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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37 views

In digital physics, how would additional information such as velocity be encoded into bits? [closed]

Assuming that at the bedrock of reality, there is some unary particle from which everything is derived, such that there either is a unary particle in some space or there isn't, how would information ...
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How to handle bra-ket in logarithm?

$\newcommand{\ket}[1]{\left| #1 \right>}$ $\newcommand{\bra}[1]{\left< #1 \right|}$ Say the following two equations: $$ S = - k_B \text{Tr} (\rho \ln \rho) $$ $$ \rho = \sum _\epsilon \ket{\...
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Energy that can control itself (A unit that can process information without body) [closed]

I read a book called The future of the mind. There it suggested a conscience that exists in the form of energy without body. Ideally, I thought the energy without body may take the form of light. ...
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1answer
72 views

Von Neumann entropy of a quantum state vs Von Neumann entropy of a system

Using the Chuang and Nielsen Quantum Computation and Quantum Information book, for an introductory course in Quantum Information, I stumbled on an ambiguous (at least for me) use of the Von Neumann ...
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1answer
60 views

Information to Energy equations?

Are there are any known formulas or equations that can calculate information from energy or energy from information? One of them, I believe, is the Bekenstein bound which is the maximum information ...
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2answers
155 views

Why does information loss in quantum collapse not threaten determinism?

When Hawking argued that information is lost in black holes, this triggered the "black hole war" because it threatened determinism, which would mean the laws of physics are only true on average. But ...
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49 views

Are strings capable of information processing? If so would string computers be more powerful than quantum computers?

A deterministic computer is weaker than quantum computer at least quadratically for (almost) all kinds of tasks. This is proved and the difference arises from Grover's search algorithm, which allows ...
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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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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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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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1answer
26 views

If mass and energy are same what will be the equivalent of a homogeneous ball in terms of energy and information?

We can observe an object with mass as it has a well defined boundary but it is not the same with energy. What may happen to the information or data that exists with an object and is needed to ...
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72 views

Why is it necessary to irreversibly erase a memory?

I know that the most accepted resolution of the Maxwell's demon paradox was proposed by Landauer and revolves around the fact that the demon's memory is finite and will have to be erased at some point....
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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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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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66 views

Information loss in black holes

Doesn't quantum collapse or decoherence mean that information is being lost all the time? So why is the loss of information in black holes such a big deal?
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How come no information can travel faster than light when we can measure a black hole's mass? [duplicate]

So I learned about the Schwartzchild radius, which is the radius of an object's event horizon. But how we define an event horizon is that it's a region of space where the gravitational acceleration ...
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1answer
77 views

Amount of Information of a Galaxy? [closed]

Just like the title suggests, how much data/information does a galaxy have in (bits)? Like the Milky Way galaxy for example?
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300 views

Bekenstein Bound

This info is from Wikipedia In physics, the Bekenstein bound is an upper limit on the entropy S, or information I, that can be contained within a given finite region of space which has a finite ...
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1answer
215 views

The 'Conservation of Information' myth

PBS Spacetime recently released a video talking about 'why information is never destroyed in Quantum Mechanics' I'm surprised to see this myth to persist even to this day. We know that unitarity and ...
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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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2answers
67 views

Contradiction of the extension of the electric field of a charge to infinity

The usual point of view is that the electric field is distributed to infinity and the information about displacement of a charge translates to every other charge in the universe with the speed of ...
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1answer
190 views

How is music encoded in a vinyl? [closed]

I'm asking about something that looks like magic to me. I know that waves can be combined into one by "summing" them, but I guess there are different combinations of waves that lead to the same ...
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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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1answer
418 views

Is there an equivalence between Boltzmann entropy and Shannon entropy..?

I have already parse other posts about this subject but none of them seems to answer completely to my interogation [ this interrogation is to put in relation with this question Is there an ...
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1answer
337 views

Is there an equivalence between information, energy and matter?

Consider the physical world as made of information, with energy and matter as incidentals. This statement must be placed in the context of the holographic principle and the works of Bekenstein ... ...
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1answer
84 views

Quantum processes from the eye of ''Laplace demon''

If an imaginary being, like the Laplace demon were to observe quantum processes, are all the states in his description of the quantum process pure states?
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1answer
102 views

Computronium and Time Dilation and Bremermann's Limit

I was contemplating computronium the other day and it occurred to me that there might be a point at which the computronium becomes so dense that gravitational time dilation effects would cause it to ...
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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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5answers
219 views

How does the lack of information increase as temperature increases?

Suppose one knows nothing about the concept of entropy. How can we argue that the lack of information/ignorance about the system typically increases with the increase in the temperature using the ...
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1answer
109 views

What is the most likely/favoured theory put forth explaining the Black hole information paradox?

What is the most likely/favoured theory put forth explaining the Black hole information paradox? Is there any theory that is most favoured that has no flaws, or most likely explains how black holes ...
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1answer
91 views

The speed of information propagation (classical, not quantum)

It seems to be a common statement in textbooks that: "For a linear wave equation with the dispersion relation $\omega_k$, the propagation speed of information is given by the group velocity." which ...
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1answer
106 views

If all the information about the universe is stored on some 2-dimensional boundary, why is a 3-dimensional “hologram” of the information needed?

If all the information about the universe is stored on some 2-dimensional boundary, why is a 3-dimensional "hologram" of the information needed? Certainly as the good Mr. William Ocam of Orange tells ...
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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 ...
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9k views

Is there a physical limit to data transfer rate?

Is there a physical limit to data transfer rate (e.g. for USB $3.0$, this rate can be a few Gbit per second)? I am wondering if there is a physical law giving a fundamental limit to data transfer rate,...
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1answer
214 views

Entropy: subjective lack of knowledge that leads to objective conclusions

There is something I really don't get about entropy. Let's consider a classical system (not quantum mechanics here). We can compute the entropy of a system via the formula $$S=-\sum_l P_l Log(P_l)$$ ...
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1answer
50 views

Question about Szilard paper : why does he say entropy decreases during expansion?

I am reading Szilard paper : http://www.sns.ias.edu/~tlusty/courses/InfoInBio/Papers/Szilard1929.pdf I don't understand some of the things he says. During the isothermal expansion of the gas, he ...
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40 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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1answer
110 views

Maximum entropy: an assumption or a fact

From what I gather (and please correct me if I'm wrong), Jaynes argues that thermodynamic and information entropy are the same since the assumption in statistical thermodynamics that the energy ...
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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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1answer
75 views

Does this experimental confirmation of thermodynamic irreversibility at the quantum level mean that information can be created/destroyed over time?

According to this article, https://phys.org/news/2015-12-physicists-thermodynamic-irreversibility-quantum.html, physicists recently confirmed thermodynamic irreversibility at the quantum level. Does ...
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1answer
157 views

Why group speed can contain information but phase speed can't?

I was watching sixty symbol on YouTube about reflective index and learnt that it is the sum of all the speed of light or phase speed that appears slower than speed of light in the medium, and also the ...
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194 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 ...
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1answer
99 views

is there a fundamental relationship between energy and information

I seems that in general that information is not conserved as opposed to energy, so any direction relationship seems unlikely but perhaps it is expressed in the quantum or other non-classical realm of ...
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1answer
154 views

How do I calculate Holevo information when information is knowable in principle, but unknown?

I am trying to better understand the meaning of Holevo information $\chi$. Suppose Alice starts with data encoded on qubits in the $\{0,1\}$ basis. She takes one of these qubits, originally in pure ...
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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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23 views

What is the minimum amount of heat created in making a random sequence?

I was thinking of a random process as: a sequence of random variables whose outcomes do not follow a deterministic pattern, but follow an evolution described by probability distributions. Given, it ...
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2answers
429 views

Deriving the Boltzmann distribution using the information entropy

I was going through my lecture notes and I found something I could not quite understand. First, it starts by deriving an expression for the information entropy (as used in physics?): Let $p_i$ be ...
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1answer
46 views

Does energy to matter+antimatter conversion increase the amount of information?

If I am not mistaken; when matter and antimatter annihilate each other and release energy, all the information except the total amount of mass, becomes lost. So, can we say that the reversed process ...
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232 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 ...