The question that will decide our destiny is not whether we shall expand into space. It is: shall we be one species or a million? A million species will not exhaust the ecological niches that are awaiting the arrival of intelligence.

It's as great a part of the human adventure to invent things as to understand them. John Randall wasn't a great scientist, but he was a great inventor. There's been lots more like him, and it's a shame they don't get Nobel Prizes.

Many of the technologies that are now racing ahead most rapidly, replacing human workers in factories and offices with machines, making stockholders richer and workers poorer, are indeed tending to accentuate the existing inequalities in the distribution of wealth.

The marketplace judges technologies by their practical effectiveness, by whether they succeed or fail to do the job they are designed to do.

But now sustainability is such a political category that it's getting more and more difficult to think about it in a serious way. Sustainability has become an ornament.

Issues relating to global health and sustainability must stay high on the agenda if we are to cope with an ageing and ever-increasing population, with growing pressure on resources, and with rising global temperatures. The risks and dangers need to be assessed and then confronted.

As species are exterminated by shifting climate zones, ecosystems can collapse, destroying more species.

The dialogue around climate change can often become mired in gloom and doom, which is understandable given the topic.