字幕表 動画を再生する 英語字幕をプリント So admittedly, we don't have a lot of concrete information about black holes. We have a lot of ideas, but we've mostly been quite literally shooting in the dark when it comes to figuring out what would happen if you went in one. Now, some theoretical revelations open up a new line of thinking, and all I can say is whooo boy here we go--black holes and string theory, time to rock'n'roll! Let's review the pieces: black holes are objects in space that are seemingly infinitely dense and swallow everything, including all kinds of radiation, including visible light. Past their event horizon, or the point past which you can't escape their pull, they're so dense they seem to warp gravity. And theoretically, they have a point inside them called their gravitational singularity: the point where that density coalesces into its infinite-ness and space and time as we know them no longer exist. Ok, casual. Then we have string theory, which unifies our conflicting understandings of the quantum world and gravity. In the string theory, the particles we think make up the standard model of physics are actually all just the same kind of string, vibrating at different resonances to give each 'particle-like entity' its unique characteristics. Black holes are also gravitational puzzles, so string theory seems like a natural fit for helping us understand how they work. Because that's the thing about black hole singularities, too. The point at which time and space cease to exist has obviously never been physically observed, it's just the point at which our math breaks down. Which is also the point where we start to identify paradoxes presented by black holes, and the many theories that set out to resolve those paradoxes...start to get a little wild. We're still constrained by the math we DO have. The way we primarily try to describe the physics of the world is through the laws of conservation, things that can neither be created nor destroyed under the conventional laws of the observable universe...like information. In this context, information means quantum information--the characteristics of a particle that make it what it is. Its fingerprint, if you will. And black holes, those tricky guys, present problems because they seem to subvert at least one of these--the law of conservation of information. Resulting in the information paradox, first put forward by Stephen Hawking. See, black holes are supposed to swallow everything that gets too close because they're so dense, but Hawking showed that they're also radiating energy. This thermal radiation, which we now call Hawking radiation, means black holes could eventually waste away to nothing, radiating out all the energy and matter that went into them....but none of this matter would contain its original information, meaning all that information is just gone forever, violating that law of conservation. And this leads to many fun lines of inquiry. Since black holes were discovered in 1916, physicists have been trying to figure out what would happen if you went in one, like with your human body. Y'know, 'cause they're quirky like that. Theorists a few years back put forward a new idea that actually resulted in the identification of another related paradox. The prevailing idea has been the 'no drama' theory, where if you're an astronaut who crosses the event horizon of a black hole, you wouldn't notice. Until you reach the singularity, that is, and you are quite suddenly 'spaghettified' by the impossibly intense gravitational pull. Which sounds very pleasant indeed. But then where did you go? To try and rectify the information paradox, physicists have put forward a newer, more dramatic theory about what happens to you--the firewall. They argue that you, the astronaut, must be incinerated as you pass the event horizon and that's how your information is conserved. Cue the fuzzball. By replacing the particles in a black hole with strings, you get a theoretical black hole model called...a fuzzball. Very scientific. Instead of the membrane of an event horizon, past which you'd get pulled into a point of infinite density, the fuzzball model has no event horizon, and no singularity. It's...a fuzzy ball. A tangled ball of strings that looks a little more like a planet than our current typical imaginings of a black hole. And those strings, vibrating with the possibilities of multiple dimensions, make up a hot, vibrating extremely dense mass that would incinerate you on impact. This is where the string theory fuzzball model of black holes and the relatively new firewall paradox meet and may have common ground--some theorists think the firewall is the hot fuzzball. And are very put out that it took the rest of the physics community so long to catch up. But here's the thing. All of this is conjecture. Big conversations are still happening in the physics community about how to think about black holes and the many problems they pose. String theory is still just a theory. And the applications of string theory in this particular case are very general--in any of these models, we still don't have any clear way that the information of that astronaut entering a black hole is conserved and then recycled...but string theory is a fun--and useful--voice in the loud symphony that is theoretical astrophysics. While we're speaking, scientists are hard at work taking the first photo of a black hole that would totally change the way we think about all of this. So where's the photo, you ask? We've got a video all about that here. Don't forget to subscribe to seeker for all your black hole needs, and I'll see you next time on Seeker.