For many, to live in a universe that may have no purpose, and no creator, is unthinkable.

The root cause of the looming energy problem - and the key to easing environmental, economic and religious tensions while improving public health - is to address the unending, and unequal, growth of the human population. And the one proven way to reduce fertility rates is to empower young women by educating them.

The fact is that people would rather cling when they're afraid of something to a priori beliefs than rather open their minds about it.

Organized religion, wielding power over the community, is antithetical to the process of what modern democracy should define as liberty. The sooner we are without it, the better.

We all trust each other to some extent. We have to rely on experts to some extent, but we should learn to be sceptical.

The ultimate arbiter of truth is experiment, not the comfort one derives from one's a priori beliefs, nor the beauty or elegance one ascribes to one's theoretical models.

If our species is to survive, our future will probably require outposts beyond our own planet.