"Albert Einstein is undoubtedly one of the most fascinating and influential figures of the modern era. As a preeminent physicist, he radically transformed our understanding of the universe."

- Edited excerpt from Albert Einstein, Albert Einstein Archives, The Hebrew University of Jerusalem

In this series about Albert Einstein’s body of work, his discoveries are related to today’s research, technology, and common knowledge. Series themes include "How did Einstein know that?" and "How did Einstein figure that out?" and they focus either on conveying a major concept or on the reasoning that led to it. These articles will also cover Einstein’s major 1905 writings and address his general theory of relativity. In consideration of 2005 being designated as the World Year of Physics, the release of these articles is especially appropriate.

To give a clearer sense of how Einstein reached his conclusions, some mathematical equations and details may be included from time to time. Usually, the chief significance of these details is simply to demonstrate that Einstein found certain features of the physical world to be related in important ways.

Articles in this series include:

Commonizing Uncommon Sense - The universe that Einstein discovered—in which time doesn’t pass at the same rate for everyone, space bends, and chance prevails where we would expect certainties—seems strange to us, but becomes easier to understand once we realize that our everyday situation is the unusual one.

How High Up Is That Place? How Far In The Future Is That Event? – "Up" is a direction that depends on where you stand. "The future" is also a direction, and which direction it is depends on how you move. The first idea is ancient; the latter realization we owe largely to a discovery of Albert Einstein.

E=mc² – What's the Speed of Light Got to Do With It? – "Energy equals mass times the velocity of light squared." So what exactly does the velocity of light have to do with it?

"Seeing the Wind" – How do we know there's a wind, when we can't see the wind? In 1905 Einstein found a similar way to show the existence of atoms, even though at the time we had no way to see atoms.

Another Side of Light - The fact that light is a kind of wave is common knowledge today, and a hundred years ago the theory that light is some kind of wave was already well confirmed by experiment. But at that time Einstein found, in a newly-discovered physical law, a clue that there was more to light than the wave theory of those days seemed to suggest.

Solid Cold - By the early 20^th century, the way in which temperatures of solid objects changed as they absorbed heat was considered strong evidence that matter was not made of atoms.  Einstein used some recent discoveries about light to turn this assessment around.

Einstein and the Daytime Sky - The distinction between a fluid's liquid and gaseous phases breaks down at a certain temperature and pressure; when illuminated under these conditions, the fluid looks milky white, like a common opal.  Einstein found how this relates to the reason the sky is blue.

The Momentum of Light - The theory of relativity suggested that the energy quanta of light should also be quanta of momentum as well. Yet the new quantum theories of the day were proving accurate even though the momenta of light quanta hadn’t been accounted for. Would these quantum theories still prove accurate when momentum was included?

The General Theory of Relativity - Einstein's special theory of relativity addressed the problem of the invariant speed of light in vacuum by showing the interrelationship of space and time.  The general theory of relativity showed how the shape of spacetime could explain the mechanism of gravity.

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