Cleverly designed experiments are the key.

I’m struck again by the irony that spaceflight-conceived in the cauldron of nationalist rivalries and hatreds-brings with it a stunning transnational vision. You spend even a little time contemplating the Earth from orbit and the most deeply engrained nationalisms begin to erode. They seem the squabbles of mites on a plum.

Each of us is a tiny being, permitted to ride on the outermost skin of one of the smaller planets for a few dozen trips around the local star.

Atoms are mainly empty space. Matter is composed chiefly of nothing.

But down deep, at the molecular heart of life we're essentially identical to trees.

So those who wished for some central cosmic purpose for us, or at least our world, or at least our solar system, or at least our galaxy, have been disappointed, progressively disappointed. The universe is not responsive to our ambitious expectations.

What is called for is an exquisite balance between two conflicting needs: the most skeptical scrutiny of all hypotheses that are served up to us and at the same time a great openness to new ideas. If you are only skeptical, then no new ideas make it through to you. On the other hand, if you are open to the point of gullibility and have not an ounce of skeptical sense in you, then you cannot distinguish useful ideas from the worthless ones.