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http://en.wikipedia.org/wiki/Big_Bang_Theory
Tensor and Van and I began began another discussion in the dark energy thread about the expansion of spacetime. Cougar mentioned it as well. I'm specifically curious about the presumed size of the physical (mass) universe and how that relates to General Relativity and the absolute speed of objects with mass. As I understand BB theory, there is a presumption of gravitational force (associated with mass in GR) at the moment preceding the singularity. This would seem to suggest the presence of mass, and therefore the presence of the tensor fields of GR. In GR however, nothing with mass can travel faster than light, and in no way could the tensor fields ever "expand" faster than light because objects with mass cannot travel faster than light. I'm therefore very puzzled how the universe can be larger than 27.4 billion light years across if the universe in only 13.7 billion years old. What am I missing that allows any object that contain mass to travel faster than light? Last edited by ManInTheMirror; 05-January-2007 at 11:03 PM.. |
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Space between objects expands. This gives the illusion of movement.
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New Orion's Arm Site . The Starlark . Against a Diamond Sky (OA Novella Collection) . OA Flickr set |
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![]() Here's an article by the BA's friend, Robert Roy Britt, that addresses that very question. |
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As far as I know, there was never a "time" when "spacetime" (space with particles of mass) did not exist. I say this because the BB theory itself talks about gravitational fields being present throughout the process. "Space" in the sense of a "pure vacuum" may never have existed for all I know. We however are describing the "expansion" of particles with mass, not what can and cannot happen in a "pure vacuum". I really don't understand what you mean when you say "space" is "expanding". What exactly is expanding if not the mass particles within the tensor field of spacetime? Last edited by ManInTheMirror; 06-January-2007 at 01:03 AM.. |
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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell |
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As far as I can see, it's a simple question about mainstream physics, well-suited for BAUT's Q&A section (this OP contains no ATM claims, proposals, etc ... as far as I can see). |
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Or, perhaps, you are presenting an ATM idea, dressed up in words that have a slightly-less-than-random relationship with modern physics? Or maybe you are simply (very) confused about what the concordance model in cosmology (a.k.a. "BB") actually is? Is so, why not start a thread in the Q&A section? Perhaps something like "according to the Big Bang Theory, the universe started with a single point that encapsulates ALL necessary energy to create all matter found in these milions of bilions of galaxies - is this an accurate summary of modern cosmology?" or "according to the Big Bang Theory, is space-time expansion creating matter? or is matter self-creating?" |
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It is profoundly impossible for the ad hoc "invisible cheeseburger force" to not exist, if we assume the validity of the expansion of space for the simple reason that "invisible cheeseburger forces" are, by definition, the cause of that effect. I've not had time to really give Tim's first reference a thorough read through, but already I see things headed in that direction. I'll comment more when I've been through the paper, and I have a better idea of how the expansion of "space" (whatever that is) presumably affects real life "spacetime" according to these papers. Are the spaces inside of atoms "expanding" too, or is this a special "peek-a-boo" force that is shy around science labs like DE? |
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They are trying to salvage the "limiting speed" hypothesis of SR theory.
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No, I am trying to precisely define what it is that is "expanding" in any physical sense. The term "space" is pretty vague. Does that mean the space inside the atoms are all expanding too?
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I am not a cosmologist, so I can only give you the dumbed down version;
yes, the space inside our local group of galaxies is expanding, and the space inside the Earth, and inside atoms; but the expansion is very weak, so cannot overcome the forces which hold those objects together. Gravity, nuclear forces, and so on make sure that these objects do not expand in the same way that the Universe as a whole does. I beleive that the expansion does actualy inflate atoms, the Earth, and the Local group slightly, so that they are larger than they would be if expansion didn't exist;but I don't think that has been measured (as far as I know). It is an incredibly small expansion on the scale of anything we can directly measure.
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New Orion's Arm Site . The Starlark . Against a Diamond Sky (OA Novella Collection) . OA Flickr set |
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MITM, can you define what you mean by a "Tensor Field"?
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Some try to tell me, thoughts they cannot defend,... - Moody Blues. Neptune- The original Dark Matter. The author feels that this technique of deliberately lying will actually make it easier for you to learn the ideas. - Donald Knuth |
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No, because that would make physical things get bigger. Some people just need the "expanding space" thing to account for all galaxy speeds of c and above, relative to the earth. This term became popular in the '90s when the high speed galaxies (high redshifts) began to be discovered in large numbers, after we had been told for nearly a hundred years that nothing could exceed c relative to the earth.
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Some try to tell me, thoughts they cannot defend,... - Moody Blues. Neptune- The original Dark Matter. The author feels that this technique of deliberately lying will actually make it easier for you to learn the ideas. - Donald Knuth |
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That would be appropriate since it is itself an ATM concept.
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I say there is an invisible elf in my backyard. How do you prove that I am wrong? Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability. The Leif Ericson Cruiser |
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Whether or not the space between subatomic particles expands, or the earth, or solar system or galaxy expand, is entirely dependent on the cosmological model. In the old standard big bang cosmology, the universe banged & then coasted. In that model, the expansion was not associated with any force, so nothing that was bound could expand, not a galaxy cluster, not a galaxy, not a planet & etc. However, the advent of accelerating expansion models has accelerated the confusion over expansion. Cosmological models that include phantom energy as the cause of accelerated expansion can lead to big rip cosmologies in which everything, including the subatomic particles themselves, are ripped apart. Other models continue to maintain bound structures. The current state of observational cosmology is quite unable to constrain the models, so you can delve through the literature and find just about anything. This may not be the answer you are looking for, but it's a good first crack at it.
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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell |
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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell |
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Right, I agree with that.
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Sure:
http://en.wikipedia.org/wiki/Tensor_fields Quote:
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