Consequently, no object with a finite mass can achieve the speed of light and this places a limit on the superluminal motion
. Only waves like the light electromagnetic waves, that have no mass, travel at the speed of light.
Revisiting Barry Cox and James Hill's theory of superluminal motion
: a possible solution to the problem of spinless tachyon localization.
In Chapter 5, Hudson takes up a puzzle about the apparent inconsistency between certain views in mereology and the a posteriori denial of superluminal motion
Astronomers had previously observed superluminal motion
of material expelled by GRS 1915+105, notably during a giant outburst 3 years ago (SN: 9/3/94, p.
But even without human involvement, with inanimate instruments doing the observing, do the rules of quantum mechanics allow for superluminal motion
? A careful analysis of the experiments that tested Bell's theorem shows that the only objects that move faster than light are mathematical creations of our imaginations, like the quantum wave function, which are not physical objects.
It should be noted, that in  superluminal motion
is allowed only for particles or signals whereas superluminal motion
for reference frames is forbidden.
This superluminal motion
is now known to be an optical illusion caused when matter moves at near-light speeds almost directly toward Earth.
Last June, at a meeting of the American Astronomical Society in Minneapolis, he and his colleagues reported their recent observations of superluminal motion
in a jet of gas at the center of the galaxy M87.
Thus, for the particle with the non-zero mass, even at u' > c, the term "superluminal motion
" is conditional.
Radio observations have shown that M87's jet evinces superluminal motion
: it appears to race away from the galaxy's core at faster-than-light speed (S&T: January 1995, page 15).
The appearance of superluminal motion
is held to be an optical illusion, but the illusion imposes serious difficulties on attempts at an explanation.
Owen (National Radio Astronomy Observatory) reported this latest case of "superluminal motion
" at a recent meeting of the American Astronomical Society.