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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37
votes
6answers
6k views

Why is information indestructible?

I really can't understand what Leonard Susskind means when he says that information is indestructible. Is that information that is lost, through the increase of entropy really recoverable? He ...
47
votes
5answers
3k views

What is information?

We're all familiar with basic tenets such as "information cannot be transmitted faster than light" and ideas such as information conservation in scenarios like Hawking radiation (and in general, ...
29
votes
3answers
16k views

Maximum theoretical data density

Our ability to store data on or in physical media continues to grow, with the maximum amount a data you can store in a given volume increasing exponentially from year to year. Storage devices continue ...
8
votes
3answers
2k views

Maxwell's Demon Constant (Information-Energy equivalence)

New Scientist article: Summon a 'demon' to turn information into energy The speed of light c converts between space and time and also appears in e=mc^2. Maxwell's Demon can turn information supplied ...
22
votes
5answers
2k views

Where does deleted information go?

I've heard that, in classical and quantum mechanics, the law of conservation of information holds. I always wonder where my deleted files and folders have gone on my computer. It must be somewhere I ...
10
votes
3answers
2k views

How efficient is a desktop computer?

As I understand it (and admittedly it's a weak grasp), a computer processes information irreversibly (AND gates, for example), and therefore has some minimum entropy increase associated with its ...
6
votes
2answers
146 views

How can the microstates be measured with zero energy expenditure?

James P. Sethna. Statistical Mechanics. Exercise 5.2: What prevents a Maxwellian demon from using an atom in an unknown state to extract work? The demon must first measure which side of the ...
10
votes
2answers
16k views

Maximum theoretical bandwidth of fibre-optics

Ignoring hardware at either end and their technological limitations, what is the maximum theoretical bandwidth of fibre optic cables currently in use / being deployed in a FTTH type situations? I ...
9
votes
7answers
11k views

Why is the decibel scale logarithmic?

Could someone explain in simple terms (let's say, limited to a high school calculus vocabulary) why decibels are measured on a logarithmic scale? (This isn't homework, just good old fashioned ...
9
votes
3answers
1k views

Are Electromagnetic Waves The Only Means of Transmitting Information?

We've been using EMF to transmit energy (information) for over a century. I was wondering is there any other way to send a message on long distances, even faster than EMF waves can travel? For example ...
3
votes
1answer
717 views

Should entropy have units and temperature in terms of energy? [duplicate]

I've been thinking about entropy for a while and why it is a confusing concept and many references are filled with varying descriptions of something that is a statistical probability (arrows of time, ...
0
votes
2answers
135 views

From what we know about QM and Elements could we simulate the Universe in a Computer?

From what we know now about Quantum Mechanics and Elements, could we simulate life the Universe at a Quantum to Element level? If we can't assume enough to create a sim, what fundamentals are we ...
87
votes
1answer
3k views

Is it necessary to consume energy to perform computation?

As far as I know, today most of the computers are made from semiconductor devices, so the energy consumed all turns into the heat emitted into space. But I wonder, is it necessary to consume energy ...
31
votes
5answers
3k views

What is the most efficient information storage?

What is the most efficient way to store data that is currently hypothesized? Is it theoretically possible to store more than one bit per atom? Until Floris' comment, I hadn't considered that ...
13
votes
8answers
811 views

What counts as information?

What counts as information? In e.g. the EPR experiment why is one entangled particle knowing instantaneously the state of the other not counted as 'information'. Edit Following a discussion in the ...
9
votes
3answers
2k views

How many bytes can the observable universe store?

Is the number of states in the Universe countable? What framework could be used to answer the question in the title?
1
vote
3answers
293 views

Quantum entanglement: does it necessarily imply superluminal information transfer? [duplicate]

From what I understand, information is communicated instantly between two quantum-entangled particles regardless of the spatial distance between them. However, does this necessarily imply superluminal ...
1
vote
1answer
196 views

OAM states for wireless communications

Can someone give me an overview of how OAM states are used in communications? Using Orbital Angular Momentum States seems like a hot topic for communications. I read a few articles about the basic ...
3
votes
1answer
362 views

Microsecond trading with neutrinos

The Spread Networks corporation recently laid down 825 miles of fiberoptic cable between New York and Chicago, stretching across Pennsylvania, for the sole purpose of reducing the latency of ...
0
votes
2answers
146 views

How can Maxwell's Demon erase information while a black hole can not?

It is stated, that information can't disappear even in black holes. On the other hand, it is stated, that mystic beings, like Maxwell demons, can easily erase any information if they just pay with ...
4
votes
3answers
251 views

If nothing ever falls into a black hole, why is there a puzzle about information?

From an outside perspective, nothing can ever pass the event horizon. It just scooches asymptotically close to the event horizon. So (from our perspective on earth), when a black hole reduces in ...
2
votes
1answer
216 views

Physical structures that trap information

I labeled this question "soft" because it might not make any sense. Anyway, what I'm wondering is if there's a notion in physics that deals with the ability of matter to trap information. For ...
1
vote
3answers
97 views

Speed of heat / quantification of heat and other magnitudes

Is the speed of heat infinite? When solving the heat equation in a semi-infinite bar, we can see that a pulse in the finite end draws an immediate change in every point of the bar. So, at any given ...
16
votes
4answers
1k views

Ignorance in statistical mechanics

Consider this penny on my desc. It is a particular piece of metal, well described by statistical mechanics, which assigns to it a state, namely the density matrix $\rho_0=\frac{1}{Z}e^{-\beta H}$ ...
17
votes
1answer
530 views

In there such a thing as the Black Hole Information Paradox?

When I first heard about the black hole information paradox, I thought it had no content. At the time, papers about it had been written for numerous years and they keep on coming. Now that the press ...
10
votes
1answer
504 views

How does Landauer's Principle apply in quantum (and generally reversible) computing

I understand that a reversible computer does not dissipate heat through the Landauer's principle whilst running - the memory state at all times is a bijective function of the state at any other time. ...
10
votes
2answers
472 views

Would the horizon of a black hole be different for a tachyon than for subluminal matter or photons?

One of the most useful black hole analogies I've seen imagines that space is "flowing" like a river into a black hole, and the point at which it flows in faster than c is the horizon. This analogy ...
10
votes
2answers
2k views

How is information related to energy in physics?

I recently attended a talk by Dr. Ravi Gomatam on 'quantum reality', where the speaker suggested, that conservation of energy is not a fundamental law, and is conditional, but the conservation of ...
8
votes
3answers
2k views

How are physics and computer science getting united? [closed]

How is theoretical computer science getting united with physics? Phenomena like Quantum Computing uses Quantum Mechanics to be able to compute things, how are computers helping not just to model our ...
8
votes
5answers
2k views

How is thermodynamic entropy defined? What is its relationship to information entropy?

I read that thermodynamic entropy is a measure of the number of microenergy states. What is the derivation for $S=k\log N$, where $k$ is Boltzmann constant, $N$ number of microenergy states. How is ...
6
votes
4answers
832 views

Uncertainty Principle for Information?

I'm not familiar (yet) on how Information theory can be emerged/used in QM/QFT but I was thinking about this question: While we have Heisenberg uncertainty principle on measuring coupled observables, ...
4
votes
3answers
386 views

Entropy and Information

Several posts and my classes in thermodynamics equate increase in entropy with loss of information. Shannon clearly showed that the information content of a message is zero when its entropy is zero ...
3
votes
3answers
399 views

Has anyone ever tried to formulate physics based on computer science or information processing?

Some physicists and university researchers say it's possible to test the theory that our entire universe exists inside a computer simulation, like in the 1999 film "The Matrix." In 2003, University ...
6
votes
1answer
358 views

What is the information geometry of 1D Ising model for a complex magnetic field?

Consider the one-dimensional Ising model with constant magnetic field and node-dependent interaction on a finite lattice, given by $$H(\sigma) = -\sum_{i = 1}^N J_i\sigma_i\sigma_{i + 1} - h\sum_{i = ...
3
votes
2answers
277 views

Number of bits needed to express physical laws?

What is the minimum number of bits that would be needed to express a given physical law, like the law of universal gravitation? How many bits are needed to express each of the four fundamental forces? ...
2
votes
2answers
2k views

Are information conservation and energy conservation related?

as evident from the title, are both, conservation of energy and conservation of information two sides of the same coin?? Is there something more to the hypothesis of hawking's radiation other than ...
1
vote
4answers
171 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 ...
6
votes
4answers
2k views

Exorcism of Maxwell's Demon

I am possessed! Yes, with the thinking that if there is actually a Maxwell's Demon, then it would open the negligible weighted door which would ultimately make the second law invalid. But really can ...
5
votes
2answers
88 views

On unfocused images, their information content and possible restoration

So, when an image is out of focus the light of any given point of the object does not refocus exactly at one point on the screen, but is spread out around a region, such that the light of the image at ...
3
votes
1answer
436 views

How large is the information collected from an inverse femtobarn of collisions?

I ran into this while looking at measures of humongous amounts of data. How does the information (data) collected in an inverse femtobarn exposure compare to a gigabyte of data ?
2
votes
1answer
195 views

Reference paper to support information — energy relation ($kT \ln2 \rm\frac{J}{bit}$)

In answer to Maxwell's Demon Constant (Information-Energy equivalence) there is stated that one bit of information allows to perform $kT \cdot \ln2$ Joules of work. Which paper supports the ...
1
vote
3answers
205 views

If a star were to suddenly dissapear, would it still have gravity?

I am wondering whether or not literally anything can travel faster than the speed of light. For example, if gravity from a star immediately ceases to have an effect if it suddenly and magically ...
0
votes
2answers
136 views

sending information over a wire--mechanically [duplicate]

Possible Duplicate: Is it possible for information to be transmitted faster than light? I've thought about this since I was a little kid. I know it isn't exactly feasible, but it still ...
-2
votes
1answer
95 views

Is information propagated across a medium in any other way than waves?

Is information propagated in any other way than waves? Please distinguish "propagation across a medium" from information "storage within stable states of matter", which might difuse or interact ...