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Drakheim
2004-Feb-25, 04:22 PM
That is resistant to The Big Rip theory only because of personal feelings reguarding everything just ending? I know that it is probably going to happen given our understanding of dark energy and dark matter to this point, but it dosent mean I have to like it :lol:

JohnOwens
2004-Feb-25, 05:15 PM
I always wanted a closed, positively curved universe myself. :(

Spaceman Spiff
2004-Feb-25, 06:35 PM
That is resistant to The Big Rip theory only because of personal feelings reguarding everything just ending? I know that it is probably going to happen given our understanding of dark energy and dark matter to this point, but it dosent mean I have to like it :lol:

The "Big Rip (http://antwrp.gsfc.nasa.gov/apod/ap030303.html)" scenario is a hypothesis describing a possible end state :o of the universe if "dark energy" takes on a particular form. If, however, the dark energy is actually a constant (aka the "cosmological constant" like the one Einstein inserted into his equations), then the Big Rip will not likely happen (unless, for example, the vacuum decays to a lower energy state), though certainly our observable horizon will shrink with time. If so, then astronomers who study distant galaxies are now enjoying their hayday :) .

SciFi Chick
2004-Feb-25, 08:02 PM
You are not the only one. I'm still holding out for evidence of the cyclic nature of the universe, similar to that found here on Earth in the seasons. :)

Maksutov
2004-Feb-26, 06:02 AM
You are not the only one. I'm still holding out for evidence of the cyclic nature of the universe, similar to that found here on Earth in the seasons. :)

Same here.

There's something very attractive, almost reassuring, about a universe that pulsates, that perhaps recycles itself in recurring acts of rebirth.

Ut
2004-Feb-26, 06:13 AM
I agree whole heartedly about a cyclic universe being comforting. It's for that reason that I think it's untrue. Just about every time we latch on to something for the sake of comfort, it gets ripped from our hands. The universe doesn't have a baby blanket.

Maksutov
2004-Feb-26, 06:36 AM
I agree whole heartedly about a cyclic universe being comforting. It's for that reason that I think it's untrue. Just about every time we latch on to something for the sake of comfort, it gets ripped from our hands. The universe doesn't have a baby blanket.

I don't know. Some of those super string theory membrane models look an awful lot like outing flannel. :)

Argos
2004-Feb-26, 02:55 PM
That is resistant to The Big Rip theory only because of personal feelings reguarding everything just ending? I know that it is probably going to happen given our understanding of dark energy and dark matter to this point, but it dosent mean I have to like it :lol:

You´re not the only one. I think that the idea of a closed universe comforts us; it gives a meaning to the things. I myself (and I don´t know why I behave such way) nurture the idea of a closed universe, the kind that will end in a big crunch. I’m desperately hoping for the announcement that they found the missing matter. :)

However, an open universe can also be a cyclic – infinite - universe. By the time the Big Rip occurs, the current universe will be so rarefied that there will plenty of opportunities for the fluctuations of the zero-point energy start a new inflation and a new universe(*). The quantum fluctuations of the vacuum may be viewed as the physical manifestation of some principle of infinity , for in the wake of every ripped-out universe a new one will born.

(*) It’s interesting to note that such universe would be generated by the same laws as one that would arise from a singularity formed by a previous closed universe´s big crunch, for both types depend on quantum phenomena to set up their initial states. So, something tells me the geometry of the universe does not really matter, if you are considering some kind of eternal return.

Reacher
2004-Feb-26, 04:55 PM
And am I the only one who finds the term 'pulsating universe' not attractive in the least?


...start a new inflation and a new universe.

Not that it will even remotely matter by then, but what effect would the outside universe have on this new one? Will entropy over the massive period of time between then and now make it such that there will be no effect? What I mean is, could elements that aren't yet formed in the new one be forced into it as it's edge travels along, presumedly annihilating everything in it's path? And yes, I do know that it's only a theory.

Ilya
2004-Feb-26, 07:37 PM
I think that the idea of a closed universe comforts us; it gives a meaning to the things. I myself (and I don´t know why I behave such way) nurture the idea of a closed universe, the kind that will end in a big crunch. I’m desperately hoping for the announcement that they found the missing matter.

Excuse me? You find the idea of everything in existence collapsing into ball of fire and utterly destroyed COMFORTING? You have a strange notion of comfort!

An eternally expanding open universe allows intelligence to survive forever - by transferring into ever-lower-energy substrates and becoming ever slower. Closed universe offers no such solace - although neither does the Big Rip.

To me a cyclical universe offes some hope only if there is a way to pass some information from one cycle to the next. If ALL information is destroyed between cycles, and one cycle has no way to influence the next, then calling them "cycle" or "sequential" becomes meaningless. They might as well exist in parallel and all end simultaneously.

Argos
2004-Feb-26, 08:47 PM
And am I the only one who finds the term 'pulsating universe' not attractive in the least?


...start a new inflation and a new universe.

Not that it will even remotely matter by then, but what effect would the outside universe have on this new one? Will entropy over the massive period of time between then and now make it such that there will be no effect? What I mean is, could elements that aren't yet formed in the new one be forced into it as it's edge travels along, presumedly annihilating everything in it's path? And yes, I do know that it's only a theory.

We´re on slippery ground here…Frankly, I can´t give you an answer without resorting to useless – and somewhat naïve - speculation. BUT,

The big rip represents the end of all interactions between physical entities. By the time the big rip occurs, every piece of matter in the universe will be separating from the next one at the speed of light, by the expansion effect of the dark energy. After the big rip, even virtual particles will be dispersed, turning the matter and energy fields weaker and weaker, approaching nullity. In that circumstance, no information exchange will be possible anymore. The current universe will be exactly like nothing, zero. Quantum mechanics allows for creating energy (therefore matter) from fluctuations in the nothing, and that´s what I meant with my post. What will emerge from an exhausted open geometry, dark-matter-driven universe is a brand new inflating bubble, with different rules, established by different initial conditions.