Recipe for the Universe - Just Six Numbers

The galaxy pair NGC 6872 and IC 4970 indicate the vastness of the Universe. Light from the bright foreground star has taken a few centuries to reach us; the light from the galaxies has been travelling for 300 million years. The Universe must be this big - as measured by the cosmic number N - to give intelligent life time to evolve. In addition, the cosmic numbers omega and Q must have just the right values for galaxies to form at all.

Photo - European Southern Observatory

This is a startling conclusion. The very hugeness of our Universe, which seems at first to signify how unimportant we are in the cosmic scheme, is actually entailed by our existence! This is not to say that there couldn't have been a smaller universe, only that we could not have existed in it. The expanse of cosmic space is not an extravagant superiority; it's a consequence of the prolonged chain of events, extending back before our Solar System formed, that preceded our arrival on the scene.

This may seem a regression to an ancient 'anthropocentric' perspective - something that was shattered by Copernicus's revelation that the Earth moves around the Sun rather than vice versa. But we shouldn't take Copernican modesty (some-times called the 'principle of mediocrity') too far. Creatures like us require special conditions to have evolved, so our perspective is bound to be in some sense atypical. The vastness of our universe shouldn't surprise us, even though we may still seek a deeper explanation for its distinctive features.

Cosmology comes of age

The physicist Max Born once claimed that theories are never abandoned until their proponents are all dead - that science advances 'funeral by funeral'. But that's too cynical. Several long running cosmological debates have now been settled; some earlier issues are no longer controversial. Many of us have often changed our minds - I certainly have.