Dartmouth College physicist and astronomer Gleiser claims that while there are limits to what we can learn about the universe, every dead-end reveals new avenues of inquiry. He explores this paradox in The Island of Knowledge: The Limits of Science and the Search for Meaning.

What first sparked your idea that no matter how much we search, we can never know all there is to know about our universe?

I think it was always in the back of my mind. It seems presumptuous to me that we humans, with our finite brains, could actually know everything. Then about three years ago I was at a conference where they invited me to talk about the laws of nature. And that provided a perfect context to go ahead and think about it.

The cutting edge of physics seems focused on things we can’t see, let alone measure, like superstrings and multiverses. Are theories like these pushing at the edges of what we know?

This book is intended to be a grounding exercise. If you cannot get any data to test a theory, I believe it cannot be considered a physical theory. I think it’s wonderful to have these great, ambitious ideas, but we have to listen to nature. We have to be extremely careful about how to incorporate new ideas in the scientific enterprise.

Your book talks primarily about the physical sciences. Should we expect the same limits in biology?

Well, with cognitive science, I think there are limitations to how much knowledge we can acquire about intelligence and the mind. There may be some hybrid of human and machine 300 years from now that could understand what consciousness means for us humans, but right now, we can’t. With biology, it’s a little better. Look at proteins. They’re extremely complex machines, but they’re also something we can isolate and study. You can’t do that with the universe because you can’t look at the universe from inside out. And you can’t do that with the mind either because we can’t get outside ourselves to see exactly who we are.

Do scientists react positively to the idea that there are some questions that will never be solved, and that they must always be prepared to change direction?

I think it can be liberating. We are very much a product of our curiosity—and our short-sightedness. There are questions we can ask now that, 100 years ago, we didn’t even contemplate the possibility of. Sometimes a new tool will open a whole new universe, like the telescope and the microscope did. The notion that we can know everything, that everything is understandable, is a pretty heavy demand on our creativity. We should be humble enough to understand that there will always be something new out there. The way knowledge advances is by finding mistakes; we need to be wrong to know what questions to ask next. To me, the fact that there is this element of surprise, that we can’t be sure exactly if we’re going in the right direction, is a wonderful thing.