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  • So there have been two papers published this week about one of our favorite subjects, and that's black holes in particular.

  • What's it like falling into black holes?

  • Now I've gone and spoken to Tony all about it, and he's given a bit of an overview of what's in the papers.

  • Bit of a taste on.

  • Also in this video, I've done a few illustrations and graphics just address things up a little bit, so don't take them too seriously.

  • If you do want to read the papers themselves and see the slightly more dry diagrams in the papers, go and have a look at them.

  • I've put the links in the video description.

  • Under this video, they're free to go and have a look at.

  • But I should warn you, there are a little bit on the complicated side.

  • Every morning we read our academic papers that have come out on did was speed something really interesting happening today and then this week.

  • Basically, we were rethinking what we think happens when you fall into a black hole.

  • So the picture's changed completely.

  • There's some real big shots over in their California that sort of they this one paper out this one out A couple of days ago, there was this one by Lenny Susskind, which was out today, which is sort of completely rethinking what happens when you fall into a black hole.

  • So it's pretty big stuff.

  • So the way that we traditionally thought of what happens in a CZ you fall into a black hole.

  • What?

  • It kind of depends on whose perspective you're taking it from.

  • So if you imagine me new Brady, we went to a black hole.

  • You stayed on the outside of the black hole and annoyingly decided to chuck me in.

  • So I'm falling towards the black hole's over there somewhere.

  • Imagine right.

  • So I'm drifting towards accelerating towards it.

  • What do you see?

  • You see my clock slowing down.

  • So you see, sort of essentially time slowing down for May, so as if I'm suspended.

  • Imagine the event horizon of the black hole is here.

  • As I approach it, your time is slowing down from your what you see on literally ill as they approach the event horizon would then stop.

  • You would see much time stopped for me.

  • Now where is all this happening?

  • This is all happening on this what's called a stretched horizon, which surrounds its a little region that surrounds the event horizon.

  • It's a thermal reason it's hot.

  • So you would see May suspended.

  • Okay, then you would see me, fam allies.

  • Well, literally, I would sort of burn up.

  • Okay.

  • And then I will come back to you as a stream of hawking radiation.

  • This is the type of radiation which comes out of a black hole, which spares the name of Stephen Hawking.

  • Now, that's what you saw watching me fall into a black hole.

  • Okay, now what would I see as I fell into the black hole?

  • What would I actually see myself?

  • Well, this is the old picture.

  • This is what changed.

  • Now there's nothing special.

  • East.

  • We thought there was nothing really special about a black hole event horizon.

  • Really.

  • It's not a region of strong curvature, strong, strong gravitational fields.

  • It's just a place in space where something where does happen.

  • But there's nothing strong about the gravitational fields there on because of that by Einstein's principle of equivalence, nothing really weird should happen as you cross it.

  • And indeed that's what we thought was the case that as you cross a black hole event horizon.

  • I'm falling through the black hole, the rent.

  • But horizon from my perspective.

  • What do I see?

  • I don't see anything much.

  • So you just see me pointing the camera?

  • Yeah.

  • And eventually, you know.

  • Okay, maybe some effect time effects of, you know, our relative juice for relative velocities.

  • But generally within the reed, I wouldn't see anything remarkable happens across the horizon.

  • Eventually, after a long time, it was a big black hole.

  • I would approach the black hole singularity, which is miles back over there now.

  • Okay, But I would approach a black or similarity there.

  • There are strong gravitational fields there.

  • I would turn to spaghetti on, Do you know it would be Good night, May And then I actually me.

  • That sounds like a whole bottle through these papers.

  • Which one?

  • Which came out earlier this week.

  • The other which came out today, It discussing that process.

  • Not from your point of view.

  • Braiding watching me fall in.

  • Think everyone still agrees on that, but from the point of view of the guy falling in.

  • So this statement that nothing much happens as you cross the black hole horizon.

  • People aren't saying that's the case now.

  • Needs a real big guns, right?

  • These guys in Santa Barbara and at Stanford who you know, have made their names in various of the topics and physics and un, including black hole physics and the's a big guys.

  • What do I see now is I fall into the black hole while it's a lot more unpleasant, essentially is you approach the black hole horizon.

  • You just get across it on, then splats you hit what's called a firewall.

  • They're calling it five.

  • Or you could see that essentially the black hole horizon.

  • If the black hole is old enough, it has to be an old enough black hole and the horizon will tenant of firewall and you literally space and time would just end for you, essentially like a black hole singularity.

  • But now it's jumped right out towards the event horizon.

  • It's tricky.

  • I don't think I fully understand it myself, you know, as I said, I only read this paper smarting, So yeah, it's still absorbing it and okay, so let's give it a go.

  • They're applying quantum mechanics in the logic of quantum mechanics, to a black hole to come to this conclusion.

  • In particular, I said here said at one point that this black hole had to be an old enough black hole.

  • What I mean by old on old black hole in this context is one that is in myth.

  • Admitted you know, at least half of the information it contained when it was formed.

  • Okay, so you know, black holes forms and it gives off this radiation.

  • It's admitted that more than half of that radiation, if that's the case, then you have something important happens.

  • So I went to imagine basically a little bit of radiation, which came out early on a little bit.

  • Radiation is just coming out now, okay?

  • Or it's cool out late and it's sort of sitting on the edge of the stretch, rising.

  • Now they are entangled.

  • If the black hole is old enough, those two bits of radiation, they're entangled.

  • Those two points are entangled, as in the exterior region, where all the radiation is on the edge of the Stretch Horizon base.

  • See what I mean by being entangled?

  • I mean essentially know about each other.

  • If I know about the radiation out here, I could know about the radiation sort of on the edge of the horizon.

  • Here's the other statement.

  • They're supposed be nothing special about the black hole horizon.

  • Okay, that's what we previously thought.

  • So now you've got this little bit of radiation just outside the stretched horizon.

  • There's nothing special about the event horizon.

  • So imagine something just inside the event horizon, but still inside this stretch to rising.

  • Well, those two were also gonna be entangled because they're so close to one another.

  • There's nothing special about the horizon, so they're entangled as well.

  • Okay, so now you have a situation where the thing on the just outside the horizon is completely determined by the thing very far away on also the thing just inside the horizon.

  • But the thing very far away.

  • And the thing just inside the horizon, a completely independent systems and you can't have something controlled by two completely independent systems.

  • Okay, so what?

  • The conclusion is, there must be actually something wrong with our assumptions there.

  • And the conclusion is that the thing that's wrong is that the horizon is a special place.

  • That the two points on either side of the event horizon, but still living in this stretch to rise.

  • And actually, you know, they aren't entangle day, but, you know, they don't know about each other on the implication then is is that, you know, literally you have it.

  • You have a singular point.

  • You have a singularity have a large region of space time curvature at the horizon.

  • Okay, And that's essentially what happens.

  • Another way of looking at it is that you will inevitably you can use these similar arguments to conclude that you will inevitably encounter Quanta.

  • As you approach the black hole horizon.

  • You will never tell you I can bring you back.

  • I'm just doing a video of Brady.

  • Okay, I'll call you back in.

  • I'm nearly done just in the middle of it.

  • So it was, um Oh, yes.

  • Another way of looking at this and playing similar arguments is you can argue that there's as you approach the black hole, you will prevent her eyes, and you will inevitably encounter Quanta a little sort of fluctuation little particles that bits of radiation, that you have high energies.

  • You know who's any arbitrarily high in principle that that's what the subject of the first paper was really about the one by geopolitics, skin friends, Andi.

  • And that's why it's far well, so that's where they came up with this idea of fire?

  • Well, yeah, but of course it's lighting.

  • It gets slightly complicated as well, because, you know, the minute useful in yourself, you all to the position of the would be horizon anyway.

  • So actually gets a little bit subtle.

  • So what Lenny Suskind's arguing for is that, actually, so you fall in so you don't actually encounter anything immediately, but you do pretty down quickly.

  • Okay, Basically, it's proportional sentence your size that, you know, it's it's how big you are, you know?

  • So that's sort of the smaller you are, the quicker you will encounter something.

  • It's sort of the other debate that they're still arguing about.

  • How old is the black hole Have to bay?

  • So I discussed, you know, and should be more than half the should have admitted more than half of its radiation.

  • Well, it's some arguments about that, you know.

  • Is it this page time or is it something called the fast scrambling time?

  • You know, and I makes quite a difference.

  • For example, if you apply this discussion to a solar mass.

  • Black holes are black hole with same masses of sun to be old enough for this to happen.

  • Well, if you it could be that you know, such a black hole would have the old in the age of the universe for this to be important.

  • But also, it could be that it might only have to be 1/10 of a second old.

  • So they're still still arguing the numbers.

  • So this old notion of spaghetti ification is it being replaced with, like, this kind of incineration?

  • Yeah.

  • Eso eso termination is how air for case of this is actually argue like this in the papers.

  • What do you call it?

  • So geopolitics.

  • Skin that call it burn up.

  • Okay.

  • So, Actually, and Lenny Susskind complains about Isis is not better.

  • Not that sort of indicate some sort of gradual process.

  • Where you been?

  • Up almost.

  • And he actually says its termination.

So there have been two papers published this week about one of our favorite subjects, and that's black holes in particular.

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墜入黑洞(新聞)--60個符號。 (Falling into Black Holes (NEWS) - Sixty Symbols)

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    林宜悉 發佈於 2021 年 01 月 14 日
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