Talk:Big Rip

Time until the end of time

From the article:

"The authors of this hypothesis calculate that the end of time would be approximately 10³⁰ years after the Big Bang, or 10²⁰ years from now."

That puts the Big Bang 10³⁰ - 10²⁰ years in our past, which is 10³⁰ years ago to all intents and purposes -- eh?

This has been sorted by 64.218.161.210

Why does it say: "35 billion years after the Big Bang, or 20 billion years from now."? 10²⁰ and 10³⁰ are significantly higher. Are there any references for this? --Driux 01:54, 19 October 2006 (UTC) Nevermind, it was obviously originaly supposed 30 billion, instead of 10³⁰ etc. Driux 14:51, 7 November 2006 (UTC)

Phantom energy

The article should mention that matter with w < -1 is phantom energy as opposed to a cosmological constant or quintessence, and link to phantom energy (I haven't done myself this because there isn't yet a page on phantom energy, and I don't know enough about it to write one) --Jomel 22:47, 13 Aug 2004 (UTC)

Big Rip vs. big rip

I have renamed it back to the capitalized version. By similar reasoning to Big Crunch, Google shows that most references use the capitalized version, because the context is usually referring to a one-time hypothetical future event (the Big Rip) rather than a generic term (a big rip). -- Curps 20:34, 7 Mar 2005 (UTC)

"End of time"

Would the Big Rip really be literally (not just metaphorically) the "end of time" in the same way as the Big Crunch? Wouldn't it mean that the universe would still expand eternally, just very fast and without anything interesting?

Nickptar 01:25, 30 Mar 2005 (UTC)

There is a reason why this has been labeled as the possible end of time. How is time measured? It is measured as a sequence of events or phenomenon. Something must happen, which is a reference from which time is measured. After the big rip, there would be no interactions between various bodies in the universe. So, essentially, there is nothing to measure time against. The concept of time becomes meaningless. So, time actually ends. This is very interesting as even in the case if the universe ends in a big crunch as opposed to a big rip, time ends again as all future points to singularity. And, singularity is dimensionless. Here again, time is meaningless.

- Shobs [1]

Yes, but, if you consider time to be an illusion, and that everything in embedded in spacetime, time wouldn't end. Things would be just static, but time would go on. Also, consider the string theory, which states that particles are vibrating strings. Vibrations are certainly caused by the passage of time. Of course, string theory and the spacetime philosophical viewpoint are just theories, but I'm mentioning them, anyway, to show both aspects of the issue.--Orthologist 16:54, 15 February 2007 (UTC)

Shrinking?

Is the word "shrinking" a misprint? I don't see how a universe that is shrinking would prohibit interactions between its components.

Imagine you're an ant living on the surface of a balloon. And the balloon is being inflated.

Now, if you start at your house, and you walk around on the balloon, you find that if you get too far from home- you can never get back! That's because the expansion of the balloon means that your walking speed isn't enough to overcome the expansion- the distance between you and home is expanding as fast as you can walk!

That distance, which is the limit to how far you can get is the analogue of the 'observable universe' in the real world, except it's not ants walking around, it's light wizzing around!

If the speed of expansion of the balloon increases, then the observable universe shrinks, eventually your house falls apart.WolfKeeper

Basically, once different parts of an object are in different parts of space that are moving apart at the speed of light then the object is going to disintegrate. (It's the same principle as a black hole .)WolfKeeper

Alright, so the individual components of matter are accelerating away from each other at a rate which prevents signals from being received, and so they cannot receive an "attraction" signal from the strong force, etc.? I can understand this aspect; I just don't follow the usage of the word "shrinks" in your explanation. Is it because the universe will expand faster than the speed of light? --Original poster from above.

The expansion is linear per metre per second (e.g. 0.01cm per metre per second). So if two points are far enough apart they are moving away from each other at the speed of light (more precisely, the distance between them is increasing at faster than the speed of light). That's called the observable universe. So light can never go from one object to the other if they are initially more than that distance apart.

So, if the rate of expansion increases, the observable universe shrinks.WolfKeeper

Ah, thank you. That makes much more sense.

It's possibly not the best word to use, methinks - the observable universe will actually be increasing in size, as it can never decrease as time increases (it's defined as how far away photons can be coming from - that must increase as dictated by the speed of light),

No, the distance would actually be reducing; it's not just amount of matter. The volume of the observable universe decreases as the expansion rate goes up.WolfKeeper 21:24, 28 April 2006 (UTC)

however the amount of matter in the observable universe will be decreasing (i.e. bits will be 'dropping off the edge'). This isn't a contradiction because the density is being reduced, in this case due to the expansion of space (i.e. the separation between particles) rather than matter moving around. Mike Peel 16:43, 28 April 2006 (UTC)

Doesnt this article miss that the expansion of the universe is accelerating in two ways? 1) there is more space to expand as it expands. 2) hubbles constant is actually increasing. Not noting the second confused me when reading, because i forgot the second. The second one is the one causing the visible universe to shrink, the radius of the visible universe is H/c with H hubbles constant (so its constant if H and c constant). Note that i do not know general relativity.(yet)

Black holes and the Big Rip

What would happen with a black hole in a Big Rip? 194.85.123.85 13:07, 15 April 2006 (UTC)

If I understand correctly, our current models treat black holes to be point objects (much the way fundamental particles are treated as point objects with a probability wavefunction describing where you might interact with them). This would make them unaffected by the big rip (though they'd still eventually evaporate via Hawking radiation). In practice, I'd expect very strange things to happen when the size of the observable universe became smaller than the size of the event horizon. I _think_ what happens is that as the size of the observable universe shrinks, the size of the event horizon shrinks as well, so that they never come in contact, but in practice we'd need a good theory of quantum gravity to understand what happens under conditions extreme enough for this to be a problem. A physicist specializing in relativity can give you a more accurate answer than I can. --Christopher Thomas 04:57, 24 April 2006 (UTC)

Ah, but...

Y'all want to hear a bit of irony?

If any of this is correct, none of us will ever know it. In fact, it's possible that none of humanity will ever know it. Funny how science and mysticism both tend to circle around to the same distant, indiscernible point... ;)

--Iamlima 07:02, 28 April 2006 (UTC)

Really? Very insightful - most of us were of the impression the big rip would happen within a few years of it being theorized. --NEMT 18:13, 21 August 2006 (UTC)

Everything after the Big Rip

What does everything turn into after the Big Rip? I see atoms get destroyed, but into what?

Torn apart as in reduced to fundamental particles, flying apart at the speed of light.WolfKeeper 01:24, 23 May 2006 (UTC)

Whereas fire destroys wood into ash, what does the Big Rip destroy anything into? Nothing is not the answer; everything has to be destroyed into something. --Shultz IV 00:44, 23 May 2006 (UTC)

We don't know what happens when quarks get ripped apart. When quarks get ripped apart from each other more quarks get formed. So you could end up with a runaway creation of quarks, and it could conceivably form a black hole or something; which might counter the expansion. But really, your guess is as good as anybodies. It may just be that everything ends up as fundamental particles, that just are flying apart at faster than the speed of light; so the universe would still be there, but wouldn't be doing anything very interesting.WolfKeeper 01:24, 23 May 2006 (UTC)

If you pull apart quarks, you get more quarks, but that takes energy. Wouldn't that tend to act as a brake on expansion?--RLent 06:14, 26 January 2007 (UTC)

How could the runaway creation of quarks form "a black hole or something?" --NEMT 18:14, 21 August 2006 (UTC)

Maybe the total mass of the quarks becomes so huge it reaches a "critical mass" of sorts. --WikiSlasher 14:46, 30 October 2006 (UTC)

List of doomsday scenarios

Could use votes to save this article, thanks MapleTree 22:17, 28 September 2006 (UTC)

Size of the universe

How can the edges of the universe be 46.5 billion light years away when the universe is nowhere near that old? —The preceding unsigned comment was added by 69.22.232.20 (talk • contribs) on 12:46, 15 March 2007.

This is covered at observable universe. Light from distant galaxies has travelled about 13 billion years to reach us. However, these galaxies continued to move away from us as the universe expanded. 46 billion light-years is our estimate of where they are now. --Christopher Thomas 15:44, 15 March 2007 (UTC)

So what you mean is that the universe may be 13 billion years old, but the rate of expansion is faster than the speed of light so much so that the edges of the universe are 46.5 billion light years apart?

And, with reference to what you said, say for example, Star X is at the edge of the observable universe currently, is Star X's actual position at the edge of the universe currently? Mysterial 16:08, 18 March 2007 (UTC)

A star that we see now as being 13 billion light years away is indeed much farther away now, as we saw it 13 billion light years away 13 billion years ago. Different parts of the universe do expand FTL relative to each other, yes; this gives us a cosmological horizon, with an exact distance that depends on how we assume the expansion rate changes over time.

Saying that Star X is at the "edge of the universe" isn't quite correct. There isn't an edge, or at least not one that anyone's seen. What the size value says is that the edge of the observable universe - the part we can presently see - is farther away than it looks, due to expansion over time. --Christopher Thomas 17:16, 18 March 2007 (UTC)

Ok.. if there isn't an edge, how does the universe expand in size? I mean, I assume what you meant is that it is infinitely huge and has no boundary. But if this is so, what can the universe expand into? Since the universe is still expanding, there should be some sort of boundary limiting it so that it makes sense to say that the universe expanded from say, Size A to Size B. Mysterial 16:19, 21 March 2007 (UTC)

See Metric expansion of space for details about this. The usual analogy given is to consider a balloon with dots on it, being inflated. The dots represent galaxies, the balloon represents space. By looking at how distant galaxies move with respect to each other, you can infer that space is expanding, and how fast it's expanding. The equations of relativity have certain solutions corresponding to an expanding universe, which are assumed to represent the type of universe we're in. --Christopher Thomas 20:31, 21 March 2007 (UTC)