In message kPkTd.81133$Yu.56373@fed1read01, "N:dlzc D:aol T:com
(dlzc)" writes
Dear Chris O'Riordan:

"Chris O'Riordan" wrote in message
roups.com...
The conventional explanantion for the superluminal motions observed in
many quasar-type jets is that it is an optical illusion due to the jets
being oriented at a fairly narrow angle to our line of sight.
...

If the jets are truly superlumenal, how is it that we can see light from
them? Since we *do* see light from them, and their spectra are
"reasonable", the rest is "tricks of geometry". If they were superlumenal,
the light could never leave...

We could see Cerenkov radiation (it's been looked for in searches for
tachyons) but presumably the spectrum from a jet doesn't match what's
expected for Cerenkov radiation, so that's not the answer.
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