| All such reports of FTL activity in the observered universe have been limited
to gas jets. All reports of super-luminal gas jets (which I believe is the
name given to these jets) have been explained as "APPARENT" motion
as compared to real motion. Basically, certain circumstances (and I
don't recall the specifics, but I think these are close) such as if the
jet is approaching us at an angle, or maybe straight on, as compared to
receding from us, give these jets the appearance of traveling faster
than light. But it is only an appearance, and the light boundary still
holds. NO stars have been postulated as traveling faster than light.
My mind frankly boggles at such a concept.
PeterT
I suspect the report in .0, if true, is based on math, and not on observations.
And, if it's based on math, I'll bet a lot of people will be anxious to
check his calculations.
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| re .2
It's questionable as to whether a star travelling away from us at
greater than the speed of light would actually be observable.
Even if the guy's mathematics are flawless, this doesn't guarantee any
correspondence with the real universe.
Hopefully the base noter will be able to find some more concrete info.
For info on apparent super-luminal motion see note 351.1 in the
PHYSICS conference. That's the FAQ. I extract here some of it.
================================================================================
Index of Subjects
-----------------
:
8. Special Relativistic Paradoxes and Puzzles
:
(c) The Superluminal Scissors
:
EFFECTS DUE TO THE FINITE SPEED OF LIGHT updated 28-May-1992 by SIC
----------------------------------------
There are two well known phenomena which are due to the finite
speed of electromagnetic radiation, but are essentially classical in
nature, requiring no other facts of special relativity for their
understanding.
(1) Apparent Superluminal Velocity of Galaxies
A distant object can appear to travel faster than the speed of
light relative to us, provided that it has some component of motion towards
us as well as perpendicular to our line of sight. Say that on Jan. 1 you
make a position measurement of galaxy X. One month later, you measure it
again. Assuming you know it's distance from us by some independent
measurement, you derive its linear speed, and conclude that it is moving
faster than the speed of light.
What have you forgotten? Let's say that on Jan. 1, the object is D
km from us, and that between Jan. 1 and Feb. 1, the object has moved d km
closer to us. You have assumed that the light you measured on Jan. 1 and
Feb. 1 were emitted exactly one month apart. Not so. The first light beam
had further to travel, and was actually emitted (1 + d/c) months before the
second measurement, if we measure c in km/month. The object has traveled
the given angular distance in more time than you thought. Similarly, if
the object is moving away from us, the apparent angular velocity will be
too slow, if you do not correct for this effect, which becomes significant
when the object is moving along a line close to our line of sight.
Note that most extragalactic objects are moving away from us due to
the Hubble expansion. So for most objects, you don't get superluminal
apparent velocities. But the effect is still there, and you need to take
it into account if you want to measure velocities by this technique.
References:
Considerations about the Apparent 'Superluminal Expansions' in
Astrophysics, E. Recami, A. Castellino, G.D. Maccarrone, M. Rodono,
Nuovo Cimento 93B, 119 (1986).
Apparent Superluminal Sources, Comparative Cosmology and the Cosmic
Distance Scale, Mon. Not. R. Astr. Soc. 242, 423-427 (1990).
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