Question: Greene's "The Hidden Reality": the holographic principle

Ted King

On pp. 260-261 of "The Hidden Reality" Brian Greene says the following:

Susskind and 't Hooft stressed that the lesson should be general: since the information required to describe physical phenomena within any given region of space can be fully encoded by data on the surface that surrounds the region, then there's reason to think that the surface is where the fundamental physical processes actually happen.

I puzzled over this for quite awhile and it seems as though Greene, probably inadvertently, phrased this somewhat more decisively than is justified - that is, the "then there's reason to think that the surface is where the... processes happen" part in particular. It seems that he hasn't provided reasons why something that can be is anything more than a theoretic possibility rather than what is the case.

Perhaps I'm being too pedantic, but when I first read this I was led by his phrasing into thinking that what he was stating about the holographic principle was something that some physicists have good reason to think is more than a theoretic possibility.

Of course, I could easily be misconstruing the whole issue or missing some critical aspect of it. I am also aware that scientists who popularize complex issues oftentimes understandably use imprecise language that can cause misunderstandings that are avoided by more precise formulations that scientists steeped in the technical language of the discipline are able to avoid. That's why I'm asking for help in understanding this. Is the holographic principle essentially only a theoretic possibility that is consistent with our best understanding of physics or are there actually other reasons to think that it is more than a "mere" theoretic possibility? Or am I misunderstanding the issue?

jedishrfu

I know they apply this to the surface of a BH.

phinds

Quote by jedishrfu

I know they apply this to the surface of a BH.

No, they apply it to the "event horizon" of the black hole, which is a place in space that does not exist in any material way. It's just the point at which light can no longer escape the gravitational pull of the black hole. How this insubstantial place can hold information is a total mystery to me, and if I understand it correctly "they" do NOT just say it COULD store the information, they say it DOES store it.

If I understand it correctly, Suskind also believes that all of the information in the observable universe is contained on the sphere that is the boundary of the observable universe as seen from earth. This makes even LESS sense to me. At least the black hole event horizon has some effect that is measurable even if it is not a material place. The sphere that defines our observable universe is just a point we DEFINE in space. It has no real characteristics at all, so the concept that information can be stored there just seems like lunacy to me.

Suskind seems like a really bright guy and a good physicist, so I figure I must be missing something in all this but I've never been able to figure out what. I hope this thread will lead me to some understanding of what just seems crazy to me.

Ted King

I should have been more clear - I have a separate question about how a person falling through a black hole can "simultaneously" appear to an outside observer to have vaporized at the horizon due to Hawking radiation and whatnot, but to the person they will seem to have gone "through" the horizon basically intact (at least for awhile until gravitational tidal forces cause other problems). That paradox seems somehow to be "resolved" by the holographic principle, but to my understanding, Greene doesn't explain how in his book (he seems to gloss over the issue).

I meant to be referring to Susskind's conjecture that this could (does?) apply to the known universe as a whole rather than to only black holes.

jedishrfu

Quote by phinds

No, they apply it to the "event horizon" of the black hole, which is a place in space that does not exist in any material way. It's just the point at which light can no longer escape the gravitational pull of the black hole. How this insubstantial place can hold information is a total mystery to me, and if I understand it correctly "they" do NOT just say it COULD store the information, they say it DOES store it.

If I understand it correctly, Suskind also believes that all of the information in the observable universe is contained on the sphere that is the boundary of the observable universe as seen from earth. This makes even LESS sense to me. At least the black hole event horizon has some effect that is measurable even if it is not a material place. The sphere that defines our observable universe is just a point we DEFINE in space. It has no real characteristics at all, so the concept that information can be stored there just seems like lunacy to me.

Suskind seems like a really bright guy and a good physicist, so I figure I must be missing something in all this but I've never been able to figure out what. I hope this thread will lead me to some understanding of what just seems crazy to me.

Sorry for not being clear, I had leave in mid post but I think you knew that.

phinds

Quote by Ted King

I should have been more clear - I have a separate question about how a person falling through a black hole can "simultaneously" appear to an outside observer to have vaporized at the horizon due to Hawking radiation and whatnot, but to the person they will seem to have gone "through" the horizon basically intact (at least for awhile until gravitational tidal forces cause other problems). That paradox seems somehow to be "resolved" by the holographic principle, but to my understanding, Greene doesn't explain how in his book (he seems to gloss over the issue).

The person does NOT appear to have "vaporized" at the event horizon; that's nonsensical. He DOES appear to an outside observer to have slowed down almost to a stop while he himself notices nothing and just keeps on going. This is not a paradox of any kind and does not need any resolution.

I meant to be referring to Susskind's conjecture that this could (does?) apply to the known universe as a whole rather than to only black holes.

I assume that by "known universe" you mean the observable universe. That's what my rant was about.

phinds

Quote by jedishrfu

Sorry for not being clear, I had leave in mid post but I think you knew that.

No, I have no idea why you would think that I knew that.

Ted King

Quote by phinds

The person does NOT appear to have "vaporized" at the event horizon; that's nonsensical. He DOES appear to an outside observer to have slowed down almost to a stop while he himself notices nothing and just keeps on going. This is not a paradox of any kind and does not need any resolution.

I assume that by "known universe" you mean the observable universe. That's what my rant was about.

I did mean mostly "observable", except I wasn't sure that term is inclusive enough to include what physicists are talking about when they are applying the holographic principle to the "whole" universe.

As to why I said "vaporized", here is what Greene says on page 257 of "The Hidden Reality":

One essential perspective is yours, as you freely fall toward a black hole. Another is that of a distant observer, watching your journey through a powerful telescope. The remarkable thing is that as you pass uneventfully through the black hole's horizon, the distant observer observes a very different sequence of events. The discrepancy has to do with the black hole's Hawking radiation. When the distant observer measures the Hawking radiation's temperature, she finds it to be tiny; let's say it's 10-¹³ K, indicating that the black hole is roughly the size of the one at the center of our galaxy [a supposition made earlier in the text]. But the distant observer knows that the radiation is cold only because the photons, traveling to her from just outside the horizon, have expended their energy valiantly fighting against the black hole's gravitational pull; in the description I gave earlier, the photons are tired. She deduces that as you get ever closer to the black hole's horizon, you'll encounter ever-fresher photons, one that have only just begun their journey and so are ever more energetic and even hotter. Indeed, as she watches you approach to within a hair's breadth of the horizon, she sees your body bombarded by increasingly intense Hawking radiation, until finally all that's left is your charred remains.

As a personal observation, if the attitude I sense in your response is indicative of what I'm likely to encounter on a regular basis here, I think I'll be inclined to ask my questions and make my comments on another forum.

phinds

Quote by Ted King

I did mean mostly "observable", except I wasn't sure that term is inclusive enough to include what physicists are talking about when they are applying the holographic principle to the "whole" universe.

As to why I said "vaporized", here is what Greene says on page 257 of "The Hidden Reality":

Well, I'm flabbergasted by Greene's comment. It makes no sense to me at all and I've never heard anything like it but he knows more than I do so I assume I'm missing something.

"whole" universe is not a particularly meaningful term inasmuch as it seems to mean exactly the same thing as just "universe". Everything outside of the observable universe is just speculation, but many of us believe that it just goes on exactly as what is inside our observable universe. As I recall, Suskind talks bout the holographic information on the sphere of the Observable Universe, which is what my rant in post #3 was about.

As a personal observation, if the attitude I sense in your response is indicative of what I'm likely to encounter on a regular basis here, I think I'll be inclined to ask my questions and make my comments on another forum.

Yeah, this is a fairly hard-nosed forum. If you can't take blunt criticism, you may well not find this place congenial. BUT ... it's the best forum on the internet for getting good answers to questions about physics. Most of the good folks here are more patient than I am. In fact I was just complimenting DaleSpam in another thread for how patient he is and he's hardly the only one.

Ted King

Quote by phinds

Well, I'm flabbergasted by Greene's comment. It makes no sense to me at all and I've never heard anything like it but he knows more than I do so I assume I'm missing something.

I went back and read further along and realized why I had said that Greene had suggested a resolution to the seeming paradox, but I had not recalled some important parts of what he said - continuing from the quote I cited above:

Which perspective is right? The claim advanced by Susskind and others is that both are. Granted, this is hard to square with ordinary logic - the logic by which you are either alive or not alive. But this is no ordinary situation. Most saliently, the wildly different perspectives can never confront each other. You can't climb out of the black hole and prove to the distant observer that you are alive. And, it turns out, the distant observer can't jump into the black hole and confront you with evidence that you're not. When I said the distant observer "sees" you immolated by the black hole's Hawking radiation, that was an oversimplification. The distant observer, by closely examining the tired radiation that reaches her, can piece together the story of your fiery demise. But for the information to reach her takes time. And the math shows that by the time she can conclude you're burned, she won't have time left to then hop into the black hole and catch up with you before you're destroyed by the singularity. Perspectives can differ, but physics has a built-in-fail-safe against paradoxes.

I really don't know how to interpret that and that's why I said Greene seems to gloss over the resolution to the seeming paradox. In my memory I thought he was suggesting that Susskind's thoughts about the holographic principle were the nature of the resolution, but on rereading what Greene says here, that isn't actually clear at all.

Incidentally, this URL seems to have extended excerpts from "The Hidden Reality" book in case you wanted to read up on it some:

http://www.epubbud.com/read.php?g=9QDTX6S4&p=126

phinds

Quote by Ted King

I went back and read further along and realized why I had said that Greene had suggested a resolution to the seeming paradox, but I had not recalled some important parts of what he said - continuing from the quote I cited above:

I really don't know how to interpret that and that's why I said Greene seems to gloss over the resolution to the seeming paradox. In my memory I thought he was suggesting that Susskind's thoughts about the holographic principle were the nature of the resolution, but on rereading what Greene says here, that isn't actually clear at all.

Incidentally, this URL seems to have extended excerpts from "The Hidden Reality" book in case you wanted to read up on it some:

http://www.epubbud.com/read.php?g=9QDTX6S4&p=126

Good grief. I appreciate your attempt at "clarification" but I gather you're just as bemused by Green as I am. I just don't follow any of your quotes from him at all but I don't think I'm going to pursue it with him since what I've read here just makes my head hurt.

jedishrfu

These statements by Greene are related to the holographic universe idea. It came from applying information theory to a BH event horizon and noting that as matter falls into the BH it's event horizon enlarges. It was theorized that the information was captured on it.

Anyway, Wikipedia describes it under 'holographic principle'

Sorry this may be a redundant post already know its holographic duh.

*granpa*

if the holographic principle is right then every particle is simultaneously everywhere and is (potentially) interacting instantaneously with every other particle

Ted King

Quote by phinds

Good grief. I appreciate your attempt at "clarification" but I gather you're just as bemused by Green as I am. I just don't follow any of your quotes from him at all but I don't think I'm going to pursue it with him since what I've read here just makes my head hurt.

It seems to me that Greene is conflating an epistemological issue with an ontological one. That is, he seems to be saying that there isn't a paradox of whether he died at the event horizon or went through it alive because we can't KNOW whether or not he died. But whether or not he died is actually an ontological issue - an issue of what actually happened not an issue of what we know about what happened. Are there some situations where physicists equate the epistemological with the ontological? If so, what is the justification for that?

Ted King

Quote by jedishrfu

These statements by Greene are related to the holographic universe idea. It came from applying information theory to a BH event horizon and noting that as matter falls into the BH it's event horizon enlarges. It was theorized that the information was captured on it.

Anyway, Wikipedia describes it under 'holographic principle'

Sorry this may be a redundant post already know its holographic duh.

Thanks for replying. Hopefully someone can shine some light on this holographic issue and we'll get a projection of the reality of the situation. :)

Ted King

Quote by granpa

if the holographic principle is right then every particle is simultaneously everywhere and is (potentially) interacting instantaneously with every other particle

I wasn't aware that that was an implication of the holographic principle. Assuming it is, then I wonder if that is a result of the mathematics of quantum mechanics. From what I can discern (which isn't a lot, I'll concede), it seems as though the mathematics of the wave function sort of suggest that every particle is actually interacting with every other particle.

*granpa*

Quote by Ted King

Quote by granpa

if the holographic principle is right then every particle is simultaneously everywhere and is (potentially) interacting instantaneously with every other particle

I wasn't aware that that was an implication of the holographic principle. Assuming it is, then I wonder if that is a result of the mathematics of quantum mechanics. From what I can discern (which isn't a lot, I'll concede), it seems as though the mathematics of the wave function sort of suggest that every particle is actually interacting with every other particle.

not only that but if every particle does interact instantaneously with every other particle then QM and relativity could easily be combined.
You just set c=infinity

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jedishrfu	These statements by Greene are related to the holographic universe idea. It came from applying information theory to a BH event horizon and noting that as matter falls into the BH it's event horizon enlarges. It was theorized that the information was captured on it. Anyway, Wikipedia describes it under 'holographic principle' Sorry this may be a redundant post already know its holographic duh.

granpa	if the holographic principle is right then every particle is simultaneously everywhere and is (potentially) interacting instantaneously with every other particle