Interview with the author

How can we detect life on a planet we can’t visit?

Signs of life are written in a planet’s light, if you know how to read it. Light carries energy, and if the right energy hits a molecule, it swings and rotates. Just as stamps in a passport show what countries you’ve visited, the chemical make-up of an alien world’s atmosphere is encoded in light that has passed through that atmosphere and then arrived at our telescopes – including any signs of life on that world.

Are we on the verge of finding life?

On average, every fifth star in the Universe harbours a planet that could be like ours: rocky, not too hot, not too cold. The 200 billion stars in our Galaxy mean billions of possibilities. But we must figure out how not to miss signs of life on other worlds. I built the Carl Sagan Institute to connect ideas from different thinkers in different disciplines. That, along with using our planet’s history as our Rosetta stone, is critical to give us the best chance.

Where should we focus our attention?

For the first time in history, we have a telescope, JWST, that can catch enough light from potentially habitable worlds to explore them. We truly live in an amazing time. That is why I wrote this book now, because we are on the verge of discovering the answer to the 1,000-year-old question: are there other, alien Earths out there? Look up into the sky, find your favourite star and allow yourself the freedom to wonder. What if we are not alone in the cosmos?