Asri-unix.541
net.space
utcsrgv!utzoo!decvax!ucbvax!menlo70!sri-unix!ES@MIT-MC
Sat Jan 16 14:55:54 1982
Absolute velocity of the Earth
From: Gene Salamin <ES MIT-MC AT>
The tenets of special relativity, that absolute velocity is physically
meaningless and that there is no lumeniferous ether, are generally considered
as established because of the agreement between the predictions of the
theory and experimental results. Although there is no ether with respect
to which we can measure the velocity of the Earth, the vacuum of space is
actually filled with black body radiation at a temperature of 3 K, and
it is possible to define one's velocity with respect to this radiation.
An observer is at rest when the radiation is isotropic (independent of
direction). An observer in motion with respect to the black body
radiation will measure a higher temperature in the direction toward which
he is moving, and a lower temperature in the direction opposite, as a
consequence of Doppler shift. The optical absorption length for this
radiation is larger than the radius of the known universe, so the reference
frame defined by the radiation is of a cosmological scale (although not
necessarily of the entire universe). Using balloon carried microwave
sensors, the "absolute" velocity of the Earth has been measured. It
is something like 300 km/sec.
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