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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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Definition of heat from stat phys [duplicate]

I don't really understand how to couple the idea of entropy as info with heat. Let's say that you have an isolated system. A cube with a a series of movable partitions parallel to a face of the curve. ...
Lina Jane's user avatar
9 votes
4 answers
7k views

Imagining Graham's number in your head collapses your head to a black hole

My question is how does the above phenomenon, as mentioned in Numberphile here, occur in a semi-quantitative way through physical laws. (i.e saying statistical mechanics implies that is not ...
Mahammad Yusifov's user avatar
-2 votes
0 answers
46 views

Does quantum entropy take into account the quantum uncertainties present in a system?

The von Neumann entropy of a mixed state is non-zero, and this makes sense as mixed states are just statistical descriptions of quantum systems, so there's some amount of classical uncertainty causing ...
Pratham Hullamballi's user avatar
0 votes
2 answers
75 views

How much information is encoded in a ball on a field? [closed]

Consider a soccer ball placed on a planar field of finite dimension (just like a soccer field). How much information can be realistically encoded in the position of the ball on the field?
Noumeno's user avatar
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-4 votes
1 answer
82 views

Transmitting Data faster than the speed of light using entangled particles [duplicate]

If we have a pair of super-asymmetrical entangled particles, and move them a light year away so that they retain their quantum entanglement, and we set a clockwise spin (or vertical polarization) as 0 ...
SWIRF's user avatar
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0 answers
34 views

How is free energy in thermodynamics related to free energy in information theory/neuroscience?

Background In thermodynamics, free energy refers to either Helmoltz ($U - TS$) or Gibbs ($H - TS$) free energy, the quantity that is minimised at equilibrium in a closed system maintained at constant [...
Jake Levi's user avatar
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1 answer
45 views

Are all types of noise a result of lack of complete knowledge about the given system? What does this say about the physicality about information?

I am currently studying the basics of quantum information theory. When we study a system (classical or quantum), any undesirable influence out of our control is usually referred to as noise, and this ...
Pratham Hullamballi's user avatar
0 votes
2 answers
133 views

Does information always gravitate?

I'm trying to wrap my head around Bekenstein's loose argument that a bit of information added to the black hole corresponds to an added Planck surface area to its horizon. In it, he argues that one ...
Lourenco Entrudo's user avatar
0 votes
2 answers
44 views

Compensating thermal entropy with informational entropy

Suppose you have a Maxwell demon scenario where particles in a box get sorted out by a goblin so that the entropy of the box decreases. Landauer (1960) proposes that the net entropy loss would be ...
manoroli's user avatar
0 votes
1 answer
52 views

Do superluminal shadows drop the local temperature on distant objects?

There are lots of examples online of the scenario of someone with sufficient machinery casting a shadow of their thumb on the moon. It's argued the shadow travels faster than light, instantaneously ...
Svenn's user avatar
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-8 votes
3 answers
216 views

How Taylor series is compatible with special relativity?

In mathematics, an analytic function is defined by its possession of a Taylor series with a positive radius of convergence ($R_c​>0$). Notably, certain analytic functions—such as holomorphic ...
Omid's user avatar
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2 votes
1 answer
294 views

Hawking Radiation paradox

How does Hawking radiation help in information conservation? Doesn't it create a paradox, as the particle-antiparticle pair created at the event horizon has nothing to do with the matter that has ...
Bhavya Panda's user avatar
3 votes
1 answer
119 views

Information Loss in Chaos Theory

Is it accurate to suggest that in chaos theory, information is in practice lost due to the impossibility of characterizing the system's state with infinite precision, making it unfeasible to run the ...
Omid's user avatar
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0 votes
1 answer
121 views

Black hole information paradox

I read that it is generally believed that information is preserved in black hole evaporation, and people's views only diverge when it comes to how information is preserved. Is this true?
FACald's user avatar
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2 votes
2 answers
91 views

E. T. Jaynes and heat death

On E. T. Jaynes view, thermodynamic entropy of a system is, up to a multiplicative constant, the same as the the information entropy for the predicted distribution with maximum uncertainty conditioned ...
Gödel_vonNeum4nn's user avatar
0 votes
2 answers
109 views

Way to get information from inside black hole to outside?

So imagine a black hole the size of 100 km, and then there is a giant rod that is 50 km and pretends that the rod doesn't get broken due to tidal forces, and also assumes that the rod has a mini-robot ...
Roghan Arun's user avatar
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2 votes
1 answer
84 views

Proving that a positive partial transpose (PPT) state is non-distillable

I am attempting to prove the following statement: A positive partial transpose (PPT) state cannot be distilled. I would like to do so using the following facts: Let $\rho$ represent a bipartite ...
oki-dogz's user avatar
3 votes
3 answers
103 views

What's the limit on the length of string that can be pulled by a person? [closed]

Imagine it's pre-industrial times, and a king wants to keep control of his vast empire. One of the biggest problems was how slow it was to transmit information; it could take weeks to be notified of ...
Reuben Matthews's user avatar
5 votes
2 answers
182 views

A version of Maxwell's Demon using Norton's dome to erase information for free?

Norton's dome is a thought expriment that shows Newtonian mechanics is non-deterministic. It has the shape of a dome (see exact details of its construction on the linked page) with a rather peculiar ...
Hadi Khan's user avatar
  • 531
0 votes
4 answers
104 views

Why carrier wave cannot transfer information?

In the concept of wave modulation, I'm having trouble to understand why carrier wave cannot transfer information. My assumption is that the reason for that is due to the fact that the frequency, ...
Sagigever's user avatar
  • 545
2 votes
1 answer
79 views

Fisher information of parametric channel

Suppose $\Phi_\theta$ is a quantum channel whose action can be written for any state $\rho\in \mathcal S(\mathcal H_S)$ in the Stinespring representation as $\Phi_\theta(\rho)= \text{Tr}_E(U_\theta (\...
Quantastic's user avatar
1 vote
2 answers
69 views

How does information 'move'? [closed]

Information cannot be transmitted faster than the light. However, I am confused about the meaning of 'transmission' of information. How does the information 'move'? If I calculate the future state of ...
tneserp's user avatar
  • 49
0 votes
0 answers
68 views

About information transmission speed [duplicate]

Einstein says information cannot be transmitted faster than light. Say I set an alarm that ring at 9:00 am. I go to school, and wait until 9:00 am. Then I tell my friends that my alarm rang. If the ...
tneserp's user avatar
  • 49
8 votes
1 answer
565 views

Could information be transferred through a wormhole?

There was a paper published recently about the possibility of sending messages through a wormhole,see reference here. It has also been speculated that any entangled pair of particles—even particles ...
Cristian Dumitrescu's user avatar
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0 answers
74 views

Is there physical significance to the Gateaux derivative of entropy?

Is there any physical "force" generated by a difference in entropy or information between two regions? There is some confusion between thermodynamic entropy and information entropy, but one ...
Jackson Walters's user avatar
1 vote
2 answers
132 views

Entropy and information - Heat generation in computers

I understand that part of the heat release from a computer comes from resistive heating, but to my understanding it is also linked to entropy changes and information - such that even a superconducting ...
Woodenplank's user avatar
2 votes
0 answers
35 views

Is the optimal POVM of a mixed state the same as the optimal POVM of the pure states in its ensemble?

If I have a mixed state, where each pure state in the ensemble has the same optimal POVM (by optimal I mean POVM for which the classical Fisher information is the same as the quantum Fisher ...
andr_pandr's user avatar
1 vote
1 answer
67 views

Does the master equation break down for negative times?

I'm studying stochastic dynamics and have encountered the framework of the master equation for the study of continuous time Markov processes. First, I'll state some general definitions and then say ...
Felipe A. Barretto's user avatar
0 votes
0 answers
147 views

The difference between classical and quantum entropies

The von Neumann entropy $-\mathrm{Tr}(\rho\ \log\rho)$ of a quantum thermal state with $\rho=\frac{1}{Z}e^{-\beta H}$ gives the thermal entropy, see e.g. this question. The von Neumann entropy is a ...
gshxd's user avatar
  • 133
1 vote
0 answers
55 views

Does a shredded book contain more or less information (or the same) than the original book

If I shred a book into numerous pieces, and scatter them, so that the original text is completely unreadable, then for me, as a reader, the book has lost all its information. Its entropy has greatly ...
Phil's user avatar
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0 votes
1 answer
78 views

Can, in theory, information escape an event horizon via a specialized setup?

Can, in theory, information escape an event horizon via a specialized setup? Specifically, send a beam of photons to be barely—just barely—inside the event horizon, then wait for hawking radiation to ...
Lukephil Brecht's user avatar
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0 answers
25 views

Communication via entanglement [duplicate]

For years now i have in my haed a thought experiment for information exchange via quantum entanglement. And i am aware that something must be wrong with it but i can't figure out what it is. The ...
GMatthes's user avatar
2 votes
0 answers
61 views

(Generalized) Jarzynski equality

Sagawa and Ueda ref, generalized the Jarzynski equality in the presence of a feedback control, leading to the following equation: $$ \langle e^{-\beta(W-\Delta F)-I} \rangle = 1.$$ Can I interpret ...
Display name's user avatar
1 vote
2 answers
116 views

How information of accelerated charged particle travels, if photon is absorbed?

There is an electrostatic field around the electrically-charged particle (particle is the source of that field). When the particle accelerates, it emits photon. Photon travels at finite speed. ...
Stdugnd4ikbd's user avatar
2 votes
2 answers
443 views

Which theory can resolve black hole information paradox?

I am new, not have expert level knowledge. But I have studied about black hole information paradox. The black hole doesn't kept any information which passes event horizon. Which can break physics. Is ...
user avatar
3 votes
0 answers
55 views

Is the informational approach to thermodynamics generally accepted as "correct"?

This question is about the "ontology" as it were of statistical mechanics. In my limited reading of (equilibrium) statistical mechanics texts, I have encountered two viewpoints for what is &...
EE18's user avatar
  • 1,095
0 votes
1 answer
107 views

Faster than light communication by entangled photons [duplicate]

Faster than light communication is not possible. If I measure the polarization of an entangled photon and it turns out to be right circularly polarized. In that instant, dont I know that someone ...
Richard Coppack's user avatar
-1 votes
1 answer
216 views

How much information is in a hydrogen atom?

How much information is contained in a hydrogen atom (a bound electron and proton) at room temperature? There are bounds that set limits on the amount of mass/energy that can exist in a given region ...
Jackson Walters's user avatar
1 vote
0 answers
26 views

Mutual information between energy levels

I have the following partition function $$Z(\beta_1,\beta_2) = Z(\beta_1)Z(\beta_2) +Z(\beta_1,\beta_2)_c$$ Thus, I have a non-zero mutual information $I(Z(\beta_1);Z(\beta_2)) = S(Z(\beta_1))+S(Z(\...
Display name's user avatar
3 votes
3 answers
2k views

The Journey of an Electromagnetic Wave Exiting a Router

I'm learning a bit of how WiFi works under the hood, and have a basic grasp of the general process. First, you make an internet request. Your computer then sends out a WiFi signal which your router ...
Loic Stoic's user avatar
0 votes
0 answers
25 views

What information is gained when just one single half of an entangled photon pair is detected, following its transmission through a polarizer?

My admittedly limited understanding of QM is that it is a matter of probabilities whether or not a photon is (re)transmitted through a polarising filter and that these are a function of the relative ...
tonyess's user avatar
4 votes
0 answers
64 views

Shannon's information theory on open systems

A university professor on Library and information science told me that he considers Shannon's information theory too limited since it doesn't apply to open systems. I couldn't find info to back up ...
Pablo A's user avatar
  • 155
0 votes
0 answers
24 views

How can entanglement entropy be quantified between lattices of differing structures?

Suppose there are two 1 dimensional particle lattices, both with differing distances between particles and not necessarily the same number of particles. Each particle exists in a superposition of spin ...
FIREREED's user avatar
4 votes
1 answer
731 views

Entropy expressions for Bose-Einstein and Fermi-Dirac statistics

We are all familiar with the Boltzmann-Gibbs-Shannon entropy formula: $H_{\text{BGS}} = -\sum_{k}p_{k}\log{p_{k}}$ In information theory, this can be interpreted as the expectation value of the "...
IchVerlore's user avatar
3 votes
2 answers
294 views

Information theory in classical mechanics

I've only ever heard about information theory being used in stuff related to probability distributions, which makes sense because information and entropy are related. However, I'm having trouble ...
user avatar
1 vote
2 answers
365 views

Why are CT scans much smaller than the raw data?

I'm not too familiar with CT, but I worked with medical CT images long ago, and recall that the raw data, recorded by the scanner was way bigger than the 3D image itself (Both were 16-bit TIFF files, ...
MWB's user avatar
  • 548
2 votes
1 answer
71 views

Landauer limit - cost to avoid changing a bit already equal to desired value

If I have a bit and I do not know what the current value is, is it possible to use less energy than $E_b = k_b T \ln(2)$ so that if the bit value is already equal to what you want, you don't waste ...
Bob's user avatar
  • 137
1 vote
1 answer
70 views

Correlation and thermodynamics [closed]

I have two systems that are correlated, their energy levels are not independent: $\rho(E_1,E_2) \ne \rho(E_1)\rho(E_2)$. So I wanted to quantify the amount of dependence they have, I used the mutual ...
Display name's user avatar
1 vote
1 answer
53 views

Why isn't correlation in the description of entangled states just a sign of model information redundancy? [closed]

Two entangled particles are described (modeled) such that there may be a correlation between parts of the model. That is, measuring one of the pair provides information about the other. Why isn't ...
DavidJ's user avatar
  • 119
0 votes
1 answer
102 views

Landauer's principle debunked?! "Information entropy and thermal entropy: apples and oranges"

I was asking a question about sustainability of reversible computers against entropy. I referenced Landauer's principle to frame my question and someone told me in the comments that Landauer's ...
Willpergg's user avatar

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