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How do black holes destroy information and why is that a problem?

backreaction.blogspot.com

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Re: How do black holes destroy information and why is that a problem?

#71

Post by westurner »

chasd00 wrote: post #29

man, watch the PBS YouTube channel SpaceTime. They're short, informative, and very well done. they dedicate a handful of episodes to getting you ready for Hawking radiation. https://youtu.be/qPKj0YnKANw

"Why Quantum Information is Never Destroyed" re: determinism and T-Symmetry ("time-reversal symmetry") by PBS SpaceTime https://youtu.be/HF-9Dy6iB_4

Classical information is 'collapsed' quantum information, so that would mean that classical information is never lost either.

There appear to be multiple solutions for Navier-Stokes; i.e. somewhat chaotic.

If white holes are on the other side of black holes, Hawking radiation would not account for the entirety of the collected energy/information. Is our visible universe within a white hole? Is everything that's ever been embedded in the sidewall of a black hole shredder?

Maybe even recordings of dinosaurs walking; or is that lemurs walking in reverse?

Do 1/n, 1/∞, and n/∞ approach a symbolic limit where scalars should not be discarded; with piecewise operators?

Re: How do black holes destroy information and why is that a problem?

#72

Post by ww520 »

maffydub wrote: post #68

(I am not a physicist.) One thing I've struggled with around black holes is what it means for anything to fall into a black hole. From a reference frame outside the black hole, observing an object falling into the black hole, don't we observe time slowing down as the object approaches the event horizon? In this reference frame, does it ever cross the event horizon, or does it just asymptotically approach it? If it do…

The object has physically fallen through the event horizon and long disintegrated but the imprint of its falling toward the event horizon is slowing down to the outside observer. The falling object emits photons along the way which are what the observer sees. These photons of the falling object shining toward the observer have to travel greater and greater distance in the warped spacetime as the object getting near the event horizon so the photons appear to slow down. The spacetime is being "stretched" (warped) more as getting closer to the blackhole. The event horizon is at the point where the spacetime is "stretched more than" the distance the photons can travel to come out.

Re: How do black holes destroy information and why is that a problem?

#73

Post by anarazel »

continuational wrote: post #60
acoma wrote: post #48

Earlier quoted context omitted.

Not quite. Dropping a column or updating a row is typically irreversible.

In PostgreSQL, schema changes are transactional.

> In PostgreSQL, schema changes are transactional.

With a few exceptions (that refuse to run in an explicit transaction): E.g. {CREATE, DROP} DATABASE, {CREATE, DROP} TABLESPACE, {CREATE INDEX, DROP INDEX, REINDEX} CONCURRENTLY, REINDEX {SCHEMA, SYSTEM, DATABASE}.

Re: How do black holes destroy information and why is that a problem?

#74

Post by H8crilA »

Strilanc wrote: post #58
hyperpallium wrote: post #5

> The important thing is that all evolution equations that we know of are time-reversible. I've heard this before, but it's so surprising to me, when one of the simplest mathematical operations - addition - is not reversible. e.g. if a+b=4 , you can't infer the values of a and b (beyond their linear relationship). This non-injectivity is a kind of summarising, with less information, where more than one state maps to…

Actually addition is reversible, as long as you do it inline. The inverse of `a += b` is `a -= b`. An example of an action that's not reversible is masking: `a &= b`. But if you dig deep enough into the physics, you find that these kinds of irreversible actions are actually always implemented in a way analogous to the following: // a &= b acquire zero'd register z from environment z ^= a & b z ^= a a ^= z z ^= a disc…

See also the Linear logic, a logic in which discarding information is disallowed:

https://en.m.wikipedia.org/wiki/Linear_logic

Re: How do black holes destroy information and why is that a problem?

#75

Post by KSS42 »

openasocket wrote: post #69

The other major example of a time-irreversible operation/object is much more mundane: the collapse of a wave function. I've never been able to find a decent layperson's explanation of what the wave function collapse really means, and why physicists seem to have no issue with it being time irreversible but seem quite concerned with black holes

Physicists do have a problem with it.

See : https://backreaction.blogspot.com/2019/08/the-problem-with-q...

Sabine Hossedfelder also discusses it in her book Lost in Math.

Two books on the subject are reviewed in the Booklab podcast, episode 20:

http://booklabpodcast.com/booklab-020-what-is-real-and-beyon...

Featured Books:What is Real? by Adam Becker; and Beyond Weird by Philip Ball.

Quantum physics has been with us for more than 100 years – but what is it actually telling us about the world?

Re: How do black holes destroy information and why is that a problem?

#76

Post by garmaine »

openasocket wrote: post #69

The other major example of a time-irreversible operation/object is much more mundane: the collapse of a wave function. I've never been able to find a decent layperson's explanation of what the wave function collapse really means, and why physicists seem to have no issue with it being time irreversible but seem quite concerned with black holes

That’s because physicists do have a problem with it, and not all believe the wave function collapse is real.

Re: How do black holes destroy information and why is that a problem?

#77

Post by zcrackerz »

anarazel wrote: post #73
continuational wrote: post #60

Earlier quoted context omitted.

In PostgreSQL, schema changes are transactional.

> In PostgreSQL, schema changes are transactional. With a few exceptions (that refuse to run in an explicit transaction): E.g. {CREATE, DROP} DATABASE, {CREATE, DROP} TABLESPACE, {CREATE INDEX, DROP INDEX, REINDEX} CONCURRENTLY, REINDEX {SCHEMA, SYSTEM, DATABASE}.

Also, try adding a value to an enum via ALTER TYPE ... ADD VALUE

Re: How do black holes destroy information and why is that a problem?

#78

Post by anarazel »

zcrackerz wrote: post #77
anarazel wrote: post #73

Earlier quoted context omitted.

> In PostgreSQL, schema changes are transactional. With a few exceptions (that refuse to run in an explicit transaction): E.g. {CREATE, DROP} DATABASE, {CREATE, DROP} TABLESPACE, {CREATE INDEX, DROP INDEX, REINDEX} CONCURRENTLY, REINDEX {SCHEMA, SYSTEM, DATABASE}.

Also, try adding a value to an enum via ALTER TYPE ... ADD VALUE

Not anymore ;). Well, at least in the upcoming PG 12.

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit...

  commit 212fab9926b2f0f04b0187568e7124b70e8deee5
  Author: Thomas Munro 
  Date:   2018-10-09 12:51:01 +1300
  
      Relax transactional restrictions on ALTER TYPE ... ADD VALUE (redux).
There's still some restrictions:

> This patch removes that restriction, and instead insists that an uncommitted enum value can't be referenced unless it belongs to an enum type created in the same transaction as the value.

Re: How do black holes destroy information and why is that a problem?

#79

Post by abakker »

swebs wrote: post #22
TeMPOraL wrote: post #18

Earlier quoted context omitted.

IANAPhysicist, but couldn't information be radiated away? When you have a particle and antiparticle annihilating, the information about what collided and when is carried away by the radiation from that annihilation event; nothing remains at ground zero to be inspected. As matter traverses the accretion disk and falls towards the event horizon, couldn't information about it be radiated away? As an observer, you could…

Outside the event horizon, sure. But imagine the (extremely) far future when the universe is dominated by black holes and even those photons have been absorbed. You would not be able to extract any information about the past universe aside from its mass.

This may be a naive question, but, how do we know that the mass we measure for a black hole is equivalent to the things that went into the black Hole? We can’t have any observational data on what went into them in aggregate - is it not possible that the mass of black holes that we estimate is incorrect in some fundamental way? Or just that e.g. energy that enters them also becomes mass?

Re: How do black holes destroy information and why is that a problem?

#80

Post by aserafini »

mannykannot wrote: post #40
hyperpallium wrote: post #5

> The important thing is that all evolution equations that we know of are time-reversible. I've heard this before, but it's so surprising to me, when one of the simplest mathematical operations - addition - is not reversible. e.g. if a+b=4 , you can't infer the values of a and b (beyond their linear relationship). This non-injectivity is a kind of summarising, with less information, where more than one state maps to…

Ha! I had not looked at it that way before. Insofar as addition is an abstract representation of merging two collections, we are abstracting away the information that links each element of the resulting collection to the one it came from.

Isn’t this exactly the same for subtraction, multiplication and division?
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