Talk:Big Rip

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[edit] 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)

[edit] 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)

[edit] 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)

[edit] "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)

If time is an illusion, then there really is no time to go on. It would probably be more accurate to say that time is the result of vibration of strings than the reverse.--RLent 21:15, 26 March 2007 (UTC)

If so, if it was true and this is the end of everything... What will happen to our spirits? Would that die too? Would we see nothing? Would we all be resurrected in another universe? --62.31.182.173 (talk) 16:15, 21 February 2008 (UTC)

I wouldn't worry about our "spirits," since if they exist we can assume they do not obey typical physical laws, meaning there is absolutely no way to know anything about what would happen to them in physically hypothetical circumstances (they might, for example, be part of a different universe, in which the big rip does not occur). Also consider that in 50 billion years, the universe will look considerably different, and there is now way to know if we will exist. Even if we did exist, of course we would "see nothing," because we would die, if not when our home planet(s) is(are) flung from its(their) orbit(s), which is, keep in mind, a full 3 months before the end, then when our bodies are torn apart, which obviously will occur before you get down to the molecular or atomic level, and eventually the true 'end.' And of course, The Big Rip is so far an unlikely theory.Eebster the Great (talk) 19:35, 18 March 2008 (UTC)

[edit] 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)

I guess the idea is sort of like having your ruler grow longer faster than you can inflate your ballon. If your balloon started out as the length of 5 rulers, and you inflate it fairly quickly, but the ruler grows even faster, clearly the balloon will be the relative size of fewer and fewere 'feet' and if the ruler is the only thing to compare it to, it will in a sense be "shrinking." This is not at all clearly explained, though, and it took me a while to figure it out (if I'm even correct, about which I'm not sure).Eebster the Great (talk) 19:41, 18 March 2008 (UTC)

[edit] 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)


I think this is the most interesting question here. Because quantum mechanics prohibits things with mass having zero size, and black holes have mass, they must have a physical size. Therefore, when the Big Rip gets to them, they will expand. What they will expand into is a very interesting question. In the case of a supermassive black hole, there's a lot of mass that can be "unpacked" during a Big Rip. A quantum theory of gravity will likely be needed to predict this event. But once that mass is unpacked beyond the event horizon, a lot of energy associated with that mass will be released. Assuming the conservation of mass and energy holds within the event horizon, all of the mass/energy inside the horizon is still there, less only what has leaked as Hawking radiation. As discussed in another entry below, the forces binding gluons and other leptons together may well slow down the local expansion acceleration rate for some period of time. This might well be the start of a "Little Bang" on a localized scale. Makes you wonder whether our Big Bang was another universe's little one ... that would not violate the entropy principle either. I would appreciate any quantum physicists who might care about the quality of discussion on this starter page to comment. Thanks! SammySlim 21:37, 7 September 2007 (UTC)

Why does quantum mechanics prohibit massive objects having zero size? The way I understand it, leptons at the instant of observation with infinitely uncertain velocity have zero size (which of course is impossible in the same way absolute zero is, but is infinitely approachable). Essentially, when a wave function collapses, the particle has a size limited only by the Heisenberg uncertainty principle, which doesn't really give the size of the object but the uncertainty of its location, and even that uncertainty is zero if the velocity is infinitely uncertain. What law are you referring to?
Also, since the event horizon of a black hole is dictated by gravity, I don't think its size would be affected by the size of the particle horizon until the particle horizon becomes actually smaller than the event horizon. I have no idea what would happen here, since the event horizon isn't literally filled with matter, but is just a theoretical construct. Once this size is reached, I imagine the event and particle horizons would be one and the same as they shrank down to near-zero. Since the black hole currently is treated as having zero size, no spontaneous eruption or anything would happen there, although I suppose anything emitted via Hawking radiation would almost instantly exit the black hole's particle horizon. If this is the case, the Big Rip ultimately would isolate every particle except black holes, which would still remain intact until they eventually evaporate away. Even quarks, I suppose, would be torn apart from eachother so that even hadrons cannot exist, and the universe would be an endless space of isolated elementary particles.Eebster the Great (talk) 19:51, 18 March 2008 (UTC)

I think this is the most interesting question here. Because quantum mechanics prohibits things with mass having zero size, and black holes have mass, they must have a physical size.

[edit] =

As I understand them, black holes do not contain mass at the actual singularity. They are distortions of space caused by mass, which is then crushed out of existence, but leaving the distortion behind. The distortion is unable to cure itself back to flat space again, even if no new matter enters the black hole and the hole becomes empty when all matter inside is crushed.

When the particle horizon shrinks to the event horizon, it simply begins to stretch out the space of the black hole. The particle horizon is operating on space, and is not subject to the constraints imposed by the event horizon, eg that even light may not escape.

Recall even light cannot go faster than light in any reference frame, but two objects embedded in space can recede from each other faster than light, when the space between their locations expands faster than light. 59.167.103.33 (talk) 08:53, 20 April 2008 (UTC)

[edit] 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)
Well, the creation of new quarks consumes energy and this would have to be extracted from the expanding force, i.e. the dark energy. So, unless dark energy has some really strange properties (such as getting stronger when energy is extracted from it) or i'm missing a basic point in particle physics here this would certainly slow down the expansion, either by stealing energy from the expanding force or by creating mass and thus gravity that would overwhelm the the dark energy. --89.55.137.35 00:30, 12 August 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)
So theoretically, the big rip will literally renew the universe! 82.12.86.64 20:50, 26 August 2007 (UTC)
Every mass has an associated volume and an associated schwarzschild radius. For matter of normal mass and normal density the schwarzschild radius is much smaller than the radius of its volume defined by mass and density. The schwarzschild radius grows with m, the radius of the volume of the object grows with the 3rd root of m. So the schwarzschild radius will grow faster than the volume radius. So at a fixed density the schwarzschild radius will exceed the volume radius if you add more and more mass. for example it requires insane densities to collapse an object as heavy as earth to a black hole. But when you accumulate a huge amount of something with a normal density it'll still collapse to a black hole (for this example: it would 150,000,000 times the sun's mass in standard-density water would collapse to a black hole all by itself) --89.55.144.157 23:43, 19 September 2007 (UTC)

We know so little, there is so much speculation. For all we know a Big Rip could be the next stage in a cyclic model. The observable universe could just be one side of a spectrum and we might never know what the other side is and whether it's nature is to loop around back to before the big bang. All just silly talk from me. :/ --99.225.10.18 (talk) 07:14, 30 January 2008 (UTC)

Even if we had runaway quark creation slowing down the expansion of the universe and recreating hadrons, it wouldn't "renew" the universe, since a renewed universe would also have leptons, photons, and W and Z bosons, which this isolated universeling wouldn't have. Also, this recreation of particles from dark energy would seem to violate entropy.Eebster the Great (talk) 19:56, 18 March 2008 (UTC)

[edit] List of doomsday scenarios

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

[edit] 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)
Thanks, I've understood it much better now. Mysterial 15:39, 27 March 2007 (UTC)

[edit] Observable Universe Shrinking or percentage of the observable universe shrinking?

Call me crazy, but why does this predict that the universe will rip itself apart? It talks about how if the observable universe becomes smaller than a structure, it's forces would no longer work and cause it to disintegrate. That might be true, but it neglets a lot of facts.

Firstly, what is the observation point? It talks about individual galaxies tearing each other apart, then solar systems, stars, etc. This assumes that anything outside the observable universe does not hold true to the laws of physics. This assumes that if we can't see it, it must be dictated by different laws, or no laws at all, in this case. Whether I can see it or not, doesn't affect how well it it follows standard laws. The main curiosity, is that since it says the individual structures tear themselves apart, that means that the observable universe is encapsulated around structures. It sounds like there is an observable universe around may atoms, my planet, my star, and my galaxy. If you look from my perspective, as the observable universe gets smaller than my galaxy, my galaxy would shatter. If you look from the point of view of Andromeda (when its observable universe shrinks smaller than itself), the milky way would have shattered a long time ago, because the edge of observable universe is just now touching itself. Call my crazy, but the milky way can't shatter at time A, 100 billion years from time A, and 10 billion years from time A. It will shatter when it shatters, it cant' do it more than once.

But this all sidesteps the main problem.... how is the observable universe shrinking because of this phantom energy? The PERCENTAGE of the observable universe from Earth may be shrinking, but nothing I've seen holds up a theory that the actual edge of observation is shrinking.

--Yogurtron 18:19, 8 June 2007 (UTC)

You misunderstand what is meant by the "edge of the observable universe" (which I think should more appropriately be replaced with "particle horizon"). We don't just not know about things outside of the observable universe, they literally cannot have any effect of any kind on anything inside it, since no forces move faster than light, and the observable universe is based on the speed of light. Physics would (presumably) hold just fine for objects outside of the observable universe, but they wouldn't be attracted to us at all. If our observable universe were smaller than the solar system, the Earth wouldn't orbit the Sun (although, of course, both would be gone by this time). When the observable universe is smaller than an atom, the electrons no longer would orbit the nucleus, and when it is smaller than the nucleus, the nucleons no longer would be attracted to one another. It is unclear what would happen when it gets smaller than a proton, since the physics of free quarks isn't well developed.Eebster the Great (talk) 21:24, 18 March 2008 (UTC)

[edit] confusing

The article should explain in details how scale factor/fabric of space make this rip, what exactly is expanding.And how matter is measured in this fabric.

Space isn't literally a 'fabric', obviously; what is meant by that is that the nature of space itself expands. Essentially, you can think of it as distances themselves increasing, or everything in the universe becoming farther apart. There also isn't really a 'rip', just things no longer being attracted to or related to one another. —Preceding unsigned comment added by Eebster the Great (talk • contribs) 21:27, 18 March 2008 (UTC)

After reading the article, 1 thing attracted my attention. The Universe is only ment to be 13.7 billion years old, yet, its claims that the galaxies will move outside the abservable Universe which is 46.5 billions light years away, if the Universe is only 13.7 billion years old how can we see further than that.

[edit] The Five Ages of the Universe: Inside the Physics of Eternity

Is anyone familiar with this book? It lays out a scenario similar to this Big Rip, only the end of time occurs at 10^100 years, which is a mear factor of 10^87 years larger than laid out by the 50 billion year estimate. Is anyone capable of comparing the merits of each author's methods here?

-GK, 1/16/08 —Preceding unsigned comment added by 72.205.20.248 (talk) 02:05, 17 January 2008 (UTC)

[edit] Quantum Entanglement outside of the Observable Universe

After reading this article, I wondered about the single quantum effect I have heard about that appears to occur simultaneously in distant places (rather than spreading at the speed of light), which is quantum entanglement. Basically, if I have two entangled photons, and I force one to flip spins in a magnetic field, the other one will IMMEDIATELY flip spins as well. If our observable universe is shrinking, then it would be possible for previously entangled particles to no longer be in eachother's sphere of influence. When this happens, they should be "ripped" apart, but couldn't they still affect eachother at least in one sense, since they are entangled? Could this in theory allow for information to be transmitted outside of the observable universe?Eebster the Great (talk) 21:31, 18 March 2008 (UTC)

Never mind, I read part of the Wiki article on entanglement, and I see now that no information can be transmitted via entanglement unless there is a classical channel. It's still interesting, though, that separate spheres would still be linked in one sense by entangled pairs.Eebster the Great (talk) 22:24, 18 March 2008 (UTC)