Special Relativity: Einstein )The laws of physics don’t depend on your state of motion 2)Everyone who measures the speed of light gets the same answer No “reason”: just a fact of nature Hmm, still c. c, of course Hey, what’s the speed of this light beam?

Aberration of Light Moral: direction of light beam is relative

w w Relativity of Time and Space To outside observer: Distance across box = w Time to cross box = w/c To inside observer: Distance across box > w Time to cross box > w/c

Paradox: What happens if the person inside the moving car holds the laser pointer?

Relativity of Simultaneity To inside observer, light beams hit top and bottom simultaneously To outside observer, downward beam hits first (car catches up) - upward beam hits next (chases car)

Time Dilation 2 events occur in the same PLACE shorter time interval Same events viewed from outside: different places longer time interval Time appears to flow more slowly inside the car, as viewed from the outside

Lorentz Contraction To outside observer: Length of box = l To inside observer: Length of box > l External calipers appear to be contracted l >l <l Box doesn’t fit inside calipers simultaneously