throopw@dg_rtp.UUCP (Wayne Throop) (10/23/86)
NOTE: followup-to set to sci.astro
A recent issue of Science News had a bit on the apparent "FTL"
gas/plasma jets that occur now and then. They invoked special
relativity as the favored explanation, saying something like "The jets
are moving FTL in *our* frame, but they are moving STL in their *own*
frame." This seems to be nearly pure male bovine excrement.
SR says that *nothing* can move FTL as measured from *any* frame.
Further, the speed of anything at all "in its own frame" is zero, so
that isn't an explanation of anything. The last time I heard this
discussed, it was purely an optical illusion having nothing to do with
SR, but rather to do with the angle at which we are observing the gas
jet, so that we are (in essence) seeing its lifetime in "fast motion".
Can anybody say if the reporter mangled the story into
unrecognizability, or just what is going on here? Just what *is* the
current idea about these "FTL" jets?
--
You run and you run to catch up with the sun, but it's sinking,
racing around to come up behind you again.
The sun is the same in a relative way, but you're older,
shorter of breath and one day closer to death.
--- Pink Floyd
--
Wayne Throop <the-known-world>!mcnc!rti-sel!dg_rtp!throopwjames@reality1.UUCP (james) (10/27/86)
How about an effect with something like a lighthouse? Have a bright beam rotating very, very fast, with a long flat screen a fair distance from the lighthouse. If the lighthouse rotates the beam fast enough, the spot on the screen moves faster than light. You could achieve any speed you wanted this way. Nothing material is moving that fast, and there is no threat to that precious causallity. Yet the abstract concept of the "spot" clearly can move faster than light. If you had a hard time telling the difference between a "spot" and a real object which looked like a spot... I thought that the above was pretty much the conclusion as to what these FTL objects were. I don't know what could act as a screen here or what could be used as a lighthouse, but such an answer seems somewhat more likely than something actually moving FTL. -- James R. Van Artsdalen ...!ut-ngp!utastro!osi3b2!james "Live Free or Die"