tag:blogger.com,1999:blog-22973357.post2602898262751590715..comments2020-07-02T02:25:07.952-04:00Comments on Sabine Hossenfelder: Backreaction: Is the universe a hologram? Gravitational wave interferometers may tell us.Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger28125tag:blogger.com,1999:blog-22973357.post-37856594899483666962019-04-13T10:25:19.392-04:002019-04-13T10:25:19.392-04:00The simplest “derivation” that Bekenstein-Hawking ...The simplest “derivation” that Bekenstein-Hawking entropy is an area law is the following (Susskind used it in some lecture):<br />Throw 1 bit of information into a black hole (BH) with radius R and mass M. 1 bit could be represented by a photon with wavelength λ∼R, so there is no additional location information. We will also ignore polarization and further factors like π. <br />The energy/mass Reimondhttps://www.blogger.com/profile/04669340425105889539noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-32927136928497402472019-04-11T15:09:26.407-04:002019-04-11T15:09:26.407-04:00Holograms are amazing. I find it surprising that n...Holograms are amazing. I find it surprising that nature herself hasn’t found a way of using them. I could be wrong - but doesn’t appear to be any naturally occurring holograms in the natural world. But if the holographic principle is true, then I guess she has, even if it’s not how we usually see them. <br /><br />Susskinds book on black holes and his long running argument with Stephen Hawking Moziburhttps://www.blogger.com/profile/11836761141351221660noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-9434628020724949482019-04-10T05:58:05.290-04:002019-04-10T05:58:05.290-04:00Hi Jean,
-sorru for the delay
in reply.
...Hi Jean,<br /> -sorru for the delay<br /> in reply.<br /> Your thinking is correct. I apologise for the misunderstanding. hi Sabine<br /> - some of my teachers<br /> are not of this era.<br /> - Some of my teachers<br /> of this era are no longer alive. ...and yet,.<br /> Some of the lessons they taught (or I thought I learned) are given new life ( or'understanding') A.C.https://www.blogger.com/profile/08901144737333895284noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36366848276172640732019-04-08T23:17:04.269-04:002019-04-08T23:17:04.269-04:00Fun post thanks. Will think about this. When prese...Fun post thanks. Will think about this. When presented this way, it's actually interesting. One of the big problems with GR as a field theory is that a lot of stuff goes on even classically inside a volume element that cannot be reduced to surface terms. In the context of GR the upshot is no local conservation of energy (see Dirac's little book). I had not seen holography presented this drlhttps://www.blogger.com/profile/05424774416249451584noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-69466220528290114452019-04-08T05:22:42.292-04:002019-04-08T05:22:42.292-04:00What you say was predicted by the loop quantum gra...What you say was predicted by the loop quantum gravity people. Spacetime as a quantum foam would force short wavelength photons on a more tortuous path. This would result in a sort of dispersion. The simultaneous arrival of different wavelengths of photons from very distant burstars meant this is wrong.Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-61919683964078853782019-04-07T22:05:41.837-04:002019-04-07T22:05:41.837-04:00Hi dr Bee,
your attention refers to the real issu...Hi dr Bee,<br /><br />your attention refers to the real issue. How there could be anisotropy in 3d space volume?<br /><br />I think the correct holographic surface is asymptotic surfaces of elementary particles. The space volume could be an emergent isotropy of interactions of elementary holographs. <br /><br />You must search for the fluctuations in particles. Alas, we know the uncertainty Eusahttps://www.blogger.com/profile/14114706429392111062noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-51850225985313599642019-04-07T08:55:52.642-04:002019-04-07T08:55:52.642-04:00It would appear that Verlinde et al. are treating ...It would appear that Verlinde et al. are treating spacetime like a fluctuating turbid media (with some specific correlations) and trying to figure out what can be measured in this case. Which is a refreshing turn away from bigger colliders.<br /><br />Two comments come to mind: <br /><br />1. why don't they use the well-known theoretical framework for beam propagation in turbid media?<br /><Matiashttps://www.blogger.com/profile/11934544458974206202noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-34352123938592299442019-04-06T18:28:39.681-04:002019-04-06T18:28:39.681-04:00I read the paper by Verlinde and Zurek and find no...I read the paper by Verlinde and Zurek and find no terrible fault with it, other than a big question. The central assumption of this paper is with equation 17 as I see it. There they define the entropy of the causal wedge or two light cones merged at their bases. This is treated as a holographic screen. The authors work the Green propagators on the system. The Greens function for two coordinate Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-67773111801590207632019-04-05T21:22:49.362-04:002019-04-05T21:22:49.362-04:00Conformal symmetry is the rescaling of a metric wi...Conformal symmetry is the rescaling of a metric with g_{ab} → Ω^2g_{ab}. The Schwarzschild metric term g_{tt} = 1 - 2GM/rc^2 would presumably similarly transform. However, with O(1) rescaling as Ω^2 and radius as O(ℓ) rescaling as Ω the mass part of this rescales as Ω. This would at first glance here appear to tell us that black holes are not conformal.<br /><br />It is the mass that does this Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-45571483632280200422019-04-05T19:41:16.057-04:002019-04-05T19:41:16.057-04:00The philosopher in me wants to remind you of the i...The philosopher in me wants to remind you of the individuals operating the hologram... They may change the answer before the problem is written down Francishttps://www.blogger.com/profile/01153305261372597803noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-79915051433702829362019-04-05T16:24:57.730-04:002019-04-05T16:24:57.730-04:00"bag of milk"?"bag of milk"?barronhttps://www.blogger.com/profile/17809661163219400995noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80760290550570515682019-04-05T08:54:48.497-04:002019-04-05T08:54:48.497-04:00@A.C.
In that case, the holographic principle pro...@A.C.<br /><br />In that case, the holographic principle probably corresponds with the interior surface of your eyeballs. The relationship with concept formation will be hexagonal grid cells (which have recently been represented in artificial intelligence to simulate navigational capabilities). And the basic mathematical elements relating to hexagons and tetrahedra will be found in Volume II of &mlshttps://www.blogger.com/profile/15862021650071892590noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-87655189647763104702019-04-05T07:49:32.259-04:002019-04-05T07:49:32.259-04:00Does quantum holography require the world to have ...Does quantum holography require the world to have a conformal symmetry? Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-22085536946333233002019-04-05T07:25:00.572-04:002019-04-05T07:25:00.572-04:00A.C., I think that’s originally from Plato ...A.C., I think that’s originally from Plato ...JeanTatehttps://www.blogger.com/profile/08737430572613792118noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-61481273635514278202019-04-05T05:47:47.586-04:002019-04-05T05:47:47.586-04:00They are related. An elementary bipartite entangle...They are related. An elementary bipartite entanglement is an instance of ℂ^2/SL(2, ℂ) = A that is an abelian group such as U(1) or SO(2) for the entanglement phase. Similarly we can write SL(2, ℂ) = ℂ^2/U(1). For ℂ^2 a complex realization of spacetime holography is a reduction on this by a parameter, say ℝ with some regular sequence given by the U(1), which is the radial distance to a black holeLawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18872353187854601762019-04-04T23:48:41.626-04:002019-04-04T23:48:41.626-04:00Hi Sabine,
what if
- to take a question fr...Hi Sabine,<br /> what if <br /> - to take a question from one of my favorite teachers.-<br /> all . our perception<br /> (ultimately)<br /> was no more than<br /> Shadows<br /> <br /> - on the wall of a cave.<br /><br /> All Love, A.C.https://www.blogger.com/profile/08901144737333895284noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74479766026609311432019-04-04T23:00:32.637-04:002019-04-04T23:00:32.637-04:00 Hi Sabine,. (and friends)
interesting convers... Hi Sabine,. (and friends)<br /> interesting conversation.<br /> But what if?<br /> ( to take a question from one of my favorite teachers) Reality.<br /> indeed, (regardless,for a moment,- technology, mathematics, et.al.) our perception based on our perspective, based on our point of view. - may be no more than (ultimately)..<br /> .. shadows . <br /> on the A.C.https://www.blogger.com/profile/04994876510058676257noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-14817505199094216632019-04-04T17:53:18.082-04:002019-04-04T17:53:18.082-04:00Whatever other merit there may be to this line of ...Whatever other merit there may be to this line of investigation, it has this in its favor: On the surface at least (pun unintended), it's testable.Dwight Thiemehttps://www.blogger.com/profile/01267204443440458331noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-60051843429431071722019-04-04T14:37:37.252-04:002019-04-04T14:37:37.252-04:00One way to look at quantum entanglement is to reje...One way to look at quantum entanglement is to reject the assumption of counterfactual definiteness which is made when deriving Bell's inequality. We can then explain experimental results by introducing hidden variables. The experimenter's choice of measurement, with the experimenter being in the same universe as the entangled particle being measured, is not independent of the particle Qhttps://www.blogger.com/profile/10542938146428749817noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-2508180090984946452019-04-04T12:45:54.192-04:002019-04-04T12:45:54.192-04:00Hi Steve,
For all I can tell, no. In the present ...Hi Steve,<br /><br />For all I can tell, no. In the present paper, they really do not calculate an actual measurement result. Instead, they calculate what happens with the path of a photon. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-89079424513405352722019-04-04T11:17:39.713-04:002019-04-04T11:17:39.713-04:00I have not read this paper yet. I have only downlo...I have not read this paper yet. I have only downloaded it. I will try to comment more carefully in the future after reading it. That may happen after this blog thread has gotten cold.<br /><br />I tend to think the entanglement entropy force is for a stretched horizon. I do not think there is holographic content with just any surface. The merger of two black holes defines a zero entropy change Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-72353734522786124322019-04-04T10:45:09.288-04:002019-04-04T10:45:09.288-04:00The LIGO uses many photons to produce a signal. Ea...The LIGO uses many photons to produce a signal. Each photon would have an uncorrelated delay due to this effect. They would average any detectable signal therefore reducing it's effect. Has this idea been accounted for?steve blazohttps://www.blogger.com/profile/01328672442492595421noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-2340053894864365302019-04-04T07:31:30.598-04:002019-04-04T07:31:30.598-04:00TME,
What is "actually an old idea"? Sp...TME,<br /><br />What is "actually an old idea"? Space-time fluctuations? Holography? Testing holography with gravitational wave interferometers? It would help if you could be somewhat more precise.<br /><br />In case you are talking about random walks due to space-time fluctuations, yes, that idea is decades old. Almost all of these approaches violate Lorentz-invariance, however, and Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-79210035239627394462019-04-04T06:10:27.862-04:002019-04-04T06:10:27.862-04:00Loops and tensors and holograms? (Oh my.)
"T...Loops and tensors and holograms? (Oh my.)<br /><br />"The relation between loop quantum gravity (LQG) and tensor networks is explored from the perspectives of the bulk-boundary duality and holographic entanglement entropy."<br />https://journals.aps.org/prd/abstract/10.1103/PhysRevD.95.024011<br />Philip Thrifthttps://www.blogger.com/profile/03021615111948806998noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-35677392554820156332019-04-04T05:52:01.569-04:002019-04-04T05:52:01.569-04:00Isn't this actually an old idea? Basically, if...Isn't this actually an old idea? Basically, if you assume that each Planck voxel introduces a Planck length's uncertainty to any time or distance measurement, you get a random walk that scales as l_p sqrt(N) where N = L/l_p, and thus <br /><br />sigma_L = sqrt(L l_p), <br /><br />where sigma is the uncertainty, L the Length of your Interferometer and l_p the Planck length. Look, for TMEubankshttps://www.blogger.com/profile/00271298679549213444noreply@blogger.com