For a long time there was a discrepancy between the age of the universe determined by linear expansion (~12 billion years) and its age based on the age of its stars (~15 billion years). That has now been apparently resolved by the accelerating universe (but do not ask me how- that is just what I read).

The story goes that since the early universe was expanding rather slowly compared to now, we can trace back to the big bang using a nonlinear curve to find that the universe is actually 15 billion yeras old, or more. One analysis puts it at 30 billion years. So that is an indication of the approximations involved.

When the universe age was thought to be much less than the age of the oldest stars, that was taken as evidence of black holes suddenly exploding into a sub-universe, which would lead to the universe expansion we are talking about. The sub-universe would intermingle with the stars already in the old universe, and so on. But that hypothesis is now gone from the scientists bookself because of the new finding that the expansion of space is speeding up.

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Regarding the infinite universe- we have no idea how big it is. If inflation theory is correct, we see only a tiny speck of the whole universe.

Most physicists seem to believe that the universe is huge but finite, and that it turns back on itself, so that light in a sense just goes around in circles. But the circles are so huge and the universe so young (BTW, that is why the night sky is dark) compared to its size, that we will never see the returning light, at least not for at least another 1,000 billion years.

If the string cosmologists are correct, we will experience another big bang long before that. However, it seems that we have reacheed diminuishing returns for understanding the universe. As far as I can tell it's all metaphysics from now on.

Regards,

Richard

• The latest estimate that is widely accepted is btn 12-15 billion - harvey1 - April 10, 2002 - 15:29 UTC