Re: It is said that tachyons travel backwards through time...

Hi Chris,

You are asking a lot of questions. I try to answer them, one after one.

As far as I know, tachyons occur in some string theories as ground states (lowest energy state), which is a string that does not wobble but moves with a constant velocity (vibrational modes of the string correspond to different particles). They are peculiar states, that's why people don't want them to appear. In the late sixties bosonic string theory arose, and it was due to the ground state being tachyonic that this theory was discarded. Supersymmetry was introduced to get rid of tachyons. The problem with them is that they have negative mass und move faster than the speed of light. I don't think that there are many people who suggest that tachyons are physical particles. They are negative mass states, so eventually all particles should decay into tachyons emitting vast amounts of energy, if no principle forbids that.

In these string theories the tachyon is treated on the same footing as any other elementary particle, it is not composed but it as elementary as electrons and quarks. So they are supposed to be pointlike particles. If tachyons moving faster than the speed of light exist and one could use them to transmit information, it can easily be seen - using space time diagrams - that one could transmit information into its own past. That is clearly very problematic.

I don't think that tachyons play a role in chaos theory, since classical systems exhibit chaotic behaviour, too. Butterfly effect is an outgrowth of the system's sensitive dependence on initial conditions. Only small changes in initial conditions cause an enormous effect. There is nothing really "mysterious" about that. And I don't think that the displacement or addition of a single particle has on a larger scale any effects at all.

A Möbius loop is a band which has only one side. Think of long rectangular sheet of paper, twist it and glue the ends together. That's a Möbius band. Following the loop with a pencil and drawing a line you will eventually come along "both" sides of the band. Since you cannot change sides in a continuous way there is only one side.

I hope I could help you,
greetings,
Michael.