Should we find a second form of life right here on our doorstep, we could be confident that life is a truly cosmic phenomenon. If so, there may well be sentient beings somewhere in the galaxy wondering, as do we, if they are not alone in the universe.

Until now, physical theories have been regarded as merely models with approximately describe the reality of nature. As the models improve, so the fit between theory and reality gets closer. Some physicists are now claiming that supergravity is the reality, that the model and the real world are in mathematically perfect accord.

It may seem bizarre, but in my opinion science offers a surer path to God than religion.

The temptation to believe that the Universe is the product of some sort of design, a manifestation of subtle aesthetic and mathematical judgment, is overwhelming. The belief that there is "something behind it all" is one that I personally share with, I suspect, a majority of physicists.

Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that NASA's budget is too small for the job.

Wheeler hopes that we can discover, within the context of physics, a principle that will enable the universe to come into existence "of its own accord." In his search for such a theory, he remarks: "No guiding principle would seem more powerful than the requirement that it should provide the universe with a way to come into being." Wheeler likened this 'self-causing' universe to a self-excited circuit in electronics.

The secret of life does not lie in its chemical basis . . . Life succeeds precisely because it evades chemical imperatives.