A cosmic hall of mirrors

Featu September 2005

Most astronomers think that the universe is infinite, but recent
measurements suggest that it could be finite and relatively small.
Indeed, as Jean-Pierre Luminet describes, we could be living in an
exotic universe shaped rather like a football

At a Glance: Cosmic topology

• There are three possibilities for the curvature of the universe: space
can be flat, spherical or hyperbolic
• The geometry of the universe depends on its curvature and also on its
topology, which governs the way space is connected and so determines if
it is finite or infinite
• Measurements of the cosmic microwave background constrain the
curvature of the universe and provide hints about its topology
• Recent data suggest that the universe might be multiply connected,
like the left- and right-hand sides of the screen in a computer game
• Since the early 1990s the number of cosmo-topologists around the world
has grown to more than 50

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http://physicsweb.org/articles/world/18/9/3/1