Talk:Universe

unintentional

My recent edit was an accident. I did not even know I had visited the page--JimWae (talk) 04:38, 15 December 2012 (UTC)

The universe is mysterious Bhny (talk) 17:36, 15 December 2012 (UTC)

93 billion light years in diameter - really?

The statement that the Universe "is believed to be at least 93 billion light years in diameter" is not a factual statement about the universe; the statement that the Universe "is at least 93 billion light years in diameter" is not adequately supported by the reference (or anything else); neither statement belongs in the article. Dr5t3v3 (talk) 08:38, 2 January 2013 (UTC)

The reference literally states: "Today diameter of the observable universe is estimated to be 28 billion parsecs (about 93 billion light-years)."TR 12:22, 2 January 2013 (UTC)

Exactly - estimated by who? Is there a citation? The reference is not a research article, or research of any form. It is pure opinion. Dr5t3v3 (talk) 02:42, 14 January 2013 (UTC)

The source is a textbook, which is a perfectly acceptable reliable source. Textbooks rarely give citations for the facts they present. That does not make the facts they present "pure opinion". Given the time frame, the estimate in the book is probably based of the WMAP 5 year data.TR 15:23, 14 January 2013 (UTC)

Within the Big Bang model, how can the diameter of the universe be greater than about 27.5 billion lightyears (i.e., radius = age of universe from centre at speed of light)?? Unless expansion occurred faster than the speed of light???--Jeffro77 (talk) 04:09, 25 February 2013 (UTC)

It did. See Inflation (cosmology). — HHHIPPO 07:34, 25 February 2013 (UTC)

I think you probably mean cosmic expansion rather than inflation - inflation was a specific phase in the very early universe. The key point is that the light or other radiation that we observe from the furthest visible objects (which ultimately means the cosmic microwave background radiation) was emitted 13.7 billion years ago, but during that time the universe has expanded so those objects are now about 46.5 billion light years distant, giving the observable universe a diameter of approximately 93 billion light years. So, yes, the space between us and the most distant objects is expanding at a rate that is numerically greater than the speed of light (although the two quantities are not really comparable). Gandalf61 (talk) 11:57, 25 February 2013 (UTC)

Thanks. I also had a read of Faster-than-light#Universal expansion earlier.--Jeffro77 (talk) 12:05, 25 February 2013 (UTC)

Interesting point to add...

I'm not able to come up with a way of phrasing this that would seem to fit into this article, but I have found an interesting point that may be worth mentioning:

http://news.yahoo.com/higgs-boson-particle-may-spell-doom-universe-152236961.html

The point of the article is that new research on the Higgs Boson seems to suggest that the Universe may eventually collaps in on itself, or ultimately be destroyed billions of years in the future. Again, I think this may be worth noting. Additionaly sources will be needed. -Poodle of Doom (talk) 19:15, 19 February 2013 (UTC)

It's not that it will collapse in on itself in the classical sense, it's that a nucleation point could form, inside which the universe would to jump to a lower, more stable energy level. The nucleation point would expand outward at the speed of light, so a single "tear" wouldn't be enough to "destroy" the universe as we know it. — Gopher65_talk 00:27, 20 February 2013 (UTC)

Still, wouldn't this be something relevant to add to the article? At that, you can see that my understanding of this isn't necessarily enough to add the point to the article. -Poodle of Doom (talk) 03:14, 20 February 2013 (UTC)

I'm no expert in theoretical physics, but is this related to False vacuum#Vacuum metastability event? And since this page already links to Ultimate fate of the universe anyway, maybe this point should be mentioned in either one instead of here. Reatlas (talk) 07:41, 20 February 2013 (UTC)

Yeah. My understanding of this work is that if we're in a false vacuum (probably are), a nucleation event is more likely than previously thought. — Gopher65_talk 22:51, 20 February 2013 (UTC)

Yeah, the placemeant of the newly found info in the above mentioned articles would be better. However, I think it should be lightly alluded to here. -Poodle of Doom (talk) 05:02, 22 February 2013 (UTC)

Unsolved problems

The sentence "Physicists remain unsure about what preceded the Big Bang model and also the ultimate fate of the Universe" in the lede has multiple issues:

• What preceded the Big Bang model is not the question here, it's what preceded the Big Bang.
• It remains unclear if the second part (and also...) refers to what preceded or to unsure about.
• Physicists is unclear: some of them? all of them? How about non-physicists, are they sure?
• The question is actually a bit broader: it's not only what preceded the Big Bang, but first of all if preceding is a well-defined concept at all at that point.

The previous version, "What preceded the gravitational singularity before the Big Bang and the ultimate fate of the Universe remains an unsolved and speculative problem in physics", was in some respects better, but also had its issues:

• Talking about a gravitational singularity before the Big Bang is a bit questionable.
• Problems are not speculative, answers are.
• It would be nice to link to List of unsolved problems in physics, but that page doesn't mention the preceding the Big Bang part.

Here's a suggestion for another rephrasing: "What, if anything, preceded the Big Bang, and what will be the ultimate fate of the universe remain unsolved problems in physics." Any thoughts? — HHHIPPO 17:51, 14 May 2013 (UTC)

I disagree.

• If we remove "model" we are not being specific enough
• "Physicists" as worded gives a general perspective
• Gravitational singularity is unproven
• We should speak about physicists not physics. Pass a Method talk 19:18, 14 May 2013 (UTC)

The sentence is poorly constructed at best, misleading at worst. It needs to be reworded. 04:11, 15 May 2013 (UTC) — Preceding unsigned comment added by Gopher65 (talk • contribs)

1. Why is it unspecific? What else could it be confused with? Using the phrase "big bang model" is like prefixing every use of gravity and evolution with "the theory of".
2. Physics is an academic discipline, which physicists study. How exactly is "physicists" more general than "physics"?
3. Has been removed.
4. This is the same as number two. Reatlas (talk) 14:53, 15 May 2013 (UTC)

I broke it into 2 sentences. I think it reads much better. I removed "model" as this is logically wrong. What preceded the "Big Bang Model" was another model (Solid State?). Bhny (talk) 15:22, 15 May 2013 (UTC)

I can live with the new version, but still think physics would be better than physicists: it's not only physicists who wander about this question and are unsure what's the answer, it's also laypeople. So the statement is at least incomplete. If one interprets physicists as meaning all physicists, then it's also wrong: there are physicists who also are creationists and they feel pretty sure they know the answer. Of course one could also interpret it as some physicists, that's the 3rd problem: ambiguity. Unsolved problem in physics avoids all that. There's a reason we have an article List of unsolved problems in physics, but not List of things physicists are unsure about.

P.S.: Bhny, I guess you mean steady state, not solid state ;-) — HHHIPPO 18:38, 15 May 2013 (UTC)

haha yes Bhny (talk) 20:18, 15 May 2013 (UTC)

Semantics: the "Universe" vs. a "universe"

This isn't a big deal, but I think it would be a good idea just to throw in a line about how the Universe is a proper noun that is capitalized if one refers to the universe in which we live. This contrasts with a "universe" which is a hypothetical or model cosmological object, such as the theory of there being more than one universe. PirtleShell (talk) 22:07, 15 May 2013 (UTC)

Just a small mistake

It's actually, nothing, and I'm really sorry, I must come off as a miss "know-it-all", but I just want to tell you that, you've made a mistake with the translations. To be precise, in the "etymology, synonyms and definitions" section, in the third paragraph, where you say "Related terms were matter, (τὸ ὅλον, tò ólon, see also Hyle, lit. wood) and place (τὸ κενόν, tò kenón)." you are a little bit wrong. "τό κενόν" in greek, actually means "the vacuum" and it was used to describe... well, non other but the vacuum of space. What you're looking for is "χώρος" which is the exact translation of "place" (in physics)
Again, sorry to bother you :) — Preceding unsigned comment added by 109.242.93.193 (talk) 19:00, 26 May 2013 (UTC)

"universe" common usage means EVERYTHING, so no "multi-verses"

i think whoever talks about multiple universes is violating the spirit of the word, since it is designed to indicate everything. those other aspects would merely be a subset of the universe, and referring to them as 'other universes' is a horrible description.