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Author | Topic: Where did the Big Bang come from. | |||||||||||||||||||||||||||
Scripp_man Inactive Member |
This may sound irrelevant to the topic, but there are two main theories for the end of the universe: The universe will expand forever and the universe will end in a Big Crunch (Sort of the opposite of the big bang; All the matter in the universe comes together.). Well, in reference to the latter, couldn't this have also been where the Big Bang came from? All the intelligent creationists (Oxymoron? Just kidding of course,) at this point will probably ask, "Well then, where did the Universe come from before the Big Bang that caused the Big Crunch?" To which I'd have to respond, "It has always existed." Something must have existed forever for any theory to really be compliant with facts of any sort. In creationism, there is a superior being. But, in evolutionism, maybe not as a whole but at least in part believes that matter has existed forever. This, if you think about it, seems much more probable than something we have no DIRECT evidence of, such as a superior being or flying fish that have existed forever outside the material realm.
Let me know what you think.
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forgiven Inactive Member |
quote: we're kinda getting there in the 'one step at a time' thread
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TrueCreation Inactive Member |
"This may sound irrelevant to the topic, but there are two main theories for the end of the universe: The universe will expand forever and the universe will end in a Big Crunch (Sort of the opposite of the big bang; All the matter in the universe comes together.). Well, in reference to the latter, couldn't this have also been where the Big Bang came from? All the intelligent creationists (Oxymoron? Just kidding of course,) at this point will probably ask, "Well then, where did the Universe come from before the Big Bang that caused the Big Crunch?" To which I'd have to respond, "It has always existed." Something must have existed forever for any theory to really be compliant with facts of any sort. In creationism, there is a superior being. But, in evolutionism, maybe not as a whole but at least in part believes that matter has existed forever. This, if you think about it, seems much more probable than something we have no DIRECT evidence of, such as a superior being or flying fish that have existed forever outside the material realm."
--I don't think that the universe could have existed forever in your scenario. You've given two possibilities, a big crunch and an expansion forever. What kind of mathematics have you followed which allow you to assume that an infinitesimal amount of BB events have taken place and that they all had the 'big crunch' effect (sounds like Hovind's jargon?) and never expansion forever. --BTW - welcome to the forum! ![]() ------------------ ![]() [This message has been edited by TrueCreation, 11-25-2002]
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joz Inactive Member |
quote: TC infinitesimal usually means not many...... Maybe you should have said infinite....
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Scripp_man Inactive Member |
Well, seeing as i'm only a freshman in high school, and that no calculations to date have concluded that the universe has enough or doesn't have enough energy to escape the effects of gravity and become a big cruch. But it is almost certain that if there is enough matter, there has to be some dark matter in the universe that we cannot see but that affects gravity. I have absolutely no proof or even much evidence of my little theory. Except the fact that matter and energy exist and we can interact with them. Whereas with a superior being, we cannot.
[This message has been edited by Scripp_man, 11-25-2002]
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TrueCreation Inactive Member |
"TC infinitesimal usually means not many......
Maybe you should have said infinite.... "--Oops ![]() ------------------ ![]()
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TrueCreation Inactive Member |
"Well, seeing as i'm only a freshman in high school, and that no calculations to date have concluded that the universe has enough or doesn't have enough energy to escape the effects of gravity and become a big cruch. But it is almost certain that if there is enough matter, there has to be some dark matter in the universe that we cannot see but that affects gravity."
--I'm sure there are plenty of theories addressing whether the universe will end with a 'big crunch' or everlasting expansion. And dark matter is a hypothesis derived for explanation of an unsolved problem, not a hypothesis derived directly from observation. I'm a Junior in high school, though I try to manage in these up-paced and rather intelligent discussions as best I can. "I have absolutely no proof or even much evidence of my little theory. Except the fact that matter and energy exist and we can interact with them. Whereas with a superior being, we cannot."--And how did you deduce that one? After-all, a supernatural being is obviously above the natural, implying intestability to any such intervention. ------------------ ![]() [This message has been edited by TrueCreation, 11-26-2002]
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Beercules Inactive Member |
There are a lot of theories on exactly what caused the big bang, but without a quantum theory of gravity, it will be hard to know much for sure. I'll outline some of the possible explainations below.
An oscillating universe has already been mentioned, so I'll address that first. The idea of a big crunch seems outdated, as scientists cannot find anything near the amount of mass that would make the universe closed. Worse yet, it was discovered in 98 that the universe is expanding at a faster and faster rate as time goes by, suggesting a repulsive energy source will cause the universe to expand forever - closed or not. No one knows exactly what this source of energy is, but one candidate is quintessence. It is the dark energy I'm sure you've heard about by now. Quintessence is a field that pervades all of space, and this energy is said to be causing the acceleration. What's unique about this field, is that eventually the positive energy of this field will drop down to zero - and then into negative numbers. This would cause the universe to pull into a big crunch, regardless of the value of omega. But what happened before the big bang, if there is no big crunch? One theory comes from inflation, which has been the mainstream big bang cosmology for the past 20 years. Inflation holds that a small region of the universe (far smaller than a proton in fact) inflated to the size of a grapefruit in a mere fraction of a second. This was caused by a scalar field, which at the end of the inflation decayed and converted it's energy into a sea of fundemental particles. This inflation is believed to be the cause of the cosmic background radiation, and everything in our visible universe is said to have been created then. Inflation works with a pre-existing spacetime, and does not say anything about the beginning of the universe itself. Modern inflation theories say that the mechanism for inflation is still present, and will occur in various regions of the universe from time to time. So all the evidence for the big bang can be explained by inflation, making the claim that the universe had a beginning - an assumption without justification. M theory also has been applied to cosmology, and one that describes the big bang is called the ekpyrotic universe. Our cosmos is a 3D brane in embedded in an 11D bulk spacetime. Another brane with an opposite charge is said to exist beside ours in the large 5th dimension. These branes will collide every trillion years or so, converting the energy of the collision into quarks, leptons, and all the stuff need to create galaxies. The branes bounce back after colliding, and so this is a cyclic model. A simulation of this model can be found here: http://feynman.princeton.edu/~steinh/brane.html There are others, of course. But I think the 3 above are at the top of the list.
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Beercules Inactive Member |
quote: Keep in mind that a finite universe must eventually collapse, assuming there is no cosmological constant. If there was a big crunch in the past, then it means either A. the cosmological constant is zero, or B. the cosmological constant is a dynamic field, and can have a negative value. I'm not aware of any scenario where the universe could bounce from a big crunch, and then expand forever.
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bambooguy Inactive Member |
I'm suprised to find someone advocating a cyclical bang/crunch cycle to the universe. I always assumed this was part of the psuedo-science of Carl Sagan. Here's my one question. If singularities are outside the sphere of modern physics, how do inflationary or M-brane theories help? Because singularities such as the pre-bang universe are dimensionless, how do superstring or dimension-based theories explain the force which caused a singlarity to explode? I'm sorry, I don't have a very good understanding of inflationary or M-brane theories. Thanks for any help.
Evan
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Percy Member Posts: 23144 From: New Hampshire Joined: Member Rating: 5.8 |
BambooGuy writes: I'm suprised to find someone advocating a cyclical bang/crunch cycle to the universe. Since you didn't use the little reply icon at the bottom of each message there's no indication of which message you're replying to. If you're replying to the initial post, then I guess I'd say that a cyclical universe was at one time part of the pantheon of possibilities that cosmologists considered. This possiblity is now moot since we now know the expansion of the universe is accelerating. If you're instead replying to Beercules in Message 8, then I'm not sure the cyclicity he refers to is a bang/crunch model, especially in light of the fact that Beercules not only knows about the accelerating universe, he was the one who first mentioned it in this thread.
I always assumed this was part of the psuedo-science of Carl Sagan. The "pseudo-science" part seems a bit strong. Though Carl Sagan had his detractors, the practice of pseudo-science isn't an accusation I've ever heard thrown his way. Even his fiction books have a firm scientific foundation. Why are you associating Sagan with pseudo-science?
If singularities are outside the sphere of modern physics,... By "outside the sphere" I hope you only mean that this is a poorly understood area at this time.
...how do inflationary or M-brane theories help? Because singularities such as the pre-bang universe are dimensionless, how do superstring or dimension-based theories explain the force which caused a singlarity to explode? Yes, this was a point I also didn't follow in Beercules message. Do the particles created by colliding branes begin life in a singularity? --Percy
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Beercules Inactive Member |
Apparently not. Both inflation and brane collision models do not involve singularities. Inflation occurs in pre-existing space-time, which may or may not have had a beginning. The brane collision does away with the classic singularity as well, as both 3 dimensional branes are infinite, and during the collision the only thing that becomes singular is the extra 5th spatial dimension.
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ME2 Inactive Member |
another way to view this how can the big bang come from anywhere since nothing exsited before (t=0) no time or anything to "cause" the big bang.this initial cosmological singularity is self-contradictory and the question of what caused the universe's origin.
some see this "event" not having a prior cause because there simply did not exist any instants before(t=0) nor any prior causes.. thats my .02
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singularity Inactive Member |
I have always wondered what happens to considerations of probability of something coming out of nothing. Surely when you have an infinite "space" of nothingness existing for an infinite "time" then even if the chance of something spontaneously "happening" is infinitely small it is still certain to happen eventually.
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zipzip Inactive Member |
http://www.nasa.gov/HP_news_03064.html
The latest from the WMAP satellite strongly suggests that the universe will continue to expand forever.
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