Unexplained static from the edge of the universe

Astronomers announced Jan. 7 that they've just discovered a mysterious static coming from everywhere in the sky, apparently. It's coming from the edge of the universe. And they have no clue what it is.

Whoa! That's so 1960s. That's when Bell Labs radio astronomers Arno Penzias and Robert Wilson discovered the cosmic microwave background radiation – a constant hiss picked up by a microwave antenna they were testing. The hiss came from everywhere in the sky, and they wanted to get rid of it. But they couldn't. As it turns out, it represents the feeble afterglow of the Big Bang. And its discovery scored the two scientists a Nobel Prize.

It remains to be seen what this latest discovery means. (A more-formal presentation of the results appears here.) The team that announced it has sent out an SOS to the whiteboard-and-marker types – the theorists – to try to come up with a plausible explanation. But whatever the cause, the results present astrophysicists with something they dearly love: a new, inexplicable (for now) puzzle.

The story begins in July 2006, when a team of scientists launched a remarkable balloon into the skies over Palestine, Texas. Their project is called ARCADE.  It aims, among other things, to hunt for the vanishingly faint signatures of heat from the first stars that populated the early universe roughly a billion years after the Big Bang.

The balloon drags a 6,000-pound payload up with it. The payload? Seven sensitive radiometers kept at near absolute zero by 500 gallons of liquid helium, all encased in a special container known in the biz as a dewar. The radiometers scan the sky and measure the strength of the radiation they receive at several radio frequencies. The data are used to generate a map of radio sources that stand out against the cosmic microwave background.

Al Kogut, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., and the project's leader, dubs it "the flying cold tub." Cruising altitude: 120,000 feet.

Instead of the heat signatures they were hunting, "to our surprise we found an unexplained radio static ... that fills the early universe," Dr. Kogut says. It was much too intense to be the first stars, and even too intense to be the accumulated radio static from all of the galaxies in the radiometers' view.

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