In 1908 Hermann Minkowski gave the four-dimensional(spacetime)
formulationof special relativity[1]. In fact, HenriPoincare[ ´ 2]
rst noticedin1906that the Lorentz transformations had a geometric
interpretation as rotations in a four-dimensional space with time as the
fourth dimension. However it was Minkowski, who succe- fully decoded the
profound message about the dimensionality of the world hidden in the
relativity postulate, which re ects the experimental fact that natural
laws are the same in all inertial reference frames. Unlike Poincare, ´
Minkowski did not regardspacetime - the uni cation of space and time -
as a convenientmathematical space, but insisted that this absolute
four-dimensional world, as Minkowski called it, represents physical
phenomena and the world more adequately than the relativity postulate:
"the word relativity-postulate. . . seems to me very feeble. Since the
pos- late comes to mean that only the four-dimensional world in space
and time is given by the phenomena. . . I prefer to call it the
postulate of the absolute world"[3]. The impact of Minkowski's ideas
on the twentieth century physics has been so immense that one cannot
imagine modern physics without the notion of spacetime. It would hardly
be an exaggeration to say that spacetime has been the greatest
discoveryinphysicsofall times. Theonlyotherdiscoverythatcomesclosetospa-
time is Einstein's general relativity, which revealed that gravity is a
manifestation of the curvature of spacetime. But it was the discovery of
spacetime, which paved the way for this deep understanding of what
gravity really is. Einstein saw the link
betweenthegeometryofspacetimeandgravitationonlyafterheovercamehis
initial hostile attitude toward the notion of spacetime.
