Seth Lloyd - What Happens in Black Holes?

Seth why are black holes such an important part of modern physics where it becomes like a laboratory even though we can never get to them approach them in reality but it becomes such an important laboratory for discerning physical laws yeah black holes are things that are so dense that light when it falls in can't escape it classically nothing can escape it Stephen Hawking figured out quantum mechanically maybe stuff can escape but black holes represent in some sense the extreme of gravitational physics they curve space-time so much that the ordinary behavior of light and matter becomes extremely extraordinary moreover at the center of a black hole is what's called a singularity it's a place where the gravitational fields are so strong that all the known laws of physics break down so trying to contemplate a black hole is like contemplating the edge of the universe what specifically what are the some of the specific questions we can ask about black holes Stephen Hawking showed that black holes are not entirely black they're kind of gray because of quantum mechanical tunneling as it's called they can actually radiate out of particle so electron hole pairs created out of nothing right at the edge of the black hole part of it falls into the one of the particles falls into the black hole the other escapes to affinity and the one that fell in have negative energy so it takes energy away from the black hole from the black hole radiates everything all around us is full of so-called virtual particles pairs of electrons and positrons that come out of nothing and then return to them but in the presence of a black hole one of the particles can have negative energy so let's say the positron has negative energy and falls into the black hole and now the electron has positive energy it's liberated and I can escape to infinity and the net effect of this is that the black hole is giving up radiation it's as if the electron had escaped from the well so this is Hawking's theory of how black holes can lose mass and a very interesting question has come up over the last 30 or 40 years about whether information can escape from a black hole as well because normally we say information can only go at the speed of light light can't escape from a black hole so information can't escape from a black hole that's the usual picture of black holes but maybe just maybe because of some funky quantum mechanical effect these electrons and positrons that are escaping from the black hole maybe they contain somehow the information about what's been going on inside the black ball and how the black hole is made and so what are the different theories that that that are contrasting with each other so um right now there is a theory in string theory called the firewall which basically says man if something falls into a black ball that's bad news but we really believe that information is never lost so the firewall is this thing made out of fire like a wall right outside the horizon of the black hole that prevents anything from falling in and thereby keeps the information outside of the black ball so that's one way you could actually and preserves the the concept of that information can you can't be lost that's right this comes from string theory because string theorists believe very fervently that information has never lost for reasons I won't go into you asked so another possibility is well another possible is the information falls in the black hole and then that's it this is what Bill Unruh says he says it gone it goes away it never comes out suck it up right that's another possibility a third possibility is due to a phenomenon related to what's called teleportation that the information about what falling into the hole can actually escape in the Hawking radiation um now teleportation is something from Star Trek where you know you D materialize Kirk or we're here and you re materialize them over there and in fact teleportation is a reality at least at the level of individual quantum particles and the way that you do to know teleportation in quantum mechanics is let's you say you create something like an electron hole pair over here they have some kind of like funky quantum correlation called entangled which is a natural state of death and then you want to teleport something from over here what you do is you say you take say this electron over here you make a measurement on it together with half of the electron hole pair let's say the positron and then you send the results of that measurement over here and that allows someone who is interacting with this electron to reconstitute the real information sort of like freeze-dried reconstituted and this is something that works and people have been demonstrating quantum teleportation now for decades work like a decade and a half at least so one way that you could escape from the black hole as a variation of teleportation now teleportation on its own won't work actually you're in good shape right because you have these electron positron pairs say electron escaping through infinity positron falling in if you could just make a measurement with the stuff that's inside the hole with this past return over here and send the information out by God you could escape but of course you can't send the information problem that's why their black holes that's why they're called flat so but what if what if when you made this measurement by some freak quantum accident the measurement always gave the same result now if a measurement always gives the same result you don't have to send the result outside the black hole because there's no reason and always give the same result so if the measurement always gives the same result if if the singularity the black hole does what so-called projection it forces your positron together with the electron you're trying to help escape it forces them onto some state always the same state then by gum this electron that's now outside of the hole is the same as the electron that's inside the hole so this is a mechanism called the Horowitz maldacena mechanism john christow and I have done a lot of work on it this also seems to be in a way that information can escape apply and what would be the significance of data for truth well it would mean that at least in principle you could dive into a black hole and make it up at the moment I wouldn't recommend

Channel: Closer To Truth

Views: 17,834

Keywords: Seth Lloyd, Closer To Truth, Physics, Black Holes, Universe, Cosmology, Cosmos, Science, Space

Id: vbS8D15JFP4

Length: 6min 6sec (366 seconds)

Published: Mon Apr 04 2016