmo0, you removed the following claims with the comment "removed factual inaccuracies":

• "The Hubble volume is also known as the 'Hubble sphere,' its radius as the 'Hubble radius' or 'Hubble distance,' and the boundary of the volume as the 'Hubble limit.'"

• "Per Hubble's law, objects at the Hubble limit have an average comoving speed of c relative to the center. Contrary to common belief, this does not define the boundary of the observable universe. The observable universe has a much larger radius, about 46 billion light years, and the most distant object we can see, the primordial fireball (the source of the cosmic microwave background), has a comoving speed of about 3.3 times c."

Can you please explain what's inaccurate about these? -- BenRG 17:14, 1 October 2007 (UTC)

Apologies for the first one: you were right and I was confused. The problem with the second one is that it implies that the primordial fireball is receding from us at 3.3c, which is misleading. Objects in the region of space that we observe as the primordial fireball are currently receding from us at 3.3c, but the fireball itself (as far as it can be said to be receding at all when it no longer exists) appears to be receding at less than the speed of light. Similarly, objects at the Hubble limit are observed to be receding at a fraction of the speed of light, but are currently receding at the speed of light, which is what confused me over the first point. I hope what I've now written makes sense. Cosmo0 18:46, 1 October 2007 (UTC)

[edit] Actual Volume?

(4/3) * 13.8 billion light years^3 * pi = 11008442251073380127723994828776 light years^3

8.46732406*10^47 meters^3 per light year^3

1.10084423*10^31 * 8.46732406*10^47 = 9.32*10^78 meters^3

That's a lot of space :) Rm999 09:21, 4 October 2007 (UTC)

[edit] Merger proposal

Articles Hubble volume and Observable universe are written on the same principle and should therefore be merged.

I don't know exactly what the process for merging is, but I have placed tags on the pages involved . Beast of traal T C _ 13:14, 8 October 2007 (UTC)Beast of traal

This (or something similar) has already been discussed (see the talk page for observable universe). Although the term "Hubble Volume" is often used as a synonym for the observable universe, it also has a more strict definition, which is actually somewhat smaller than the size of the currently observable universe, although I agree the two are related. Cosmo0 21:10, 8 October 2007 (UTC)

Ok, I'll take the tags off. Thanks. Beast of traal T C _ 23:47, 1 November 2007 (UTC)Beast of traal