Special Theory Of Relativity | V. A. Ugarov

This book is a very comprehensive treatment of the Special Theory of
Relativity with all advanced topics treated well.

It is in this book that I first read about the superluminal
speeds which are possible and are indeed result of STR. Section 8.1
deals with these phenomena and there are 5 of them discussed here. These
are for real and are indeed observed in nature. For example the
hot-spot in case of radio jets appeared to move at
faster-than-speed-of-light. The easiest one which you can indeed do is
to take a torch and make a spot on the wall, there is no limit on how
fast the spot can travel. Let us see what Ugarov has to say on this
topic:

Let us place a searchlight at the origin of
coordinates and start rotating it at the angular velocity $latex
\Omega$. Let us circumscribe a stationary sphere of radius $latex c$
around the origin. Then the light spot will run along the surface of
this sphere at the linear velocity $latex v = \Omega c$. This velocity
can exceed the velocity of light. The example of such a beam is provided
by a rotating pulsar. The light spot of the Crab Nebula pulsar runs
along the Earth surface at the velocity equal approximately to $latex
10^{22} m/s$. But as in the previous cases no signal is transmitted at
such a velocity. As a matter of fact, every point of a screen (the
Earth) receives a new portion of light energy from a searchlight
(pulsar), but not from a neighbouring point of the screen. Therefore, it
is impossible to transmit information from one point of the screen to
another.

The 4-forms, electrodynamics,
transformations are discussed with substantial emphasis on the physical
meaning. These kind of discussions make this book a wonderful resource
to learn.

The book was translated from the Russian by Yuri Atanov and was first published by Mir in 1979.