Standing the Test of Time (and Space)

Why the hundredth anniversary of Einstein’s greatest theory might be its most triumphant

Denizens of Elizabethan England dismissed a short-lived sensation as a “nine days’ wonder.” Andy Warhol spoke of fame lasting mere 15 minutes. These days, a reality-TV star would be lucky to light up the Twitterverse for that long.

If anyone has defied the fleeting nature of celebrity, however, it’s Albert Einstein. He is arguably the greatest scientific icon in history, going by the strictly empirical measure of how often his likeness appears on coffee mugs and T-shirts, not to mention a conspicuous tendency among authors to cram his name into book titles hoping for stronger sales. Perhaps the longevity of his fame proves that the flow of time is relative, indeed.

Sixty years after his earthly demise, Einstein’s stardom is primed for a grand revival yet again—not that he has ever strayed far from the headlines, mind you, for much of his adult life and even from beyond the grave (though there is no actual grave in his case). The ostensible reason for the latest upswing in Einstein-mania is the centenary of his much-hyped theory of general relativity. Physicists around the globe are organizing week-long conferences and publishing hefty volumes to celebrate. You didn’t expect street parties, did you?

It is a masterpiece worthy of hype and celebration, for sure. Equating gravity with geometry, the theory posited that a massive object, like the Sun, would warp the fabric of space-time around it. The hackneyed, and imprecise, analogy is of a bowling ball sagging the fabric of a trampoline. Stunning vindication came four years later, in 1919, when photographs of a solar eclipse, taken by intrepid English scientists who traveled to Brazil and to the African island of Principe, revealed a tiny deflection of starlight matching Einstein’s prediction. The findings caused a media commotion, propelling Einstein’s name into the stratosphere of fame. The legend of the superstar scientist was born.

Since then, general relativity has survived every conceivable scientific test, as well as endless crackpot assaults, for a hundred years. That ain’t no mean feat.

Those who challenged the theory haven’t fared so well. Take the case of the astronomer Thomas Jefferson Jackson See, a renowned telescopic observer and a charismatic public speaker (the naval captain’s uniform adorning his six-foot-four figure didn’t hurt). While much of the world toasted the eclipse result, See accused Einstein of plagiarism and worse. He denounced general relativity as “a crazy vagary, a disgrace to our age!” The poor chap didn’t seem to grasp what he was up against: Made a virtual pariah by the scientific community, he spent the rest of his quarrelsome life at a navy yard in California. Today See is remembered for little beside the controversies he wrought in his heyday, while public adulation of Einstein continues unabated.

General relativity is not only elegant and successful as a theory. It is also surprisingly handy. Astronomers use it to “weigh” the dark matter that dominates distant galaxy clusters and to discover alien planets through a technique known as “microlensing.”

At this point, you might say: Sure, Einstein was one smart fellow, but what good has his highfalutin theory done for the rest of us? In fact, general relativity underpins a multibillion-dollar industry right here on planet Earth. And, you might want to thank the secular saint of science the next time your plane lands safely in bad weather.

That’s because the global positioning system would not work properly without relativistic corrections: Internal clocks of GPS satellites would tick at different rates depending on their location in the Earth’s gravitational field. If these offsets weren’t accounted for, you might drive into a corner café, or worse, a pilot might miss the ground by miles. Perhaps Einstein wasn’t that smart after all: Imagine the windfall his heirs would inherit had he found a way to patent this particular application of relativity.

Despite the countless verifications of general relativity over the years, in the celestial realm and closer to home, scientists are not done with testing the theory yet. I, for one, am grateful for their insatiable, almost desperate, hankering to look for cracks in this grand edifice. It gave me a good excuse to do somersaults in zero gravity, on a parabolic flight operated by the European Space Agency, as a team of French physicists fine-tuned their apparatus (and a few unfortunate souls, with strained faces, were strapped in their seats, bravely resisting the overwhelming urge to puke). Their aim is to test whether rubidium and potassium atoms fall at exactly the same rate, as required by general relativity. The so-called equivalence principle has been tested already to a precision of one part in ten trillion. That may seem plenty good enough for most people, but most people are not scientists.

Meanwhile, American physicists are now trying to test—and exploit—another critical prediction of general relativity. Using two identical facilities, nearly a continent apart, the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) is listening for rumbles generated by cataclysmic cosmic events. The experiment began collecting data in mid-September, after a 200-million-dollar overhaul that makes it much more sensitive than its predecessor, and the physics community is already buzzing with excitement. The direct detection of gravitational waves, which squish and stretch space itself, would not only bear out Einstein—as if he really needs yet more vindication—but also open up an entirely new way to explore the most violent bits of the universe.

Thus, a century after its conception, general relativity is on the verge of its most spectacular success. Chances are that its author Einstein, too, will continue to flout the ephemerality of fame for a while longer.