Scientists are human. We have our blind spots and prejudices. Science is a mechanism designed to ferret them out. Problem is we aren't always faithful to the core values of science.

If we have the power to turn another planet into Earth, then we have the power to turn Earth back into Earth.

Private enterprise can never lead a space frontier. It's not possible because a space frontier is expensive, it has unknown risks and it has unquantified risks.

We're quite happy with our Big Bang description of cosmic origins. But actually, the Big Bang accounts for what happened only after the beginning. The beginning itself, and especially what happened before, remains the biggest mystery of all.

If the only time you think of me as a scientist is during Black History Month, then I must not be doing my job as a scientist.

If the Sun exploded, we wouldn't know about it for 8 minutes and 20 seconds. Light and gravity take that long to reach us. Then we would vaporize.

Darwin's theory of evolution is a framework by which we understand the diversity of life on Earth. But there is no equation sitting there in Darwin's 'Origin of Species' that you apply and say, 'What is this species going to look like in 100 years or 1,000 years?' Biology isn't there yet with that kind of predictive precision.