mark@cci632.UUCP (Mark Stevans) (05/22/87)
Just what is this "Aspect experiment" that may imply faster-than-light information transfer? Gravity waves 2? Mark "Mr. Curious" Stevans cci632!mark
biep@cs.vu.nl (J. A. "Biep" Durieux) (05/25/87)
In article <1275@cci632.UUCP> mark@cci632.UUCP (Mark Stevans) writes: >Just what is this "Aspect experiment" that may imply faster-than-light >information transfer? Gravity waves 2? As far as I understood: suppose we take some small particle (I don't know which, it doesn't matter either, so let's call it a moron). Morons have the tendency to fall apart into two let's call them half-wits, which always have opposite spin. So if one of them spins left, the other one spins right. Now close your eyes (that's the important part of the experiment) and shake a moron till it falls apart. Since you didn't look (and you hope nobody else did), nobody knows the spin direction of either particle. In quantum-mechanical terms, that is: either particle is in an overlap of two states (spinning left and spinning right, remember Schroedingers cat). Such an overlap is described mathematically as a complex (in any sense) "wave-function". Now jump into your car and follow one of those half-wits. After some time you overtake it, grab your magnifying glass, and (the magic word in QM) *observe* that the particle spins left (say). At this very same moment, at some far distance, the wave-function for the other half-wit collapses into the description of a right-spinning particle. So the information that you observed your particle must have travelled in zero time to the other half-wit. FTL information transfer. <Applause> Now this is written somewhat jokingly, as I cannot quite see why this reasoning is so exciting for physicists, and perhaps I don't understand a bit of it (perhaps if my companion particle collapsed...), for me it is just information transfer from one mental concept in my brain to another, but the experiment (someone actually tried it out) has caused, and still causes every now and then, lots of excitement. Perhaps one of the philosophical physicists can comment on this? (If they aren't already bored of it, for it keeps popping up in their newsgroup, I believe.) -- Biep. (biep@cs.vu.nl via mcvax) You can distribute this iff your recipients can. Which they can iff *their* recipients can. Which...
drw@cullvax.UUCP (Dale Worley) (05/26/87)
Biep gave a really good exposition of this. Has anyone figured out a way to use this to transfer information faster than light? Clearly, as he described it, we get to deliver a bit to two places simultaneously. But, what I want is to transmit information from one observation point to the other. Dale -- Dale Worley Cullinet Software UUCP: ...!seismo!harvard!mit-eddie!cullvax!drw ARPA: cullvax!drw@eddie.mit.edu Un*x (a generic name for a class of OS's) != Unix (AT&T's brand of such)
erhoogerbeet@watmath.UUCP (05/27/87)
In article <766@klipper.cs.vu.nl> biep@cs.vu.nl (J. A. "Biep" Durieux) writes: [some deleted] >in QM) *observe* that the particle spins left (say). At this very same >moment, at some far distance, the wave-function for the other half-wit >collapses into the description of a right-spinning particle. So the >information that you observed your particle must have travelled in >zero time to the other half-wit. FTL information transfer. <Applause> I don't understand. If one observer finds the spin, and the spin of the other particle is automatically known, how is the second observer going to know that he should look at the half-wit number two at the correct time? Would they not need to look *simultaneously* at the particle to find out? Which defeats a purpose somewhere, I think. Not only that, but can the spin be controlled? If not, how can you transfer information? Just thought I'd ask. ------ --------- ------------------------------------------ erhoogerbeet@watmath.uucp "`The Guide says there is an art to flying,' ehoogerbeets@wateuler.uucp said Ford,`or at least a knack. The knack lies Edwin (Deepthot) in learning how to throw yourself at the ground Hoogerbeets and miss.' He smiled weakly."