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. ...

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1answer
29 views

Physicists use of “Information” [on hold]

this is a philosophical question for physicists to answer. Elsewhere here on physics.se I learned that "information contained in a physical system = the number of yes/no questions you need to get ...
1
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0answers
31 views

How difficult is it to construct the time inverse of a state? [closed]

This is a vague question, but I hope it can have some sort of answer. Given an isolated state, classical or quantum, of finite size, how difficult is it to actually produce a state that is the time-...
1
vote
1answer
35 views

Is energy required to preserve information on a disk?

I was just wondering if the large files I have on my PC, which have remained there for years, take up some energy to remain preserved. Just curious. Maybe a silly question after all, but I would like ...
3
votes
1answer
32 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?
4
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2answers
133 views

What is the black hole information paradox really? [closed]

Preliminaries What is the black hole information paradox really? Is it a sophisticated way to ponder and debate the existence of an operator on the boundary that can tease out the interior of a ...
1
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0answers
38 views

Is it possible in this Universe to communicate a bit of information with energy that scales sub-linearly with distance?

If we look at all the ways that people do communicate information, they all seem to have a cost "at least linear in distance." For example, communicating over a wire has attenutation, so the energy ...
5
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2answers
62 views

Books on entropy [closed]

What books introduce entropy in a intuitive, elementary way (at most, for a person with undergraduate physics studies)? The book should not necessarily introduce entropy in relation only to ...
8
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4answers
387 views

Is information entropy the same as thermodynamic entropy?

Context In one of his most popular books Guards! Guards!, Terry Pratchett makes an entropy joke: Knowledge equals Power, which equals Energy, which equals Mass Pratchett is a fantasy comedian ...
1
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4answers
125 views

Information, entanglement and EPR

I'm currently trying to understand why superluminal information transport is not possible. Therefore, I would like to get some help concerning the definition of information or the general setting. ...
1
vote
1answer
64 views

Does conservation of information mean that the direction of causality is arbitrary? [duplicate]

If it is the case that the information content of the universe is conserved, and the past can be constructed from a complete knowledge of the future just as easily as vice versa, then is there any ...
3
votes
0answers
38 views

Implication of non-positive tripartite information

Hayden et al 2011 showed that tripartite information is non-positive given Ryu-Takanayagi formula. (For definition of tripartite information, see for instance section 4.4 of this paper) Is there ...
4
votes
3answers
332 views

Speed of Dark experiment, does it *really* travel faster than light? [duplicate]

I have seen many folks doing this Moon shadow experiment concluding that shadow from point A on the Moon can travel to point B on the Moon faster than light. What I fail to understand here (and I am ...
0
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0answers
33 views

Is it feasible to store large amounts of information on DNA molecules (for years)?

This initially might seem like a biology based question, but I want to concentrate on the physics of DNA molecules, used purely as a manmade stable substrate for storing information. A 2013 Ted Talk ...
2
votes
1answer
36 views

Is Entropy Maximized, or Just Increased?

Do different real processes involve different rates of change of entropy? (Is the rate of change of entropy constant with time throughout all regions of space, or perhaps in other words, constant with ...
0
votes
1answer
75 views

What gives a particle its identity?

A lot of very smart people have stitched together the standard model, and I accept it. I don't understand it, but I assume there should be a mechanism of sorts that gives a particle some fundamental ...
1
vote
1answer
40 views

What processes create or destroy information?

From a classical standpoint, it seems pretty clear that information can be easily lost. If you knock over a bookshelf and the books fall out, it seems like their initial order on the shelf cannot be ...
-1
votes
1answer
41 views

Is there a way to prove information entropy?

Information entropy is a very general term involving everything from the tendency of material to decay (in all the 3 meanings) to the fact that you need energy to sort your books alphabetically. Let'...
5
votes
1answer
80 views

Holevo Information and Quantum Mutual Information

This question is about the difference between Quantum Mutual Information and Holevo Information of quantum channels. From http://arxiv.org/pdf/1004.2495.pdf equation 7 we know that the sum of quantum ...
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votes
2answers
67 views

Can a non-entangled qubit be teleported by entangling it?

Let's say I have a qubit that is not entangled in state $\psi$. I want to teleport this qubit by entangling it with another qubit but still getting $\psi$ back in the end. Is this possible, or would ...
3
votes
1answer
44 views

About the holographic principle

I read at a book this quote "As the degrees of freedom of a particle are the product of all the degrees of freedom of its sub-particles, were a particle to have infinite subdivisions into lower-...
0
votes
1answer
86 views

Can a system be PERFECTLY simulated by a quantum (and classical) computer? [closed]

This is a thought experiment, and as such will assume some crazy things. Let's say I decide to perfectly simulate my university as it is right now. I use a magic machine to instantly scan the entire ...
1
vote
1answer
47 views

Shannon entropy and information function

I'm trying to solve a exercise about Shannon entropy. I've tried some things but I can't solve it, and couldn't find information on the internet. Let's see. We have the Shannon entropy, and a system ...
0
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0answers
48 views

Deriving an upper limit to the information in a human brain

For this question I am presuming that the human brain works deterministically and all information in a human brain is, once you get down to the lowest level, stored through the arrangement and other ...
1
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0answers
25 views

What are some good books on foundations of Thermodynamics [duplicate]

I am not looking for some introductory texts, graduate text, etc. I am looking for something that addresses to foundational problems in thermodynamics and statistical mechanics.
0
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0answers
47 views

How many atoms do we need to store a bit?

And which kind of storage (HDD, flash, blue-ray, etc) has the most efficient atoms/bit ratio?
4
votes
2answers
185 views

Maxwell demon with memory storage

Let's consider a classical Maxwell demon as described in wiki https://en.wikipedia.org/wiki/Maxwell%27s_demon. It spends energy for measuring velocities and coordinates of some particles and uses the ...
13
votes
2answers
400 views

Did merging Black Holes in GW150914 give up entropy and information to the gravitational waves, since they lost 3 solar masses?

Since the final Black Hole (BH) had 3 solar masses less of mass than the original binary BH, it seems the 2 BHs lost mass, and with it event surface area, entropy, and information. If that came from ...
3
votes
0answers
64 views

Can Observation change entropy?

I don't know whether this even makes any sense, but if 'observation' can be considered as 'recieving and reading information', can an act of observation (of a system) change (increase or decrease) its ...
1
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1answer
46 views

Reference for statistical mechanics from information theoretic view

I am interested in knowing if some one here knows book/notes for statistical mechanics from the information theoretic viewpoint.
0
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1answer
42 views

Is total order and total chaos equal?

Imagine an ideal gas which possesses maximum entropy. It´s not difficult to describe the state of the system because once you know some part of the system you can say how the whole system looks like. ...
0
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0answers
48 views

Can a massive imploding sphere smash the holographic principle and conservation of information into oblivion?

Let $\text{BH}_1$ be a black hole of mass $M_1$, zero charge and angular momentum, and event horizon radius $R_1=\frac{2GM_1}{c^2}$. Alice is loitering at distance (all distances here are from the ...
0
votes
2answers
97 views

Does quantum entangled particle release energy when its “twin” is measured? [closed]

So I was just thinking a bit, and I came up with a couple of questions. As we all know the scenario: We have two quantum entangled particles. Let's call them A and B. We like to measure the state of ...
1
vote
1answer
116 views

Understanding the delayed choice quantum eraser from a quantum information stand point

A continuation of Understanding the quantum eraser from a quantum information stand point What quantum circuit would correspond to delayed choice? In particular, the decision of whether to not to ...
3
votes
1answer
148 views

Understanding the quantum eraser from a quantum information stand point

Is there a way to understand the quantum eraser experiment in terms of quantum information? In particular, is there a quantum circuit that would function as a quantum eraser experiment? The issue I'm ...
2
votes
1answer
54 views

Quantification of uncertainty, or information loss, when modeling a physical system?

Say I have a physical circuit (say a battery, wires and an incandescent lamp) that I want to model. To model it I could perhaps use: traditional circuit theory some kind of finite element analysis ...
0
votes
1answer
77 views

Why doesn't the quantum eraser violate the no-deletion theorem?

In the quantum eraser experiment and its variants, you basically have a double slit experiment, where you detect which slit the photon went through, but then forget this information. My question is, ...
0
votes
1answer
41 views

Is the information that a human brain (and body) “contains” superflorous to the information contained within the atoms of the body?

Layman here. I recently watched this video talking about Stephen Hawking's theory of hairy black holes. The speaker mentions, as I've heard before, that once "something" has entered a blackhole its ...
0
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0answers
46 views

Thermodynamic reversibility, Landauer's principle, and Maxwell's demon

A lot of the literature surrounding Landauer's principle (and relating it to Maxwell's demon) talks about whether or not a logically irreversible process can be thermodynamically reversible. But why ...
3
votes
1answer
97 views

Infinite bits to describe a qubit

In the Quantum Computation book by Nielsen and Chuang, the authors write in the context of quantum teleportation "Even if she (Alice) did know the state |w> , describing it precisely takes an ...
3
votes
4answers
208 views

Is it possible to learn about an event that occurred outside of your observable universe?

I have mixed intuitions about this. On one hand, nothing can travel faster than the speed of light and if there is enough space between you and an event then a signal will get stuck in the middle of ...
1
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0answers
48 views

Best introduction to the link between information and thermodynamics

I have a solid understanding of classical thermodynamics, as well as a reasonable understanding of statistical mechanics and some of the philosophical issues regarding entropy. However, I've never ...
0
votes
1answer
74 views

Rotation on the surface of the Bloch sphere?

I have two questions. Is rotation of a state by an angle $\theta$ about the $\hat{n}$ axis of the Bloch sphere the same as the rotation of the sphere about $\hat{n}$ axis by an angle $\theta$? I ...
3
votes
3answers
227 views

Is Bekenstein entropy limit inconsistent with universal continuity?

It is unknown whether the universe is discrete or continuous in its intricate quantum level structure. See for example: Can universal continuity be experimentally falsified? Is the universe finite ...
2
votes
1answer
44 views

What information do we lose when we increase whale songs to our hearing range?

TV documentaries on marine life often feature the evocative sounds of whales communicating with each other (apparently), over very long distances. The frequency of baleen whale sounds ranges from 10 ...
4
votes
3answers
108 views

The speed of information

Does this expression have any rigorous meaning? Intuitively ,I feel that information about an event or a system in my environment propagates to me at a certain "speed". Does this correspond to ...
0
votes
1answer
74 views

The simulation hypothesis and the halting problem [closed]

I have a basic knowledge of classical and quantum information which isn't remotely enough to make me an expert on the subject. That being said, reading some questions about the simulation hypothesis ...
1
vote
0answers
47 views

Does Time-Reversal Violation imply a microscopic Arrow of Time?

I have a questions regarding the relation of time reversal violation and existence of a microscopic direction of time. It seems to me that the following definition for T-symmetry and arrow of time ...
2
votes
4answers
330 views

Is amount of entropy subjective?

From all sources I have seen it follows that the proof you can't decrease the amount of entropy in the Universe is given only statistically - the order is just one of the many ways how things can be (...
0
votes
2answers
74 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 ...
2
votes
1answer
85 views

Is there a definition of relative Renyi entropy?

Is there a Renyi entropy analogue of ``$H(X \vert Y)$" ? If yes then is there any known meaning to that? Googling around I found a few different notions, equation 18 here, http://arxiv.org/abs/...