In places where gravity is very strong, time as we understand it can break down completely. At the edge of black holes, for example, the powerful gravitational pull slows time dramatically, says Prescod-Weinstein. And upon crossing the black hole’s point of no return, known as its event-horizon, she says space and time flip. Far from the Earth, time gets extremely weird. Black holes can cause it to stretch and even break down entirely.
“You end up in a region where space now has an arrow, and it’s one direction … and time doesn’t have an arrow like it did before,” she says. “There’s really no sense of time.” -[Source](https://www.opb.org/article/2022/12/28/researchers-say-time-is-an-illusion-so-why-are-we-all-obsessed-with-it/)
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Typically space-time is represented as a joint fabric because of how gravity impacts time. If you think about how time works, it flows in one direction, only forward.
When you cross the event horizon and they say this gets ‘flipped’, it means gravity is now so strong, there’s no way you can escape the blackhole any more because light can’t even escape at this point. Because of the ridiculous amount of gravity, time essentially ceases to exist as a concept.
You’ve probably heard this or similar but as an example, if an astronaut fell into a blackhole with a blinking LED on their suit, while their partner was watching from a safe distance in the shuttle, the astronaut falling into the blackhole wouldn’t notice anything different about their light blinking, however to the observing astronaut in the shuttle, their light blinks would get stretched out becoming longer and longer, until eventually it just appears completely lit and no longer blinking. This is the concept of time of slowing (and eventually stopping / ceasing to exist) due to gravity.
As you continue being pulled into the blackhole, and that time slows to a standstill, space now only flows one direction – which is through the blackhole.
Time and space depend on the observer. And various effects can rotate or squish them together.
What looks like “forwards in time” to one person can be “downwards” to another person.
When viewed from the outside something near the event horizon of a black hole has almost all of its “forwards in time” direction rotated into a “downwards” direction, so it seems to experience very little time instead being forward downwards (i.e. falling; falling happens when our “moving through time” motion is rotated into someone else’s “downwards” direction).
Locally, from the object’s point of view, things look fairly normal (although there may be some very steep gravitational gradients and tidal forces).
**TL;DR**
She is asserting that space and time swap their behaviors; space goes from every-way to one-way and time goes from one-way to every-way.
**THE SPACE PART**
Outside of a black hole, there are a countless number of these imaginary “space arrows” sticking out of an object. They represent the directions an object can move in so far as space is concerned (as opposed to time.)
If gravity is negligible, then all “space arrows” should point directly out from that object at a roughly equal distance or velocity, and the object can move freely (every-way).
However, when another object’s gravity is applied, the “space arrows” are altered – they’re squished or bent a little bit towards that object, and become more so as gravity increases.
Once the event horizon of a black hole is passed, every last one of those “space arrows” now points closer to the center of gravity. Some of them get there slower, others get there faster, but it isn’t possible to move any further away, because no directions exist anymore that lead further away.
And, at some point close enough to the center, every “space arrow” should become indistinguishable from just having one arrow leading straight towards it. (One-way)
**THE TIME PART**
Time is generally presumed to go from past to future only. (One-way)
Gravity is known to apparently slow time; satellite systems like GPS have to account for this in order to work properly.
Since time is not so tangible as space is, nobody is quite sure on the physics of time to begin with – therefore, the workings of time under absurd levels of gravity are also not certain. Some scientists suspect that time may have more than one dimension, or that space itself is a form of time or vice versa, and there are many theories on what exactly either of those means. It is clear, however, that space and time are both affected by gravity in very similar ways.
At the very least, time might be slowed down so intensely within the event horizon of a black hole that it’s no longer a meaningful concept. But maybe time is already more complicated than that, and a black hole blows it the hell up into a complete mess that lets objects go forwards and backwards and side to side and do backflips. (Every-way)
Scientists also debate over whether black holes violate causality due to the “black hole information paradox”. Normally, one past leads to one future, and the “fingerprints” of that past are everywhere in that future. But black holes don’t appear to have all those “fingerprints”, meaning multiple pasts have the same future. The easiest way to resolve this is to find the fingerprints. Otherwise, you’d have to disprove causality.
**TL;DR**
She is asserting that space and time swap their behaviors; space goes from every-way to one-way and time goes from one-way to every-way.
**THE SPACE PART**
Outside of a black hole, there are a countless number of these imaginary “space arrows” sticking out of an object. They represent the directions an object can move in so far as space is concerned (as opposed to time.)
If gravity is negligible, then all “space arrows” should point directly out from that object at a roughly equal distance or velocity, and the object can move freely (every-way).
However, when another object’s gravity is applied, the “space arrows” are altered – they’re squished or bent a little bit towards that object, and become more so as gravity increases.
Once the event horizon of a black hole is passed, every last one of those “space arrows” now points closer to the center of gravity. Some of them get there slower, others get there faster, but it isn’t possible to move any further away, because no directions exist anymore that lead further away.
And, at some point close enough to the center, every “space arrow” should become indistinguishable from just having one arrow leading straight towards it. (One-way)
**THE TIME PART**
Time is generally presumed to go from past to future only. (One-way)
Gravity is known to apparently slow time; satellite systems like GPS have to account for this in order to work properly.
Since time is not so tangible as space is, nobody is quite sure on the physics of time to begin with – therefore, the workings of time under absurd levels of gravity are also not certain. Some scientists suspect that time may have more than one dimension, or that space itself is a form of time or vice versa, and there are many theories on what exactly either of those means. It is clear, however, that space and time are both affected by gravity in very similar ways.
At the very least, time might be slowed down so intensely within the event horizon of a black hole that it’s no longer a meaningful concept. But maybe time is already more complicated than that, and a black hole blows it the hell up into a complete mess that lets objects go forwards and backwards and side to side and do backflips. (Every-way)
Scientists also debate over whether black holes violate causality due to the “black hole information paradox”. Normally, one past leads to one future, and the “fingerprints” of that past are everywhere in that future. But black holes don’t appear to have all those “fingerprints”, meaning multiple pasts have the same future. The easiest way to resolve this is to find the fingerprints. Otherwise, you’d have to disprove causality.
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