What’s it like to fall into a black hole (again)? What does the outside universe look like? Is there any way to avoid your grisly fate at the singularity? I discuss these questions and more in today’s Ask a Spaceman!
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EPISODE TRANSCRIPTION (AUTO-GENERATED)
Yes. I've done this episode before about what it's like to fall into a black hole. And, yes, I wanna do it again. Why? Because this is this is my show.
Alright? And I can do whatever I want. But the real reasons are that, one, way back when I did that episode, it's one of the earliest episodes, wasn't it? I said something wrong. I said something about being able to see the entire future history of the universe, and, you know, that's not true.
And so here I am, like, four years later getting around to a correction. And two, there's a lot of really cool stuff to talk about that I didn't mention when I did that episode. So it's time for a Why not? Let's fall into a black hole again because the first time just wasn't good enough. And I'm gonna follow along here with a particular article or series of articles and one pages I found, and I rarely give credit because, like, I pull sources from all over to to make these episodes, but I gotta give a shout out to Andrew Hamilton, a professor at University of Colorado in unknown relation to Alexander Hamilton, who really dug into the physics and made what he calls a black hole flight simulator that lets you fly around and into black holes and describes the views and what happens to the coordinate system.
And it was I may have spent a good two or three days just playing around. So I want to share some of that fun with you. And why are we wasting any time? Let's fall into a black hole. Okay?
Let's do it again. But hold up. Before we get too excited, we need to define what is a black hole. Like we hear the phrase black hole all the time, and I even did an entire episode on, like, do black holes exist and and and this and that and how they form and and but what is a black hole? What exactly are we falling into, and what does it mean to fall into one?
A black hole, for the purposes of this episode, is a singularity. It is a point of infinite density in space. It's what happens when you crunch enough material down into a small enough volume that the gravity is so strong that nothing else can compete or resist against that force of gravity. And so gravity just pulls and pulls and pulls and pulls and pulls, and it doesn't stop. And it takes all that stuff and crimps it down into an infinitely tiny point.
Now, we know that doesn't exist. That's not real. I'll talk about that again at the end. I've talked about it before in other episodes for the purposes of this discussion about what it's like to fall into a black hole, that is this is it. We are headed towards a singularity.
That's our goal. When we say fall into a black hole, we mean travel towards a singularity, this feature in space time. Now, it turns out that these singularities, these black holes aren't entirely featureless. You you need to actually describe them, and there's three different numbers that we can use to describe a black hole. Its mass, its charge, and its spin.
So how much stuff is in it, how much electric charge it has, and how fast it's spinning around. With those three numbers, you can completely and totally characterize a black hole. There's a phrase here that could only be invented by physicists. They say that black holes have no hair in the sense that they don't carry any extra interesting information. It's just mass, just charge, just spin.
There's nothing else that you can use to describe a black hole. It has no hair because that makes sense, I guess. But anyway, there's a caveat here because there's always caveats here. Black holes aren't always hairless. I'm not exactly comfortable with this terminology myself, but I'm gonna power through it.
Black holes aren't entirely hairless. When they're just forming or when they're merging or when they're doing something active, then you need more things to describe than just mass charge and spin. It's a different set of equations, a different solution to general relativity. It's a different thing when they're doing something active. But when they're just hanging out in space time, not bothering anyone, minding their own business, not really doing anything interesting, they have no hair.
They can only be described by mass, charge, and spin. So the most complicated black hole you can have is massive, has a lot of extra charge, and is spinning. I'm not gonna talk about that. Why? Because what I wanna talk about, the simplest possible kind of black hole is already weird enough for one episode.
If you want me to talk about charged black holes and spinning black holes and ring singularities and potential wormholes and closed time like curves and inflation instabilities and all this juicy terminology, just hit me up. Ask away. Ask a spaceman@gmail.com if that's your preferred mode of electronic communication. But, yeah, I can talk about I can talk about charge and spinning black holes in another episode. For now, we're gonna talk about black hole that has no charge and no spin.
This is the simplest kind of black holes, the first kind of black hole discovered in the mathematics by Carl Schwartzschild, who found the solution for black holes, like, a year after Einstein published general relativity. Like, this is one of the first things someone did. Like, hey. What about black holes? I'm like, wow.
You went all the way to the weird stuff, Schwarzschild. Good for you. But here we are. We have a singularity. We have a point of infinite density.
We have no electric charge, no spinning, but we have all that stuff, all that mass crammed into an infinitely tiny point. Far from the black hole, it's nothing special. It's just like orbiting a star, but not so bright. Why? Because gravity is gravity.
There's this common misconception that black holes pull on their surroundings or vacuum cleaners or suck like don't get close to a black hole might suck you in. Like, they do pull things towards them, but no more than anything else in the universe. If I have a star, if I have the sun, it pulls on stuff around it because it has mass, but I can orbit around. If I have enough energy, I can orbit it. If I have even more energy, I can escape it.
No big deal. If I have a black hole with the mass of the sun, then everything else is the same. If I have enough energy, I can orbit it. If I have more than enough energy, I can escape from it. Its vicinity, like, it just just whatever.
Gravity is gravity is gravity. You can orbit a black hole all day long if you feel like it. They do suck, but no more than anything else, like just the gravity, the exact same mass. No big deal. But the view of a black hole is weird.
First thing, that singularity, that point of infinite density is surrounded by something. It's surrounded by a shell, a spherical shell, something that we call the event horizon. I'll talk about that more in a little bit, but just the black hole itself is the singularity. The event horizon appears as a consequence of that singularity. We wondered, and we still wonder, if singularities can exist in the wild, naked, so to speak.
Again, I am not in charge of terminology. We wonder if there are naked singularities, singularities without an event horizon around them. We're pretty sure there aren't, but, you know, this is pretty sketchy physics. So for now, we're gonna look at this black hole. We're not gonna worry about any of that.
There is a singularity. The singularity itself is the black hole. The presence of a singularity manifests this thing called the event horizon, which is what we consider the boundary of the black hole. In the view of the black hole, even though you're orbiting it just like you would orbit a star, the view is very different than the view of a star. First off, the event horizon is black, pitch black, absolute vantablack, like, just super black.
No light is escaping from its surface. It's a sphere of nothing. It's a big ball of nothing, and the gravity around it is so extreme that it bends the path of light in a visible way. Like, every gravitating thing in the universe bends light, but normally not in a noticeable or detectable or measurable way. And, again, the mass of a black hole isn't anything special.
Like, if it's five times the mass of the sun, it's the mass of five suns. What makes it special is that all that mass is concentrated into such a tiny volume, an infinitely tiny volume, but a tiny volume. That's what makes it special. So even though the mass isn't anything ridiculous, its density is by definition ridiculous. It is technically infinite density, and that makes the physics weird.
It's still just gravity, still just general relativity, but it's general relativity in its most extreme limits, and that's what makes things special. Like, you get some really, really, really intense gravitational lensing. If there's something behind the black hole like a star, if you stick a star behind the black hole, then light from that star goes in all directions because that's what light from a star does. The black hole itself blocks the view from behind it, so you can't see the star directly. But some of the light coming from the star is going at an angle, and kind of grazes the surface of the black hole, and because of the strong gravitational lens and because of the bending of space around it, actually pulls those light rays in and you end up seeing the star anyway.
Even though you can't look directly through the black hole to see the star, you can see the star on either side of the black hole. Because light that would normally miss you by a million light years gets bent and beamed right into your eyeball. If it's perfectly positioned, if that star was dead center behind the black hole from your point of view, then you would actually see a ring of light, like a halo of light surrounding that black hole. We call these Einstein rings, and they're really cool. If something's off center or there's a big object, you'll just see this really weird distorted vision of it.
But, basically, you can see behind a black hole even though you can't see through it, and that's due to the bending of light itself. If something is in orbit around that black hole, then it will get red shifted in its orbit as it goes away from us and then blue shifted on its way to us. So you'll see some very pretty colors on either side of the black hole. To keep things simple for our journey into a black hole, we're gonna pretend there isn't an accretion disk. There's nothing else falling in.
It's just us. Just, again, just keep the math simple. And there's something funny about this sphere of nothing, this ball and nothing of the event horizon itself, the black hole itself. It's looks larger than it should, especially as you get closer. So you can calculate.
You can measure its mass. From its mass, you can measure the size of its event horizon. That's all baked in the mathematics of general relativity. It's, you know, just something you can do in the back of a envelope. And then based on your distance from it and you know how big it is, you can figure out how big it should appear on the sky, pre standard astronomical calculation.
And the black hole is gonna be bigger than that. Why? Because of the bending of light. You can see or I should say the event horizon appears bigger than it should because of the extreme bending of gravity. And I think this this is the first part where the weirdness of gravity really sets in.
Like, yeah, okay. Surface where light can't escape, okay. Singularity, confusing, but I can I can swallow it? Bend lensing of light that that's pedestrian, but the black hole is bigger than it should be or appears larger than it should be. You can put this in perspective.
You can see if the if you painted a dot on the North Pole of the black hole and a dot on the South Pole, you can really do this, but go work with me here. You say, okay. Here's the North Pole. Here's the South Pole. You can see both the North and South Poles at the same time.
They would both be oriented towards you. Even though they're on opposite sides of that sphere, on opposite sides of the ball, they would both be oriented towards you. You could see the northern and southern poles at the exact same time because of the extreme bending of space. It's almost like you have this ball of nothing, which is the event horizon, the boundary, the surface of the black hole. But because of the extreme bending of space, it's almost like that ball gets unfolded a little, stretched out, and it gets worse the closer you get to it.
Like, you could be just, you know, relatively close to the black hole, and you'd expect to fill up, say, you know, a tenth of your sky. Instead, it fill it's filling up, like, half your sky because of the extreme bending of light and the bending of space. One way to understand how space is acting around a black hole is to imagine a waterfall. You see, in in relativity, in special and general relativity, you're allowed to build different pictures of the same physical situation, and everything's fine. So one way to view a black hole is it's just statically, like, it's there and it's bending space, and if you get close, you kinda tumble in.
Okay. That's that's one valid view. Another valid view is that space is flat, but instead rushing and flowing in like space itself is flowing into the black hole. That's another valid view. General Relativity will let you use both descriptions.
So as you get close to a black hole, space is flowing towards the black hole. So you have to work a little bit, you know, to to stay in orbit, but you can do it just like space is flowing towards the Earth because of the Earth's gravity, but it's pretty easy to stay in orbit around the Earth or around the sun. You have to work a little bit harder around a black hole. You can do it. You can do it.
But as you get closer to the black hole, space itself in this in this viewpoint, which is a valid viewpoint, space itself is flowing faster and faster and faster. Like, maybe it's flowing in at a tenth the speed of light or half the speed of light or 90% the speed of light or 99 the speed of light. So the closer you get to the black hole, the harder you have to work not to get caught up in the flow of space itself, the more energy you need to have to beat the flow of space. And there's a certain point close to the singularity where space is flowing into the singularity so quickly that it exceeds the speed of light. That point, that distance from the singularity where space is flowing inwards like a river faster than the speed of light, that is the event horizon.
It's like a river heading towards a waterfall. As long as you have enough energy, you can keep paddling, you can keep your motor running, you're good. You can fight the flow of the river. But if you go tumbling over the edge, if you get caught in that waterfall and you pass that boundary, then you can paddle all you want. You can run your motor all you want.
It doesn't matter. You're in the waterfall, and you're gonna crash down to the bottom of the waterfall along with all that water. You can't fight the flow of the water once you cross the threshold of that waterfall. Once you cross the event horizon, you can't fight the flow of space. It's flowing it's just flowing in too quickly.
You can't do it. So the event horizon is that boundary that anything that gets too close to the singularity within that boundary to escape, to leave would have to fight that flowing space and go faster than the speed of light and it can't. So that's why it's black. And because nothing can escape the event horizon itself, this also means that nothing can appear to cross. If someone's watching you and for the purposes of this analogy, we're gonna have you fall into a black hole while I stay out here.
Could have been me, but you volunteered. I remember distinctly remember you volunteering. Thank you. If I were to watch you fall into a black hole, you're emitting light, maybe you're on the radio, you're chatting, you're waving, you're doing all sorts of things, vaguely astronaut y things. As you get closer to the black hole, the light from you gets red shifted.
Why? Because if you admit a bit of light, it has to fight all this inward rushing space to get out. And so by fighting all the inward rushing space, it loses energy, and light with lower energy is redder. And so the closer you get to the event horizon, the redder and redder and redder you get, and then you're down in infrareds and then microwaves and then radios. It's gonna be a really, really red picture of you because the light that's being emitted by you has to fight all head space, all that flowing space, and it loses energy.
It gets exhausted. And it finally gets it's like, I made it. I made it, guys. I'm here. I'm here.
I'm gonna jump in water. I need to sit down for a bit. It's really red. You will also appear slow. And this closer you get to the event horizon, this boundary, this edge of the waterfall, the slower you will appear to get because clocks run slow in strong gravity.
It's true on the Earth. We can measure it. It's legit. It's a real thing. And around a black hole, it's extreme.
Why? Because you're very, very close to this intense concentration of mass. It's not the raw mass itself of a black hole that's doing the dirty deeds. It's the concentration of mass. It's the density.
And the closer you are to that extreme source of density, that extreme curvature in space, the slower your clock runs. So as I watch you fall in, you get slower and slower and slower and redder and redder and redder. And there's a moment when you do cross the event horizon, but I'll never see that moment. Why? Because there's that moment when you cross that boundary, you're gonna emit a bit of light.
But the space at that boundary, space itself is flowing inwards at the speed of light, at that boundary. That's the definition of the event horizon. So if you emit a bit of light, it's like as your boat goes over the edge of the waterfall to send out some signal, but but the signal's caught in the waterfall itself. Or, like, you try to jump out right at you're at the edge, but you're there. You're at the edge.
You're never gonna escape. So I never see that last final goodbye as you cross the event horizon. You send that signal, but the signal never makes it out. It can't beat the onrushing flow of space. So from my perspective, you never actually enter the black hole.
You just get pasted onto the surface. You get redder and redder, dimmer and dimmer, slower and slower, infinitely red, infinitely slow, infinitely dim, but you never quite cross the boundary. But from your experience, you don't get glued to the surface. You don't get pasted onto the boundary. You don't become a part of the event horizon.
No. You just fall. You just fall. You just head for that singularity. Why are these perspectives different?
Well, this is the whole point of relativity that nobody agrees on anything in relativity. Everyone has different views about duration of events and distances between points. Relativity is the language that allows different observers with different viewpoints to translate from one another. But that's the whole point. Relative.
Relativity. It's all relative. Depending on your viewpoint, you're gonna have a different description of what happens, and this is the most extreme example where an observer distant from the black hole will never see you fall in, but you will fall in just fine from your perspective. And both of these perspectives are equally valid. Both of these perspectives are equally real.
Both of these perspectives are are physics, are are I'm are true. My perspective of you getting Pesa on the surface is just as real as your perspective falling through. And if that doesn't make any sense, well, I'm sorry. I didn't make the universe. I just try to explain it in a podcast.
So you fall into the black hole. It's not an altogether pleasant journey. There are these things called tidal forces that are horrible. Tidal forces well, I mean, in normal gravity, like the gravity of, say, the moon and the Earth, tidal forces aren't cute. They make the tides.
They stretch out the Earth. As the moon orbits the Earth, it stretches out the Earth a little bit, stretches out the earth a little bit, especially the watery bits. It stretches them along one direction, the direction pointing towards the moon, and also squeezes the earth on the sides. It squeezes it. So it stretches both stretches and squeezes simultaneously.
And then as the Earth does its orbit, it changes where it stretches and where it squeezes. So you get the rising and falling of the tides. It's cute. Alright. Around a black hole, you get stretched out.
Your feet are a little bit closer to the black hole, so they experience a a stronger gravitational pull than your head does. So you get a difference in gravity and differences in gravity are what make you stretch. Meanwhile, your sides, you can imagine little arrows attached to your sides like right at your abdomen. And go ahead. If you're in public, put your hands right at your midsection, right at your abdomen so you can follow along in real time.
And if people are wondering what you're doing, just say, I'm I'm falling into a black hole. Don't don't bother me. You're falling towards the center of the black hole. The singularity is right in the middle. So you're not really falling straight down.
If you can imagine these little arrows, your little hands attached to your sides, they they're pointed inwards just a tiny tiny bit because that's the center. That's the actual center. And the closer you get to the center, the more the arrows are gonna point inwards instead of just down. Mostly down, you're still going down, but you're also going in a little bit. And so you can imagine if you see these arrows, they're pointing down from you but pointing in a little bit just a tiny tiny bit to point towards the center.
That means there's a gravitational force that's pulling you down, gravity, but that same gravity is also squeezing you on the sides just a little bit. So not only are you getting stretched out head to toe, your middle is getting squeezed from the tidal forces. This is called spaghettification, and that's, like, the one jargon term I can get behind. Different black holes have different sizes. They have different masses, and they have different event horizons.
You might or might not make it to the event horizon before you're obliterated by the tidal forces. For a small black hole, let's say a few times the mass of the sun, the event horizon is relatively close to the singularity, and so you're ripped apart by tidal forces before you even hit the event horizon. For a giant black hole that's, like, millions or billions of times more massive than the sun, then that event horizon is very far away from the singularity. And so you can actually pass through this thing the event horizon before the tidal forces become an issue, and that's pretty cool. Means you can survive the passage through an event horizon.
In general, you're destroyed about a tenth of a second before hitting the singularity independent of the size of the black hole. So if you hit the you know, when you're about a tenth of a second out, that's when the tidal forces become too strong and you'll be ripped apart. If it's a small black hole, you're still outside the event horizon when you still got a tenth of a second to go, and so that's when you get destroyed. If you're a big black hole, then it's inside the event horizon. So let's assume you're falling into a big black hole so that we can keep the fun going.
Your view as you approach the event horizon is going to become increasingly distorted, and you can see the black hole getting larger and larger and larger. That ball and nothing is unfolding and stretching. It's now eating up a good chunk of your vision where all you see is the black hole way bigger than it should, way bigger than it should because of the extreme stretching of and bending of space. That black hole, that ball of nothing is getting stretched out to eat up an immense amount of your view. And then here it is, the moment we've all been waiting for, the crossing of the event horizon.
You are going to reach, you're going to get inside of a black hole and experience what it's like. But first, you have to cross this boundary, the event horizon. And the best word I can use to describe crossing the event horizon, this event is meh. That's right. Meh.
Nothing special. Crossing the event horizon. There's no line in space. There's no boundary. There's no party.
There's no red alert. It's a mathematics thing. The event horizon is the consequence of the appearance of a singularity in general relativity. It's simply there in the math. It's not a physical thing.
Like, it is a physical thing as in this is the point in which space is flowing in inwards faster than the speed of light, but it's not like a wall or even like a speed bump. Outside this radius, space is flowing inwards slower than the speed of light. Inside this radius, space is flowing inwards faster than the speed of light. Either way, space is flowing inwards. Either way, gravity is doing its thing.
Either way, the tidal forces are doing their thing. It's all it's it's just a matter of strength. Nothing special happens. Now I should say this is in general relativity. Once we introduce quantum mechanics, some weird stuff could event happen at the event horizon.
Different episode, Hawking radiation, great great story. But in pure general relativity, nothing special happens at the event horizon. There's this common misconception, which, I I described when I first talked about this years ago. There's this effect called relativistic beaming, where as you approach the speed of light, your view of the outside world gets concentrated into a small cone around you, and then that view also gets blue shifted to higher and higher energies. And so as you're falling into a black hole, you're approaching the speed of light, and so you might expect your view of the outside universe to get concentrated into a small disk, behind you and then that disk vanishes at the moment of crossing the horizon.
That that doesn't happen. That's true for if you were to hover above the event horizon. Like, if you were to try to fight space, that in rushing flow of space at the edge of the waterfall, like, you're right at the edge of the waterfall, man, you're gunning it with your motor, you're paddling, you're sweating, yeah, you're getting a good workout in, you're fighting the flow of gravity, that is what will happen. That will be your view like the entire future history of the universe will play out before you in a small little disc right above you. Okay.
But in free fall, if you're just literally falling into a black hole, that doesn't happen because light is falling in with you. Like you're looking around at the universe as you fall in, that's light from the universe that's hidden in your retina. It's it's coming in with you. You fall into the black hole. Light is still falling in with you, still hitting your retina.
Light still hits you. It is distorted. It is blue shifted, but it doesn't go away. You can still see the outside universe. From the inside of a black hole, you can still see the outside universe.
But what does happen to your view, it doesn't compress into a cone because of this so called relativistic beaming effect. Instead, because of the extreme tidal forces, remember those little arrows attached to your abdomen and your little experiment that you did in public where you put your hands to the side and point them a little bit inwards. Well, as you get closer and closer to singularity, the hands, the arrows point more and more in. And so the light that falls around you, the light that's coming in with you, there could be light that's coming in like you can imagine a photon that's coming in right next to you, normally wouldn't hit you at all, wouldn't hit your eye. But because of the extreme tidal forces get bent inward and pulled to you.
And so your view of the outside world actually gets concentrated into a band around your waist. And it's red shifted above and below and blue shifted in that band and just gets worse and worse the closer you get to the singularity. And after you cross the event horizon, the event horizon still appears below you. Dramatic pause, intentional. It was there.
Did you feel it? Yes. I'm going to say it again. After you cross the event horizon, the event horizon still appears below you. From the outside of the black hole, the event horizon is that ball and nothing.
And you get closer and closer and closer to it, and it swallows up more and more and more your vision, and then you can calculate with your mathematics in your science. You know when you've crossed the boundary of that event horizon. In the event horizon, that ball of nothing still appears below you or in front of you depending on, you know, how you're oriented. Why? Because like I said, the event horizon is imaginary.
It's a mathematical thing. There's not a actual wall boundary at the surface of a black hole in general relativity. It's just the transition point for the flow of space. But what is that sphere of nothing? Like, I can like, we've all seen by now pictures from the event horizon telescope.
There's a ball of nothing right there. What is that if not a boundary? What is the image of the event horizon that we see? What is that black thing? That black thing is the infinitely redshifted surface of the star as it collapsed to form a black hole.
When that black hole forms, when the star and black holes form from the collapse of massive stars. When the star collapses, eventually there's a point where the densities become too great. Nothing can compete against gravity. All material is rushing in, forms the black hole. But we never get to see that from the outside world Because just like you falling in, when that entire surface of the star reaches that boundary point, it gives off some light, but the light never reaches us.
What we call or what we see as the surface of a black hole is really the ghost of the dead star, infinitely redshifted so it appears black. After you fall into the event horizon, after you fall into the black hole, after you cross that boundary, that ghost of the star, that leftover light, infinitely redshift light, is still in front of you because it got in before you. Just like if I dove into the black hole after you, I would see you in front of me the whole time until I hit the singularity because you went in before me. So that ghost, that infinitely redshifted image of the star that formed the black hole is in front of you always. You can't see past the singularity.
That's where the star went. The star went to the singularity. You can't see past it, so that continues to look like the event horizon. And now because of the extreme curving of space and because of the tidal forces, that singularity, that ball of nothing continues to fill up most of your vision both in front of you and behind you. And around you in this band is the distorted view of the outside universe of all the light that fell in with you, and the singularity starts to stretch and stretch and stretch to fill the horizon.
And it appears that way because of these extreme tidal forces that point in and this ball of nothing stretches and stretches that you thought it was stretching before, but now it's really stretching. So even though the singularity from the outside appears as a point, as you get closer to it, it stretches out to look like an entire surface. It starts to fill up your horizon from edge to edge, and you can't escape because space is falling too fast. Space is flowing faster than the speed of light, and you can't fight it. Something even funnier is happening.
You start contributing to Patreon. Go to patreon.com/pmcenter to learn how you can keep this show going inside or outside of a black hole. It doesn't matter. I will still do this podcast. It's just a question of how many people are able to listen.
Go to patreon.com/pmsutter. That's pmsutter. Tell her how you can keep the show going. What's the funny thing happening inside of a black hole is that you can't stay still. You are forever in motion because space is flowing all the time.
You can't stay fixed, and this messes up our sense of time and space. Outside of a black hole, you can be perfectly still in space, but you must move forward in time. You can't escape your fate. You You can't escape the future, but you can stay still in space. Like, man, I don't wanna go over there.
I don't wanna go to that restaurant, so I'm not gonna go there. But you're still gonna get older. Inside of a black hole, you can't be still in space. You must move towards a particular point in space. Think about that.
Think about, like, man, I don't wanna go that restaurant. First, it's impossible for you to stay still, so you're always walking, you're always driving. And no matter how you walk, no matter how you drive, no matter which way you turn, the restaurant is always in front of you. Like, this is something out of some sort of Kafka nightmare. Like, you turn down the street, like, oh, that's rest that's that restaurant that I don't want good, so I'm gonna turn left.
And you turn left, there's that restaurant right in front of you. And you and you and you find you the brakes don't work on your car, so you turn right right and there's the restaurant in front of you. You try to back up and go in reverse, you look behind you and there's the restaurant behind you. No matter where you look, no matter where you go, the restaurant that you don't wanna go to is in your future. That's what happens inside of a black hole.
You must hit the singularity. You have no choice. You can't stay still. The singularity is literally your future. All your futures contain the singularity.
You always move from past to future outside of a black hole. Inside of black hole, you always move from the event horizon to the singularity. The event horizon is always in your past, and the singularity is always in your future. All roads go from the event horizon to the singularity, and you will reach it in finite time according to a watch on your wrist and according to your brain. For the most massive black holes, you have a few seconds.
You will hit the singularity. You can't ever really see the singularity because it's always in your future. So that ball of nothing isn't the singularity itself. That's the ghost of the dead star that felt that collapsed in before you fell into the black hole. The actual singularity is always in your future.
You can't see the future. I can't see what tomorrow looks like until I'm already there. You can't see the singularity until you reach it. As you approach the singularity, which you can't fight, it appears to broaden and stretch and instead, because of the extreme tidal forces, it looks like you're landing a spaceship on a giant pure black featureless world, And when it completely fills up the horizon and is perfectly flat, that's when you've quote unquote landed on it, and that's when you've reached the singularity. And the entire surrounding universe appears to collapse on the edge of that horizon, and you have been obliterated.
You have reached the point of infinite density. In fact, the word point isn't necessarily the right word to use here because it's not really a dot. It's a boundary in three-dimensional space. It's a future. It's a fate, not a location.
It's a boundary where general relativity just gives up. What actually happens at singularity? Probably something weird. And let's face it. Probably, the event horizon is really weird too.
We haven't incorporated quantum mechanics into this story of what happens when you fall into a black hole. But from the point of view of general relativity, just like you can't know your future until you're actually there, you can't know what's in a singularity until you're actually there. I am promoting an AstroTor cruise that will stay very far away from any black holes. Go to astrotours.co,astr0t0urs,.co. We're We're doing a cruise in September 2020 to The Caribbean, mine ruins, stargazing off the deck.
It's gonna be a blast. Last one we did was so much fun. Join me. Go astrotours.co. Registration window is really short.
It's only, like, a hundred bucks to sign up. Get your name on the list. Get your name on the list and then we'll we'll figure everything else out later. Kinda like a black hole except way more fun and you get to live. Thanks to Steve b on email, Martin n on Facebook, Julius s on YouTube, Joyce s on email, Randy w on email, and John w on email for the questions that led to today's episode.
And of course, thanks to my top Patreon contributors this month, Matthew k, Helgeby, Justin z, Justin g, Kevin o, Doug and m, Corey d, Barbara k, Nudredoo, Christy, Robert m, Nate h, Andrew f, Chris l, John, Elizabeth w, Cameron l, and Nalia, and hundreds more, literally hundreds more who are keeping this show and all my education outreach activities going. I really appreciate that's patreon.com/pmsutter. Hit me up with questions on ask a spaceman dot com, ask a spaceman at gmail dot com, hashtag ask a spaceman on social media, following me on social media at paul mattzutter. Buy my book. My book is still out.
You can still buy it on Amazon, Barnes and Noble, and all that places. Your place in the universe. And I will see you next time for more complete knowledge of time enhancements.