Why Does E=mc2?

What do the words “space” and “time” mean to you? Perhaps you picture space as the blackness between the stars as you turn your gaze toward the sky on a cold winter’s night. Or maybe you see the void between earth and moon sailed by spacecraft clad in golden foil, bedecked with the stars and stripes, piloted into magnificent desolation by shaven-headed explorers with names like Buzz. Time may be the tick of your watch or the reddening of the leaves as the earth’s yearly circuit of the sun tilts northern latitudes toward shade for the 5 billionth time. We all have an intuitive feel for space and time; they are part of the fabric of our existence. We move through space on the surface of our blue world as time ticks by.

During the late years of the nineteenth century, a series of scientific breakthroughs in apparently unrelated fields began to force physicists to reexamine these simple and intuitive pictures of space and time. By the early years of the twentieth century, Albert Einstein’s colleague and tutor Hermann Minkowski was moved to write his now-famous obituary for the ancient arena within which planets orbit and great journeys are made: “From henceforth, space by itself, and time by itself, have vanished into the merest shadows and only a kind of blend of the two exists in its own right.”

What could Minkowski have meant by a blend of space and time? To understand this almost mystical-sounding statement is to understand Einstein’s special theory of relativity—the theory that introduced the world to that most famous of all equations, E = mc2, and placed forever center-stage in our understanding of the fabric of the universe

Space and Time

What do the words “space” and “time” mean to you? Perhaps you picture space as the blackness between the stars as you turn your gaze toward the sky on a cold winter’s night. Or maybe you see the void between earth and moon sailed by spacecraft clad in golden foil, bedecked with the stars and stripes, piloted into magnificent desolation by shaven-headed explorers with names like Buzz. Time may be the tick of your watch or the reddening of the leaves as the earth’s yearly circuit of the sun tilts northern latitudes toward shade for the 5 billionth time. We all have an intuitive feel for space and time; they are part of the fabric of our existence. We move through space on the surface of our blue world as time ticks by.

During the late years of the nineteenth century, a series of scientific breakthroughs in apparently unrelated fields began to force physicists to reexamine these simple and intuitive pictures of space and time. By the early years of the twentieth century, Albert Einstein’s colleague and tutor Hermann Minkowski was moved to write his now-famous obituary for the ancient arena within which planets orbit and great journeys are made: “From henceforth, space by itself, and time by itself, have vanished into the merest shadows and only a kind of blend of the two exists in its own right.”

What could Minkowski have meant by a blend of space and time? To understand this almost mystical-sounding statement is to understand Einstein’s special theory of relativity—the theory that introduced the world to that most famous of all equations, E = mc2, and placed forever center-stage in our understanding of the fabric of the universe the quan