Taking a major step toward nailing down the vital statistics of the cosmos, astronomers Wednesday unveiled a much anticipated, exquisitely detailed "ultrasound picture" of the baby universe when it was just 300,000 years old.

The feeble glow of the universe from that era, stretched to infrared wavelengths by its subsequent expansion, contains a fossil-like imprint of how the it behaved in the first instant of its existence. Encoded in this picture is the simple blueprint on which cosmic expansion, density of matter and other fundamental parameters of the universe left everlasting marks.

This rapid expansion would have ironed out any primordial curvature of space so that the universe is geometrically "flat." This means the universe is precisely balanced between perpetual expansion and ultimate collapse from the gravity of the matter within it.

"This is an intriguing result," astrophysicist David Spergel of Princeton University told SPACE.com. "The BOOMERANG experiment has confirmed an important test of the inflationary model. There have been hints for about two years, but the BOOMERANG data is the best evidence yet."

The results also independently confirm recent surprising observations that imply the universe is pervaded by a mysterious repulsive force. This force is said to emanate from the emptiness of space to push galaxies apart, making the universes rate of expansion speed-up. In light of the new findings, this "dark force" is probably required to balance out the total matter-energy content of the universe needed to make it "flat." Astronomers largely concede there is not enough matter alone in the universe to put it at the now-required critical density.

"This is the long-awaited result," says astrophysicist Mario Livio of the Space Telescope Science Institute. "Their new and much better data shows quite conclusively that the universe is flat and in agreement with the data from supernovas [which show the universe is accelerating]."

All this new information is gleaned from a snapshot view of a large portion of the sky. The shot was taken in microwave wavelengths as the telescope floated at an altitude of 22 miles (37 kilometers) over the dry Antarctic pole, offering a crystal-clear view of the infrared sky. The observations were made by an international team of over 30 astronomers led by P. De Bernardis of the University of Rome.

The telescope looked all the way back to a twilight-zone era before stars, galaxies and planets ever existed. All there was to look at was an empty sea of ripples created by sound waves, an imprint of the first instabilities in the fledgling universe. They set the foundation for the building of galaxies in vast filamentary clusters.

These ripples were caused by gravitational forces that compressed pockets of primordial plasma until they rebounded from the pressure of light, like squeezing a rubber ball. These oscillations created waves like the sound waves from the surface of a vibrating speaker cone. This set up peaks and troughs in space like the undulating surface of a backyard swimming pool. This surface appears as temperature fluctuations in the microwave background that give the 300,000-year-old universe a speckled appearance.

In the same way those waves created in a swimming pool depend on the size and geometry of the pool, the cosmic waves depended on the geometry of the universe.

A flat universe makes waves that are abundant at a very specific separation on the sky. Inflation predicts that the wave peaks should be no smaller than one degree apart on the sky (twice the full moons diameter) and this is exactly what BOOMERANG found. Larger separations would have indicated an eventually collapsing universe.

According to the Big Bang theory, the universe started as a hot and dense fireball and then expanded and cooled. When the universe was about 300,000 years old, it faded from dense hot plasma to a pitch-black vacuum that allows for light to travel freely. This makes up the cosmic microwave background seen today.

When it was accidentally discovered in 1965, the microwave background was found to be remarkably uniform across the sky. In 1992, NASAs Cosmic Background Explorer (COBE) satellite discovered temperature variations, or ripples, at very large scales that reflected density fluctuations in the primordial soup of particles of the early universe. However, COBE could only see blotches nearly as big as the Big Dipper's bowl. To understand the true initial conditions of the early universe astronomers needed to see much smaller-scale topography, like looking at hills instead of mountain chains.

Numerous other microwave background observations are under way. In fall of 2000, NASA will launch the Microwave Anisotropy Probe (MAP) to chart much more of the microwave sky. MAP has about the same angular resolution as BOOMERANG and will cover 100 times more sky than was analyzed in the BOOMERANG data. In 2007 the European Space Agency will launch the Planck Observatory to make a similar all-sky map.