Why Time 'Stops' in a Black Hole

Blackholes are a breakdown in the equations of spacetime. This means both space and time no longer behave the way we would expect of them.
Today we explore the breakdown in time around blackholes and what it means to interact with the event horizon, or the place where time appears to stand still.

Further Reading/Consumption:

Black Holes & Time Warps: Einstein's Outrageous Legacy - Kip Thorne

[ButWhySci]

A lot of people are asking what the opening shot is supposed to be. Yea... it was my attempt to show that someone cannot occupy the same space as someone else but they both see the clock move the same way because their spacetime is essentially the same. I dunno... I needed some animation to go there while I talked lol.

[terrancecollins]

The model used to demonstrate the “slowing” of light was like a revelation to me lmao

[HorseNuggets]

After many explanations about the "slowing down" of time near objects with gravity, this video finally did it in an extremely elegant way that truly made me understand. This is a masterpiece

[WINuFAIL]

Using the higher vs lower dimensional view of the Universe and how in one the photon appears to stop moving is one of the most brilliant visual representations of this I've ever seen.

[Pons-GG]

The side-by-side demonstrations of what is happening in 2D vs 3D is by far the best way I have ever seen this concept explained. Thank you so much for the amazing visuals!

[wgpoprock]

Storage company ad after this video: “Are you having any issues with space?”
Me: “You have no idea.”

[CJMac]

You're the first to actually answer my, "What about an impossibly long rod?" question that stumped my lecturer when I asked about it. And you went into great detail, thanks!

[LundinSebastian]

"A black Hole is not a pleasant scenario"

Underrated quote.

[JaySteetsArt]

"Extremely Crazy-long Rod" was my nickname in high school. Subbed.

[feynstein]

5:25 There is a reason, actually. People make this mistake because they associate the speed of light light. When in fact it's the speed of causality. The value of this speed is arbitrary, but it must be finite. If it were infinite, all of the interactions in the universe would happen simultaneously, and time wouldn't exist. Think of the entire history of the universe until its end like a movie. The length of this movie is determined by how fast you play it. This is analogous to the speed of causality. The faster the speed, the shorter the movie. If the speed were infinite, it would no longer be a movie. It'd just be a photo. Time exists because there is a delay between something happening here and its effect being felt in another part of the universe i.e. effects cannot propagate instantaneously. This inability is what is manifested as the speed limit of causality. Light just happens to be one of the things that can travel at this speed. This is actually the essence of special relativity. I find it kind of sad that most people either don't understand this, or instead focus only on the math, without thinking about its implications, or origins.

[VargoProductions]

Dude, this is easily the best demonstration of time dilation that I've ever seen. I have never understood how this would be possible, but I (at the very least) have somewhat of a grasp now. Thanks, man.

[mattmurphy]

I’m very confused by the first video of a person stepping into another persons chair. I’m subbed.

Edit: I was unaware of the step sibling trope comments this would spawn...

[Wunba]

Thank you for finally explaining this in an understandable way! I’ll probably be back here again in 6 months when I need to understand this concept again. 😂

[quehagoconmividasos]

I've seen a lot of videos about black holes, I just clicked on yours because your username "but why" caught my attention. Im glad. You really gave me a new, different perspective on an explanation I've heard a lot of times before but never fully understood

[artisanrox]

The illustration contrasting the 3D and 2D views of falling in the black hole, and comparing it to 4D/3D understanding of black hole physics made time dilation clear for the first time I've been interested in this subject. Fantastic.

[sorlag]

The space bending effect is really interesting. From the outside, black holes look like spheres, at least we think. But when you enter and the darkness wraps around, and you see the universe as a window above, it's almost as if you've entered an actual hole or hellish well of some kind. It's like a hole you can enter from every angle. It only just hit me how hole-like black holes actually are... Well... At least until you actually enter them.

*EDIT:* Turns out it isn't like in But Why's video. Watch ScienceClic's video "What would we see if we fell into a Black Hole?"

[JACCO]

One thing to remember as well, is that in theoretical example of floating above the event horizon, the distances between atoms would stretched to maintain their positions within the fabric of spacetime (which is why the rod seems to be longer and longer from your perspective). So as a conscious being, the electrical impulses that make up our thought processes are actually traveling much greater distances and it takes longer for them to move between neurons. So as far as you are concerned time is moving normally be side you can only perceive time as fast as your neurons can transmit signals.

In theory you could watch the entire history of the universe pass outside the black hole in a couple of minutes if spacetime is warped enough (and you didn't get Thanos'd by the warp ripping your atoms apart) because it takes the electricity THAT LONG to traverse the distances between your neurons.

[davidmurphy]

1:00 _"This is not a pleasant scenario"_

That, my friend, may be one of the greatest understatements in history.

[idkjustleavemebeplease]

That opening animation was perhaps the most perplexing thing about this, as the rest was explained very well and in great detail. Also, if space time can expand at the speed of light, is there a point where it might expand past the speed of light.

[thewebheadgt]

This is the best explanation of Black Holes I've ever seen.