2
E = mc
Year of Discovery: 1905
What Is It? The first established relationship between matter and energy.
Who Discovered It? Albert Einstein
Why Is This One of the 100 Greatest?
For all of history, matter was matter and energy was energy. The two were separate,
unrelated concepts. Then Einstein established the relationship between matter and energy
by creating the most famous equation in the history of humankind, E = mc2. (The second
most famous is the Pythagorean Theorem for a right triangle, A2 = B2 + C2.)
Einstein’s equation for the first time defined a quantified relationship between matter
and energy. It meant that these two aspects of the universe that had always been thought of
as separate were really interchangeable.
This one equation altered the direction of physics research, made Michelson’s calculation of the speed of light (1928) critical, and led directly to the nuclear bomb and nuclear energy development.
How Was It Discovered?
In 1903, 24-year-old Albert Einstein landed a job as a patent clerk for the Swiss patent
office. His whole job was to check the technical correctness of patent submissions. Though
he had always dreamed of, and aimed for, a career in science, he had utterly failed to gain an
entry into that world. He had failed high school and was barred from teaching.
He had married his high school girlfriend. He was a low-level bureaucrat scraping by
in Berne, Switzerland, and it seemed that that was all he would ever be.
Though he had been shunned in his formal education, Einstein was still a passionate
amateur mathematician and physicist. He spent virtually all of his free time mulling over the
great mysteries and problems facing physicists of the day.
Einstein worked best through what he called mind experiments. He searched for vivid
mental images that would shed new light on, and provide a new perspective on, complex
physics problems. Then he applied the mathematics he knew so well to explain the images
and to understand their physics implications.
By 1904 Einstein was attempting to extend the existing physics of the day by focusing
on the relationships between light, space, and time. He was able to show that light exists as
both waves and as particles. (A particle, or quanta, of light we call a photon.)
111