By Dr. Marciene Mattleman

PHILADELPHIA (CBS) – What’s E=mc²? Chances are you don’t know what it means, but you know that it’s connected to Albert Einstein, whose birthday is celebrated by scientists this week.

Einstein was born in Germany in 1879, then moved to Switzerland for his education and the beginning of his scientific career.

When Hitler came into power in 1933, he came to the United States.

In 1939, he wrote to President Roosevelt urging him to approve the development of uranium enrichment, which led to the creation of the atomic bomb. In 1949 Einstein became a US citizen, and later in his life he became an advocate for nuclear disarmament and subsequently opposed the hydrogen bomb.

Einstein is considered the most influential physicist of the 20th century, recognized the world over for his theory of relativity and theories of space, time, gravity, light, and matter.

Learn more on the Internet: view videos of his life.  And if anyone asks you about E=mc², you can tell them it means that energy and mass are different forms of the same thing.