When Stockholm called Michael Rosbash on Monday to tell him that he had won the Nobel Prize in Physiology and Medicine for discovering the physical basis of the biological clock, he responded: “You’re kidding me.” Perhaps he was astonished because the award was asynchronous — his crucial work was done ages ago. Last year, too, the Nobel Foundation had shown that it was out of phase with the world by honouring theoretical work in the topology of matter, ignoring the Laser Interferometer Gravitational-Wave Observatory (Ligo), which had detected gravitational waves 12 months before the ceremony. Vindicating a prediction made by Einstein a century ago, following from the theory of general relativity, it was the biggest thing in physics since the discovery of the Higgs boson. To general disgust and the delight of the bookies, Ligo didn’t get the prize.
In 2017, the Royal Swedish Academy of Sciences has made amends by honouring the Ligo leadership — Rainer Weiss, who designed the most sensitive instrument ever made by the human race, Kip S Thorne, who narrowed down the signals and frequencies it was designed to seek, and Barry C Barish, who built the project hands-on.
What exactly did Ligo see — or hear, to be precise, since the signature of the first gravity wave detected on September 15, 2015, was translated into a sound that was between a chirp and a ping?
It heard the collision of two massive black holes that had spun around each other at maniacal velocities and then collided 1.3 billion years ago, when life on earth had barely begun. The cosmic incident was not visible, since light cannot escape the event horizon of a black hole, but it can be inferred by radiation in the vicinity of the maelstrom of matter and energy. It also spread gravitational waves, ripples propagating at the speed of light across the fabric of space-time. When the first Homo sapiens walked the plains of Africa millennia ago, the waves were sweeping through the Magellanic Cloud, and they reached Earth in September 2015, producing tiny disturbances at Ligo’s laser interferometers in Louisiana and Washington state, apart from the Virgo instrument in Italy. It produced a tiny chirp that shook the world of quantum physics.
For years until the discovery of the Higgs boson, there was a crisis in physics. The method of science consists of developing theory and then confirming it in the laboratory. Without the second step, theory remains unverified. The Higgs boson was the last element of the standard model of physics which remained unobserved in the wild. So theory was being built on theory for years on end, and the laboratory was left far behind. Maybe it was all being built on sand?
With the discovery of the Higgs boson, the laboratory caught up and theory was vindicated. However, the century-old prediction of gravitational waves remained untested — actually, it dates back to Henri Poincare’s postulate of 1905. Now, Ligo has provided yet another assurance of the patency of the standard model. Gravitational waves were inferred earlier, and Russel A Hulse and Joseph H Taylor Jr won a Nobel for it in 1993. But Ligo made the first direct observation of a gravitational wave, producing a twitch in an instrument.
Looking ahead, gravitational wave astronomy will give humanity access to parts of space and time which have remained invisible. Unlike electromagnetic radiation like light, which traverses space-time, they are ripples within the very fabric of space-time. They are not scattered by matter, and will allow instruments to peer impossibly far into the gulfs of space — and correspondingly far back in time. Parts of the universe which have remained dark to optical and radio telescopes will now become visible. Black holes and neutron stars — bodies so dense that a spoonful of their substance would weigh as much as the earth — will yield up secrets never seen before.
Anything with mass produces gravitational waves when it accelerates. You produce scads of gravitational waves every time you dance, but they are not strong enough to be picked up by instruments. But anything with a gigantic mass, like a black hole or a neutron star, would generate measurable waves, rendering hitherto hidden phenomena visible. In the past, telescopes have been sent into space to get a clearer view of the universe, unimpeded by the dust, clouds and background radiation of civilisation. The best-known is the Hubble telescope, and one of its peers even seeks gravitational waves — the European Space Agency’s LISA Pathfinder. But since gravitational waves are not scattered, one could logically bury a detector in a coal mine, and it would still see the light of distant stars — in its own spectrum, not that of visible light. In the incredibly close future, this form of telescopy will open a new eye on space and time, and let us see the universe as it has never been seen before, in the myriad invisible colours of gravity’s rainbow.
2016 WINNERS: In the 1970s, MICHAEL KOSTERLITZ & DAVID THOULESS overturned then current theory that superconductivity or suprafluidity could not occur in thin layers. They demonstrated that superconductivity could occur at low temperatures and also explained the mechanism, phase transition, that makes superconductivity disappear at higher temperatures. In the 80s, DUNCAN HALDANE discovered how topological concepts can explain the properties of chains of small magnets found in some materials.