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"The Hubble length {\displaystyle c/H_{0)) c/H_0 is 14 billion light years in the standard cosmological model, somewhat larger than {\displaystyle c} c times the age of the universe, 13.8 billion years." Why is that? — Preceding unsigned comment added by 192.249.47.217 (talk) 14:36, 25 August 2017 (UTC)
I believe these are the same thing, but someone coming to this topic might have a hard time working that out. It might be best to use Hubble constant rather than parameter as that is the more common term.
I don't want to change it myself in case I'm wrong; and if I am wrong then "Hubble parameter" should be properly explained or linked to a topic which actually explains it. Gk007 (talk) 04:29, 2 June 2014 (UTC)
The whole reason I'm reading about this sort of thing is that I find it very interesting (I suppose I have better things to do but Wikipedia is addictive) so forgive me for not understanding but I noticed that an Event Horizon is mentioned in this article. It's quite appropriate in the sense that objects moving out of range at a certain speed will no longer send information back to us, but isn't an event horizon typically a physical boundary from which objects can only pass in one direction? The linked article on event horizons discusses black holes to the exclusion of hubble volumes. I haven't changed anything because I'm not confident about which article is amiss. Cheers. SneakyWho am i (talk) 15:10, 4 March 2009 (UTC)
Cosmo0, you removed the following claims with the comment "removed factual inaccuracies":
Can you please explain what's inaccurate about these? -- BenRG 17:14, 1 October 2007 (UTC)
That's a lot of space :) Rm999 09:21, 4 October 2007 (UTC)
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
"The term "Hubble volume" is also frequently (but mistakenly) used as a synonym for the observable universe; the latter is larger than the Hubble volume.[2][3]"
It would seem that the observable universe is smaller than the Hubble volume, since we can see less than the limits of the Hubble volume as the "edges" recede away. Please reply, else I will make the correction "latter is larger than" to "latter is smaller than" —Preceding unsigned comment added by 70.52.148.201 (talk) 20:30, 23 April 2009 (UTC)
[Main article] "This is because 1 / H0 gives the age of the universe by a backward extrapolation which assumes that the recession speed of each galaxy has been constant since the Big Bang. In fact, recession speeds initially decelerate due to gravity, and are now accelerating due to dark energy, so that 1 / H0 is only an approximation to the true age."
There is the above silly statement in the main article that a guy or a gal responsible for it should fix a.s.a.p.
The problem with it is of course that "gravity" (some time ago we agreed rather on the term gravitation) couldn't cause neither deceleration (nor acceleration to be sure) since garavitation does not add any energy to the system of free falling bodies (since there is no action at a distance in a real world - or at least in Einstein's world, in which we might be living, or at least it was never proved otherwise).
In my opinion it might be better for readers of wikipedia if wikipedia diddn't promote prejudices from ancient times when gravitation was controlled only by Newtonian math. We already know a great deal more about the universe and wikipedia should follow rather the knowledge than the prejudices that even Newton didn't share. Jim (talk) 10:55, 30 October 2010 (UTC)
I think that this article has slightly misrepresented the observability of distant objects. Any object that was ever within the Hubble sphere will always be observable, but the light from it will continue to be redder and more aged as the object appears to approach the speed of light. Their time appears to slow down more and more. (Similar to light from an object falling into a black hole.) A better way of saying it is that light emitted (now) from objects (now) beyond the Hubble sphere will never be seen. - Allyn
For instance the CMB appears to have a red shift of about 1100X. This means that it takes three years to observe one day of aging of the surface radiating the CMB. That surface continued to move away from us for those three years, but we can only see the next day's light. An observer that is on the 13 Billion year old galaxies that formed where we currently observe the CMB can also observe the CMB from 13 Billion year ago emitted from our current location. - Allyn — Preceding unsigned comment added by 97.65.82.66 (talk) 16:31, 20 December 2011 (UTC)
Is the 1/H0 an error? It looks like both instances are supposed to be c/H0, not 1. Or am I wrong? 137.150.14.176 (talk) 11:07, 3 December 2012 (UTC)
This may just be a lack of firm understanding of comoving vs. proper distance on my part, but this statement in the article:
seems to me to refer to proper not comoving speed: Comoving distance says "Comoving distance factors out the expansion of the universe, giving a distance that does not change in time due to the expansion of space", and "Proper distance ... can change over time due to the expansion of the universe": so shouldn't an expansion-caused speed be referred to as proper not comoving speed? KaiGetrost (talk) 20:39, 25 April 2013 (UTC)
Actually nowadays the mean discausality electromagnetic wavelength is longer than the Hubble volume (due to the overlapping Hubble volumes which hold the universe as a whole with some hypernymic/superordinate causality that merely holds the universe as a whole and isn't related to interaction (common) causality). If we deem Hubble volumes as standalone marbles without to focus on spacetime as a whole, the mathematical description is wrong. — Preceding unsigned comment added by 2A02:2149:8200:6E00:1CD2:E750:1821:8A8A (talk) 13:27, 25 November 2021 (UTC)
that the official name for this concept is not Hubble Bubble. 84.71.42.186 (talk) 12:43, 11 January 2022 (UTC)
Where are these terms mentioned anywhere outside of Wikipedia / mirrors (WP:CIRCULAR)? Does anyone know? I can't find mention of these anywhere. El_C 13:58, 16 October 2022 (UTC)
Obviously, the both things cannot be true at the same moment. The second link cited says the universe is decelerating. Reciprocist (talk) 02:37, 24 July 2023 (UTC)
P.S. It seems, the second source is outdated, it is from 2003, when accelerating expansion was not yet known.--Reciprocist (talk) 02:40, 24 July 2023 (UTC)