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Without Albert Einstein, We’d All Be Lost

One hundred years ago this week, on Nov. 4, 1915, Albert Einstein, working alone in wartime Berlin, submitted the first of four scientific papers that would change the course of physics and our view of the cosmos. His general theory of relativity is perhaps the greatest achievement of a single human mind. Although it made Einstein the most famous scientist in history, he did not live to see the full impact of his ideas.

Only now, a century later, are we gathering apples from the tree he planted: black holes that tear stars apart and produce the most violent explosions in the universe; cosmic gravitational lenses that distort images of faraway galaxies, as if seen through a funhouse mirror. And perhaps the biggest wonder of all: a comprehensive and detailed understanding of the evolution of the universe. Amazingly, in just 100 years, humankind has uncovered 13.8 billion years of cosmic history.

Albert Einstein in an undated photo

Only after Einstein’s death in 1955 did his theory become an active and respected scientific field. Fifty years ago the first physical evidence of the big bang was observed. This famous cosmic microwave background or “first light”—a signal produced a mere 380,000 years after the creation—you can actually observe in your home. Roughly 1% of the static on a blank television screen is caused by light particles dating from the beginning of time.

The past decade has brought a new cascade of discoveries. The most important is that we now know precisely what we don’t know. Einstein’s theory allows us to measure the weight of the universe and thereby its energy content. This has been a shocker.

All known forms of matter and energy—that is, all the particles and radiation that make up us, the Earth, the sun, all planets, stars and intergalactic clouds—comprise just 4% of the grand total. The remaining 96% is made of unknown forms of “dark matter” and an even more mysterious “dark energy,” which permeates all of space and drives the universe to expand faster and faster. These days there is a lot of talk about the 1% of society, but from a cosmic point of view, we are all part of just 4% of the cosmos.

What explains the enduring impact of Einstein’s theory of relativity? It is the combination of elegant mathematics and deep physical intuition. As with all of Einstein’s contributions, his equation relates two things that at first seem totally disconnected. On one side we find the airy geometries of space and time, on the other side the real matter and energy in the universe. Simply put, matter tells space how to curve and space tells matter how to move.

What can we learn from this century-long quest?

First of all, as for so many things in life, the most difficult part is the beginning. Doing this research is like finding the beginning of a roll of Scotch tape. Once you have found it, after a lot of scratching, you can start to unroll the tape. Einstein dated the beginning of his grand theory to what he called “the happiest thought of my life.” It occurred in 1907 when he observed workers on a roof and realized that if they fell down they would be weightless while falling. Never underestimate the power of imagination.

Second, even Einstein had trouble accepting the most radical implications of his theory. He initially objected to the idea of an expanding universe, created in what scientists now call the big bang. Black holes and gravitational waves stretched even Einstein’s imagination too far. But the great thing of science is that a theory can be smarter than its discoverer and have a life of its own.

Third, many of the effects Einstein predicted were too small or too distant to observe in his lifetime. We had to wait for new technologies to magnify these minuscule effects. For example, without the theory of relativity the GPS devices that we all use every day to find our way would not function. The effects of time delays in the rapid communication with satellites of a few billionths of a second, as predicted by Einstein’s theory, translate into a drift of GPS positions of 7 miles a day. Without relativity we would all be lost.

Finally, unlike what headlines suggest, science is not only about the discovery of new particles, genes or technologies. Sometimes it is about asking deep questions about familiar things that are right in front of us. We live every day with space, time and gravity, when we ride in a car or climb the stairs, or look up at workers on a roof. It took an exceptional mind to question the very fabric of our reality and turn it upside-down.

Let us never forget the power of one individual to single-handedly change everything we know about our place in the universe. Even if that idea takes a century to come to full bloom.



Mr. Dijkgraaf is the director of the Institute for Advanced Study in Princeton, N.J., where Albert Einstein worked the last 22 years of his life.