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CHORGENSOTRUFORX
May6-04, 07:00 AM
Can someone help me to understand exactly what Bohm did to indicate the possiblity of faster than light communication. Bohm did something to the akin of splitting a particle and than changing the direction of one half of the particle and the other half responded so quickly that light would not have had time to traverse the area between.

turin
May6-04, 01:02 PM
It sounds like entanglement. I would try posting in the QM board.

People still argue about entanglement to this day. The majority consensus is that information cannot be transmitted by this mechanism, even though microscopic influences can. There is a group at my former university who works on, among other things, the theory behind using entanglement for an information channel, but a causal control signal is still required in their theory.

selfAdjoint
May7-04, 08:55 PM
Can someone help me to understand exactly what Bohm did to indicate the possiblity of faster than light communication. Bohm did something to the akin of splitting a particle and than changing the direction of one half of the particle and the other half responded so quickly that light would not have had time to traverse the area between.

Bohm did not do this. The suggestion upon which the Aspect & Clause experiments were done was made by Bell, who developed his famous inequalities as a test for quantum mechanics. Bell was a partisan of Bohm's view and hoped for an experimental outcome that would favor Bohm's theory. But in fact the results came out as quantum mechanics predicted.

Bohm's version of quantum mechanics is held to violate relativity because it features a pilot wave that drives the particle, and they have to interact faster than light. Or so the traditional Bohm theory went. Modern "Bohmists" have tried to eliminate that feature.

Riko
May12-04, 12:15 PM
isnt it impossible to measure someting faster than the speed of light, let alone know of its existance because it would not be visible at all? :confused:

selfAdjoint
May12-04, 08:12 PM
isnt it impossible to measure someting faster than the speed of light, let alone know of its existance because it would not be visible at all? :confused:

Particles travelling FTL are not forbidden by relativity. You can not _accelerate up to and past_ the speed of light, and if you could send information FTL it would violate causality, because some inertial observers could receive it before it was sent. This aspect of tachyons (as FTL particles are called) was used by Gregory Benford in his famous novel Timescape, in which a tachyon message is sent back in time to warn people off a dangerous course of action.

Tachyons are a natural product of naive string theory, and one of the motivation of the development of superstrings was to eliminate them. However string field theory has found a use for them, so the story goes on.