Talk:Future of an expanding universe

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Universe should be nearly pure vacuum in Dark Era (assuming proton decay)[edit]

The convergence of the Hubble Parameter to a future value of 55.4 km/s/Mpc implies the universe will double in size every ~12.2 billion years. After 10100 years, the universe will have expanded by a factor of more than (and by 10200 years, by ).

An estimate of the average particle density (~) after such immense expansion suggests the universe will be nearly pure vacuum. Given that estimates of the future size of the cosmological event horizon converge to ~16 Gly, and also the estimate of a total of 1097 subatomic particles in the universe, it would seem that almost all such particles would be forever removed from the possibility of interaction with other particles, and the chance of particle collision would be beyond unlikely and continuing to decline exponentially with the continued expansion of the universe. Even if there were 10100,000 subatomic particles, most such regions of ~(16 Gly)3 would be absent any particles of all. (It really doesn't matter what the exponent is of the subatomic particle estimate is, if expressed directly in decimal form - the result doesn't appreciably change. Similarly even if you increased the radius of the event horizon to Gly, most such regions are still unlikely to contain any particles).

Rsbaker0 (talk) 14:34, 25 March 2019 (UTC)[reply]

Expansion of Dark Era section[edit]

The text added several hours ago seems to be a paraphrased version of narration in the YouTube video “TIMELAPSE OF THE FUTURE” by melodysheep https://m.youtube.com/watch?v=uD4izuDMUQA

I’m unsure if a YouTube video is generally an acceptable reference for Wikipedia. If it is, the video is linked above and takes you to YouTube.

Savie Kumara (meow) 02:33, 24 June 2020 (UTC)[reply]

Savie Kumara Hi there. I found it. I feel like it is a bad reference (you cite Timelapse of the Future, all melodysheep does is comppilating--whaa?) and that it should be replaced with a different style of writing. I'll try edit it. GeraldWL 14:08, 29 July 2020 (UTC)[reply]

Isn't this all just a theory?[edit]

Everything we know about the outer edges of our universe is limited to our own understanding at the present time. Isn't everything on this article just a "theory"? And if so, shouldn't there be a disclaimer to that effect? Rhythmnation2004 (talk) 18:55, 9 December 2020 (UTC)[reply]

WP:NODISCLAIMERS and everything is just a theory. Nothing in all reality is known to really exist, since they could just be a figment of your imagination. Afterall, we only know what our mind interprets, not what really exists out there. We could be in The Matrix. Also, the intro section already says it is hypothetical/theoretical. -- 67.70.26.89 (talk) 19:42, 10 December 2020 (UTC)[reply]

"Big Freeze" listed at Redirects for discussion[edit]

A discussion is taking place to address the redirect Big Freeze. The discussion will occur at Wikipedia:Redirects for discussion/Log/2020 December 9#Big Freeze until a consensus is reached, and readers of this page are welcome to contribute to the discussion. -- 67.70.26.89 (talk) 11:05, 12 December 2020 (UTC)[reply]

galaxies outside the Local Supercluster or outside Local Group are no longer accessible?[edit]

"The galaxies in the Local Group... are gravitationally bound to each other" So far, so good. What's confusing here is that this section then segues into using the Local (or Virgo) Supercluster here instead of Local Group. The implication is that the expansion that causes galaxies to move beyond the cosmological horizon doesn't apply to galaxies that are part of our Supercluster even though they may be outside the Local Group. But what's stopping that expansion, the Hubble flow, from having every galaxy not gravitionally bound to the Local Group eventually moving beyond the cosmological horizon? The source for "supercluster" doesn't mention the "Local Group" at all and I think we shouldn't be using a source here that doesn't address the intuitive concept that if the Local Group defines what's gravitionally bound to us then what's beyond will presumably continue to recede away from us. Ethan Siegel's work makes it very clear that he would say we need to use Local Group throughout here, not Supercluster, and the "true limits of humanity – the final border we will never cross" video on Youtube that consulted multiple experts, apparently including Siegel, explicitly addresses the possibility of interaction with the Maffei Group which is just outside the Local Group to say that if one departed for there soon at light speed yes one (or the ship anyway) could catch up to it (after 11 million years) but it would still continue to recede such that anyone who did catch up with it would, together with those galaxies, still eventually be lost to us beyond the cosmological horizon. All this to say that references to Supercluster here should be changed to Group and an additional source used.--Brian Dell (talk) 23:04, 18 January 2022 (UTC)[reply]

10^10^10^56?[edit]

At the end of the article, it is stated that the probability of producing a new Big Bang is roughly 10101056 years. However, in that paper cited doesn't appear that number. I've tried to research it but I have nothing about it, at least in some credible source. I suggest adding "citation needed" or more information in that section, if not take it out completely. Artistosteles (talk) 13:33, 12 March 2023 (UTC)[reply]

Equation 45 shows P ~ 10−101056. No idea if that is probability per year though. CWenger (^@) 17:34, 12 March 2023 (UTC)[reply]
Could be per year, per nanosecond, or per age of the universe and the number wouldn't be written any differently. Aseyhe (talk) 00:11, 11 August 2023 (UTC)[reply]