MadSci Network: Astronomy |

Posted By:

Area of science:

ID:

Hi.

This is an excellent question. I believe a totally satisfactory answer
would require a pretty intense study of General Relativity, plus lots of
tensor equations. The short form: Matter does not only exist in spacetime, it
*creates* spacetime. The density of matter (both magnitude and
distribution) sets up the boundary conditions for the Einstein equations.
[The Einstein equations are the equations that describe how matter distorts
spacetime and how matter responds to distorted spacetime.]
In effect, the density defines the metric, the "rulers" that measure spacetime.

Under proper conditions, it's possible to find a metric whose time-dependence implies a shrinking Universe. [Indeed, the conditions are quite simple. A uniform distribution of matter must either result in an expanding or contracting Universe, which means that spacetime would be shrinking.]

Try the links in the MadSci Library for more information on Astronomy.

MadSci Network, webadmin@www.madsci.org

© 1995-1998. All rights reserved.