faustus (02/06/83)
There is one interesting example of seeming FTL information transmission that, as far as I can tell, has not yet been explained. This is the phenomenon of the collapse of the wave function for a particle. When there is a particle in a certain region of space, its position is described by a wave function which when squared gives the probability of finding the particle in any given place. When a measurement is made, the wave function is modified to reflect the new state of knowledge: if the particle is there, the wave fn becomes 1 at that point and 0 elsewhere. It is concievable, then that given a wave function that extends over a certain extent of space, two measurements can be made that are far apart in space and close together enough in time that there is no causal link between them (is this called 'time-like seperated'?) Then, one is faced with two alternatives: either there is a possibliity of finding the particle at both points (as there has not been enough time for the wave fn to convey the fact that the particle has been found at one point, and therefore cannot be anywhere else, sort of...) and thereby violate conservation of lots of things, or the wave function could instantly collapse everywhere and make sure that the particle is found in only one place, but introduce FTL data transmission. Einstein was quite upset about this paradox, understandably, and so were a lot of other physicists, but I don't think it has been resolved yet. Wayne Christopher faustus@berkeley ucbvax!faustus
CSvax:Pucc-H:Physics:els (02/11/83)
In the first article, I fell into a trap that is easy to be caught by.
If you want to talk about causality and the speed of light as a limit to
information transfer, then you had better apply ALL of special relativity!
You can't have it both ways. Once you assume S.R. operates, then talk of
probability and wave functions must be suitably altered, meaning that the
point is rendered moot.
els[Eric Strobel]