A parallel universe?

[Peterhouse]

I read an article in the paper recently about tacyons, faster than light objects. There has been debate as to whether they exist or not. Some say that Einstein's theories makle it impossible to accelerate to the speed of light, others say that these objects have been travelling faster than the speed of light forever.

Anyway, I began to think about this when I remembered my physics teacher telling me that if something travels faster than the speed of light then it should have a reflected image or mirror image, or something along those lines.

Well, if these tacyons are everywhere as some suggest, then surely there must be some sort of parallel or reflected universe, possibly inside our own universe.

Your comments please. Possible? Or am I talking out of my rear end?

[madmax]

The simplist explanation I've come across for this "mirror image" for tachyons is the following:
Say your standing in a train station. The "Tachyon Express" is due to pass through. The "Tachyon Express" is a train that travels at 2C (2 times the speed of light). It will not make a stop at this station, just pass through going from north to south.
Because it is travelling faster than the light reflecting off it, it will reach the station before any of the light reflecting off it does. Thus it will just suddenly appear in front of you at the scheduled time.
Of course it continues on southward at 2C. Now the light reflecting off of it as it continues on it's way is only able to travel at C, so it will appear to move south at the speed of light (even though it is really travelling at 2C).
BUT, at the same time, all the light that reflected off it as it approached the train station is finally reaching the station as well, so that at the same time you see it leaving to the south you will see it leaving to the north at speed C, even though it will appear to be facing south.
To summarize: the "Tachyon Express" will suddenly appear in front of you, then appear to move away in both directions at the same time.
Scientists have looked for phenomina that behave this way, but have not found any yet, though some odd things have been seen that maybe might possibly be related.
Tachyons could exist in our regular old universe, and would superficially not appear to be anything strange, there would just be unexpected behaviors (just as the "Tachyon Express" still looks like an ordinary train, it just behaves oddly).
Mind you this would require some very serious modifications to Relativity due to the energy limitations normally implied in both SR and GR.
I hope I have not further confused the issue.

[Bob B.]

Some say that Einstein's theories makle it impossible to accelerate to the speed of light, others say that these objects have been travelling faster than the speed of light forever.

I don't know all that much about relativity, but my understanding is that particles can travel at either sub-light or faster-than-light speeds; they just can't travel AT light speed.  Thus the speed of light is a barrier that can't be crossed.  This does not preclude the possibility of particles that have always existed in the FTL realm.

[Khanthavone]

... elaborate for the laymen...

[snake river rufus]

I think what Bob is saying is that a particle/object can come into existance, to be 'born' say, traveling faster than the speed of light. Or a particl/object  can come into existance traveling slower than C(speed of light). The first cannot slow down below C and the second cannot speed up to or pass C. In effect, if you are traveling less than 186,000 miles per second that is your limit. You can't pass that limit, it's the end of our reality.
Not to butt in

[DonPMitchell]

No one has yet observed tachyons.  The idea is based on the observation that if a particle has imaginary mass, m*sqrt(-1), then it would travel faster than light, but could never go slower than light (for the same reasons that real mass cannot go faster than light).  But it is not known if this corresponds to anything that really exists, or even if tachyons can interact with regular matter or be used in any way, if they do exist.