How long does it take light to travel from this text to your eyes? Assume a distance of 40 cm.?

Answer 1

1.33 nanoseconds.

Light travels at exactly 299,792,458 meters per second. Rounding off and using units appropriate in the age of nanotechnology this gives 30 cm per nanosecond (one one-billionth of a second). I work with nanosecond precision sensors (avalanche photodiodes) in my lab and we often add addtional coaxial cables in the meter range to delay our signals when necessary.

Its also interesting to note that a 1GHz computer can only send signals a distance of 30 cm in one clock cycle. A 100GHz chip would have to be smaller than 3mm so you can see that we will need a major change in chip design to get much faster than this.

Answer 2

LIGHT TRAVELS AT A CONSTANT 186,000 MILES PER SECOND IN A VACUUM.
It'll travel to your eye faster than you can blink.