The gravity that you feel from an object depends on two things: how much stuff is in that object - how much mass it has, and how close you are to it. PHIL: Sure! What makes a black hole a black hole is its intense gravity. So can we start with an overview of what makes a black hole a black hole? PHIL: Oh my pleasure, I'm really happy to support the museum.ĮRIC: So it turns out a lot of people ask us this question only having heard of black holes as awesome, powerful things in space, and not really knowing what they are. Plait, thanks so much for being here on Pulsar. Phil Plait, author of Death From the Skies: These Are the Ways the World Will End. Could the earth ever be destroyed by a black hole? Joining me is the person I usually think of when I'm contemplating planetary annihilation: the Bad Astronomer, Dr. And today we're going to put our planet in peril by answering a question we get with surprising frequency. Or if you do, at least you should also worry about literally everything else as well.ERIC: From the Museum of Science in Boston, this is Pulsar, a podcast where we search for answers to the coolest questions we've ever gotten from our visitors. So what I’m trying to say is don’t worry about black holes. And it doesn’t help that astronomers like to play coy when asked about them either, often suggesting, “Maybe!” when they instead should have said, “There is absolutely no reason to think so.” Black holes are mysterious-or rather they seem mysterious. I know nobody asked, but I blame the media. It takes something with the density of a black hole to trap light, but it only takes the gravitational pull of, like, three Earths to keep us trapped forever. And even our best rockets have no hope of escaping a Jupiter-sized planet. We have a hard enough time “escaping” Earth’s gravity. And all of those are millions of times more abundant than black holes.Īnd as for the whole “you can never escape” thing. Even a baseball in low Earth orbit has the kinetic energy of a freight train at cruising speeds. A small- to medium-sized asteroid is more than big enough to smush you. Falling into one is indeed a death sentence-after all, even light can’t escape! But I got news for you-falling into a star ain’t great either. Earth would keep going (without us or perhaps with our frozen corpses) around the Sun in the usual 365-day year.Īctually stars are way more dangerous! Our new black hole won’t give you a sunburn or irradiate our astronauts.īut black holes are dangerous. In fact, if you replaced the Sun with a black hole of the same mass, nothing would change (other than we’d all freeze to death). So, as long as you don’t intentionally aim for one, you’re fine. Above the event horizon (the point at which light cannot escape), they play by all the same rules as everything else-i.e., in order for you to fall in you’d have to be on a collision course with it already or it’d have to break some conservation laws. Just because we don’t completely understand them doesn’t mean that everything is possible. Once you cross the event horizon all bets are off as to what they’re like inside.īut none of that means they’re magic death magnets that will rip the Sun from the sky and gobble up Earth. The math you need to describe them is pretty complex. Weird stuff happens to time due to their insane gravity. They warp space enough to fold it in on itself. Modern theories include the idea that our entire existence is a holographic projection onto the event horizon of a black hole. Heck, one of the shows playing right now includes a trip through a black hole that connects two points in space, one of which is inside our solar system-and it’s not totally unreasonable. Most of the interest is positive, but it’s become apparent there’s also quite a bit of anxiety about black holes, too-stemming mainly from the sentiment that they are like giant roombas that move around and suck things up-and that we might get consumed by one and die.Ĭrazy oddball theories about black holes have been around for about as long as we’ve known about them. With it has come a corresponding swell in questions, including the “Why take a picture of a black hole?” topic we covered last week. There’s been a very welcome bump in interest surrounding black holes since the recent picture dropped. *unless you’re very bad at flying your spaceship.
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