We will never be able to see the birth of the universe, when all was an opaque soup of subatomic particles and radiation. But two balloon-borne experiments have done the next best thing: Instruments have snapped detailed images of the cosmos as it looked when it was just 300,000 years old. They may not look like much, but to scientists these baby pictures could not be lovelier. The pictures strongly indicate that the overall shape of the universe is flat, exactly as predicted by the latest version of the Big Bang theory.
Two competing research teams made the pictures by lofting telescopes— called MAXIMA and BOOMERANG— into the stratosphere. There the instruments could measure the cosmic microwave background, the ubiquitous radiation that emerged when the infant universe had cooled enough for light to travel freely. Hot and cold clumps of matter, which later evolved into giant clusters of galaxies, left faint but distinct imprints in the primordial glow.
MAXIMA measured a patch of sky 22 times wider than the full moon while flying 130,000 feet over east Texas for seven hours. BOOMERANG observed a larger area of the southern sky during a 10 1/2-day circuit around the south pole. Both experiments revealed the features in the microwave background in unprecedented detail. More important, they showed those features have not been distorted, even though the radiation has been journeying through space for billions of years.
"That tells us that light travels in straight lines," says astrophysicist Paul Richards of the University of California at Berkeley, head of the MAXIMA team. "There is only one kind of space in which you can have two parallel lines that will never meet, and that is a flat, continuously expanding universe." That's good news for doomsday worriers: Such a universe will grow forever, never falling back and obliterating itself in a big crunch.