history of measuring the speed of light....

this is pretty interesting:

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/measure_c.html

by 1983 the speed of light was measured to enough precision that it made more sense to redefine the meter in terms of the speed of light. making the speed of light a nice round 299,792,458 m/s. and one meter is now defined as the distance covered by light in a complete vacuum in 1/299,792,458 of a second rather than a physical object of a fixed length.

makes sense, sort of scary numbers come up when measuring nanometers and microns. one billionth of a meter? those cesium clocks are pretty damn accurate.

My AP physics teacher had to recreate the spinning mirror experiment in college. It's amazing to see how scientific numbers change over the years, and to see how accurate they were in the given time period.

That is pretty cool!

-tom