Over 100 years ago, Albert Einstein grappled with the implications of his revolutionary special theory of relativity and came to a startling conclusion: mass and energy are one. E = mc2 was just one of several extraordinary breakthroughs that Einstein made in 1905, including the completion of his special theory of relativity, his identification of proof that atoms exist, and his explanation of the nature of light, which would win him the Nobel Prize in Physics.

[text adapted from pbs.org]