Janna Levin is the Claire Tow Professor of physics and astronomy at Barnard College of Columbia University, and has contributed to an understanding of black holes, the cosmology of extra dimensions, and gravitational waves in the shape of spacetime. She is also director of sciences at Pioneer Works, and the host of Scientific Controversies.
1. You wrote your book Black Hole Blues about LIGO before gravitational waves were detected, which is awesome. Are there any unverified experiments that you have your eye on next? First off, so many people told me not to write the book — because LIGO either flat-out was not going to succeed, or if it did, it wouldn’t be for another 4–5 years. So I ended up writing the book very much from the Climbing Mount Everest point-of-view — it was about the struggle, not knowing if you were going to succeed, and that for me was so much more exciting. Science is really about the climb, so to speak. The other experiments that are like that right now include Event Horizon Telescope, in that same area: black holes. Event Horizon Telescope is an attempt to literally resolve the shadow of the event horizon of the black hole.
2. What would be the single most exciting cosmological theory to see proven within your lifetime? It would be incredible to really understand how black holes evaporate through Hawking radiation. It would be amazing to see if black holes really evaporated, if they exploded at the end of their lives, and if there was some sort of string theory understanding for what happened to everything that once fell into a black hole.
3. We’ve been thinking a lot about the Fermi paradox. If The Great Filter is real, what side of it do you think humans are on? Are you asking if we’re about to go extinct? Or are we on the opposite end of long survival? You know, I think there may be more than one Great Filter, and so I think we’re on the other side of one but maybe not on the other side of the other. And this is totally conjectural — people always ask me “What do you believe?” and I’m always quick to say I have to be agnostic as a scientist. It’s not about what I believe. But, best instinct, I suspect that we’re on the other side of this very rare event, which is probably the transition from single-cell organisms to multi-cell organisms.
4. Should humans become an intergalactic species? Should. The moral imperative should? I like exploration. You know, if we could do it, we’d have to do it. The question is, would we do it responsibly? And, you know, the answer to that is probably only some of the time. But yeah, of course we should. Also, the stuff we send to other planets often hasn’t been sterilized against the possibility of depositing human microbes on the moon or on Mars. There have probably been extremophile microbes on things that we’ve sent into the solar system.
5. String theory, multiverse theory, holographic universe theory — what gives? If you had to put your money on a mind-bending theory- which one is it and why? They are all in some sense due to string theory. String theory is the theory that led to the idea of the multiverse. The multiverse is really the idea that there is a ginger root of space time — each root is its own big bang. I don’t think they’re competing ideas, is my point. They may all be true, or some of them may be. I think holography is really interesting and really profound. It’s also why people start to say things like “maybe there’s no interior of the black hole.” Maybe the feeling that we live in a 3D world is only an illusion.
