Speed of light is roughly 186 000 miles per second, and roughly 300 000 kilometers per second, and as it turns out, 186 000 is very much different from 300 000.

Speed of light is roughly 186 000 miles per second, and roughly 300 000 kilometers per second, and as it turns out, 186 000 is very much different from 300 000. The beauty of fine structure constant is that it comes out to be the same numerical value regardless of what units you choose for your measurement.