“People think of black holes as dense objects, and they get caught up in the ‘monster truck’ aspect, that they destroy things,” Levin says in Episode 442 of the Geek’s Guide to the Galaxy podcast. “And I think that it detracts from some of the more eerie and austere and gorgeous aspects of this very strange phenomenon.”
A century of sci-fi shows have conditioned us to think of black holes as whirlpools in space, violent maelstroms that reach across the void to suck in passing starships. But Levin says the reality is much different, and that you might fall into a black hole without even realizing it.
“If you were in empty space with complete darkness, and you were right outside a black hole, you wouldn’t know it was there,” she says. “And if you crossed the event horizon, it would be completely undramatic. You could float right across, and not really realize anything was happening, because there’s nothing there.”
Despite their fearsome reputation, black holes can be safely manipulated with gravity and magnetism, and it might even be possible to draw power from them, though doing so won’t be practical any time soon. “I once tried to imagine what it would take for a black hole battery to power New York City,” Levin says. “I think I concluded we would have to use all the resources in the solar system, essentially. Maybe we’d have to make it out of the moon, or a giant Earth-sized magnet. It would be very, very hard to get a lot of power out of it.”
Another possible use for black holes would be to see beyond your lifespan. A person who flew into a supermassive black hole could survive for as a long as a year, and would still be able to receive messages from outside. Due to time dilation, those messages could reveal the entire sweep of future history.
“If you knew you had a year to live, but wanted to see your grandchildren born, you could go on this epic journey, so that your children have time to grow up, have their children, and you get to see your grandchildren born,” Levin says.
Listen to the complete interview with Janna Levin in Episode 442 of Geek’s Guide to the Galaxy (above). And check out some highlights from the discussion below.
Janna Levin on publishing:
“Everyone [at the publisher] was really excited about the concept of this sweet little book, and I think once it arrived, we were all delighted with how tiny it is. I think it’s really a special attribute. Nobody said [it should be longer]. My people are really decent folk. I find that they really believe in the book as the book should be, and they don’t buckle to that kind of psychology, mercifully. Otherwise I don’t think I’d get anything published, if commercial appeal was—I mean, do people really think, ‘Oh, I’d love a book on whether the universe is infinite or finite. And maybe we could have a novel about mathematicians’? So I feel very fortunate to have those collaborators.”
Janna Levin on Pioneer Works:
“I am the director of sciences there—I started the science studios there—and we have a lot of live events, or we used to, pre-pandemic. We would have 1,200 people shoulder-to-shoulder in a sweltering hot hall—a beautiful, three-story-high old ironworks factory—for a conversation on animal consciousness, or many-worlds, or a conversation with Richard Dawkins. Of course we can’t do that right now, and maybe won’t ever be doing that again. That just might be something we’ll look back on in movies and think, ‘Oh my gosh, can you imagine? People shoulder-to-shoulder like that?’ … The surprising thing to us was that there was such a big audience for it. We weren’t sure we would get anybody showing up when we started.”
Janna Levin on black hole weapons:
“If you put a spinning black hole in a magnetic field, it will create tremendous havoc. The jets are basically like giant ray guns, where high-energy particles—X-rays, gamma rays—are being flung along these magnetic fields, creating thin jets that then break out of the galaxy and can punch into other galaxies—and we’ve actually observed that—destroying, presumably, any exoplanets that would be in that part of that galaxy and any sentient life that was trying to emerge there. So you do not want to be in the line of fire of a jet, because with it would come all the attendant biological consequences of being struck by lots of radiation. … [Aiming those jets] is not impossible, but it’s pretty tricky.”
Janna Levin on detecting black holes:
“It could be a real navigational hazard. How would you know you were driving right into one? You might notice because you were not going on the path you had intended, because your engines were no longer successfully keeping you on track and you were drifting toward something, and you would start to notice you were off course. So that would be a way to notice it, but if you happened to be heading straight for it, and it was completely un-illuminated by any background light, you wouldn’t necessarily know. … If you were floating near enough, you could conceivably hear it, even in vacuum, because your eardrum would oscillate in response to the [gravitational] waves more readily than the rest of you.”