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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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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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37 views

What if a black hole is an API? [closed]

I realize that the black hole works extremely like a software application programming interface (API) that connects the server to its client. The only difference is that the black hole is a single way ...
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15 views

Forecast in cosmology survey : loss or gain of information with cross-correlations

In the context of a forecast in cosmology, I am currently working on Fisher's formalism which is part of a more general theory, that of information. My problem applies to estimating cosmological ...
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23 views

Proof of continuous Shannon entropy

In Jaynes' Probability Theory: The Logic of Science, there is a quick derivation of continuous entropy in chapter 12. He does so by taking the discrete definition of entropy and combines it with ...
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1answer
57 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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27 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....
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2answers
96 views

Information content in black holes

Bekenstein-Hawking formula for entropy of a black hole tells us that information content in a black hole is proportional to its area which is in fact proportional to the mass^2 of the black hole. The ...
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1answer
41 views

Entropy, Thermodynamics and Information

This is a bit of a shower-thought, so forgive me if it is ill-conceived or a stupid question! It occurred to me that, to preserve information, you need to use energy. For example, say you have a book ...
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168 views

Why do physicists say information can't travel faster than light speed?

I often hear in physics videos light speed is the ultimate speedlimit two parts of the universe can communicate at, or even that speed of light is actual speed of causality. Where does that notion ...
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1answer
28 views

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
52 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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20 views

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
31 views

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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31 views

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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24 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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47 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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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
61 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
56 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
67 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
80 views

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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0answers
6 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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1answer
153 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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21 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
112 views

Why is information indestructible in quantum mechanics? [duplicate]

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

Information Density of Spacetime [closed]

How much information is required to completely describe a given volume in spacetime?
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41 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
10 views

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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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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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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3answers
112 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
4k views

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
216 views

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
101 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
127 views

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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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
68 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
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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
67 views

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
50 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
81 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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57 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 ...
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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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2answers
89 views

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{\...