Universe is Finite, "Soccer Ball"-Shaped, Study Hints

Sean Markey
National Geographic News
October 8, 2003

What is the shape of the universe? The question has tantalized humankind since civilization first gazed toward the heavens.

Theories about whether space is finite or infinite, flat or curved have blazed in the firmament of scientific discourse with varying intensity over time, burning brighter or fading in the face of new data and competing ideas.

Now a new study of astronomical data only recently available hints at a possible answer: The universe is finite and bears a rough resemblance to a soccer ball or, more accurately, a dodecahedron, a 12-sided volume bounded by pentagons.

If proven by further evidence and scrutiny, the model would represent a major discovery about the nature of the cosmos.

"What makes it exciting now is it's not a matter of idle speculation," said Jeffrey Weeks, a freelance mathematician in Canton, New York, and study co-author. "There's real data to look at and the possibility of getting a definite answer."

Weeks, recipient of a MacArthur Fellowship or so-called "genius award," arrived at the model with a team of French cosmologists while studying cosmic background radiation observed by NASA's Wilkinson Microwave Anisotropy Probe (WMAP).

With a microwave antenna pointed into deep space and shielded from local interference emanating from the sun, Earth, and moon, the spacecraft has recorded the clearest soundtrack to date of the microwave radiation echo of the Big Bang, the event most scientists believe created the universe.

Cosmic Afterglow

Like the visible light of distant stars and galaxies, cosmic background radiation allows scientists to peer into the past to the time when the universe was in its infancy. Density fluctuations in this radiation can also tell scientists much about the physical nature of space.

NASA released the first WMAP cosmic background radiation data, collected since October 2001, in February.

Combing through those observations, Weeks and his colleagues found that the most telling information supplied by WMAP was, in fact, the resounding echo of what was missing. Density fluctuations on the largest scale were far weaker than expected, a gap Weeks and colleagues say is best explained by a finite universe.

To illustrate the concept, Weeks points to the analogy of an ocean and a bathtub. While the ocean (an infinite universe) can support 40-foot-long waves, a bathtub (the finite universe) is simply too small. The bathtub cannot support waves longer than the length of the tub itself.

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