Freethinker Posted May 17, 2004 Report Share Posted May 17, 2004 Originally posted by: nick33Space-time cannot account for this symmetry breaking. http://www.cc.rochester.edu/College/RTC/Borge/aniso.html Hence there has to be something wrong with the big bang created space-time. We're waiting to find out what this is that's wrong with the BB based on this link. Link to comment Share on other sites More sharing options...
Bo Posted May 26, 2004 Report Share Posted May 26, 2004 Just to same some words about the fact that the big bang probably isn't the whole story:- first of all there is a paradox; The big bang is predicted by general relativity, however under the circumstances at which the big bang should took place, general relativity isn't a valid theory, one needs a quantum theory of gravity... and that doesn't exist (yet... there is only one serious candidate: string theory)- there are strong indications that any theory of quantum gravity implies an undivadable fundamental length (known as the planck length about 10^-34m i believe). Since the big bang theory implies that the universe started as a 'point' this is inconsistent with the ideal that we can't go to smaller scales then the planck length.- if string theory is true then some of our spatial dimensions (string theory predicts 10) should behave differently then others. Big bang theory cannot explain this as yet (and i personal dont think it will ever...) So: yes there are problems with the classic big bang theory. but the 'main principle' behind it probably is right. To say anything further with real confidence we need a quantum theory of gravity. Bo Link to comment Share on other sites More sharing options...
Freethinker Posted May 26, 2004 Report Share Posted May 26, 2004 Originally posted by: BoJust to same some words about the fact that the big bang probably isn't the whole story:- first of all there is a paradox; The big bang is predicted by general relativity, however under the circumstances at which the big bang should took place, general relativity isn't a valid theory, one needs a quantum theory of gravity...Actually, based on the BB, the "laws" that our physical existence perates under were not in place. That happened some short time AFTER the BB. Thus we would not expect to ever find any SR, GR or QM theories that would explain the BB. - there are strong indications that any theory of quantum gravity implies an undivadable fundamental length (known as the planck length about 10^-34m i believe). Since the big bang theory implies that the universe started as a 'point' this is inconsistent with the ideal that we can't go to smaller scales then the planck length.Again, things such as the planck length (you missed the decimal point, it is 1.6*10^-35m) did not come into play till a short time after the actual BB. An interesting side note is that Zeno theorized about a minimum smallest distance 2500 years ago. At least I find it interesting. Link to comment Share on other sites More sharing options...
Bo Posted May 27, 2004 Report Share Posted May 27, 2004 Actually, based on the BB, the "laws" that our physical existence perates under were not in place. That happened some short time AFTER the BB. Thus we would not expect to ever find any SR, GR or QM theories that would explain the BB. i don't completely agree with you here. As we go near the time of the big bang; which basicly means: go up in temperature and pressure, at a certain point (age of the universe~ <10^-10 sec, T > 10^15 K) It becomes impossible to describe the particles by our normal language of QFT or GR (mathamaticly speaking: The schwarzschild radius and the wavelength of the particles becomes roughly the same scale). your point that ordinary BB theory predicts laws of nature to come just 'out of thin air' is still somewhat paradoxal with the above. because we dont know which laws of nature (at times < 10^-10 sec) should come out of thin air, then how can we say at all that that should happen? I always felt that as one of the dissapointments of BB theory (which, for t > 10^-10 sec does a great job) Again, things such as the planck length (you missed the decimal point, it is 1.6*10^-35m) did not come into play till a short time after the actual BB. first of all: thanks for the correction But also here i think i can restate my previous point (just replace 'laws' by 'structure of space time' or so): As long as we dont know how to describe the early universe for all times, it is impossible to say anything sensible... Finally about Zeno: yups; zeno's idea's are very neat (read "godel escher bach" by douglas hofstadter: 1) it's one of the greatest books ever written; 2) It alsoo has some fine thnings about Zeno's paradoxes Bo Link to comment Share on other sites More sharing options...
Freethinker Posted May 27, 2004 Report Share Posted May 27, 2004 Actually, based on the BB, the "laws" that our physical existence perates under were not in place. That happened some short time AFTER the BB. Thus we would not expect to ever find any SR, GR or QM theories that would explain the BB.As we go near the time of the big bang;...It becomes impossible to describe the particles by our normal language of QFT or GRI thought that was what I basically said. your point that ordinary BB theory predicts laws of nature to come just 'out of thin air'I would not use that arbitrary of a description. I don't see where the BB "predicts" any specific outcome of laws. In fact in a multi-universe the "laws" that eventually take effect could be any number, in fact an infinite numbr, of possibilities. That we exist in this one only shows that this one was one of the probable results. 100% probable in fact. I always felt that as one of the dissapointments of BB theory (which, for t > 10^-10 sec does a great job)I think that is based on your desire to assume that this is THE resultant universe of a BB event. As I said, I do not see where the BB REQUIRES this outcome and thus why be disappointed that it does not predetermine it? As long as we dont know how to describe the early universe for all times, it is impossible to say anything sensible..."Definitive", perhaps not, but I do think we can make some "sense" (sensible) out of it. Finally about Zeno: yups; zeno's idea's are very neat (read "godel escher bach" by douglas hofstadter: 1) it's one of the greatest books ever written; 2) It alsoo has some fine thnings about Zeno's paradoxes Zeno's arrow paradox just blows me away. How he could foresee QM and uncertainty 2500 years ago! And thanks, that's just what I need right now, another book to add to my ever growing list! I've heard about it before. Guess I will have to make it a more definite list item. Link to comment Share on other sites More sharing options...
Bo Posted May 27, 2004 Report Share Posted May 27, 2004 ah when i was typing my previous reply i had some feeling that we probably both mean the same, but just say it a little differently Godel eshcer bach is in my oppinion one of the most brilliant books written on mathematical grammar, logic, artificial inteliggence, things like that. The book is quite old (1979) So some of the information is outdated, but still.... Bo Link to comment Share on other sites More sharing options...
Freethinker Posted May 27, 2004 Report Share Posted May 27, 2004 If 1979 is "quite old", I'm in serious trouble! lol But I recently finished Plato's Republic. That is a few years older. I will need to read this book though. Yes, I tend to explain things less "critically" (technically detailed) here as many visitors do not have a strong scientific background. In fact it is good to have someone directly involved in the fields so often discussed. Glad you joined us. Link to comment Share on other sites More sharing options...
Tormod Posted May 28, 2004 Report Share Posted May 28, 2004 Originally posted by: Boah when i was typing my previous reply i had some feeling that we probably both mean the same, but just say it a little differently Godel eshcer bach is in my oppinion one of the most brilliant books written on mathematical grammar, logic, artificial inteliggence, things like that. The book is quite old (1979) So some of the information is outdated, but still.... Bo Bo, feel free to write something about the book for our Books section. It is a book that several of our users would be interested in. Tormod Link to comment Share on other sites More sharing options...
Recommended Posts