The Beginnings of the Universe

http://www.sunspot.net/technology/bal-te.cosmos12feb12,0,4178250.story?coll=bal-home-headlines

Astronomers unveiled yesterday the most detailed picture ever made of the infant universe, a snapshot that solves some of mankind's oldest riddles - from when the first stars began to shine to how the universe will end.

The eerie image, compiled by a NASA space probe in a lonely orbit on the dark side of the moon, shows the universe as it was just 380,000 years after the big bang got everything started.

"This picture is worth more than a thousand words," said David Spergel, a Princeton University astrophysicist who is part of an international team that announced the results yesterday in a news conference at NASA headquarters in Washington.

The most startling finding, astronomers say, is that the first stars ignited only 200 million years after the big bang, much earlier than they originally thought.

"They have first evidence for the end of the dark ages," said Michael Turner, an astrophysicist at the University of Chicago.

The results also add to existing evidence that the universe will meet its end with a whimper, expanding forever until our galaxy, the Milky Way, is alone in a sea of darkness.

In announcing their findings, the scientists displayed an image that looks like a tie-dyed T-shirt design, an oval of blues, greens, yellows and reds representing infinitesimal temperature differences that existed across the universe long before the stars, planets or any other heavenly bodies in the sky were formed.

The "hot spots" represent clumps of primordial matter that evolved into today's galaxies.

Scientists created the image with data from NASA's Wilkinson Microwave Anisotropy Probe (WMAP), whose twin telescopes make a complete sweep of the sky every six months. The spacecraft, launched June 30, 2001, measures cosmic microwave background radiation, a spectrum of light often described as the afterglow of the big bang. It's invisible to the naked eye and even to the powerful Hubble Space Telescope, although it does show up as "snow" on TV sets in fringe reception areas.

To cosmologists, this microwave radiation is the sand of time, capturing the footprint of every major event in the early history of the universe.

"It's an extremely valuable fossil," said Charles Bennett, an astronomer at the Goddard Space Flight Center in Greenbelt and leader of the team.

The results confirm and flesh out puzzling scraps of evidence about the cosmos that astronomers have gathered during the past decade with instrumented balloons, satellites and the Hubble telescope.

The probe has made the most accurate calculation yet of the universe's age: 13.7 billion years, a number accurate to within 200 million years - stopwatch precision in the world of cosmology.

The probe is also confirming astronomers' suspicions that the cosmos is a strange and quirky void dominated by powerful and thus far mostly unseen forces.

The new findings "are making solid this crazy universe we appear to live in, full of dark matter and dark energy," said Turner. "Now we have to figure out what it is."

Dark matter, as far as scientists can tell, exerts strange gravitational influences, while dark energy is a form of anti-gravity propelling the universe apart at an ever accelerating rate.

In fact, the measurements made by the spacecraft show that only 4 percent of the universe is composed of the familiar atoms that make up everything we can see and feel. Twenty-three percent is dark matter, and 73 percent is dark energy, according to data provided by the probe.

The NASA team's results, which have been submitted to The Astrophysical Journal, were eagerly awaited by the world's cosmologists.

"Every astronomer will remember where they first heard the results from WMAP," said John Bahcall, a scientist with the Institute for Advanced Study in Princeton, N.J.

Anne Kinney, director of NASA's astronomy and physics division, agreed. "It will change the way we think about the universe," she said at yesterday's news conference.

Measurements from the spacecraft will help astrophysicists quickly examine a variety of existing theories about the universe's early moments and throw out the ones that don't match the data.

"It's kind of like getting the teacher's edition of your textbook," said astronomer Adam Reiss of the Space Telescope Science Institute in Baltimore. "Now you can check all the answers."

The journey to yesterday's discoveries began by accident in 1965 when two Bell Laboratories scientists heard what they thought was static on their radio telescope. Arno Penzias and Robert Wilson initially thought their instrument had been fouled by pigeon droppings, but their subsequent investigation led them to the discovery of background microwave radiation - and a Nobel Prize.

It wasn't until 1992 that a NASA probe called COBE made the first crude image of this fossil light, which one scientist on the team likened to peering into "the face of God."

But COBE's results were crude compared with NASA's latest effort, which Bennett once compared to putting two nearly equal cups of sand on a scale and determining which is short a single grain.

To measure the exquisitely subtle temperature variations across the microwave veil, engineers had to eliminate forces that might interfere with the probe's delicate thermometer, Bennett said. So the craft's on-board electronics were designed to operate without a heater in the bitter cold of space.

To get away from Earth's influences, NASA parked the WMAP satellite a million miles away on the far side of the moon.

"The Earth is like a blast furnace compared to the signal that we wanted to measure," Bennett said.

The probe will continue to collect data for three more years. Scientists such as Reiss still have plenty of questions, such as why the lights were turned on some 800 million years earlier than scientists had imagined.

"How did the universe get its act together that quickly to go from congealed soup to stars?" he asked.