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Name: Nick M.
Status: educator
Age: 30s
Location: N/A
Country: N/A
Date: 2001-2002


Question:
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 cosmology?


Replies:
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 gravitational forces.

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.

Vince Calder


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 cosmos.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois



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