Gaze deep into the night sky, and space appears to extend infinitely far in all directions. Given such a view, it’s mind-boggling to think that space might be bounded. Yet, just as the flat-seeming Earth is in fact a sphere, infinite-seeming space may curve in on itself to close up into a compact shape. Recently, the debate over the shape of space took some new twists. In the Oct. 9 Nature, a team of mathematicians and astrophysicists proposed an exciting idea. The universe may have a particular finite shape, modeled on a 12-sided geometric object known as a dodecahedron, they propose. The same week, a second group of scientists announced findings that may refute that proposal.
Both groups have based their analyses on first-year data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), which in February produced a snapshot of temperature waves shortly after the Big Bang (SN: 2/15/03, p. 99: Cosmic Revelations: Satellite homes in on the infant universe). These waves produced a puzzle: One of the longest wavelengths, known as the quadrupole, is less powerful than expected. This is like saying, in an analogy with sound waves, that the universe doesn’t play low notes.