NEWS FEATURE:
Our best view of the early cosmos
Alan Boyle, April 26, 2000 MSNBC

From December 1998: With Antarctica's Mount Erebus in
the background, scientists prepare to release a balloon
attached to Boomerang's 3,200-pound science payload,
seen at right.
 

BOOMERANG which stands for Balloon Observations of Millimetric Extragalactic Radiation and Geophysics was an experiment conducted during December 1998 and January 1999. For a little more than 10 days, a NASA balloon carried a 3,200-pound science payload around Antarctica at an altitude of 120,000 feet (almost 37 kilometers).

The payload included a specially designed telescope, with detectors cooled to nearly absolute zero (minus-459 degrees Fahrenheit). All this effort was aimed at mapping tiny variations in the cosmic microwave background radiation, which is thought to represent energy left over from the creation of the cosmos, 12 billion to 15 billion years ago.

The variations typically amount to only one-thousandth of a degree in temperature, but they contain the imprint of what the universe was like when it cooled to the point that protons and electrons could bind together to form hydrogen and helium, 300,000 to 500,000 years after the Big Bang, according to current scientific theories.

Those same theories dictate that there should be a wave pattern in those variations, like ripples on the surface of a pond or the oscillation of a sound wave. Such patterns would reflect the end of a primeval tug of war between gravity and explosive pressure and the beginning of the process that led to the formation of stars and galaxies.

The patterns first came to light in 1991, thanks to a NASA satellite called the Cosmic Background Explorer, or COBE. But scientists said Boomerang's cosmic ultrasound mapped the patterns 35 times more accurately than COBE, over 2.5 percent of the sky.

The first results from the $4 million project, involving 36 researchers from 16 organizations in Britain, Canada, Italy and the United States, were detailed in Thursday's issue of the journal Nature. Some of the principal authors discussed the findings Wednesday at a Washington briefing presented by NASA and the National Science Foundation.

These images represent the ultimate limit of our vision, Andrew Lange, a physicist at the California Institute of Technology who led the U.S. team, said in a statement. The enormous structures that they reveal predate the first star or galaxy in the universe.

Boomerang confirmed several scientific insights into the nature of the cosmos:
 

FLAT UNIVERSE

The measurements of the cosmic variations meshed with what scientists would expect of a structure that followed "flat," or Euclidean, geometry.

Obviously, that doesn't mean the universe is flat like a pool table. But it does mean that the universe was created without some kind of curvature that could lead to weird geometric distortions over long distances: Parallel lines will never cross, and the interior angles of a straight-line triangle will always add up to 180 degrees, just as the Greek mathematician Euclid declared 2,300 years ago.

That's reassuring to the physicists who come up with theories about the nature of the universe, because it confirms that they're on the right track and has a certain aesthetic appeal as well.

When cosmologists around the world hear of the Boomerang results ... they will have smiles on their faces, said University of Chicago astrophysicist Michael Turner.
 

INFLATIONARY UNIVERSE

The results are also consistent with theoretical models proposing that in the instant after creation, the universe inflated from a minute flicker to immense size. This is a twist on what used to be standard Big Bang theory, but such inflationary models are gaining increasing acceptance.
 

DARK MATTER, DARK ENERGY

Boomerang's measurements indicate that ordinary matter, known in astrospeak as baryonic matter, accounts for about 5 percent of the universe's content is measured by its gravitational effect, said Paolo deBernardis, an astrophysicist at the University of Rome, La Sapienza, and the Nature studys principal author.

That means that most of the universe consists of more exotic items: A type of "dark matter that has not been detected directly so far accounts for about 30 percent. And "dark energy" a baffling effect that counteracts gravity accounts for the other 65 percent. Such a conclusion meshes with earlier, no less bizarre results gleaned from the study of distant supernovae.

It's an extension of Copernicus, said co-author John Ruhl, a physicist at the University of California at Santa Barbara, in a reference to the once-revolutionary idea that Earth was not at the center of the universe. Now we're finding out that we're not made up of the dominant form of energy in the universe.

To account for this dark energy, physicists may have to patch up their equations with a cosmological constant a concept that Albert Einstein originally included in his theories but later discarded, calling it the greatest blunder of my life. Now, scientists think Einstein may have been right the first time.

Another implication of all this is that the expansion of the universe appears fated to speed up without end, continuing long after the last stars have burnt out.

CONTINUING MYSTERIES

Boomerang has left many questions yet to be answered, the researchers acknowledged. For example, physicists expected to see a strong second peak in the levels of background radiation, but that doesn't show up strongly in the experimental data so far. Ruhl speculated that the current margin of error in the data might have been too great to pick up the second peak, or that the scientific models might have to be tweaked to account for less of a peak.

A more thorough analysis of the Boomerang data is continuing, and further readings of the background radiation will be taken by such instruments as the Cosmic Background Imager, a specially built radio telescope in the Chilean Andes; the Microwave Anisotropy Probe, a NASA satellite due for launch this fall; and the Planck Surveyor mission, to be launched in 2007 with backing from NASA and the European Space Agency.

We're going to be basically compiling an atlas of the early universe, Lange said.

Ruhl said such efforts demonstrate that cosmology the study of our universe's past, present and future isn't just for theoreticians anymore. It's completely because of the technology revolution that it's becoming a data-driven science, he said.