How It All Started: The Best-Ever Observations of the Origins of the Universe Hint at the Way It Will End
To understand the latest discovery about how the universe began, it helps to go back to the saga of the pigeon poop. In 1964, two radio astronomers at Bell Labs were working on an antenna for the new Telstar communications-satellite system. But no matter where Arno Penzias and Robert Wilson pointed the horn-shaped antenna, it picked up a hiss. Some kibitzers suspected that bird droppings in the antenna might be responsible, so the astronomers shoveled out the guano and shooed away the birds. Still the hiss. Scientists at Princeton University eventually traced the sound to a somewhat more distant source: the hiss was radiation left over from the cosmic fireball in which the universe was created. This "cosmic microwave background radiation" has cooled off in the 13 billion to 16 billion years since the big bang, but it still fills the heavens like a faint whisper of creation. It provides such a good clue to the conditions that created the universe that in 1992, when cosmologists first measured it in detail, they declared that they were seeing "the handwriting of God."
Last week scientists announced that they had performed what amounts to a detailed handwriting analysis. Using a telescope carried by a balloon above Antarctica, the "Boomerang" experiment produced the first-ever high-resolution map of the cosmic radiation, 40 times finer than anything done before. The measurements confirm theories of how the world began by offering "the first clear images of the embryonic universe," said astrophysicist Andrew Lange of the California Institute of Technology, co-leader of the Boomerang team with Paolo de Bernardis of the University of Rome. They also offer the strongest clue yet as to how it will end.
Lange's team had headed for Antarctica in late 1998 because of the breeze. Every year, around Christmas, a strange circular wind blows around the southern continent. When the launch window opened, the team inflated a monstrous sack of helium that eventually reached the size of a football stadium, lifted a two-ton telescope 23 miles high and then circled for 10 days before returning to its starting point. (Thus "Boomerang.") Aimed at the stretch of sky between the Earth below and the balloon above, the device was able to measure temperature differences in the cosmic microwave background of less than one hundred-millionth of a degree Celsius, using devices called bolometers. (These gadgets are cool enough to have inspired a limerick: "O Langley invented the bolometer/A very good kind of thermometer./You can measure the heat/ from a penguin bird's seat,/From a distance of half a kilometer.")
The cosmic radiation was born when the universe was about 300,000 years old, long before the formation of stars. At this tender age, the cosmos was 1,000 times hotter and 1,000 times smaller than it is today. Until then, it was so hot and dense that radiation was "tightly glued to matter," as physicist Wayne Hu of the Institute for Advanced Study writes in the journal Nature, and could not escape until the universe cooled down a bit. …