Questions tagged [information]

Add this Tag for questions on information theory applied to physics, especially in the fields of statistical mechanics and thermodynamics, the black hole information paradox, complexity of dynamical and physical systems and questions to do with whether information is conserved by physical systems. Use the tag quantum information if your question is to do with information theoretic concepts applied to quantum states.

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16
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2answers
415 views

Upper bounding the Kolmogorov Complexity of the Standard Model

The Kolmogorov complexity of a hypothesis/theory/model is the shortest computer program that simulates it, regardless of how inefficient executing that program may be in terms of memory and time. I'm ...
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252 views

Renormalisation and the Fisher-Rao metric

The renormalisation group (I'm talking about classical, statistical physics here, I'm not familiar with field theory too much) can be though of as a flux in a space of possible Hamiltonians for a ...
8
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1answer
252 views

Justification of the Least Action Principle using conservation of information

In this Phys.SE question, one answer (by Ron Maimon) claims that one can make the assumption of a least action principle plausible using Liouville's Theorem as another starting point of the theory. ...
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169 views

Is it possible to derive Liouville's Theorem purely from maximum differential entropy?

Typically in physics (at least the way I learned mechanics), this is derived using the multi-dimensional divergence theorem on the $2N$-dimensional phase space i.e. $0=\partial_t \rho + \sum\limits_{...
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0answers
252 views

About the relation between entropy and Fisher information matrix

It's well known that the Fisher information metric can be given by $$g_{i,j}=-E\left[\frac{\partial \ln(p(x,\theta))}{\partial \theta_{i}}\frac{\partial \ln(p(x,\theta))}{\partial \theta_{j}}\right],$$...
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1k views

An explanation for the Landauer's principle

Has anyone understood the Landauer's principle? What is the current status? In specific, is there a theoretical derivation of the Landauer's Principle?(not the heuristic one based on Salizard's ...
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0answers
146 views

What are some good articles on trend to equilibrium?

I am interested in studying systems out of equilibrium that are trending to equilibrium. Trend to equilibrium, entropy production, etc. seem to be very tricky topics. Any suggestions will be ...
4
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234 views

Do information entropy and thermodynamic entropy evolve the same way?

Recently I asked a question about the relationship between Von Neumann entropy and heat transfer. The link is here. Is the Von Neumann entropy related to heat transfer? I feel as though the answer ...
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168 views

Bekenstein bound and “dimensionality” of information (entropy)

The Bekenstein bound says that the maximum entropy which can be contained in a (spherical) volume of space with a given amount of energy is proportional to the amount of energy multiplied by the "...
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44 views

Why can't the Schwarzschild radius be larger than the Compton wavelength?

In the second paragraph of the third page of this paper, the author makes a statement The dynamical process must now involve, not the length scale $R_{s}$, but rather the universal length $L_{CS}$....
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58 views

Is it necessary to assume that equivalent microstates cannot get transformed into inequivalent microstates to derive the Landauer principle?

The Landauer erasure principle states that to erase a bit of information from a system, the entropy of the environment will be increased by at least $k_B\log2$, or equivalently, it costs at least an ...
3
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1answer
70 views

Landauers Principle Derivation

I read about Landauer's principle and was wondering about the implications from it's original derivation. Landauer derived his principle straight foward from the second law, but I see people favoring ...
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191 views

Path integrals, Ensembles, and Information theory in QFT and statistical mechanics (POV of a mathematician)

I apologize in advance for any stupid/wrong/enraging remarks in the question. I am a mathematician and not a physicist. Consequently this question was written entirely from the perspective of a ...
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75 views

Is there a name for $I(A:B)-I(A:C)-I(A:BC)$ in (quantum) information theory?

Let $I(X:Y)=S(X)+S(Y)-S(XY)$ be the mutual information between $X$ and $Y$, where $S(X)$ is the entropy of $X$ (say the entanglement entropy of subsystem $X$ in quantum information). To characterize ...
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50 views

Is there a scheme for secure physical time-stamping?

Is there a physical phenomenon that could be used to record digital information in such a way that it has the following properties: it relies on some immutable physical law and does not rely on any ...
3
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2answers
477 views

Does the entropy of the universe change as expansion exceeds the speed of light?

The potential encoded information in a photon that is at the edge of the observable universe would seem to be lost as the universe expands. Does that loss of information contribute to the overall ...
3
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1answer
149 views

Black Hole Entropy Calculation

I was watching "Leonard Susskind on The World As Hologram" ( youtube ). At one point he describes the way Bekenstein calculates the entropy of a black hole. Paraphrasing: Take a minimally sized black ...
3
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115 views

What is the entropy of a string?

In his The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics (p. 373) Susskind states that the entropy of a string is [...] proportional to its length. ...
3
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1answer
77 views

How is physical information created?

I am not a physist, so please forgive my ignorance. I am an avid reader of popular science though. So I read about the problem of information seemingly lost at a black hole horizon. But my question ...
3
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1answer
43 views

Does the Bekenstein entropy bound present problems for unitarity in cosmological models that invovle a collapse or bounce?

If we expect the Bekenstein bound, or something like it, to hold in a collapsing universe, will that not eventually force us to accept some loss of information, or is there something I'm missing?
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29 views

Fisher Information in Statistical Mechanics

I am studying the canonical ensemble and it seems to me there is an analogy between derivatives of the partition function, which can extract energy momenta for the system and Fisher score /information....
2
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1answer
53 views

What is the information concept and how can it be measured,…?

According to the Wikipedia, ""Information of an entity is that which resolves the uncertainty of its properties"" source: Wikipedia, physical information Information contained in a physical ...
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62 views

Is information conserved in an expanding universe?

From the classical and quantum mechanical viewpoint, is information conserved in an expanding universe or not?
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32 views

What is all the known information contained in thermal noise?

I've read up a little bit on thermal noise, which is an unavoidable noise in materials when $T>0K$. Thanks to this noise, by measuring the voltage across a material, it is possible to extract the ...
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29 views

How does the information content in a holographic world add up?

I watched Leonard Susskind's great layman lecture "The World As Hologram" the other day (https://www.youtube.com/watch?v=2DIl3Hfh9tY) and it kind of makes sense to me. If Information is a conserved ...
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34 views

Information density, Bekenstein Bound, and length contraction

Is it possible to observe a region of space that has information density greater than what the Bekenstein Bound will allow when length contraction is involved? I.e. An object travels through the ...
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0answers
129 views

Why is information conservation not restricted by the uncertainty principle?

The idea of information conservation seems to be: if all field equations/states of all particles/matter/waves at a certain time are known, all trajectories/waves can be backpropagated to retrieve all ...
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75 views

Can scatter interference patterns from entangled pairs carry information?

I am having problems wrap around why you can't send information faster than light with a similar setup to the quantum eraser experiment. ( https://arxiv.org/abs/quant-ph/9903047v1 ) What I mean is, ...
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45 views

Tensor product of universe Hilbert space and black hole Hilbert space equals?

I'm a newbie struggling to parse concepts important in black hole, holographic principle and related issues. My query comes from Thomas Thiemann’s Modern Canonical Quantum Gen. Relativity, which ...
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127 views

Fisher Information & dynamical systems

Preface: I am an ecologist with a barely working background in physics. B.R. Freiden proposes Fisher Information as a unifying theory of everything (e.g., see books "Physics from Fisher Information", ...
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659 views

Information as Entropy vs. Information as Negentropy

I have been reading the chapter "Maxwell's Demon and Shannon's choice" on N. Katherine Hayles' book "Chaos Bound: Orderly Disorder in Contemporary Literature and Science" where she compares different ...
2
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1answer
153 views

How can “information” be a useful physical quantity given that its value is model-dependent?

From @Humble's answer to "What is information?": Information contained in a physical system = the number of yes/no questions you need to get answered to fully specify the system. That is, however, ...
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204 views

Is not the idea of a continuous universe and finite information density mutually exclusive?

As far as I understand, the universe is not divided into discrete units, but rather its continuous. This seems backed up by a quick search: Does the Planck scale imply that spacetime is discrete? ...
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188 views

What exactly is black hole complementarity and why is it necessary for solving black hole information paradox?

What exactly is black hole complementarity and why is it necessary for solving black hole information paradox? The first question is about the story of vacuum fluctuation causing Hawking radiations. ...
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125 views

Consequences of Entropy/Information Reversal in a System?

Can pairs of different physical systems be symmetrical under a process which would turn one of these physical system's entropic and informational contents into another system's respective ...
2
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1answer
565 views

How many bits of information can be stored in an atom?

How many bits of information can be stored in an atom? The atom in question being as big as you like, but must be stable with regard to nuclear decay
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41 views

Different duality-correlations in holographic principle?

I found an interesting article "Surface/State Correspondence as a Generalized Holography" (https://arxiv.org/abs/1503.03542) If I understood it well, the authors proposed this model to generalize the ...
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2answers
43 views

What type of energy should I use when describing the amount of energy available to increase entropy of a system?

There are many different specific definitions of energy within different physics fields: In thermodynamics we have at least U (system internal energy), F (Helmholtz Free Energy), G (Gibbs Free Energy),...
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49 views

Does an information-theoretical approach proof the equivalence of total order and total chaos?

In the light of information-theory, are a state with maximum and minimum entropy the same? In the case of gas (maximum entropy), one needs very little words to describe a part of the system, which ...
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1answer
59 views

What is the area of physics/science called that deals with fundamental limits of computation?

I am interested in learning about the fundamental limits of computation and in particular would like to read textbooks on the subject if they exist. My background is in maths and computer science - I ...
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7 views

Relation between Fisher Information Matrix and Inertia Matrix

I have been wondering whether there is a relation between the Fisher Information Matrix in a stochastic particle system and Inertia Matrix?
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23 views

information conservation

Since according to the unitarity principle the total amount of information in the universe is conserved over time, how was this information generated ? Is there a relationship between energy ...
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1answer
107 views

What is the physical interpretation of the action integral, without the stationary action principle?

I'm still wondering about the physical interpretation of the action integral of some mechanical system (classical theory here, to simplify things): \begin{equation}\tag{1} A = \int_{t_1}^{t_2} L(q, \, ...
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1answer
65 views

What is the relation between uncertainty and information obtained from a measurement?

For ex. if a measurement gives a position with twice the uncertainty as another measurement, how much less information regarding position are you getting? In other words, if uncertainty doubles, is ...
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0answers
28 views

Possible to canonically digitize analog data to create public RNG?

Suppose you have a random data source, for which different observers will often, but not always, agree on a digitization. E.g. how many sun spots are visible from Earth right now, or what's the ...
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37 views

Why can't I surpass the holographic limit by stitching together two surface areas?

Suppose I have a rectangular brick of computer memory. My brick is very thin on one side and contains so much memory that it is just one bit away from being a black hole. According to the holographic ...
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60 views

If matter cannot be transformed into information, why do we say that information about matter is lost when we talk about black hole paradox?

In this question it is said that matter cannot be transformed into information: Can matter be converted to information? But when we talk about black hole information paradox, we say that matter ...
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82 views

How is encoded the information on the surface of the volume' s boundary?

In the context of the holographic principle, who states that the entropy of ordinary mass (not just black holes) is also proportional to surface area and not volume;that volume itself is illusory ...
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41 views

Proving that Shannon entropy is maximal for the uniform distribution using convexity

I need to show that $-\sum_i{p_i \log{p_i}}$ is maximal iff $p_i=p_j$ for all $i\neq j$ using the convexity inequality: $\phi (\frac{\sum{a_i}}{N})\leq \frac{\sum{\phi (a_i)}}{N}$ I tried expanding ...
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197 views

What does the Holevo bound mean?

Suppose Alice sends $m$ qubits to Bob, and I calculate the Holevo bound $\chi$ on the mutual information between Alice's plaintext message and the bit string obtained by Bob. My understanding is that ...