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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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Could the Universe have a finite number of states?

I think most people would say the Universe is infinite, and the number of ways of arranging infinite particles in infinite space is infinite. But we know the "visible" Universe is finite, there is a ...
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1answer
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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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Information contained in matter, given black hole

I read that when a black hole consumes one bit of information, the surface area of the black hole increases by 1 planck area. $l^2_P=\frac{\hbar G}{c^3}$ Surface area of a black hole: $A_T=4\pi r_s^...
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1answer
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Is “information” in Physics analogous to metadata or properties of a Database or File?

I've been watching a lot of PBS Space Time, and I don't understand what is meant by the word "information". I.E.: "information" is lost in a black hole, etc. Is "information" real-world, actual, ...
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Why is information “lost” when it got into a black hole?

The black hole information loss paradox is the paradox that information can not be lost, but is lost when it got into a black hole. But I do not see why it is lost at all. I see it is no longer ...
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Why do we use this diagram/model for elementary particles?

The model of elementary particles is analagous to the periodic table, which is organized not only beautifully, but also functionally. The typical model for the elementary particles that pops up ...
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0answers
20 views

Maximizing mutual information with Restricted Boltzmann Machines and Monte-Carlo sampling

So I've been reading through Koch-Janusz and Ringel's, "Mutual Information, Neural Networks, and the Renormalization Group" (check it out here). I'm currently trying to reimplement some results from ...
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44 views

Do gravitational waves violate the information paradox? [duplicate]

I know when black holes collide, the remnant black hole has a lower mass than the sum of the original two masses. This is due to energy loss via gravitational wave emission. Does this violate the ...
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0answers
23 views

Meaning of Shannon Information

Is there any (simple!) explanation as to which of the following pieces of paper tape, each with the same number of holes, contains information: A simple coding of a Shakespeare sonnet The same ...
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2answers
60 views

Multiple frequencies [closed]

could someone please inform me how it is possible to send multiple frequencies down one wire? I’m referring specifically to a communication protocol known as HART. It seems they send a 4-20mA signal ...
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1answer
53 views

Is physical entropy opposite to information entropy? [duplicate]

I am currently taking a class on Decision Theory where I was introduced to the notion of "entropy" in an information theoretic setting while we were studying decision trees. I was given the following ...
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1answer
62 views

What do the area laws for mutual information and correlations actually state? [closed]

I am trying to understand what are the key points of this paper: Area laws in quantum systems: mutual information and correlations. If I understand correctly the law states that the information flux ...
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2answers
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E. T. Jaynes' subjectivism vs measurement of distributions

In his paper, E. T. Jaynes argues that entropy is a measure of our ignorance about a system. As such, the probability distribution of states $\{p_k\}$ has to be chosen in the most unbiased way, thus ...
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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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1answer
147 views

Why don't physicists interpret randomness in quantum mechanics as ignorance or limitations in our knowledge?

As the title says: why don't physicists interpret randomness in quantum mechanics as ignorance or limitations in our knowledge? Why is the randomness in quantum mechanics equations not added to the ...
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19 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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2answers
105 views

Why is information indestructible in quantum mechanics? [duplicate]

Why is information indestructible in quantum mechanics?
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1answer
61 views

Information Density of Spacetime [closed]

How much information is required to completely describe a given volume in spacetime?
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40 views

Bekenstein Bound / Holographic Principle at Extremely Low Temperatures

I'm curious about a possible connection between the Berkenstein Bound and the physical nature of information, specifically in reference to the fact that the amount of information that can be written ...
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0answers
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Entropy of superposition state vs collapse

Imagine 2 similar atoms one is in superposition state while another is collapse into 1 of the possible States fall into the black hole at the same time, do the 2 atoms lost equal amount of entropy? I ...
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0answers
33 views

Relationship between physical and information entropy [duplicate]

This question is inspired by the following example given in Barnett's book on quantum information: (PDF here, starting at the bottom of page 5) I am not a physicist, but I'll accept that the ...
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0answers
57 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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3answers
108 views

Why does less knowledge imply more correlations?

Given two systems, correlations quantify how much information we can gain about system 1 by measuring system 2. Entanglement is a type of correlations which only occurs in quantum mechanics. There ...
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1answer
73 views

Is the total information in the (visible) universe compatible with the one on the surface of a black hole with the same radius?

Is the total information available in the universe compatible with the entropy we would find on the surface of an hypothetical black hole whose radius is the visible universe one ($\sim14$ Gpc)? We ...
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3answers
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Why is the information paradox restricted to black holes?

I am reading Hawking's "Brief answers". He complained that black holes destroy information (and was trying to find a way to avoid this). What I don't understand: Isn't deleting information quite a ...
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3answers
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Is there a physical limit to memory reading and writing speed?

Is there a limit to the speed at which a memory, quantum or classical, can be read or written into? I've seen this interesting question : Is there a physical limit to data transfer rate?. Here I'm ...
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4answers
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No FTL information implies no FTL travel?

The general consensus in the scientific community is that it is impossible to transmit information faster than light. There is also speculation that it might be possible to open wormholes or travel ...
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1answer
94 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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2answers
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Can the second law of thermodynamics be derived from Quantum randomness?

The second law of thermodynamics says that the entropy of an isolated system continuously increases. Can we say that this is due to Quantum mechanics, which continuously increases the information ...
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information theory and energy mass relationship (E=mc2) - just a hunch … [closed]

I was walking on the street the other day and thought to myself, maybe E=mc2 can be derived from information theoretic principles. I did not do too much work on this, just want to brainstorm a bit. ...
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9answers
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What precisely does it mean for “information to not travel faster than the speed of light”?

This is something that's been bothering me for a while. The way we usually first hear about causality is that "nothing travels faster than $c$". But then you learn that phase velocities can ...
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0answers
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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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1answer
126 views

Is this a correct derivation of the second law or it is just nonsense?

In this article, the author makes the following argument. The difference between entropy and information is that entropy is the bits that you don't understand while information is the bits you do ...
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1answer
54 views

Bekenstein bound and black hole

I'm confused with this sentence from Wikipedia: "Upon exceeding the Bekenstein bound a storage medium would collapse into a black hole." Does that mean "the storage medium will become a black ...
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2answers
94 views

Paragraph from a Stephen Hawking's Book (Uncertainty Principle)

This is from a Stephen Hawking's Book (Uncertainty Principle). I would like to know how does the Uncertainty Principle impose a limit on the size. What does he mean? From Hawking's book: It turns ...
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1answer
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Nielsen and Chuang 2.2.3: state of a qubit after measurement

(Apologies for the poor typesetting of kets. I haven't been able to figure out how to do that on this site). On page 85 of Nielsen and Chuang's textbook, they write that the probability of obtaining ...
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2answers
49 views

Is information lost in the Heisenberg's uncertainty?

If I set a particle at a known momentum and a known position, then I would expect that I know the precise position and momentum upon measurement (assuming I can measure that well). The uncertainty ...
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1answer
76 views

Why is the term “information” used to describe a physical system [duplicate]

(With apologies that my physics background is minimal...) Why is the term "information" used to describe a physical system, such as the movement of air through a jet engine? If I understand ...
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0answers
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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 ...
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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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2answers
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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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2answers
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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
67 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
59 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
151 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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48 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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0answers
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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
64 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
27 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
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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 ...