for National Geographic News
It has been a hundred years since Albert Einstein's annus mirabilis, or "year of wonders," during which the then-26-year-old government worker wrote a series of papers that revolutionized our understanding of the universe.
To mark the occasion, 2005 has been designated by the United Nations as the International Year of Physics.
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There have, of course, been scores of groundbreaking scientific developments since Einstein's time. Yet at its core, science is still operating in the same framework that Einstein laid out a century ago.
"He changed not only science but also the way to go about good science," said Gerald Holton, a physics professor and Einstein scholar at Harvard University in Cambridge, Massachusetts. "He was not trying to find solutions to small problems but to bring all of physics under one roof."
Einstein, who was born in Germany, really was working as a lowly clerk at the Swiss Patent Office in Bern when he conceived his radical theories, which came to provide the foundation of modern physics.
He submitted his series of papers to the Annalen der Physik, the leading German physics journal at the time.
In a paper written in May, 1905, Einstein showed how the existence of atomsan idea that had been hotly debated but far from universally acceptedcould be verified by measuring the jiggling of microscopic particles in a glass of water.
The process, measuring what is known as Brownian motion, gave scientists a way to count atoms by looking through an ordinary microscope.
In June of that year, Einstein introduced relativity, a theory of time, distance, mass, and energy. He set the speed of light as the universal speed limit and showed that distance and time are not absolute but instead affected by one's motion.
"Until his day, people were tied to this idea of time as being fixed," said Clifford Will, a physics professor at Washington University in St. Louis, Missouri. "Einstein took an operational viewpoint that time is what clocks measure and nothing more." (Will is the author of Was Einstein Right?)
In a three-page add-on to the theory, completed in September 1905, Einstein derived his famous equation E=mc2. The equation shows that the energy of a body equals its mass times the speed of light squared.
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