And now for something completely different

The Michelson–Morley experiment was a seminal discovery in physics, and was the first experiment to suggest that the speed of light was not relative to anything. It’s velocity in a vacuum was absolute and this finding has been confirmed many times since their hallmark experiment.

This short presentation presents Edward Morley’s experiments to nail down the speed of light as best he could with the equipment of his day. An interactive scatter plot of his results is included.

• Five independent experiments
• Each experiment consisted of twenty independent ‘runs’
• Yielding 100 independent measurements of light speed
  (in kilometers/second)

The data used here comes from the ‘morley’ dataset found in the ‘datasets’ package that comes bundled with R.

##     Expt Run Speed
## 001    1   1   850
## 002    1   2   740
## 003    1   3   900
## 004    1   4  1070
## 005    1   5   930
## 006    1   6   850

Mouse over any dot to see a specific value from a specific experiment.

The speed of light in a vacuum is a universal physical constant that is exactly equal to 299,792,458 meters per second, or ~300,000 kilometers per second.

As the plot shows Morley’s values have considerable variation, but may be explained given the limits of his equipment.