Re: FTL Travel is Useless even if it existed?

On Aug 11, 10:02 am, Ian Parker <ianpark...@xxxxxxxxx> wrote:
On 9 Aug, 08:34, Sam Wormley <sworml...@xxxxxxxxx> wrote:



mike3 wrote:

So does this mean that afaster-than-light(FTL) system need not go
back in time? Would it be possible to have "FTL" travel that does
_not_ go back in time and because of that, does not create paradoxes
plus is also is *useful*? (Because back-in-time FTL isuselessif you
want to communicate with/travel to places in the present/future and
not the past, paradox considerations aside. See what I'm driving at?)

   Let me ask you this.... if a tachyon moves from point A to
   point B, a finite distance apart, with a velocity of 2c,

   do you not agree that the tachyon is moving FTL and that
   it take a finite anount of time to transverse the distance?

   The concept may challenge some relationships, but why
   would you say it is going back in time, when, clearly
   some time elasped in the "forward" direction.

In the case of Tachyons there are in fact 2 ways to resolve the
paradox

1) They do not interact with anything so no information is conveyed
FTL.


But if information *was* sent FTL (don't bother asking how, this is a
speculative exercise), it would go back in time and breach causality,
right? No way around it.

2) A Feynmann diagram resolves the paradox. If a tachyon is self
consistent no paradox is violated.


But would this also therefore render it useless for sending
information
(and so physical objects like starships, as the structure of them is
"information", you know)?

There has been an interesting paper published, I'm afraid I can't
recall it where the FTL paradox is resolved partly by self consistency
and partly by quantum uncertainty.

One thing is for sure. Normal mastter can never travel FTL.


.

Relevant Pages

  • Re: Paradoxs caused by Faster than Light Communciation ?
    ... caused by B receiving an instantaneous FTL message from A, given that B & A are still separated by space and it will take time for B to physically interact with A. Remember, we are talking only about FTL communication, not FTL travel. ... I can demonstrate a causality paradox to you if and only if we agree beforehand on a convention for doing this, and that convention admits such paradoxes. ... Another possibility, the one most people seem to adopt without considering any alternatives, is that A is the sender if A's time coordinate is less than B's in *any* inertial frame. ...
    (sci.physics)
  • Re: Space Travel
    ... Special Relativity has got the paradox of time travel. ... Some FAQs on FTL ... The next thread is on quantum entaglement. ...
    (sci.space.policy)
  • Re: FTL Travel is Useless even if it existed?
    ... Would it be possible to have "FTL" travel that does ... not the past, paradox considerations aside. ...    it take a finite anount of time to transverse the distance? ... Also expresses a field theoretic view of tachyons. ...
    (sci.physics)
  • Re: FTL Travel is Useless even if it existed?
    ... Would it be possible to have "FTL" travel that does ... not the past, paradox considerations aside. ...    Let me ask you this.... ... if a tachyon moves from point A to ...
    (sci.physics)
  • Re: FTL Travel is Useless even if it existed?
    ... Would it be possible to have "FTL" travel that does ... not the past, paradox considerations aside. ... you need to apply a viable theory that allows FTL ...
    (sci.physics)