The Nobel Prizes are coming in threes this year – three joint winners were announced in chemistry the other day and now a trio of American-born astronomers has captured the prize in physics. Saul Perlmutter, Brian Schmidt and Adam Riess, working separately in the late 1990s, overturned one of astronomy and physics’ fundamental assumptions about the universe, showing that the universe was expanding at a constantly accelerating – and not decelerating – rate. By J BROOKS SPECTOR.
Until the three had made their unanticipated discovery and the results had been further verified, the scientific community had reached a consensus that the universe had been expanding, but at an ever-decreasing rate of this expansion, since the original “big bang”. The big bang was the primordial explosion that created, well, everything.
Instead, the trio’s discovery has described a new understanding of the eventual end of everything – the universe eventually becomes a place of super-low temperatures and black expanses, unbroken by the light of galaxies receding from each other at incredible speeds. Until the three scientists’ work, astrophysicists had extrapolated from today’s universe to assume that the expansion of the universe was very slowly decreasing – and so that for billions of years more, the universe would continue to resemble what exists now. That is not our fate now.
As the three research teams carried out their work separately, Saul Perlmutter, Brian Schmidt and Adam Riess each found that the light emanating from more than 50 far-distant, exploding supernovas was actually far weaker than predicted by the previous understanding. What this meant in turn was that the galaxies were moving away from each other at increasing – not decreasing – speed. The research now indicates that galaxies three million light years away from Earth move at a speed of around 70 kilometers per second, but galaxies six million light years away actually move twice as fast. Very weird. How do they do it? Well, that part is still not precisely understood but the culprit appears to be dark matter.
As a result, their research predicts that billions of years into the future, the universe will become “a very, very large, but very cold and lonely place,” says the American Institute of Physics’ Charles Blue. In fact, galaxies will be flying apart from each other so quickly that their light will be unable to travel across the universe to distant observers as it does today, making the sky appear really black, explains Blue. “For almost a century the universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago,” the Nobel Prize citation reads, but Blue adds, “The discovery that this expansion is accelerating is astounding. If the expansion continues to speed up the universe will end in ice.” Just like the Robert Frost poem:
Some say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice
I think I know enough of hate
To know that for destruction ice
Is also great
And would suffice.
Phillip Schewe, of the Joint Quantum Institute of the University of Maryland and the US government, says that this discovery was “the biggest shakeup in physics, in my opinion, in the last 30 years. I remember everyone thinking at the time (that) there was some mistake.” But the trio’s finding was confirmed by other later measurements such as analyses of the microwave radiation left over from the big bang that still exists as background radiation for the universe, explained Schewe.
Fred Dylla, executive director of the American Institute of Physics, told reporters that this award recognised the confirmation of Albert Einstein’s cosmological constant, a tricky bit Einstein had inserted in his general theory of relativity, a theory that has now become one of the cornerstones of modern physics. Einstein was reputedly never comfortable with this add-on, but Perlmutter, Riess and Schmidt’s joint discovery nearly 15 years ago seems to have confirmed it anyway. This unexpected acceleration by the universe’s galaxies is powered by what scientists call “dark energy”, a cosmic force that remains one of the most perplexing mysteries of the universe for scientists. And this discovery, in turn, means that the universe will become increasingly colder as its matter spreads across ever-vaster distances.
Over a hundred years ago, H G Wells had given a first literary expression to the universe’s dismal fate when his time traveler, after pushing millions and millions of years into the future with his time machine, had described the end of everything to his dinner companions, upon his return to them in the first New Year’s Day of the 20th century. Wells’ time traveler had told his friends:
“The darkness grew apace; a cold wind began to blow in freshening gusts from the east, and the showering white flakes in the air increased in number. From the edge of the sea came a ripple and whisper. Beyond these lifeless sounds the world was silent. Silent? It would be hard to convey the stillness of it…. I saw the black central shadow of the eclipse sweeping towards me. In another moment the pale stars alone were visible. All else was ray-less obscurity. The sky was absolutely black.”
Perlmutter, 52, now leads the Supernova Cosmology Project at the Lawrence Berkeley National Laboratory and University of California, Berkeley; Schmidt, 44, heads the High-z Supernova Search Team at the Australian National University in Weston Creek, Australia; while Riess, 41, is a professor of astronomy at Johns Hopkins University and Space Telescope Science Institute in Baltimore, Maryland.
Giving an insight into how a Nobel Prize-winner reacts when they get “the call”, Riess told the AP his “jaw dropped” when he received an early-morning call at his home in Baltimore from some Swedish men and he quickly realised that they were not Ikea furniture dealers. But now, of course, he has more than enough prize money to buy all the Ikea furniture he will ever need. The Nobel Prizes are handed out every year on 10 December, the anniversary of Alfred Nobel’s death in 1896. Nobel made his fortune in explosives and then endowed the prizes with his wealth.
Although the three men’s discovery actually came some years earlier, the recognition of their work has now capped a very interesting year in physics and astrophysics. First there has been the reputed discovery of the Higgs-boson, the so-called God particle that would complete the table for sub-atomic, quantum physics. Then there was the more recent, and disconcerting, potential discovery that scientists may have measured neutrinos – another sub-atomic particle – violating one of the most fundamental parts of the generally accepted model of physics and the universe: that the speed of light is the ultimate barrier and a true universal constant. With all these ideas and issues in play, the next few years may come to rival the golden age of physics that began with identification of the sources of radiation back in the late 19th century and that continued on through to the development of atomic energy. DM
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