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Author | Topic: Big Bang - Big Dud | |||||||||||||||||||||||||||
Sylas Member (Idle past 5250 days) Posts: 766 From: Newcastle, Australia Joined: |
Full marks, Ned.
Once again, the key is to remember that the Big Bang is not an explosion. In the early universe all of space is filled with hot dense gas. As space expands, the density and the temperature of material in the universe drops. Not because it is moving, but because it has more room (space) to move. A cloud of gas above a certain size will spontaneously collapse and compress into localized clumps under its own gravity. The amount of gas required is given by the Jeans mass, and this mass increases with temperature and decreases with density. If you have more than this amount of gas, that even a perfectly uniform gas will collapse, since the tiniest thermal motions give rise to positive feedback and magnify into collapse. The collapse takes time also, and so large scale structure formation may involve more than just gravity, with shock waves or other forces speeding up localized concentrations as well. But gravity is the major contributor. For more discussion, see First Stars at solstation.com. Note that large scale structure formation in the early universe is one of the major unsolved problems in cosmology. Dark matter is expected to have an important role, but we don't know enough about dark matter to have a clear picture of the whole process. Cheers -- Sylas
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randman  Suspended Member (Idle past 4889 days) Posts: 6367 Joined: |
So crash, he doesn't know what he is talking about but hey, it all came from nothing somehow makes sense....?
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Sylas Member (Idle past 5250 days) Posts: 766 From: Newcastle, Australia Joined: |
No... "It all came from nothing" is rather a misunderstanding used almost exclusively by folks who don't know anything about the actual proposals used in science.
This has been explained in many posts of the thread. Let's try not to go over old ground; and if there are any actual meaningful comments to be made with respect to the Big Bang, let's base them what is actually used by cosmologists; not private misconceptions like "something from nothing". Modern physics is simply not able to go back to the very earliest origins of the universe.
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crashfrog Member (Idle past 1457 days) Posts: 19762 From: Silver Spring, MD Joined: |
So crash, he doesn't know what he is talking about but hey, it all came from nothing somehow makes sense....? Who said anything about nothing? How could you even have nothing? How could nothing even exist?
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cavediver Member (Idle past 3633 days) Posts: 4129 From: UK Joined: |
Randman, I've been reading your posts over a number of fora, and I've noticed that you're very open to the far-from-obvious ideas in quantum theory, and you have expressed doubts about the everyday linear nature of time.
I would encourage you to delve into General Relativity, which will reveal time to be far more bizarre than you could ever imagine. Furthermore, you will realise why statements such as "it all came from nothing" have absolutely no meaning, and even much less contentious ideas such as "in the beginning" don't always mean what you think they mean. To me, the Universe shouts God's glory, but it certainly doesn't prove His existence (by His choice I would contend).
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Mr. Creationist Inactive Member |
Sombody posted about how the gas after the Big-Bang compressed into the stars, and said that over a long time gas will naturally compres on it's own. I would like to know the scientific backing for that last statment, has it every been observed?
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Sylas Member (Idle past 5250 days) Posts: 766 From: Newcastle, Australia Joined: |
Sombody posted about how the gas after the Big-Bang compressed into the stars, and said that over a long time gas will naturally compres on it's own. I would like to know the scientific backing for that last statment, has it every been observed? Yes, we do observe this occuring right now, in some of the large gas clouds in space. That sufficiently large regions of gas must compress under gravity is a simple consequence of the virial theorem. There are some good photographs of gas clouds in the process of gravitational collapse and star formation, from the Hubble space telescope. For example, The Cygnus Wall of Star Formation, Starbirth in the Lagoon Nebula, New Stars In 30 Doradus, and M16: Infrared Star Hunt.
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gnojek Inactive Member |
Nuclear reactions do not destroy matter.
They either break nuclei apart or fuse them together. The huge release of energy is the binding energy of the nulceus, not matter becoming energy. If you want that you have to look to matter/antimatter annihillation where a particle and an antiparticle produce two photons of energy.
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Chiroptera Inactive Member |
However, it is an example of mass being converted to energy.
If energy has been released in a nuclear reaction, then the initial nuclei have a greater mass than the final set of nuclei -- the energy comes from the difference in mass. I guess mass is not quite the same as "matter", heh.
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Chiroptera Inactive Member |
This has just been posted on another message board.
New Scientist has an article about the "Crisis in Cosmology" conference just held in Portugal by the Alternative Cosmology Group, and the creationists are predictably excited about it. Does anyone know anything about this group? Are the challenges to "Big Bang" really that serious? Even if it is, should creationists really take comfort in this? Edited to fix link. This message has been edited by Chiroptera, 29-Jul-2005 12:52 AM
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cavediver Member (Idle past 3633 days) Posts: 4129 From: UK Joined: |
It's the usual supsects with Arp at the top... yawn. Check out Sylas' list of crank ideas somewhere in Big Bang and Cosmology.
I've just glanced through the abstracts of the first few contributors...to quote:
quote: and
quote: Hmmm... well I guess that means there are no non-trivial vacuum solutions. Funny, could have sworn I'd seen a few... I've got a feeling that some poor guys went there with some interesting cosmological models, only to find the place full of nutters
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Chiroptera Inactive Member |
quote: Arp is still at it? Still with the "quantized" red shifts? Or has he got something new? How I miss Hoyle. Even as his theories got shot down, at least he could move on and think of something new.
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Mr. Creationist Inactive Member |
I agree with you, it could not just come from nothing, and that is something that creationists use but should not! I do not know why other creationists say that, when it is not true, unless they do not know it is false.
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crashfrog Member (Idle past 1457 days) Posts: 19762 From: Silver Spring, MD Joined: |
The huge release of energy is the binding energy of the nulceus, not matter becoming energy. According to the little I know about nuclear reactions, the end products of both fission and fusion are less massive than the sum of the original reactants, so I think you're mistaken. Or I could be.
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cavediver Member (Idle past 3633 days) Posts: 4129 From: UK Joined: |
It all depends what you mean by mass and matter. Mass is essentially a measure of the total energy within a volume of space. If you apply e=mc^2 you have the gravitational charge (or mass) of the energy within that volume. If any energy leaves that volume, then the mass will obviously decrease. A "1kg" test mass has more mass at 100C than at 0C.
In fusion and fission, binding energy is being released from the nucleus, and so necessarily there is an asscoiated decrease in mass as that energy escapes the local volume in the form of radiation (EM, neutrinos, heavier particles). Thus the end-products (within the volume) MUST be less massive. But this is equally true for exothermic chemical reactions... The inter-nucleon binding energy is nothing compared to the intra-nucleon binding energy. Take a proton. It is made of 2 up quarks and a down quark. The rest mass of the ups is ~4MeV and the down is ~8Mev. That gives 16MeV. But the proton rest mass is 938MeV!!! That's a lot of binding energy. Unfortunately, owing to the annoying nature of Qunatum Chromodynamics, that energy is not up for grabs any time soon. This message has been edited by cavediver, 08-15-2005 04:28 AM
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