Yourgrau P. A world without time.. the forgotten legacy of Goedel and Einstein (Basic Books, 2005)(ISBN 0465092934)(176s)_PPop_

astard, there you have it!" he is reported to have screamed as he stood over Schlick's
body, the gun smoking in his hand. Thus was the Vienna Circle abruptly closed, its history
framed by a suicide and a murder.
Long considered a haven for atheism, communism, materialism and assorted other crimes
of its Jewish professors, Schlick's circle had become a target for the increasingly virulent
strain of anti-Semitism in Austrian nationalism. Schlick's death was taken to be a promising
development. "It is to be hoped," wrote one newspaper, "that the terrible murder at the
University of Vienna will quicken efforts to find a truly satisfactory solution to the Jewish
question." The writer, apparently, did not know or care that Schlick was neither Jewish nor
an atheist but rather a German Protestant. He had, in fact, but one Jewish assistant,
Friedrich Waismann, who had already been dismissed as part of the university's attempt to
rid itself of Jews. Nelbock's sentencing upon conviction was a rather lenient ten years,
whereas hanging was the customary penalty. The court cited his mental instability as a
mitigating factor. He was, however, forced to sleep on a hard bed, with a new one
delivered every three months. After the Anschluss, Nelbock became a kind of folk hero. He
was released on probation and spent the war as a geological technician for the Third
Reich. At long last, Nelbock had found work.
The Meaning of Relativity
What Schlick had been seeking in the Vienna Circle was a unified epis-temologyóa
systematic account of what can really be knownóon the basis of a philosophically coherent
interpretation of what Einstein had achieved in physics and what Frege, Russell, Hilbert
and their predecessors had achieved in the foundations of mathematics. What exactly had
Einstein accomplished, however, and what was the meaning of the new direction in the
foundations of mathematics? As the century was turning, a perceived tension had arisen
between Newton's laws of motionóaccording to which measurement should always be
relative to, and affected by, the state of motion of the observeróand the equations of the
Scottish physicist James Clerk Maxwell, one of Einstein's heroes, who had unified the
theories of electromagnetism and optics.
Maxwell's equations gave as the speed of light a velocity, denoted by c, relative to a
reference system at rest in Newton's absolute space, known otherwise as the ether, a
substance whose existence was theorized from first principles rather than empirical
evidence. This invariance suggested that one could determine whether a given reference
system was at rest or in motion relative to the ether by testing the speed of light relative
to this system. Any deviation from c would signal motion relative to absolute space. All
efforts at measurement, however, such as those performed in the famous (because
exquisitely precise) Michelson-Morley experiments, failed to detect any variation in the
speed of light, which seemed impossible: since the reference frames tested were in motion
relative to each other, they could not all be at rest in the ether! Amazingly, although
bullets shot from a moving train have a velocity that is increased by the speed of the
engine, the measurable velocity of a light beam sent out from this same engine is
unaffected by the train's speed. The classical principle of "addition of velocities" was in
peril.