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Unformatted text preview: PHY2061 R. D. Field PHY2060
Review Postulates of Special Relativity
Consider two frames of reference
the O-frame and the O'-frame
moving at a constant velocity V,
with respect to each other at let
the origins coincide at t= t' = 0.
Follow the path of a light ray that
was emitted at the origin of the
two frames at the instant they
crossed. y Light Ray
O': (t'.x',y',z') y' V O O'
x x' z' z inertial First Postulate of Special Relativity (“Relativity Principle”):
• The basic laws of physics are identical in all systems of reference
(frames) which move with uniform (unaccelerated) velocity with
respect to one another. The laws of physics are invariant under a
change of inertial frame. The laws of physics have the same form in
all inertial frames. It is impossible to detect uniform motion.
Second Postulate of Special Relativity (“Constant Speed of Light”): 2.99792458x10
• The speed of light in a vacuum has the same value, c, in all inertial
frames. The speed of light in a vacuum is always independent of the
Experimental velocity of the source of the light or the velocity of the observer.
observation! The entire theory of special relativity is derived from these two
Light Path in O-frame
d = ct Light Path in O'-frame
d ′ = ct ′ d ′ = x′ 2 + y ′ 2 + z ′ 2
(ct ′) 2 − x ′ 2 − y ′ 2 − z ′ 2 = 0 d = x2 + y2 + z2
(ct ) 2 − x 2 − y 2 − z 2 = 0 Must find the transformation that results in Invariant! (ct ) 2 − x 2 − y 2 − z 2 = (ct ′) 2 − x′ 2 − y ′ 2 − z ′2 Department of Physics relativity_1.doc University of Florida 8 m/s ...
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