Three U.S.-born researchers shared the 2011 Nobel prize in physics for discovering that the universe is expanding at an accelerating rate, a startling result that overturned prevailing theories and sparked many new questions for cosmology.
The Royal Swedish Academy of Sciences awarded half the prize of 10 million kronor ($1.5 million) to American Saul Perlmutter, while the other half will be shared by U.S.-Australian Brian Schmidt and American Adam Riess.
The three winners from left to right: Adam Ries, Saul Perlmutter and Brian Schmidt
The findings about the accelerating universe were presented in 1998 by rival research teams—one led by Dr. Perlmutter and the other headed by Dr. Schmidt, which included Dr. Riess. Both groups based their conclusions on observations of light reaching the earth from distant, exploding stars, known as supernovae.
Back then, the discovery "seemed too crazy to be right." Dr. Schmidt, in a publicly-broadcast phone call to the Swedish academy minutes after the announcement was made said.
"It was only after a fair bit of trepidation that we ended up telling our group, and then the world, that the universe was speeding up."
Dr. Perlmutter, 52 years old, heads the Supernova Cosmology Project at the University of California, Berkeley, Calif. Dr. Schmidt, 44, is the head of the High-z Supernova Search Team at the Australian National University in Weston Creek, Australia. Dr. Riess, 42, is an astronomy professor at Johns Hopkins University and Space Telescope Science Institute in Baltimore, Md.
The expansion of the universe was discovered in the 1920s. After that, it was widely believed that since the expansion rate depended on the energy content, a universe containing only matter would eventually slow down due to the attractive force of gravity.
So when the rivals teams presented their findings about an accelerating universe in 1998, cosmologists were taken aback. It's as if someone in a car "steps on the brake and finds the car accelerating" instead, said Olga Botner, a Swedish scientist who described the groups' research in a presentation to the media in Stockholm.
Both groups came to their conclusion by studying the light emitted by exploding stars known as type 1a supernovae. Such events are rare; the last that occurred in the Milky Way, for example, was in 1572. But when such stars explode, they release a huge amount of energy and can outshine an entire galaxy.
Type 1a supernovae have a similar amount of mass, so they release the same amount of energy and burn with similar brightness. The further away they are, the fainter they appear to us. By measuring their brightness, scientists can measure how far away they are.
The two teams found more than 50 distant supernovae in faraway galaxies whose light was weaker than expected. That suggested the improbable conclusion that the expansion of the universe must be accelerating.
Here Dr. Schmidt explains the Theory of the Expanding Universe at an Accelerating Rate
The Nobel committee said in its award citation.
"The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion."
But what could be causing the universe to expand at a faster rate? Scientists today speculate that the acceleration is driven by an enigmatic "dark energy" that makes up three-quarters of the universe. It was a result that Einstein, through a mistake, may have predicted in 1917.
Einstein initially hated the idea of an expanding universe. When he found that his equations didn't work for a static universe, he threw in a fudge factor—a hypothetical force that would fix the problem. He called it the "cosmological constant." (After Einstein came to accept the idea of the expanding universe he said the cosmological constant was his "biggest blunder.")
The present size of the Universe since the Big Bang is 13.7 billion years
Today, some astronomers theorize that the cosmological constant is a measure of the mysterious "dark energy" that, in turn, explains the accelerating universe.
Dr. Schmidt said.
"Thus far, every test we've made has come out perfectly logical with Einstein's cosmological constant."
Whatever dark energy might be, it seems to make up 75% of the universe. Another 5% is matter—stars, planets, trees, people. The rest is yet another mysterious thing astronomers have dubbed "dark matter."
Thus, the discovery made by the latest physics Nobel laureates prompted far more questions than it answered. The researchers "have helped to unveil a universe that is 95% unknown to science," the Swedish academy said.
COMMENTARY: I am so happy that American's Saul Perlmutter and Adam Riess, and one Australian Brian Schmidt won the 2011 Nobel prize for physics.
The Wilkinson Microwave Anisotropy Probe was launched on June 30, 2001. It is designed to operate for four years.
The Wilkinson Microwave Anisotropy Probe (WMAP) team has released the first detailed full-sky map of the oldest light in the universe on February 11, 2003. The following WMAP Map of the Universe shows the measurements with red indicates "warmer" and blue indicates "cooler" spots.
The patterns in the map are tiny temperature differences within an extraordinarily evenly dispersed microwave radiation bathing the Universe, which now averages a frigid 2.73 degrees above absolute zero temperature.
WMAP resolves the slight temperature fluctuations, which vary by only millionths of a degree. Analyses of this microwave radiation emitted only 380,000 years after the Big Bang appear to define our universe more precisely than ever before.
Measurements from WMAP resolve several long-standing disagreements in cosmology rooted in less precise data. Specifically, present analyses of the WMAP all-sky image indicate that the universe is 13.7 billion years old (accurate to 1 percent), composed of 73 percent dark energy, 23 percent cold dark matter, and only 4 percent atoms, is currently expanding at the rate of 71 km/sec/Mpc (accurate to 5 percent), underwent episodes of rapid expansion called inflation, the geometry of the Universe is flat1, and will expand forever.
Soon we will know how much dark energy there really is in the universe. Fermilab has built the world's first Dark Energy Camera, which "will survey the skies of the Southern Hemisphere and peer far back in time, allowing scientists to see galaxies as they were when the universe was only a few billion years old."
Fermilab technicians working on the Dark Energy Camera
The Dark Energy Camera is the size of a car and captures images with 570 megapixels. Created from 74 individual CCDs, the image sensor is over three feet in diameter. Even with the camera's sophisticated data-acquisition system, each photo is so big that it takes 17 seconds to capture.
Here's a time lapse video of Fermilab's Dark Energy Camera being built:
Courtesy of an article dated October 4, 2011 appearing in The Wall Street Journal, an article dated March 4, 2011 appearing in Timothy Martell, NASA's Legacy Archive for Microwave Background Data Analysis (LAMBDA), NASA's Chandra X-Ray Observatory
Comments