|Oct8-03, 03:00 AM||#18|
|Oct8-03, 05:20 AM||#19|
SelfAdjoint, Man, that's cool insight you passed on.
Thank you too Nereid, I'll digest what I've learned since last night.
|Oct8-03, 04:33 PM||#20|
[a)]Hey, I'm back. It's sunney and warm here tody.
No wonder this is stuff is theory, crap, who could possibly assemilate"so" much information.
I gotta hand it to some of you, Today I've been reading a lot. I've copied and pasted several highlighted words from your input and my brain hurts[b(].
I have read on Dirac Theory, Tensors, Einstein's Summation and a page on Arther Cayley (1821-1895) as well as many other definitions.
I may be a day or two on returning as I'm going to learn more in order to put forth some questions or thoughts that might be slightly above high school level.
"Assuming that the universe began at the same moment expansion began---call it time zero---is probably an unnecessary complication to the picture since it is no longer required by theory."
This was an important statement by one of you(i thought anyway)because it allowes for "minus infinity."
If early on the universe "was" "Just A Vacume" it seems there would still be some kind of balancing act going on between "Virtual" particles of some nature as they would be created and annililated constantly by an equle number of particles, being particle and anti-particles, causing disruptions in the cosmic sheet.
Is it too much to postulate that this went on forever, or an unmeasuable, or "Infinit" amount of time untill the uncertainty principle happens along and "SOME" particle somewhere doesn't get annililated in time.
What might theory say would happen? Would "this" spirel out of control and start some imbalence that "MIGHT" throw us into a big bang? If the bang point is ZERO then we have minus infinity and plus infinity finally in the same equation, "IF", we keep expanding untill everything is cold and dead.
O.K., I'm getting in too deep, I'll stop for now.
L8R, and thanks much for your input SelfAdjoint and Nereid.
I'm quite intruigued at this level.
Any sites that help would be good.
|Oct12-03, 04:33 AM||#21|
As you said logically the universe must have started from a point of nothing however the problrm with this is the word "started"
The essense of nothing to something is init self a false premise in that nothing co-exists only with something....more logic ....
PLease feel free to read an extract that I have at my web site on this subject. on "creational nothingness" the nature of time and nothing.
I look forward to your comments
|Oct12-03, 08:42 PM||#22|
interesting but I don't like the notion of nothing.
Even those intangeable nothings contain energy (like empty space).
so you agree that light is not a constant.
How do you suppose that it could have been faster in the past than it is today (I read an article on this several months back on quickfound.net/scitech, lots of good physics news on there)?
How do you suppose, that time exists then? What created time?
What is the purpose of time in the abscence of energy, does it still exist?
If time is dependent on energy, what are the properties of energy that time is dependent on (perhaps time is event driven)?
I wrote a little bit on my thoughts of time in a post, I did it quick and tried to draw from as many examples as I could think of,
clearly if we took the approach that time is event driven it would make a good deal more sense (wouldn't it?) and would also put some nice caps on the cosmic speed limit (because increased levels of interaction would slow time down for a particular object, resulting in even the most powerful engine decreasing in efficiency because it would stretch out that acceleration (the energy producing it) over a larger period of time, causing your vessel to require an infinite amount of energy to reach the speed of light).
This is the effect I call temporal entrophy.
There indeed are things that travel faster than light, they are the constituents of gauge fields, and these fields impose the speed limit on light.
It would be interesting to see how precise one would need to measure the speed of light to show that even an object travelling at the speed of light undergoes time, it simply does not stop (and then run backwards if you exceed the speed of light).
In such a universe it would be impossible to go back in time, and in this universe I propose that it is impossible to go back.
It is possible to go really far in time by slowing your time down by increasing your velocity, or it is possible to experience your life in the blink of an eye, by reducing your velocity (but there would be a cap as to how fast time could go relative to the earth given these gauge fields are in constant motion that regulate time).
There is nothing that really explains how entanglement seems to defy the laws of time, how one could send a message faster than the speed of light with it (unless if time were only a by-product of interaction and entanglement were a state native to everything in the universe but on such a vast scale that things appear to have a duality about them).
|Oct12-03, 09:42 PM||#23|
Modern physics does not support c-decay, nor any mechanism that might support it. There is no experimental evidence that shows it happens, and a great deal of theoretical work that shows it cannot.
There are no relativistic effects until you compare the observations of two distinct observers.
When there's only one observer, that observer will never notice anything different inside his spaceship. Only by looking outside will he see anything he would call "relativistic."
|Oct13-03, 09:44 AM||#24|
I assumed bettysfetish was female and he says to chroot:
"You may be suprised
To know that I am A longhair bass guiter player with a wife 4 kids(still at home) and I'm 48 years old and can play STAIND, NICKLEBACK, GODSMACK, or THEORY OF A DEADMAN better than anyone you've met in a while."
so now that little misunderstanding is cleared up.
Earlier in the thread (October 7) Nereid asked:
BTW, to what extent would a successful LQG...be able to address at least some part of the first 10-34s?
Nereid, part of your question you asked gets over into how LQC deals with the universe right around timezero. It predicts inflation (you dont have to put inflation in "by hand") and it removes the singularity.
There'v been a bunch of papers by a bunch of different people that you can get from arxiv by search with keywords like
loop quantum cosmology
inflation loop quantum gravity
To save the trouble of searching and choosing which articles to read, here are a couple of September ones:
Quantum Gravity and the Big Bang
Quantum Gravity and Inflation
the meaning of time becomes an interesting question around timezero and whether one can ask about time-evolution in steps smaller than Planck time (0.539E-43 second)
Loop cosmology is a radical simplification of the full theory of quantum gravity (Friedmann eqns of cosmology are much simpler than the Einstein eqns of the full GR theory). So its much easier to develop LQC and it has happened very quickly----now LQC can help guide solutions of the more difficult problems of the full LQG theory. This was reflected in the "conclusions" part of one of the papers
"With new developments in quantum geometry, quantum gravity has become a theory whcih can make concrete predictions about the very early stages of the universe. Results include possible solutions of old conceptual problems, as the singularity problem and the problem of initial conditions and also new phenomenologicial proposals which can be confronted with cosmological observations. The models currently available are most likely too simple, but more complicated ones with less symmetries [ref] and more realistic matter content are being developed. An advantage of the formalism is that the relation between models and the full theory of loop quantum gravity is known, so that lessons learned for models can be taken over to the full theory. In this way we will be able to guide developments in quantum gravity by cosmological observations."
There will be a talk on loop quantum cosmology by Bojowald at this month's "Strings meets Loops" symposium at the AEI, so this should give an even more timely summary of the state of research in that area.
There was a stringy part to your question too but I cant respond to that part because I dont know of any concrete predictions that string theory makes---seem to be an infinite supply of versions of the theory all saying different things and no way to choose
|Oct13-03, 10:33 AM||#25|
Bettysfetish raised the issue of what happened at timezero and
Nereid asked what Loop Gravity has to say about it. The most informative short discussion of this is in Martin Bojowald's 6-page paper "Quantum Gravity and the Big Bang" and he's the person that has found out the most new stuff about this in the past 2 years. So here's a quote. The abstract and a few sentences from the beginning of the paper:
Abstract. Quantum gravity has matured over the last decade to a theory which can tell in a precise and explicit way how cosmological singularities of general relativity are removed. A branch of the universe “before” the classical big bang is obtained which is connected to ours by quantum evolution through a region around the singularity where the classical space-time dissolves. We discuss the basic mechanism as well as applications ranging to new phenomenological scenarios of the early universe expansion, such as an inflationary period.
When the big bang is approached, the volume becomes smaller and smaller and one enters a regime of large energy densities. Classically, those conditions will become so severe that a singularity is reached; the theory simply breaks down. For a long time, the expectation has been that somewhere along the way quantum gravity takes over and introduces new effects, e.g. a discrete structure, which prevent the singularity to develop. This presumably happens at scales the size of the Planck length lP , i.e. when the universe has about a volume lP3.
Since at the classical singularity space itself becomes singular and gravitational interactions are huge, such a quantum theory of gravity must be background independent and non-perturbative. A theory satisfying these conditions is in fact available in the form of loop quantum gravity/quantum geometry (see [1, 2] for reviews). One of its early successes was the derivation of discrete spectra of geometric operators like area and volume [3, 4, 5]. Thus, the spatial geometry is discrete in a precise sense. Furthermore, matter Hamiltonians exist as well-defined operators in the theory which implies that ultraviolet divergences are cured in the fundamental formulation [6, 7].
Both properties must be expected to have important consequences for cosmology. The discreteness leads to a new basic formulation valid at small volume, and since gravity couples to the matter Hamiltonian, its source term is modified at small scales when the good ultraviolet behavior is taken into account. It is possible to introduce both effects into a cosmological model in a systematic way, which allows us to test the cosmological consequences of quantum gravity (reviewed in [8, 9])."
classical GR breaks down at time zero because of infinite density and curvature
quantizing GR removes the singularity---when quantized the Friedmann equations go smoothly back in time, showing a bounce at time zero
Bojowald was the first to get this result. the first time it came out was
"Absence of a Singularity in Loop Quantum Cosmology"
stringy approaches are perturbative and background-fixed but to directly deal with extreme density and curvature it helps, as Bojowald observes, to use a theory that is free of perturbation methods and background-independent. In fact to deal with timezero he says the theory "must be background-independent and non-perturbative"---which makes sense to me, dont know about you[;)]. So probably the answer to the stringy part of your question, Nereid, is limited by this consideration, but who can speak for what that theory (those theories) actually predict(s)?
|Oct13-03, 10:58 AM||#26|
Other people have followed up on Bojowalds removal of
the Big Bang singularity and development of loop cosmology. Here are some other names that will turn up papers in arxiv
about loop gravity applied to very early universe, inflation etc.
Stephon Alexander (SLAC)
Golam Hossain (Chennai, India)
As might be expected, Rovelli's "Sal" referred to this development in the recently-posted "Dialog on Quantum Gravity"
|Oct13-03, 06:01 PM||#27|
[a)]Hey, I got a question, if it's not to elementary.
How much would a "String" weigh?, you know, a "string theory" string.
Massivly heavy in bulk, I would assume.[;)]
If the string theory or point singularity proves out then wouldn't the build up of energy be "more" than the energy in the universe at our point in time?
Meaning that since the vacume must be a system like any other, it has an energy that could be calculated, I guess.
And then at the moment of the creation of mass would also have a calculable energy.
if the later has less energy than first then the vacume was thoughly "unstable." That, it seems, would, in an analogistc discription, would "Suck Us Into" the chain of events refered to as false vacume.
I'm I invisioning this close to an acceped theory?
I'm I blantently wrong anywhere?
|Oct14-03, 04:34 PM||#28|
[s(]O.K., I worded that last question really dumb. It's obvious now that I read it.
I'm gonna try to re-word that in a more sensical mannor and submit something more coherant.
If any of you get what I mean nontheless please try to help anyway.
|Oct14-03, 06:12 PM||#29|
bettysfetish: The best starter, IMHO, to String/M theory is Brian Greene's the Elegant Universe.
|Oct15-03, 04:07 PM||#30|
[:D] Thanks FZ+, I will study.
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