Martin Rees Human Quotations

And we should keep our minds open, or at least ajar, to concepts on the fringe of science fiction. Flaky American futurologists aren't always wrong. They remind us that a superintelligent machine is the last instrument that humans may ever design - the machine will itself take over in making further steps.

The practical case for manned spacef light gets ever-weaker with each advance in robots and miniaturisation - indeed, as a scientist or practical man, I see little purpose in sending people into space at all. But as a human being, I'm an enthusiast for manned missions.

Perhaps future space probes will be plastered in commercial logos, just as Formula One cars are now. Perhaps Robot Wars in space will be a lucrative spectator sport. If humans venture back to the moon, and even beyond, they may carry commercial insignia rather than national flags.

Space doesn't offer an escape from Earth's problems. And even with nuclear fuel, the transit time to nearby stars exceeds a human lifetime. Interstellar travel is therefore, in my view, an enterprise for post-humans, evolved from our species not via natural selection, but by design.

It is astonishing that human brains, which evolved to cope with the everyday world, have been able to grasp the counterintuitive mysteries of the cosmos and the quantum.

Ever since Darwin, we've been familiar with the stupendous timespans of the evolutionary past. But most people still somehow think we humans are necessarily the culmination of the evolutionary tree. No astronomer could believe this.

A monkey is unaware that atoms exist. Likewise, our brainpower may not stretch to the deepest aspects of reality. The bedrock nature of space and time, and the structure of our entire universe, may remain 'open frontiers' beyond human grasp.

The next humans to walk on the moon may be Chinese. Only China seems to have the resources, the dirigiste government, and the willingness to undertake a risky Apollo-style programme. If Americans or Europeans venture to the moon and beyond, this will have to be in a very different style and with different motives.

Indeed, the night sky is the part of our environment that's been common to all cultures throughout human history. All have gazed up at the 'vault of heaven' and interpreted it in their own way.

From the growth of the Internet through to the mapping of the human genome and our understanding of the human brain, the more we understand, the more there seems to be for us to explore.

If you represent the Earth's lifetime by a single year, say from January when it was made to December, the 21st-century would be a quarter of a second in June - a tiny fraction of the year. But even in this concertinaed cosmic perspective, our century is very, very special: the first when humans can change themselves and their home planet.