Processors and the speed of light

What does the speed of light have to do with processor speed? Quite a bit, so it turns out!

Speed of light = 299792458 meters per second, or 29979245800 centimeters per second (100 cm in a meter)

A nanosecond is 1 billionth of a second = 1/1000000000

The distance traveled by light in a nanosecond = 29979245800 * 1/1000000000 = 29.9792458 cm (~ 30 cm)


A 2.7 Ghz processor (one of the latest processors) can do 2.7 billion cycles per second, so each cycle (or step) takes 1/2.7 * 1000000000 or 1/2.7 nanoseconds.

The distance traveled by light in this time is 29.9792458 (cms/nanosecond) * 1/2.7 (nanoseconds) = 11.103424370370369 cms

This is about 3/4th of the length of a dollar bill. In the time that light travels 11.1 cms, a computer has to finish one cycle or step. This demonstrates the power of modern day processors. This is part of the reason that a process has to be so small - if it were bigger than 11.1 cms, we couldn't even send light across the processor length in the time for one cycle. This is why miniaturization has played a crucial role in the development of technology.


Food for thought, eh?!


* Learned this from udacity.com, in one of the course lectures! Check out udacity.com, an endeavor to get free quality education available to the masses.