Chance and evolution

lucaspa · #**191** 11th November 2003, 07:00 PM

Originally Posted by Mike Flynn

If we find, for example, that supersymmetry is *not true*...then M-theory will be relagated to the dust bin, and its equations may not have a solution simply because they do not describe the real universe in any way.

But evidence is mounting...and it's looking hopeful.

So I suppose I agree with you...it is about the data really.

The universe is data. That's the key connection. It's data that already exists and any theory has to yield the data we already have. That's the initial test.

The branes are extended strings...and they may have appeared as a QM fluctuation. The dimensional space that those branes inhabit could not have arisen from a quantum fluctuation. How can you get a quantum fluctuation when you have no quantum field?

It's the second sentence that I question. I have seen statements that say that spacetime itself could be the result of a quantum fluctuation. So, do your sources definitively state the second sentence?

2. MJ Duff, The theory formerly known as strings. Scientific American, 278: 64-71, 1998 (Feb.).
3. AN Arkani-Hamed, S Dimopoulos, G Dvali, The universe's unseen dimensions. Scientific American 283: 62-69, Aug 2000. Discusses idea that universe is a membrane sitting on "folded-up" dimensions.

Further research indicates that ekpyrotic does start out with a 5 D spacetime, so I guess you do have the question: where did the 5 D spacetime come from? So ekpyrotic may not be a candidate for First Cause. It can't cause the 5 D spacetime.

Mike Flynn · #**192** 11th November 2003, 10:30 PM

Originally Posted by lucaspa

It's the second sentence that I question. I have seen statements that say that spacetime itself could be the result of a quantum fluctuation. So, do your sources definitively state the second sentence?

To avoid the singularity condition, I believe #4 indicates that the universe was never any smaller than a planck-size nugget. If true, then such a space would represent a quantum field that would permit fluctuations. As you have indicated, the question is this: can a QM fluctuation give rise to the planck-size space itself?

I can check my sources on this, but I don't beleive any principle of QM allows for the spontaneous formation of *space itself* via a fluctuation. IOW, a fluctuation can't give rise to something that by definition is a quantum field. Rather, its quantum fields that give rise to fluctuations. As far as I know, there are only two types of possible QM fluctuations: pair production (vaccuum), and force particle. Even if this were *not* the case, where is the quantum field that is giving rise to a space time fluctuation if the pre-bang condition is null? Fluctuations *require* quantum fields.

Like I said, I can check my sources...but this just doesn't agree with what I have learned about QM fields and fluctuations.