Name: Nick M.
If the Universe is Geometrically "flat" (as believed by most
astronomers) how does a flat disk come from an explosion? In
addition, by definition the farther an object moves away from another
object, the less the gravitational force they have between each other.
Therefore from the Big Bang, which would have caused a RANDOM
distribution of the galaxies in the universe, why do we instead see
orderly clustered galaxies? There is no force of gravity to pull them
together because they would be travelling farther apart from each
other from the big bang. How can someone logically accept today's
While I am not an expert in cosmology, I do have an intense layman's
interest in it.
In the last decade cosmology has just become an observational science,
rather than a purely conjectural science (that's not necessarily bad, but
science ultimately must be in accord with experimental observations). I do
not think that there are good answers to your questions, yet. New observations
are requiring cosmologists to question whether the speed of light might have
been different in the early Universe(s). Ditto, the question of
The state of cosmology is in an exciting state of flux. High energy physics,
long considered far removed from astronomy and cosmology is reaching a state
of experimental and theoretical development that it is possible to create
the state(s) of matter that exists and existed inside stars and galaxies.
What goes around, comes around. The acceptance of any theory of cosmology
these days has to be tentative at best.
OK, first of all, when astronomers and cosmologists refer to the universe
being "flat," they don't mean that it has only two dimensions. They mean
that its geometry appears to be Euclidean (planar or "flat") rather than
being Riemannian (elliptical) or Lobachevskyan (hyperbolic). In layman's
terms, that means that in our universe, it appears that two parallel
straight lines are the same distance from each other along their lengths.
In an elliptical universe, straight lines would eventually meet; in a
hyperbolic universe, parallel lines would have one region of closest
approach, and diverge in both directions from there.
The distribution of mass in the universe after the Big Bang is a matter of
current investigation. There is no reason to expect that the distribution
of matter will be perfectly uniform; if you throw a water balloon at the
ground, the splat is not a perfect circle. Very small variations in the
distribution of matter shortly after the Big Bang would translate into
larger "clumpings" billions of years later.
Even if galaxies are traveling away from each other, their gravitational
fields still act on one another. In fact, though, current observations
indicate that galactic clusters are actively colliding with, engulfing, and
re-forming galaxies all the time. Gravity is a very important part of the
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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Update: June 2012