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Pyrogenic
New Member
2 Posts |
 Posted - 07/12/2001 : 11:33:52
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Poll Question:
If the universe is expanding faster, rather than slower than before, as new research suggests, how will dark matter play a roll in the future?
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Poll Status:
Locked »» |
Total Votes: 0 counted »» |
Last Vote:
never |
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Randy
SFN Regular
USA
1990 Posts |
Posted - 07/12/2001 : 12:43:21 [Permalink]
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I'm afraid our future transgalactic commuting costs will be going up, and up, and up - due to the expansion....unless they get all those pesky worm-hole gophers cleared out! 
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comradebillyboy
Skeptic Friend
USA
188 Posts |
Posted - 07/12/2001 : 20:02:37 [Permalink]
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I recently read that the rate of expansion is increasing. The article posited some sort of "dark force" at work. Any good theories on dark matter? I've seen a fair amout of informed speculation, but I dont know what the most widly held view is.
comrade billyboy |
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@tomic
Administrator
USA
4607 Posts |
Posted - 07/12/2001 : 21:56:43 [Permalink]
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Vote for option 4! I don't want the universe to collapse!!!!
@tomic
Gravity, not just a good idea...it's the law! |
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Randy
SFN Regular
USA
1990 Posts |
Posted - 07/12/2001 : 22:30:05 [Permalink]
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quote:
I recently read that the rate of expansion is increasing. The article posited some sort of "dark force" at work. Any good theories on dark matter? I've seen a fair amout of informed speculation, but I dont know what the most widly held view is.
comrade billyboy
That reminds me,....gotta do the laundry in the back closet and the damn dishes.
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bestonnet_00
Skeptic Friend
Australia
358 Posts |
Posted - 07/13/2001 : 03:29:29 [Permalink]
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Isn't dark matter already playing a role?
Radioactive GM Crops.
Slightly above background.
Safe to eat.
But no activist would dare rip it out.
As they think it gives them cancer. |
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Boron10
Religion Moderator
USA
1266 Posts |
Posted - 07/13/2001 : 04:11:41 [Permalink]
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quote:
I recently read that the rate of expansion is increasing. The article posited some sort of "dark force" at work. Any good theories on dark matter? I've seen a fair amout of informed speculation, but I dont know what the most widly held view is.
I believe Astrophysicists are still trying to come up with a valid theory to explain this one. As far as I know, the "dark force" is the best so far, but nobody can fully explain what it is or what causes it.
-Timmy! |
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ljbrs
SFN Regular
USA
842 Posts |
Posted - 07/19/2001 : 19:50:50 [Permalink]
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According to the latest theories, the universe is accelerating in its expansion and is showing no sign of deceleration. Now, of course, this might change. However, there is no data showing the universe's contraction. Eventually, all which will be left is positronium (gravitationally-linked electron/positron pairs which are separated by immense distances and which are slowly orbiting each other but will eventually meet and be annihilated before the universe finally blinks out). Then darkness...
ljbrs
Perfection Is a State of Growth... |
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ljbrs
SFN Regular
USA
842 Posts |
Posted - 07/19/2001 : 20:37:56 [Permalink]
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The cosmologists/astrophysicists believe that the energy which seems to be causing the accelerated expansion of space between galactic groups is composed of what are called *virtual particles* (particles and their antiparticles which, together, come into existence and then annihilate each other immediately). Virtual particles have been observed in the particle accelerator experiments and are good candidates for the *dark energy*, which is not the same as the *dark matter* which has been measured as making up the vast majority of the matter in the observed universe. Of course, in science, no theory is set in stone. However, the observations are there. The universe is calculated as experiencing accelerated expansion. The data shows this.
ljbrs
Perfection Is a State of Growth... |
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ljbrs
SFN Regular
USA
842 Posts |
Posted - 07/24/2001 : 21:40:59 [Permalink]
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quote:
Poll Question:
If the universe is expanding faster, rather than slower than before, as new research suggests, how will dark matter play a roll in the future?
Although dark matter which acts gravitationally in the galactic clusters is very important in that there is so much of it, it is the DARK ENERGY (variously called Lambda, Quintessence, Vacuum Energy) which is thought to be responsible for the acceleration of the universe. It is thought that the dark energy might be the virtual particles/anti-particles which are coming into and out of existence incessantly (and are seen in particle accelerator experiments as causing an accelerated expansion.
NOVA was on tonight (just finished in my time zone), and it was about the accelerating universe. My absolutely favorite topic!
Some people are skeptics. Some, like me, while being skeptical, are very excited about the possible, rather than gloomy about the impossible. I actually do not get angry with those people who have everything wrong. I feel sorry for them, because they are missing out on so very much. The true believers in phony baloney are pathetic and are to be pitied more than censured. Science is an ongoing thing. And it is always coming up with fantastic things. One wants to live forever in order to know it all (which is, of course, impossible). I do not watch television often, so this was a real treat. Tonight's NOVA subject matter was not new to me, but I could see my heroes/heroines in action. Whee!
ljbrs
Perfection Is a State of Growth... |
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comradebillyboy
Skeptic Friend
USA
188 Posts |
Posted - 07/25/2001 : 00:10:59 [Permalink]
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quote:
NOVA was on tonight (just finished in my time zone), and it was about the accelerating universe. My absolutely favorite topic!
ljbrs
Perfection Is a State of Growth...
i saw it tonight too. pretty amazing stuff if they prove to be correct. what a great puzzle, we appear to have a good handle on about 5% of reality. i was a fan of the "big crunch" idea, but we are not seeing much evidence supporting that idea any more.
the ultimate fate of the universe and the meaning of existance are examined very thoughtfully in the isaac asimov short story "the last question". asimov was a big influence in my evolution to athiesm.
comrade billyboy |
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ljbrs
SFN Regular
USA
842 Posts |
Posted - 07/25/2001 : 20:05:20 [Permalink]
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The amazing thing about this is that the scientists involved (cosmologists, astrophysicists, astronomers, engineers, et al., were expecting to be measuring the rate at which the universe was slowing down. SURPRISE!
They keep testing it and keep coming up with the same answer. The universe is not only expanding, but it is ACCELERATING in its expansion. Pretty neat stuff. Everything will all end up as energy in the very, very long run.
ljbrs
Perfection Is a State of Growth... |
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Zandermann
Skeptic Friend
USA
431 Posts |
Posted - 07/25/2001 : 20:55:22 [Permalink]
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quote:
... Everything will all end up as energy in the very, very long run.
Good!
I'm getting to the age that I can always use more energy!
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ljbrs
SFN Regular
USA
842 Posts |
Posted - 07/25/2001 : 21:08:55 [Permalink]
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I am way past that age and back into my fourth childhood. It is hard at my age to keep count...
ljbrs
Perfection Is a State of Growth... |
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Megan
Skeptic Friend
USA
163 Posts |
Posted - 07/29/2001 : 15:09:20 [Permalink]
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Ok me only 14 makes me sound like a dummy when I talk about this stuff b/c I dont know as much as the rest of you here, but I still wanted to get my lick in.
Last night, I was talking to Lisa in her hot tub and we spent a very long time talking about the universe and pretty much most aspects of it. And did I get in way over my head! I really dont understand the universe and how it works. So when I read this topic, the first thing that came into my mind is, "How and why would the universe expand?" And after reading everyone's responses, I still dont get it! So could someone please explain?
And here is another thing: Lisa and I talked about other universes. Does anyone care to explain to me how there could be enough room for another universe??
And another thing: How can we take pictures of other universes but we cant take pictures of other planets in our universe??
AARRGGHHH!! I'm so confused when it comes to this stuff!!
-Megan-
I only do what the voices in my head tell me to do. |
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Dog_Ed
Skeptic Friend
USA
126 Posts |
Posted - 07/29/2001 : 16:40:47 [Permalink]
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Megan: Don't beat up on yourself. It takes time and patience to get comfortable with some of this stuff.
Human-scale spacetime is 4-dimensional but an honest physicist will admit that ain't nobody can really visualize 4 dimensional geometry--they can do the math and experiments and they comes out so precisely right that they believe it. But for visualization purposes they reduce the 4-dimensional spacetime to 3-dimensional models. In this manner, you might visualize our good old Universe as a sphere, and our 3 dimensions of space as the 2-dimensional surface of the sphere. To the creatures on the sphere, there is *no* up or down; they have only 2 physical dimensions. Their Universe is finite--limited in size--but unbounded, ie it has no edges. If there is another universe we, as 3-dimensional superbeings, might visualize it as another sphere that does not touch the first one in any way. But if we tried to explain its location to the 2-D creatures, they would not understand: "Huh? Our Universe has no edges, no boundaries, so how can anything exist 'outside' it?" If there are other universes other than ours, the one that contains Earth, the Milky Way, and everything else, then they are 'somewhere else' in the same sort of non-visualizable way as the 2-D creature's other sphere. They doesn't fit anywhere 'inside' our Universe.
As to expansion, it's thought that the entire Universe came into existence as a tiny point of infinite or nearly infinite density, which rapidly expanded. It now seems likely that a fraction of a second after its formation the tiny Universe entered a special physical state in which gravity was a strongly repulsive force. This sounds loony in English, but the math apparently makes excellent sense--it was kind of an AHA! moment in science when Alan Guth and some others realized that this completely theoretical but mathematically consistent model called 'false vacuum' actually has *exactly* the properties which would explain why the Universe looks the way it does. Anyway, if gravity repels then the Universe would inflate itself at a tremendous rate. But as it did so it would cool (anything which expands cools) and the cooling would cause the special state to suddenly collapse into the more familar mixture of matter and energy, with gravity a weakly attractive force. But the kinetic energy of that first tremendous expansion has kept the Universe expanding ever since. New evidence suggests that there is a small but steady acceleration in the expansion...perhaps a small remnant of the special repulsive version of gravity?
I can't easily visualize the expansion of the entire Universe, except by going back to the 2-Ds world. If their sphere is being blown up like a balloon, they could see the expansion because things would be moving apart. But if you asked them what their Universe was expanding into, they would come up blank--with no notion of three dimensions they could not see where the extra 'room' for the expansion comes from. Of course we're in a similar fix; we can't see where the 'room' for expansion of our 3-D Universe comes from.
I wish I'd thought of all this myself, but it's really just an inferior version of material from several excellent books. The best (imho) is by Dr. Kip Thorne, and it's called "Wormholes, Time Warps, and Einstein's Outrageous Legacy" or something similar. You ought to give it a look; it's not difficult to understand and Thorne has a wonderful way of presenting ideas simply. Have fun!
"Even Einstein put his foot in it sometimes" |
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