APOD: The Holographic Principle (2017 Apr 23)

[dergolem]

Lovely, lovely Chris, I totally get it now.

I'm coming at this from a non-science background, but "information" as you describe it applies to my background too.

Teachers come in many forms. I am very grateful.

[geckzilla]

Teachers come in many forms. I am very grateful.

This statement is no less true by noting this, but Chris is indeed a science teacher.

[zendae1]

I can never see the 3D unless I slightly cross my eyes, and then concave and convex reverse. I still knew it was a teapot, but certainly in an altered universe. No matter what tho, if you put your cursor in the center of the teapot it looks suspended and becomes part of the scene.

[neufer]

http://www.seinfeldscripts.com/TheGymnast.html
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MR. PITT: Oh, this is very odd.

KRAMER: (looking at picture) Yeah, it's 3-D art. Computers generate 'em. BIG computers.

MR. PITT: Yes, I've heard about these. How do they work?

KRAMER: Well, you blur your eyes like you're starin' straight through the picture. And you keep your eyes unfocused. And then... (Kramer and Pitt stare at picture) Oh, oh, oh, YEAH!

MR. PITT: I don't see it.

KRAMER: Yeah, it's a , surrounded by planets, asteroids...

MR. PITT: I still don't see it.

ELAINE: Okay, Kramer, that's enough. Mr. Pitt has got work to do.

KRAMER: Ya' ever dream in 3-D? It's like the boogeyman is comin' right at you.

MR. PITT: A , where?

KRAMER: (pointing) Right in here. Just keep your eyes unfocused.
........................................................
MR. PITT: (staring at 3-D poster) I think I'm on to something!

ELAINE: Mr. Pitt! The board of directors is on the phone. They've called an emergency meeting. They want you to be there to discuss the merger!

MR. PITT: You said keep your eyes out of focus, which is misleading. You want DEEP focus!

ELAINE: (drops phone, rushes to Pitt) Mr. Pitt, you have GOT to stop staring at that poster!

MR. PITT: I see something that could be a . Is it round? Is it pointy?

ELAINE: (grabs poster, smashes it) No, you don't see it, and you're never going to see it!
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[BDanielMayfield]

This is the first APOD I've come across in a long time that I'm having a hard time wrapping my head around.
May I ask clarification on something?

In the description, this phrase: "...the information held by a black hole..."
When the word "information" is used, in this context, to what does it refer? I'm sure I'm not asking the question correctly, but information has a different meaning depending on the discipline using it.

Yours is not an easy question to answer. There are entire textbooks on the subject! And it's an area of science and math that is still evolving. At its most basic, information in physics might be thought of as all of the details that describe some system. So in the black hole example, all of the particles that have entered the black hole have physical properties like velocity, momentum, spin, and others. These properties represent information, and that doesn't seem like it should change just because the particles are now part of a black hole.

From a physics standpoint, consider some closed system (a volume of space, perhaps). If you were to measure every property of every point in that space, that would be the total information content. Classical information theory could be invoked if you then symbolically encoded that data in some way.

I'm confused too, perhaps due to a fundamental misunderstanding of what "information" means in this context. How can information survive falling into a black hole where everything is crushed by gravity?

Bruce

[neufer]

---

I'm confused too, perhaps due to a fundamental misunderstanding of what "information" means in this context. How can information survive falling into a black hole where everything is crushed by gravity?

From the outside nothing even makes it to the event horizon.

Everything is slowly frozen and squashed flat just outside the event horizon much like a going into warp drive.

[Chris Peterson]

I'm confused too, perhaps due to a fundamental misunderstanding of what "information" means in this context. How can information survive falling into a black hole where everything is crushed by gravity?

Information is generally treated as a conserved property, like mass or momentum. Not something that can be destroyed.

[BDanielMayfield]

I'm confused too, perhaps due to a fundamental misunderstanding of what "information" means in this context. How can information survive falling into a black hole where everything is crushed by gravity?

Information is generally treated as a conserved property, like mass or momentum. Not something that can be destroyed.

That particular conservation "Law" has always been very hard to understand. If we threw something (a newspaper, for example) into a fire, into the Sun or into a black hole how is its information anything but destroyed?

[Chris Peterson]

I'm confused too, perhaps due to a fundamental misunderstanding of what "information" means in this context. How can information survive falling into a black hole where everything is crushed by gravity?

Information is generally treated as a conserved property, like mass or momentum. Not something that can be destroyed.

That particular conservation "Law" has always been very hard to understand. If we threw something (a newspaper, for example) into a fire, into the Sun or into a black hole how is it's information anything but destroyed?

The fact that you can't reconstruct the paper doesn't mean that physical information has been destroyed, though. The particle states are all preserved (or altered in a way that still preserves the information of the previous state). The sort of "information" you're considering in a newspaper is different than the sort of "information" physicists usually consider.

(But I agree it's all rather confusing. It's a specialty like QM that needs to be approached in a highly mathematical way that doesn't lend itself to clean intuitive understanding by most people, myself included.)

[BDanielMayfield]

---

I'm confused too, perhaps due to a fundamental misunderstanding of what "information" means in this context. How can information survive falling into a black hole where everything is crushed by gravity?

From the outside nothing even makes it to the event horizon.

Everything is slowly frozen and squashed flat just outside the event horizon much like a going into warp drive.

"Squashed flat" equals "crushed", and I think you might be playing frame of reference tricks again Art.

Bruce

[Chris Peterson]

---

I'm confused too, perhaps due to a fundamental misunderstanding of what "information" means in this context. How can information survive falling into a black hole where everything is crushed by gravity?

From the outside nothing even makes it to the event horizon.

Everything is slowly frozen and squashed flat just outside the event horizon much like a :rocketship: going into warp drive.

"Squashed flat" equals "crushed", and I think you might be playing frame of reference tricks again Art.

His comment concerns frames of reference, but there's no trick. We never see anything cross a black hole's event horizon. It just gets closer and closer, which means it gets flatter and flatter, but not infinitely thin, and not subject to the issue of information conservation inside a black hole, because the material isn't yet inside and could theoretically be moved away from that black hole.

[Boomer12k]

No teapot for me whatever I try... but my Pareidolia is kicking in with "moose heads", flying critters... and BREASTS...and insect skeletons....Freud would have a field day... anyone got a couch??? Adjacent area??? to a PIXEL????? um....Overbleed???

:---[===] *

[Boomer12k]

---

From the outside nothing even makes it to the event horizon.

Everything is slowly frozen and squashed flat just outside the event horizon much like a going into warp drive.

"Squashed flat" equals "crushed", and I think you might be playing frame of reference tricks again Art.

His comment concerns frames of reference, but there's no trick. We never see anything cross a black hole's event horizon. It just gets closer and closer, which means it gets flatter and flatter, but not infinitely thin, and not subject to the issue of information conservation inside a black hole, because the material isn't yet inside and could theoretically be moved away from that black hole.

One way to get a "plate of Spaghetti". Get the matter out of a Black Hole.... Spaghettification?

:---[===] *

[BDanielMayfield]

From the outside nothing even makes it to the event horizon.

Everything is slowly frozen and squashed flat just outside the event horizon much like a going into warp drive.

"Squashed flat" equals "crushed", and I think you might be playing frame of reference tricks again Art.

His comment concerns frames of reference, but there's no trick. We never see anything cross a black hole's event horizon. It just gets closer and closer, which means it gets flatter and flatter, but not infinitely thin, and not subject to the issue of information conservation inside a black hole, because the material isn't yet inside and could theoretically be moved away from that black hole.

The following scenario is hypothetical, (unless there are infinite parallel timelines, etc. in which case this may have actually happened many times):

Astrophysicist Zart (from a safe observation point) sends a probe on a trajectory straight toward the center of a black hole. The probe accelerates under universal gravitation such than the probe moves faster and faster as it approaches the black hole, all the while sending back telemetry to Zart's station. Zart sees what Art described, but the probe, rather than getting "squashed flat", actually gets stretched out, spaghettified by tidal force before it very quickly [as opposed to never] crosses the event horizon.

Is anything in this scenario wrong?

Bruce

[Chris Peterson]

The following scenario is hypothetical, (unless there are infinite parallel timelines, etc. in which case this may have actually happened many times):

Astrophysicist Zart (from a safe observation point) sends a probe on a trajectory straight toward the center of a black hole. The probe accelerates under universal gravitation such than the probe moves faster and faster as it approaches the black hole, all the while sending back telemetry to Zart's station. Zart sees what Art described, but the probe, rather than getting "squashed flat", actually gets stretched out, spaghettified by tidal force before it very quickly [as opposed to never] crosses the event horizon.

Is anything in this scenario wrong?

It's good except for the telemetry part. You can't cheat mother nature. From Zart's frame there's no way to see things as they appear from the probe's frame. The signal itself is getting stretched out by relativistic effects.

[BDanielMayfield]

It's good except for the telemetry part. You can't cheat mother nature. From Zart's frame there's no way to see things as they appear from the probe's frame. The signal itself is getting stretched out by relativistic effects.

Yes, I knew this, but I should have stated it more plainly. The telemetry in effect takes longer and longer to climb back out of the BHs gravity well, and is redshifted. The point of this is that crossing the event horizon is real, but observing it from the outside is impossible.

Back to information and black holes, Doesn't the No Hair Theorem imply that all information is lost once it has entered a black hole?

Bruce

[Chris Peterson]

Back to information and black holes, Doesn't the No Hair Theorem imply that all information is lost once it has entered a black hole?

No, I don't think so. It says nothing about information loss, only that the information is not observable from outside the black hole. Black holes are not eternal- they evaporate away over time. Current conjecture is that whatever information they have consumed is returned in the Hawking radiation they radiate away.

[neufer]

Back to information and black holes, Doesn't the No Hair Theorem imply that all information is lost once it has entered a black hole?

No, I don't think so. It says nothing about information loss, only that the information is not observable from outside the black hole. Black holes are not eternal- they evaporate away over time. Current conjecture is that whatever information they have consumed is returned in the Hawking radiation they radiate away.

The No Hair Theorem is classical non-quantum and does indeed imply that all information is lost once it has entered a black hole.

Hawking radiation is quantum non-classical and does exactly what Chris says.
.............................................................................
Information basically equates to entropy which always increases:

• 1) Encyclopedia Britannica = low information
  2) Shredded Britannica = moderate information
  3) Burned Britannica = high information

.............................................................................
Classical No Hair black holes are low entropy/information.

Quantum black holes are high entropy/information.

[BDanielMayfield]

Back to information and black holes, Doesn't the No Hair Theorem imply that all information is lost once it has entered a black hole?

No, I don't think so. It says nothing about information loss, only that the information is not observable from outside the black hole. Black holes are not eternal- they evaporate away over time. Current conjecture is that whatever information they have consumed is returned in the Hawking radiation they radiate away.

The No Hair Theorem is classical non-quantum and does indeed imply that all information is lost once it has entered a black hole.

Hawking radiation is quantum non-classical and does exactly what Chris says.
.............................................................................
Information basically equates to entropy which always increases:

• 1) Encyclopedia Britannica = low information
  2) Shredded Britannica = moderate information
  3) Burned Britannica = high information

.............................................................................
Classical No Hair black holes are low entropy/information.

Quantum black holes are high entropy/information.

Now that is a wickedly good post Art, although librarians would be mortified.
In common usage we do things like reading to acquire more information, more knowledge. But a [Zart, the] mad scientist could flip out and reason; for maximum informational dispersion, let's nuke the libraries.

In view of that horrific thought, entropy is a much better word choice here.

Bruce

P.S. Peace out y'all.

[neufer]

Now that is a wickedly good post Art, although librarians would be mortified.

• I am a veritable font of 'information.'

[BDanielMayfield]

Now that is a wickedly good post Art, although librarians would be mortified.

• I am a veritable font of 'information.'

That you are Zart, I mean Art.

[RJN]

Although I didn't know it when composing the APOD text, the pictured central object is specifically a "Utah teapot", which according to Wikipedia (here: https://en.wikipedia.org/wiki/Utah_teapot), is an inside joke in the computer graphics community.

- RJN