https://www.quantamagazine.org/the-most-famous-paradox-in-physics-nears-its-end-20201029/

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

the information of the particle. I think.

Bogsnorkler said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

the information of the particle. I think.

I’ve never quite understood if that’s what they mean

Bogsnorkler said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

the information of the particle. I think.

It is now generally believed that information is preserved in black-hole evaporation. This means that the predictions of quantum mechanics are correct whereas Hawking’s original argument that relied on general relativity must be corrected.

https://en.wikipedia.org/wiki/Black_hole_information_paradox

Bogsnorkler said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

the information of the particle. I think.

I’m assuming that it’s not its address or blog or the like.

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

Effects.

Everything in the universe affects everything else. Notwithstanding equivalency, all of the physical statuses everywhere can affect the fields at any given point in space and time. If some process is applied in the universe, that physical information is normally preserved in that each piece of data is in some way reflected in the final status.

Black holes appear to break this deal.

OR DO THEY??? That’s the discussion.

dv said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

Effects.

Everything in the universe affects everything else. Notwithstanding equivalency, all of the physical statuses everywhere can affect the fields at any given point in space and time. If some process is applied in the universe, that physical information is normally preserved in that each piece of data is in some way reflected in the final status.

Black holes appear to break this deal.

OR DO THEY??? That’s the discussion.

So once a particle slips below the event horizon, it’s as if there was a form of entanglement between that particle and the ones on the outer side of the event horizon.

OR DOES IT???

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

If we had perfect knowledge of the universe in it’s current state, using the laws of physics and their associated equations we could determine the state of the universe at any time in the past or future. This is because “information” can not be destroyed. Although we don’t have perfect knowledge, we have enough that we can fairly confidently talk about the state of the Universe right back to the moment just after the Big Bang singularity stopped being a singularity. We can not, however, using the laws of physics, determine what the state of the singularity was, beyond saying “singularity” (which just means ‘something we can not describe’)… we can not describe the physical characteristics of the singularity based on the information available to us in space and time. This is because “information” from the singularity was destroyed by the Big Bang… the information required to describe the state of the singularity did not transfer in to our familiar space-time universe.

Information that does exist in space-time can not be destroyed. The laws of physics that we have so far determined would not work if it could.

The information paradox as relates to more ordinary black holes is saying that there is information which should be accessible to us, being existent in the space-time universe, which is destroyed by it’s interaction with the black hole. That which emerges from the black hole via Hawking radiation can not be measured, put in to equations and used to determine that state of matter that entered the black hole and was eventually radiated back “Hawkingly”. Given that black holes exist in the universe, in space-time, we would expect not to lose information that interacts with the black hole, yet apparently we do – paradoxically. Or do we?

esselte said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

If we had perfect knowledge of the universe in it’s current state, using the laws of physics and their associated equations we could determine the state of the universe at any time in the past or future. This is because “information” can not be destroyed.

I’m no expert on these things, but I have never seen any evidence presented for that statement, and it seems to me contradictory to the principles of quantum mechanics.

Susskind solved this.

It was never really a paradox in the first place, just an artefact of the change in coordinate system. If you stay in normal space-time coordinates then there’s no paradox.

esselte said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

If we had perfect knowledge of the universe in it’s current state, using the laws of physics and their associated equations we could determine the state of the universe at any time in the past or future. This is because “information” can not be destroyed. Although we don’t have perfect knowledge, we have enough that we can fairly confidently talk about the state of the Universe right back to the moment just after the Big Bang singularity stopped being a singularity. We can not, however, using the laws of physics, determine what the state of the singularity was, beyond saying “singularity” (which just means ‘something we can not describe’)… we can not describe the physical characteristics of the singularity based on the information available to us in space and time. This is because “information” from the singularity was destroyed by the Big Bang… the information required to describe the state of the singularity did not transfer in to our familiar space-time universe.

Information that does exist in space-time can not be destroyed. The laws of physics that we have so far determined would not work if it could.

The information paradox as relates to more ordinary black holes is saying that there is information which should be accessible to us, being existent in the space-time universe, which is destroyed by it’s interaction with the black hole. That which emerges from the black hole via Hawking radiation can not be measured, put in to equations and used to determine that state of matter that entered the black hole and was eventually radiated back “Hawkingly”. Given that black holes exist in the universe, in space-time, we would expect not to lose information that interacts with the black hole, yet apparently we do – paradoxically. Or do we?

Is it lost of rearranged, like corrupted data on a computer

The Rev Dodgson said:

esselte said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

If we had perfect knowledge of the universe in it’s current state, using the laws of physics and their associated equations we could determine the state of the universe at any time in the past or future. This is because “information” can not be destroyed.

I’m no expert on these things, but I have never seen any evidence presented for that statement, and it seems to me contradictory to the principles of quantum mechanics.

The problem with quantum mechanics lies in taking the measurements, in gaining “perfect knowledge” about the current state of things. If we could gain “perfect knowledge”, we could determine the state of the universe at any time in the past or future. In the quantum realm, the best we can do is state an approximation of knowledge based on a probability of something being actual.

Usual disclaimer I’m no expert either and probably everything I written in this and the previous post is wrong, but relating it to the BB singularity helped me conceptualize what is meant by “information” when it’s talked about in regards to black holes.

Cymek said:

esselte said:

Spiny Norman said:

Kinda on-topic.
The word information is used when talking about matter passing through the event horizon. What exactly is the information they’re talking about?

If we had perfect knowledge of the universe in it’s current state, using the laws of physics and their associated equations we could determine the state of the universe at any time in the past or future. This is because “information” can not be destroyed. Although we don’t have perfect knowledge, we have enough that we can fairly confidently talk about the state of the Universe right back to the moment just after the Big Bang singularity stopped being a singularity. We can not, however, using the laws of physics, determine what the state of the singularity was, beyond saying “singularity” (which just means ‘something we can not describe’)… we can not describe the physical characteristics of the singularity based on the information available to us in space and time. This is because “information” from the singularity was destroyed by the Big Bang… the information required to describe the state of the singularity did not transfer in to our familiar space-time universe.

Information that does exist in space-time can not be destroyed. The laws of physics that we have so far determined would not work if it could.

The information paradox as relates to more ordinary black holes is saying that there is information which should be accessible to us, being existent in the space-time universe, which is destroyed by it’s interaction with the black hole. That which emerges from the black hole via Hawking radiation can not be measured, put in to equations and used to determine that state of matter that entered the black hole and was eventually radiated back “Hawkingly”. Given that black holes exist in the universe, in space-time, we would expect not to lose information that interacts with the black hole, yet apparently we do – paradoxically. Or do we?

Is it lost of rearranged, like corrupted data on a computer

It is lost. If it was rearranged, and we had perfect knowledge, we would be able to (mathematically) reverse the process of re-arrangement and identify the original information.

esselte said:

The Rev Dodgson said:

esselte said:

If we had perfect knowledge of the universe in it’s current state, using the laws of physics and their associated equations we could determine the state of the universe at any time in the past or future. This is because “information” can not be destroyed.

I’m no expert on these things, but I have never seen any evidence presented for that statement, and it seems to me contradictory to the principles of quantum mechanics.

The problem with quantum mechanics lies in taking the measurements, in gaining “perfect knowledge” about the current state of things. If we could gain “perfect knowledge”, we could determine the state of the universe at any time in the past or future. In the quantum realm, the best we can do is state an approximation of knowledge based on a probability of something being actual.

Usual disclaimer I’m no expert either and probably everything I written in this and the previous post is wrong, but relating it to the BB singularity helped me conceptualize what is meant by “information” when it’s talked about in regards to black holes.

What you have written seems a good summary of what is often said, and is apparently accepted without question.

It would be nice to see some evidence though, or a least some further discussion of why this statement should be accepted.

Viewed from the outside, it takes every object an infinite time to get to the event horizon.
So, viewed from the outside, nothing ever reaches the event horizon.
So, viewed from the outside, no information is lost crossing the event horizon because the event horizon is never crossed.

From the point of view of the particle falling into the black hole, it falls through the event horizon in finite time, but it doesn’t lose information because it carries its information with it into the black hole. So no information is lost.

So the “paradox” of information lost as a particle passes the event horizon isn’t a paradox, because no information is lost in either frame of reference.

Susskind formalised that by saying that the information stays on the surface of the black hole so is never lost.

Information is never lost in ordinary GR, and in string theory, and in loop quantum gravity. TOEs handle everything the same way. No problem.

mollwollfumble said:

Viewed from the outside, it takes every object an infinite time to get to the event horizon.
So, viewed from the outside, nothing ever reaches the event horizon.
So, viewed from the outside, no information is lost crossing the event horizon because the event horizon is never crossed.

From the point of view of the particle falling into the black hole, it falls through the event horizon in finite time, but it doesn’t lose information because it carries its information with it into the black hole. So no information is lost.

So the “paradox” of information lost as a particle passes the event horizon isn’t a paradox, because no information is lost in either frame of reference.

Susskind formalised that by saying that the information stays on the surface of the black hole so is never lost.

Information is never lost in ordinary GR, and in string theory, and in loop quantum gravity. TOEs handle everything the same way. No problem.

Can you see the objects from the outside

mollwollfumble said:

Viewed from the outside, it takes every object an infinite time to get to the event horizon.
So, viewed from the outside, nothing ever reaches the event horizon.
So, viewed from the outside, no information is lost crossing the event horizon because the event horizon is never crossed.

From the point of view of the particle falling into the black hole, it falls through the event horizon in finite time, but it doesn’t lose information because it carries its information with it into the black hole. So no information is lost.

So the “paradox” of information lost as a particle passes the event horizon isn’t a paradox, because no information is lost in either frame of reference.

Susskind formalised that by saying that the information stays on the surface of the black hole so is never lost.

Information is never lost in ordinary GR, and in string theory, and in loop quantum gravity. TOEs handle everything the same way. No problem.

What happens when the black hole fully evaporates and there is no “surface” any more?

I actually need to present this in more detail because there are subtleties that I’ve glossed over.