----- Original Message ----- From: "Warren Ockrassa" <[EMAIL PROTECTED]> To: "Killer Bs Discussion" <[email protected]> Sent: Monday, March 07, 2005 7:30 PM Subject: Re: quantum darwin?
> On Mar 7, 2005, at 5:46 PM, Dan Minette wrote: > > >> Have you had a chance to look into superstring ideas? One thing that > >> goes away with that is the inability to determine a particle's > >> location > >> and motion simultaneously, > > > Can you point out where you got this impression? > > _The Elegant Universe_, Brian Greene. He portrays the problem, IIRC, of > particle interactions, describing how a pair of "loops" would interact > in a way different from two particles -- they'd join for a while, > forming one loop with different properties, and then separate once > again into individual loops. Since we see this as a point-particle > interaction, my understanding is that we have a hard time determining > when or where the interaction actually takes place. OK, I think there may be a problem with making a conclusion from a metaphor, then. If you look at a decent fairly non-technical explanation at: http://www3.sympatico.ca/brianfp/topics/essays/444/html/doc.html which seems to be a senior physics project, we see the following quote: <quote> Although the Heisenberg Uncertainty Principle ensures that we will never measure a particle's exact position in space, space itself is considered in the standard model to be continuous. This idea may be incompatible with superstring theory. Since quantum mechanics already dictates an uncertainty in a particle's coordinates in space and time, as well as its energy, why not extend this idea further, and hypothesize that space itself may not be continuous on the microscopic scale? This is in fact a prediction of superstring theory, which we will consider later. <end quote> In short, superstring theory, as is stated elsewhere has more indeterminacy than standard QM. Another site which has a better explanation of superstring theory is: http://www.superstringtheory.com/ which is a sorta official site of folks involved in it. This is getting close to the time where the introduction of a bit of formalism might be helpful. I think I can do it without going too deep into the math. But, first let me ask you a question. Are you familiar with eigenstates and superpositions? For example, if you measure the spin in the x direction, the spin in the y (which is orthogonal to x) is a superposition of up and down. |s> = ( |+> + |->)/sqrt(2). Is that something you've seen and feel comfortable with discussions that assume that you know it? It appears that there is some interest in the fundamentals of the issues, and I wouldn't mind putting together some stuff on those fundamentals. Dan M. _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
