Bernhard Kuemel wrote:
Hi sa, sp!
A friend learned in school that 69! is bigger than the number of
atoms in the universe. "Nonsense!" I said, "The universe is
infinite, so it has infinite atoms."
After some research it turned out that it is unknown if the universe
is finite or infinite...
Physics News Update -- Number 685, May 12, 2004
by Phil Schewe and Ben Stein
Our Universe Has a Topology Scale of at least 24 GPC
Our universe has a topology scale of at least 24 Gpc, or
about 75 billion light years, according to a new analysis
of data from the Wilkinson Microwave Anisotropy
What does this mean? Well, because of conceivable
hall-of-mirrors effects of spacetime, the universe might
be finite in size but give us mortals the illusion that it is
infinite. For example, the cosmos might be tiled with
some repeating shape, around which light rays might
wrap themselves over and over ("wrap" in the sense
that, as in video games, something might disappear off
the left side of the screen and reappear on the right
A new study by scientists from Princeton, Montana
State, and Case Western looks for signs of such
"wrapped " light in the form of pairs of circles, in
opposite directions in the sky, with similar patterns in
the temperature of the cosmic microwave background.
If the universe were finite and actually smaller than the
distance to the "surface of last scattering" (a distance
that essentially constitutes the edge of the "visible
universe," and the place in deep space whence comes
the cosmic microwaves), then multiple imaging should
show up in the microwave background.
But no such correspondences appeared in the analysis.
The researchers are able to turn the lack of recurring
patterns into the form of a lower limit on the scale of
cosmic topology, equal to 24 billion parsecs, a factor of
10 larger than previous observational bounds. (Cornish,
Spergel, Starkman, Komatsu, Physical Review Letters,
upcoming article; contact Neil Cornish, 406-994-7986,
Also see Ned Wright's Cosmology Tutorial
WMAP: Foundations of the Big Bang theory
WMAP: Tests of Big Bang Cosmology