Overview of Recent Researches on the Meaning of Relativity
Leonardo Motta, lmotta@socrates.if.usp.br
Rua Dr. Artur Neiva, 230. V Universitaria. Sao Paulo, SP. Brasil.
The theory of relativity its usually thought as 'untouchable'
well-established fact by persons that are not acquainted with it wider
than usual physics textbooks. This view is far away from truth. Since 
the birth of relativity the critic study of it never ceased, and it would 
be illogic to think otherwise, misapprehending the skeptical research with 
the religious dream.
For example, much have been discussed on the meaning of the constant 
'c'.  In 1905, Sommerfeld demonstrated that although v > c were apparently
prohibited by Lorentz transformations, in Maxwell's electrodynamics 
this is perfectly possible. Such result was explorer and expanded in quantum
electrodynamics, notably by R. P. Feynman and J. A. Wheeler who 
introduced superluminal (i.e., faster than light) virtual processes to interpret
fundamental features of Nature like foton exchange and anti-matter [1],
[2]. In quantum optics it has been measured signals in the order of 10c 
in total reflection experiments [3], [4] and even 300c in atomic mediums 
[5]!  We know that many galaxies emit apparent superluminal particles jets 
[6].  In some superstring models, solutions known as "tachyonics" emerge
naturally [7]. 
In opposition to what seems, all this results are perfectly compatibles 
with relativity. In fact, some of them emerge from the theory itself! 
Einstein and his colleague Natan Rosen, exploiting Schwarzschild black-hole 
model, found the first v > c solution on the domain of General Relativity. The
Einstein-Rosen bridges, as we call them, were largely studied by
physicists like Kip Thorne, Stephen Hawking and Roger Penrose, in such 
a manner that today we have many 'time travel machines'. Not less famous 
is the result of J. S. Bell that generalizes the Einstein-Podolsky-Rosen
(EPR) paradox, allowing time-travel in the domain of quantum mechanics
[2], [8]. This last result lead the Romanian physicist and 
mathematician Florentin Smarandache to develop a theory that allows 
arbitrarily large velocities [9], see also the Smarandache hypothesis.
With so many experimental results and theoretical insights apparently
against the idea that 'c' is a limit in Nature, it is famous the current
academic discussion of the meaning of 'c'. Some allege relativity breaks 
in face of such results [10], but these are left in a delicate situation
because the basic premise from where relativity is developed, that the
"rest" and uniform rectilinear motion are indistinguishable, is not a
principle that one arrives from hard and long thought, rather is an
experimental fact (being the Michelson-Morley experiment the most 
famous, but not the only one!).
Nowadays, the discussion of relativity is taken over all journals of 
The world and envelopes many physicists over Princeton, Cambridge,
Latin America, East European, India, Berkeley, China, Japan; at last, the 
whole globe. There is still much to learn from it, and maybe this 
understanding will come from our future deeper view on the world machinery, 
the fundamental forces, beyond the physics solid established today.
[1]: Feynman, R. P. "QED: The Strange Theory of Light and Matter",
Princeton Univ. Press (1998).
[2]: Herbert, N. "Faster than Light", New Am. Trade (1995).
[3]: Nimtz, G. Ann. Phys., 7 (1998), no. 8, p. 618. 
[4]: Chiao, R. Phys. Lett., A246: 19-25 (1998).
[5]: Wang, J. L. et al. Nature 406, 277-279 (20/06/2000).
[6]: e.g. NASA's site:
[7]: 'Tachyon' comes from the greek, 'tachys', meaning swift. Some 
models are cut so they do not have 'tachyonic modes' that could explain, 
for instance, dark matter.
[8]: Thorne, K. "Black Holes and time warps": W. W. Norton & Comp. 
[9]: Smarandache, F. "There is no speed barrier in the Universe". Bull. 
of Pure & App. Sci., Delhi, India, Vol. 17D, N.1, p.61 (1998); also at:
[10]: See for instance Rodrigues, Jr. W. A., Maiorino, J. E., Random 
Oper. & Stoch. Equ., vol. 4, 355-400 (1996), physics/9710030; Recami, E.