Talk:Bekenstein bound

message: Need a little more clarification for laymen: there's a bound for the amount of information in a finite region of space (Bekenstein bound, which depends on the amount of energy-mass in that region. Does it mean if there's an infinite amount of energy in a region of space then there's an infinite amount of information? Should there be an upper bound for energy-mass if Pauli exclusion principle really holds true? Also, if that's the case then singularity is ruled out?Mastertek (talk) 14:50, 23 October 2011 (UTC)
thread_title: Energy-mass limit in given finite space

message: I am no expert, but when it says in the first paragraph, "... or the information necessary to perfectly describe that system, must be finite if the region of space or the energy is finite," doesn't the author actually mean 'AND', as in, "if the region of space AND the energy is finite?"  The Berkenstein bound is proportional to both the radius, R, and the mass-energy, E, so if either quantity is unbounded, the resulting Berkenstein calculation will be without bound.  Right?  If I haven't misunderstood, would someone knowledgeable please fix this?  Thanks.  SJGooch (talk) 10:40, 7 January 2011 (UTC)
replies: text: I think they do, but I'll check the context.-- cheers, Michael C. Price talk 11:11, 7 January 2011 (UTC)

text: That's correct. If either the energy or radius are unbounded then the information can be unbounded, even if one of those two variables are kept constant.--Jamie Michelle (talk) 03:30, 8 January 2011 (UTC)
thread_title: Conditions of Application

message: The number of significant digits in the examples is only silly.  — Preceding unsigned comment added by 81.216.218.158 (talk) 20:52, 14 October 2011 (UTC)
thread_title:  Silly numbers 

message: :The inequality for the ratio S/E has meaning only when the entropy is strictly proportional to the number of particles, i.e. an absolute entropy with no additive constants. [Otherwise, I could always add on an entropy constant so that the inequality is violated.] R must be interpreted as the (relativistic) thermal wavelength and the inequality must be inverted. Then it will say that the slope S/E from the origin to a point is always greater than that point on the entropy curve precisely because it is concave, i.e. it bends toward the energy axis. If I is the Shannon information measure the inequality makes no sense at all. It is also apparent that the inequality can not be valid for both concave and convex functions. Only the former are candidates for the entropy. See "Boltzmann's Heat Death versus Bekenstein's Bound at www.bernardhlavenda.com and references thereinBernhlav (talk) 16:44, 4 September 2012 (UTC)
replies: text: Wouldn't von Neuman entropy be more appropriate than Shannon? DarkSky7 (talk) 16:16, 18 April 2022 (UTC)
thread_title:  Contradicts Clausius's Principle that the Entropy of the Universe Tends to a Maximum 

message: Bekenstein's bound implies that roughly spherical objects like stars collapse into black holes if too much mass is packed within too small a radius.  But a Turing machine could have an infinite rod-like tape, with a finite-sized head crawling back and forth along it, without any part of it exceeding the Bekenstein bound.  Does anyone know of any argument why an extended rod-like object must suffer gravitational collapse if it gets too long?  An easy calculation shows that the compressive force in an infinite rod due to self-gravitation remains finite, so the rod would not even need to be particularly strong. Maybe it would need to be infinitely stiff to avoid buckling, but that is a harder calculation.  However that may be, the assertion that the Bekenstein bound prevents infinite Turing machines from existing requires further demonstration or documentation.CharlesHBennett (talk) 01:00, 11 April 2013 (UTC)
thread_title:  Introduction --  Does Bekenstein bound really make an infinite Turing machine tape impossible? 

message: Since this is included in Limits to computation, please include comparisons with the storage density of actual modern hardware, and with the theoretical maximum storage density of magnetic media  — Preceding unsigned comment added by 71.167.67.219 (talk) 20:38, 5 May 2013 (UTC)
thread_title:  Comparison with actual hardware 

message: At the end of the Examples section, we have the lines "The existence of Bekenstein bound implies that the storage capacity of human brain is finite, although very large. This implication has important consequences on mind uploading, making it theoretically possible, given that physicalism is true."
This implies that the Bekenstein bound has relevance for the human brain which is manifestly false. Human brains, indeed all matter, doesn't come even remotely close to approaching the bound. No matter what the bound is or indeed whether a bound exists at all has, I think, no relevance to human brains or to mind uploading. Is it ok with everyone if I delete the lines in question? Tmfs10 (talk) 21:47, 3 June 2013 (UTC)
thread_title: Examples Section

message: Listen what Connection Machine designer says recalls The game of Life is an example of a class of computations that interested Feynman called "cellular automata". Like many physicists who had spent their lives going to successively lower and lower levels of atomic detail, Feynman often wondered what was at the bottom. One possible answer was a cellular automaton. The notion is that the "continuum" might, at its lowest levels, be discrete in both space and time, and that the laws of physics might simply be a macro-consequence of the average behavior of tiny cells. Each cell could be a simple automaton that obeys a small set of rules and communicates only with its nearest neighbors, like the lattice calculation for Lattice QCD. If the universe in fact worked this way, then it presumably would have testable consequences, such as an upper limit on the density of information per cubic meter of space.. Why do I post it here? Might be we include this into the origins, referencing the Digital Physics?--Javalenok (talk) 18:13, 31 October 2014 (UTC)
thread_title:  Cellular automata 

message: Does the Bekenstein limit only apply to computing power, or does it describe physical information, as in the disposition and energy states of the atoms within, say, a cubic millimeter? In terms of actual, physical entities (such as atoms) expressed in terms of various equations, and not an idea described by a series of 1s and 0s dictated by an electron's spin state, what would be the Bekenstein limit for a cubic millimeter?  — Preceding unsigned comment added by 96.2.91.78 (talk) 19:30, 16 January 2015 (UTC)
thread_title:  Bekenstein non-computational limit 

message: Since quantum data is measured in qubits rather than bits, shouldn't that be the unit used in this article?  Storing n bits takes n qubits, but the converse is exponentially false.   MvH (talk) 16:24, 23 April 2015 (UTC)
thread_title:  Should the word "bits" in the article be replaced by "qubits"? 

message: Substituted at 09:21, 29 April 2016 (UTC)
thread_title: Assessment comment

message: Is there some reason why the equations for entropy and information use "2π / ħ" instead of simplifying this to simply "1 / h"? It seems to me that using the un-reduced constant would slightly simplify these equations.  — Preceding unsigned comment added by 67.166.118.104 (talk) 07:01, 13 January 2020 (UTC)
thread_title:  Planck Constant vs Reduced Planck Constant