Expert: Jayendra Upadhye - 8/8/2005

Question
Can you tell me about these dark holes and how do they effect the universe?  

Answer
Edward,
If you mean "black holes" when you say dark holes..
then ..
1 - ordinary Stars like our sun form "white dwarf" stars when they
   grow old. When their central fires (nuclear fusion of hydrogen
   to helium) stop after exhausting of all hydrogen, they
   contract under gravity and "stabilize" when they have become
   quite small and have reached a surface temperature
   equalling that of "white heat".

2 - More massive stars get crushed even more by their self gravity.
   That results in their becoming neutron stars, where all matter
   is "all neutrons" only. Their density is very very high.
   They spin very fast and emit beams of enrgy, and are called
   pulasrs. Pulsars form after the star goes supernova.

3 - Even more massive stars go supernova, but the "pressure  
   balance" is not sustainable as gravity is too strong, and the
   star "implodeds on itself and becomes a point!
   That is the black hole.
   All black holes have event horizons about themselves (spherical
   nonzero volume.
   Things outside of the horizon are normal.

Black holes will be a significant contributing factor in all "dark matter" (unaccounted for but felt by its gravity).

The nucleii of spiral galaxies have been observed to have monster black holes with millions of solar masses.

In the end they may contribute to the slowing down of the universe and the starting of the "cosmic crunch".

In the virgo cluster of galaxies, we have what is called the "great attractor"..something ultimate in size and pull but which is "dark".

It is pulling all galaxies around it, including our's towards it.
we will reach there in 10s of billion years, (and find out!)

Jayen