It's a trap. once you start clicking you enter an infinite tunnel of links to more videos, been stuck here for 40 days and 40 nights

I love watching stuff like this and pretending I understand

Me: So cool that you can see the stars through his shirt! Me later: *wipes dust off screen*

This dude is a genius. Explaining topics to all of us like we are grade schoolers is not easy.

I have a hunch that PBS only pays this guy in v-necks.

I almost never understand more than a quarter of what you're talking about, at least not at first. I kind of let them soak in, watch them a few times and pick up bits and pieces. Gradually they coalesce into recognizable fragments and I can piece them into parts that make sense. Checking other sources is a great idea and I've come back to episodes after seeing other things that help me make sense of things. I like that your shows are different; you deal with some mind-blowing, counterintuitive, life-changing stuff. Summaries and simplifications have their place but I love that you get into the gritty bits. I appreciate it even more every time I consider how hard it must be to write and illustrate them. I didn't do much physics in school and none in college so some of the ideas are beyond me. That's something I'm working on remedying, partly because shows like this make me want to see the universe beyond the confines of my puny human senses and understanding. To look it in the math, I guess. After watching the E-MC2 episode for what must have been the 10th time I finally felt as if I understood what you were describing about the connection between energy and mass. It was a beautiful moment for me, full of wonder and awe and I thank you all from the bottom of my soul for it and the many others like it you've given me with your hard work.

Given the number of times Roger Penrose is cited in this KZfaq channel it is about time his contributions were acknowledged with a Nobel Prize.

This has to be one of the most substantive channels on KZfaq.

If science were taught like this to me in school, I and many others would have devoted our lives to it. Alas, at my age, I can only marvel at the beauty of the universe through the amazing explanations provided by Matt and PBS Digital Studios. Thank you so much.

So basically time can be viewed spatially because all of causality is sitting around for you to select which part of it to observe, and space is temporal because you're traversing it at a non-negotiable rate towards the inevitable singularity?

not sure which is more awe inspiring, that these ideas exist, or that this presenter can explain them

"We're interested in providing a bridge to understanding the real science." That's why I'm watching these videos, and am subscribed to the channel. I often watch an individual video *multiple* times, and often on .75 playback speed (or even .5, sometimes), in order to keep osmotically incorporating the ideas into my thinking. But that is only beneficial because the material is so dense, and there is so much here to learn. On so many Science channels there is a small portion of thin information, which though perhaps quickly understood, leads nowhere. That's my view, anyway. These videos are completely engrossing because they truly challenge me (did my English Lit / History degree in the 1990s) but don't completely shield me from the math, which I aspire to understand. Eventually. Thanks for doing it exactly this way, and please don't change.

This is one of the few channels where, when I'm told that I need to watch a previous video, they are correct. There's a LOT to understand here.

Your ability to say "Dankulous Memelord" with a straight face is super-human

This is the most mind blowing video on youtube. I'm fairly used to abstract concepts since I'm in neuroscience but I've had to watch this like 3-4 times and now I finally feel like I understand it. Amazing content.

Last time I came this early, electromagnetism was indistinguishable from weak nuclear interaction.

My first mindblow in a very long time (or space? :p ). Thank you.

I have subscribed to this channel for about 10 months now. Just wanted to say that while I initially understood perhaps 10% of what is said and am no scientist, I am now understanding far more than I used too. The presentation and explanations are top notch and fuels my desire to understand more. Also has helped me to understand what my old physics teachers tried and failed to teach me. Bravo and more please. Pat yourselves on the back.

In fact, the host MUST say "in fact" at least 100,000,000,000,000,000 times per episode. All future paths of his world line bend radially inward toward this truth.

“Matemathical”, I’ve watched this like ten times and I just caught the joke.

I don't like all the "I'm in highschool and feel dumb AF like if you agree" comments. 1. this is one of the only channels I found to actually talk science. like he said in the ending, this channel presumes you know the basics, unlike popsci and stuff like that that take twenty minutes of the same explanation heard twenty times just to get close to a level like this 2. just go and learn that stuff, don't complain but instead try to understand, whining is only diluting the comments with no new information

"Timey Whimey" Thank You for the Dr. Who reference.

I love how the titles of these videos seem intuitively impossible... But then are backed up in the content. I can't believe I actually have even a glimpse of understanding what the title means. But I kinda do now. Awesome.

I love how Crunchyroll is the sponsor! (i use crunchyroll all the time)

Got it, finally. Had to watch every video on this channel 5 times.

I will consider my life successful the day I understand this guys atleast 1 video.

Scary stuff, if you move once inside, it quickens encountering the singularity. I imagine this like being in the centre of a collapsing bubble, where the bubble wall is the singularity closing in all around you. Move in any direction and you just smack into it sooner. Weird.

I did the math over 30 years ago at uni, at the end of a long undergraduate physics sequence. Back then it was all about "Oooh! Look at what the math does!" I got absolutely nothing about what the math MEANS. Matt taking us back and forth between the math and the diagrams not only reawoke my appreciation of the math (fortunately without all the fiddly tensors and Hamiltonians this time), but also provided a physical context and "feel" for what the math tells us about our universe (especially the weirder parts). But this has got me thinking about spacetime coordinate systems, starting with the somewhat unreal flat Minkowski space. I'd like to know why so mush cosmological work is done using using Anti-de Sitter spacetime (AdS), when de Sitter spacetime (dS) is much closer to our reality (but still not the same). Why isn't all work being done in FRW (Friedmann, Robertson-Walker) coordinates? I think an episode about the various spacetime coordinate systems is in order!

0:31 "mattemathical" good one

I have now bookmarked this channel as Nap Time.

I was born with many difficulties in my life. Although I am not fully educated, I have a strong love for science and the universe. Thank you for bringing it to me. Love you

Okay, so here's my thought process... As you cross the event horizon, the infinitely small point known as a singularity suddenly shifts for you into an infinitely large wall, warped around you, which you must fall into. Even if you turned completely around you would still be falling toward the wall, getting pulled into it faster than you can escape. The outside universe has suddenly become the infinitely small point which you are now pushed away from (a white hole?). So, no matter which direction you move, you're moving toward the singularity. This makes space time-like in the case where you are falling into the singularity at a constant rate (speed of light or better) and any movement you make will only change your perception of that decent, much like outside of the event horizon it would change your perception of time. So, for you, no matter how you move you are at space interval zero (one light year per light year, we'll say) but you seem to cover more time in that distance the faster you move. To someone else in there with you, I think you'd look like you were spending more distance to move across less time. Or am I taking the swapping of space and time too literally there? Someone tell me where I'm getting this right and where I'm getting this wrong, because I had to warp my brain a lot just to get this far.

This channel is way ahead of everything else on youtube

If entropy increases over time, and in a black hole space becomes time-like, does that mean that in a black hole entropy always increases towards the singularity?

What I've learnd from this video: - Black Holes are very poetic - Black Holes are like quicksand

This episode was amazing, thank you. Y'all are doing elite-level work teaching this material.

wow, that was intense. It's baffling how our minds are able to poke around in these areas, digging beyond the fabric of our paradigm. No I'm not high.

I've said it before and I'll say it again - this is *the* best educational KZfaq channel out there right now. Great video (but, by the way, you missed the plus sign when briefly introducing the rest of the line element at 3:04).

I'd love to buy Matt a coffee & have a chat! I could listen to hime for hours, even if I don't really understand a lot of the science.

I feel like this explains that scene from Interstellar

Crunchyroll!?

I feel so bad for him having to read that crunchyroll ad at the end, lol. Great episode man.

Time is created by causality. The speed of light is the speed of causality. Ergo, time travels at the speed of light.

Brilliant episodes, brilliant information and brilliant background music!!!

I just made it through the video without getting completely lost. I've never been so proud!!!!

Love your channel, and absolutely love Cowboy Bebop. Glad to see an old show getting much deserved love.

you've managed to do what many said was impossible, to describe the inside of a black hole between the event horizon and the singularity. Absolutely brilliant video. You've earned yourself another patreon supporter. And you didn' t just cover the high concepts but all the equations, and explaining the each algebraic expression in the equations, which I really appreciate. As I understand it all black holes in reality should be rotating ones, because of the angular momentum of the original star that collapsed to form, it plus of any additional matter the black hole has swallowed up. there was a study done via a supercomputer led by Dr. Lior Burko, associate professor of physics at Georgia Gwinnett College and a team of researchers from Georgia Gwinnett College, UMass Dartmouth, and the University of Maryland who designed new supercomputer models to study the exotic physics of quickly-rotating black holes, a.k.a. Kerr black holes, and what might be found in the mysterious realm beyond the event horizon. What they found was the dynamics of their rapid rotation create a scenario in which a hypothetical spacecraft and crew might avoid gravitational disintegration during approach.while gravitational forces increase and become infinite, they do so fast enough that their interaction allows physical objects to stay intact as they move toward the center of the black hole. so then survival would come down to whether there is really a singularity at the end of the black hole trip. Probably is. But I still think of a person ending up trapped inside a strange non euclidean timeless void if their spacecraft survived the journey down a spinning kerr black hole. I also wonder whether the spacelike and timelike axis which switch actually might be a physical reality rather than just a mathematical trick. I don't know either way. I see mathematics as reality itself, so I interpret mathematical expressions very literally.

I did this at University this semester and I've got to say he basically covered everything apart from the maths. One major point our professor mentioned multiple times is that these are JUST COORDINATES. So time and space don't really switch. The coordinates switch. There are other sets of coordinates (that he mentioned at the end briefly) where they don't switch (like those in the Penrose diagram), time stays as time and space as space

I really think this is the best channel on youtube. Great content, as usual!

I DID IT! I FINALLY UNDERSTOOD IT! THANKS SO MUCH I'M SO HAPPY!

This was uploaded on march 30th. You had an excelent oppertunity to upload this on april 1st, and finish off by saying: "...into how time and space blend together. In ways perhaps the strangest place, in Time-Space." Instead of finishing with the usual motto of the channel with "Space-Time" like you do for every other video. I mean, the topic of the video was even how time and space switch roles.

Thank you for this video! Please don't pander to an audience with no prior physics background. There's already plenty of channels which do just that, and like you say, if people didn't keep up with the video, it shouldn't be hard to catch up on the intro stuff from other places. Keep making videos like this, with some meat on the bone.

Matimathical 0:34 nice pun

Crunchyroll trial and more fun math. This channel is the best!

There's time to make space, and there's a lot of space to make it in time.

I appreciate your intuitive approach to otherwise complex mathematic calculations. Absolutely fascinating!!🤔🤔🤔👍👍👍

Fascinating, the concept of time and space switching! Technically though wouldn't it be more like space taking on properties of time? As far as I can tell, time doesn't become more navigable within the black hole the same way space normally is.

What is the overlap of the groups of people who like anime and watch this channel?

Understanding first half of the video and feeling like I'm having a stroke after second half. Love it. Will come back later with greater knowledge and see if I understand

Hey I don't understand a lot of this, and it's still entertaining. I'll continue watching and learning. I really appreciate it!

in standard spacetime, accelerating through space requires the exertion of force on another body, or the emission of radiation. what would an object have to do beyond the black hole, in order to accelerate through the newly traversable "time" dimension?

very eloquent way of stating that last comment, which was a nice way of saying 'step your science game up'...

I have always wondered if space-time is digital or analog. That would be a great video.

Glad you chose this topic, I've been looking for that for a while

I watch these kind of videos whenever I get depressed. Lol..

A video about space and time being sponsored by Crunchyroll... Alright, let me get my IBM 5100.

Excelent video! Well explained, excellently narrated and very interesting.

Kind of explains where some of the concepts at the end of Interstellar came from. Still a goofy ending, but now I see some of the inspiration.

Perhaps a stupid question but in previous episodes you briefly talked about the theory behind the Alcubierre drive and the fact that if it were possible to make one it would simultaneously expand and contract space (in a way that is consistent with general relativity). My question is could such a device be used to 'pry open' a black hole by expanding the space in it faster than it collapses in on itself or does a hypothetical Alcubierre drive not alter space time geometry that way.

Please, do a video about the four fundamental forces

thank you that last statement about your goals of the channel are apparent and so very much appreciated and seeing that this is 5 years old i´m glad you haven´t changed that. theres tons and tons and tons of pre kindergarden space/science stuff out there i´d say about 95% is the same old boring ultra dumbed down stuff. we don´t need more of the very very basic 95% that market is catered to overwhelmingly. but precisely this, your channel, is such a rare gem as it provides an intermediate level of understanding that´s still comprehensible for interested lay people. i didn´t understand absolutely everything the first time around. but one sometimes just needs to pause and think for a while and you get it. this is information dense just like beautiful poem you sometimes need to unpack it for yourself and that´s the fun part. people who are interested won´t turn off in disgust the first time they come across something they don´t understand but are inclined to fill in the gaps of their understanding. and people who don´t, aren´t intereded anyways. you seem to be one of the very few people who get this. and to top it off you´ve also got some amazing production quality. so thank you again to the whole team and supporters who make this possible.

Now I understood how on movie interstellar Cooper(Matthew) was able to move in time when he moves in space.. ohhh myyyy 💟

Is this space-time dyslexia purely a "Matemathical" quirk 😆👍

All I could think of while watching this video is how this matches up impeccably with what was shown in Interstellar!

This might be something people on this channel don't want, as visualizing this stuff is easy with the diagram, but for me personally, I would love to have a 'graphical representation' of falling into the black hole, where the 'lensing' of the universe above and below were periodically stretched to normal visual parameters. Most visualizations of falling into a black hole show the image of the universe 'collapsing' into a hemisphere, and then down into a smaller and smaller point, containing the entire spherical image in a smaller conical arc radius. While I 'understand' what is happening visually, having a version of this which does a sort of window within a window view, stretching out that visual area, to show the actual events as they would appear outside the blackhole if we could explode the conical view to a 'full view' would help me greater appreciate what I am actually seeing. Likewise, if such a graphic could be simulated with this window within a window explosion of the portion of the view that represents the inward and outward universe, and also allowed for 'navigation' within the blackhole so we could 'experience' increasing the speed of our demise, and the relative 'change' in what we are seeing (What it ACTUALLY looks like to see light from the 'past' within our lightcone, with an exploded view, of what it would look like outside the extreme gravitational lensing we are forced to witness these concepts within), would make these points even more salient. I have talked to one of the astrophysics professors at my university, and he thinks this is a great idea, but unfortunately our visual arts department isn't exactly up to the task of this sort of collaboration, as it's less a 'video' (Or even a 360 video) and more of a 'game' because of all the variables that have to be considered including the movement of the perspective. Frankly I'm happy to have at least got the gist of the idea of what the visualization might look like, but it would be SOOO much cooler to actually experience it, and MIGHT make this entire video series much more intuitive for people who have trouble memorizing the covered material even if they went through it in order.

Travelling faster than light is like entering an event horizon. You disappear. 😂

Hey Matt, i'm sending this message from 2025. Just testing the new quantum computer while having a snack. Let me know if you received it. Thanks!

Chrunchyroll!?

If you look at the Schwarzchild metric, the delta r squared (area) is multiplied by the lorentz factor. While the delta t is multiplied to the inverse of the Lorentz factor. But if you look at the equations of relativity, time is usually multiplied to the Lorentz factor while space is divided by the inverse of the Lorentz factor.

I always open this mans videos when I want to sleep but can’t. I don’t know why but I swear I fall asleep in 2 minutes after the video starts.

The singularity becomes a future time, not a central place! I wonder, does this mean if we wait infinitely long we will see the inside of a black hole?

I think it would help a lot to get a approximation of what it would look like with two dimensions of space plus the time dimension. Treating space as only one and then swapping it with time simplifies it to a point where it can nicely be shown graphically, but hinders a full understanding to emerge. I do understand the 3 dimensional graphic I request is more difficult to display but hopefully you will manage to come up with something. Thank you :)

love these PBS SpaceTime videos!! makes my brain feel sooo pleasant and the narrarator/host is f*@$ing awesome

This is the best pop-science channel I have ever watched

We live in universe where everything move in one dimention without any escape. Thats what we call time, you have no choice. Maybe inside black holes, you have another universe. We might be inside one.

Even if anime isn't your thing Cowboy Bebop stands on it's own. Worth a look.

Hey Matt, you are the DUDE! I love your videos, I love the way you explain things and your explaining mood, you are so easy to listen to, and I think I will understand all of those crazy physics things by listening to your explanations. Thank you (~8.

Love the music library for these spots

Kinda explains the ending of Interstellar with the whole timeline structure that can be traversed as if its space inside the blackhole

The math was a bit tricky since I'm only in middle school but I understood all of the other concepts! Thanks for the videos

You strike a good balance of pushing the envelope just enough for those of use who are not experts but want to understand a deeper level than intro discussions.

PBS Spacetime has made it significantly easier to teach my kids physics the last several years. Now at 10 & 12, both can explain a great deal of basic physics, including a deep & respectable description of the sub atomic world. Now to be fair, the effort to teach them was happening already, and would have continued even without PBS ST, but you folks sure made it easier. -This parent thanks you.

Hyperbolic time chamber.

"Kado the answer" and "Stein's gate" are your anime's if you like this kind of thing.

Brilliant and lucid explanation.

I like how this episode starts by referencing the previous episodes for prerequisite knowledge... as if that would help me understand any of this!

Where is the video titled "Faster than Light Travel Achieved!" ?

I tend to picture a black hole as obviously a large spherical astrological object with enough gravity to keep light from escaping its boundries, and that point where light can no longer escape is the "Event Horizon" and I do agree with that, that is the point in which a photon of electromagnetic force can no longer escape. However Hawking Radiation defines that black holes will slowly evaporate over time. Well the event horizon and "Singularity" are potentially two sides of the same coin. Now the speed of light or the speed of a photon is not necisarilly defined as the speed of causality. Meaning quantum particles with lower mass and energy levels created by the interaction of other quantum particles could travel faster than the observable photon. Meaning there must be space between the event horizon and singularity where time flows fowards even if it isnt fast enough to eject these smaller escapeing particles in the tiny difference between the speed of causality and the speed of a photon. Meaning a black hole would have two horizons, one in which time is too distorted for cause to have an effect before the death of the black hole through hawking radiation, and one in which time is reversed on the flip side of the universe through a hole of the space time quantum field. Theoritically a quantum field of energy could exist at a lower energy point than the electromagnetic quantum force carrier and thus could travel faster than any limit defined by the electromagnitism that drives the universe as we know it while still having an affect, maybe dark matter maybe dark energy.

Thought experiment. Find a particle with a spin. Find another particle with a spin. (Entanglement makes things more interesting) Send one particle near orbit of a black hole or just something very massive. Send the other in a relatively straight path. Measure the spin of each particle after they traversed the paths. Will they have differed? Does gravity alter or manipulate spin?

Thanx for all you guys do. this kind of science along with chemistry has been my passion since i was a kid but have only recently started to really understanding it. 😍😆😲