Tuesday, June 1, 2010
Tidbits on Light
Discover Magazine has a primer on 20 things you didn't know about light. Some cool facts:
1) It took 500,000 years after the Big Bang for the universe took to expand enough to allow photons (light particles) to travel freely ... i.e. light didn't exist for nearly half a billion years.
2) Like all living things, humans demonstrate bioluminescence: We glow. Humans are brightest during the afternoon, around our lips and cheeks. The cause may be chemical reactions involving molecular fragments known as free radicals.
3) Light has no mass, but it does have momentum
4) Visible light is less than one ten-billionth of the electromagnetic spectrum (radio waves to gamma rays).
5) Goldfish can see infrared radiation; Bees, birds, and lizards can see ultraviolet.