# What is Information: Definition and 999 Discussions

Information can be thought of as the resolution of uncertainty; it answers the question of "What an entity is" and thus defines both its essence and the nature of its characteristics. The concept of information has different meanings in different contexts. Thus the concept becomes synonymous to notions of constraint, communication, control, data, form, education, knowledge, meaning, understanding, mental stimuli, pattern, perception, proposition, representation, and entropy.
Information is associated with data. The difference is that information resolves uncertainty. Data can represent redundant symbols, but approaches information through optimal data compression.
Information can be transmitted in time, via data storage, and space, via communication and telecommunication. Information is expressed either as the content of a message or through direct or indirect observation. That which is perceived can be construed as a message in its own right, and in that sense, information is always conveyed as the content of a message.
Information can be encoded into various forms for transmission and interpretation (for example, information may be encoded into a sequence of signs, or transmitted via a signal). It can also be encrypted for safe storage and communication.
The uncertainty of an event is measured by its probability of occurrence. Uncertainty is inversely proportional to the probability of occurrence. Information theory takes advantage of this fact by concluding that more uncertain events require more information to resolve their uncertainty. The bit is a typical unit of information. It is 'that which reduces uncertainty by half'. Other units such as the nat may be used. For example, the information encoded in one "fair" coin flip is log2(2/1) = 1 bit, and in two fair coin flips is log2(4/1) = 2 bits. A 2011 Science article estimated that 97% of technologically stored information was already in digital bits in 2007, and that the year 2002 was the beginning of the digital age for information storage (with digital storage capacity bypassing analog for the first time).

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1. ### Hello from AlessAless

hi all I am an Engineer with a PhD in Information Engineering with a great passion for physics.
2. ### Universal information: How much is enough?

A thought (it is probably as old as hills, but new to me): Physics advances by finding rules our observations obey. A good theory reduces the information needed to describe what has been observed. In each (most?) advance(s) we find that the universe actually contains (can be defined by) less...
3. ### Can Information be Defined in Physics? Exploring Attempts and Controversies

Just looking around for now, but would love to see links to attempts to define information in physics
4. ### I Can you increase the mass of a closed system with information?

Let's assume that there is a closed box, with mass M. There are some random quantum processes inside it, say radioactive decay. Let's assume that we can manipulate the decay from the outside somehow, thus 'putting information' into the box. Can that affect its mass?
5. ### Finding ##U## given information about an adiabatic process (Callen)

I was unable show that ##PV^k## must indeed equal some function of the entropy, ##g(S)##; maybe doing so would make things easier? I proceeded as below. If we assume (as is almost surely intended by Callen) that in the given adiabatic (##d Q = 0##) process we are taking ##N## as constant and...
6. ### B Entropy & Information Content: Examining the Difference

What does entropy in the following sentence means? Does it mean the same as the term "information content" before it? Is entropy more technical a term than information content? He remembered taking a class in information theory as a third-year student in college. The professor had put up two...
7. ### A Origin of BH Entropy & Info Missing Puzzle Resolution

Dear everyone, I wish to discuss in this thread a classic/semi-classic interpretation on the origin of Bekenstein-Hawking entropy and the related resolution to Hawking's information missing puzzle, which were published in Nucl.Phys.B977 (2022) 115722 and Nucl.Phys.B990 (2023) 116171 after...
8. ### I Black Hole Information path described in new article

I'm posting this in "Quantum Physics" although it is just as much "General Relativity". A paper entitled "Quantum gravitational corrections to particle creation by black holes" was published in Science Direct earlier this month. It appears to provide an event horizon mechanism for holding...
9. ### Searching for information on the General Electric J31 engine

Hi, I am currently trying to do a project related to this engine and I am trying to find information about it. I am looking for technical papers, journals or overall description of the inner workings of the engine. I am looking forward for something more in depth than wikipedia. Also...
10. ### Is the Theory of Conservation of Information Faulty?

I am searching for a definition of “information” in the concept of physics and the theory that information is conserved. Rather than a general question, here are a couple of specific questions about information. Not limiting, just two possible examples of information. The magnetic state of...
11. ### Towards a new theory of information kinematics

The physical world is highly parallel; many things are happening side by side simultaneously. This is true not only at the macroscopic scales that we can see but as far as we know down to the subatomic scales. This is referred to as the principle of locality [1], which states that an object is...
12. ### A Time Travel, General Relativity & Information Paradoxes

General relativity permits some exact solutions that allow for time travel. Some of these exact solutions describe universes that contain closed timlike curves, or world lines that lead back to the same point in spacetime. I wondered if these solutions also permits Causal loops? Such as the one...
13. ### Laboratory Rocker - type of mechanical movement & related information

Hi all I have a question about this device in https://www.thingiverse.com/thing:2948680/files. Where can I find more information/reading material about this type of mechanical movement (for example, what is the ratio between the motor circle radius, pin location and the table bearings). I wish...
14. ### A Does the theory of information have anything to offer for physics?

Is there any use for this concept in classical branches of physics? Can it be of any help for a physicist in resolving problems (or, at least, in resolving them more efficiently when compared with traditional methods)? The word «classical» means exactly that, i. e. mechanics, hydrodynamics...
15. ### More Nobel prizes in quantum information?

Alain Aspect, John Clauser & Anton Zeilinger have rightfully received the Nobel prize for their contributions to quantum information, as they were three of the main pioneers of quantum information. However, is it now impossible or very unlikely that other physicists working on this field (e.g...
16. ### I Predetermination in quantum theory and information theory

My understanding of quantum theory and information theory is that, given complete information on the state of the universe at present, it is possible to predict its state at all times in the future and past. 3 questions: 1: is this true? 2: how are quantum-probabilistic outcomes accounted for...
17. ### I Is Information a conserved quantity or not?

I've been wondering about statespace. Classically, we assume statespace is infinite (presumably so that we can depend on smooth, differentiable manifolds). But even in quantum, we assume a smooth space and time on which we define wave functions and operations (at least in undergrad quantum...
18. ### On the origin and the evolution of information in the Universe

[Mentor Note -- thread moved from the schoolwork forums to the technical forums] Homework Statement:: Tentative Note and summary on the origin and the evolution of information in the universe. Relevant Equations:: none As a teacher of physics I got many questions asked by my students when...
19. ### A Is there a lost information paradox for quantum physics?

Hi Pfs, When Stephen Hawking proposed the idea of black hole information it appeared that information could be lost. it was a problem in GR which is a dererminitic theory. Knowing initial data and Hamiltonian tells you what was and will be. It is not the case in quantum physics. things evolve...
20. ### Looking for information on hydrogen thyrator

Greetings, gentlemen. I have come into possession of what I have been told is a hydrogen thyrator. Of course I have done the requisite Googling, but do any of you old EEs have any insight on the item? Original application, general manufacture date, usage today, value, precautions in handling...
21. ### B What is Information? Exploring Quantum Blueprints w/ 71yo Writer

As a 71 year old writer who has been hooked by the quantum world I have struggled to find someone who can explain simply what is the "information" that cannot (?) escape from a black hole. Could this information, for instance, be described as the structural quantum blueprint of any form?
22. ### I Does Space Curvature Account for Gravity Between Individual Atoms?

I am trying to come to terms with the two concepts of gravity, direct attraction between bodies (say dust even) and attribution to the curvature of space (time) Looking at a physical sea coast I can envisage how every instance of the mass gravitational interactions of individual atoms or smaller...
23. ### B Where can I find information about Population III stars?

Hello. I've performed a Google search on the subject of Population III stars and come up with some results. But I'd now like to go a little further. Could I please be directed to articles and/or papers on this subject, so that I can further my interest? Thank you for any help given. Cerenkov.
24. ### Looking for information on gamma light sources

Hello, I am looking for something a bit out of my wheelhouse today, gamma light sources (10 MeV or higher on the max energy threshold). Does anyone here have experience or more information on these machines? Are they typically electron accelerators utilizing a tungsten or tantalum target? I am...
25. ### B Why is the BH Information Paradox Called a Paradox?

We don't have a quantum theory of gravity. To my B level thinking, losing information at the EH of a black hole is just one of multiple known places where QM meets relativity and it becomes clear that our understanding is incomplete. I don't see it as any different than making the same...
26. ### Biological Info: Understanding & Analyzing

"Biological Information" is a common concept in some parts of biology. It most often (in my experience) is used to refer to the sequence information in nucleic acids (nucleotide sequences in RNA and DNA) and in proteins (amino acid sequences in proteins). This is most apparent in the flow of...
27. ### I Information lost at the Big Crunch?

Let's imagine for a moment that the universe stopped expanding somehow (even though the evidence we have suggests this is not going to happen) and gravity made it contract until reaching a Big Crunch state. According to our actual understanding of physics and our current working models, Is it...
28. ### I Discussing Information Theory with non-scientists

Do you have an opinion about my summary above? Do you understand the relation between irreversible logic and irreversible process? According to Landauer, logical irreversibility implies physical irreversibility. This is still a topic of debate it seems to me. Is the debate also about what logic...
29. ### I Can concentration gradients be related to information?

I was reading a great thread that pointed me to Robert Alicki, “Information is not physical“ (https://arxiv.org/abs/1402.2414). My that appeals to me, based on the apparent fruitlessness of understanding the system otherwise. But I don't know if it's even published, and even if "everybody has...
30. ### I A new approach to the information Paradox

Summary: New black hole simulations that incorporate quantum gravity indicate that when a black hole dies, it produces a gravitational shock wave that radiates information, a finding that could solve the information paradox. Hello, Please excuse the rather "conversational" approach I'm using...
31. O

### I Information loss in black hole, why is it a problem?

If an observer never falls into a black hole, something it observes that does fall in takes an infinite time to reach the event horizon. If an observer falls into a black hole along with an object, it will not lose information on the falling object, but will lose that from the outside of the...
32. ### B Does the quantum vacuum have information?

Hey everyone, My question is simple. Has quantum vacuum information ? And can we measure it with Shannon Entropy and the other ways. By the way I just started to learn english so ı have any grammer mistake please tell me. I know this is out of subject but thank you.
33. ### B Do I have enough information to find the radius?

If there is a circle, 360 degrees, and 2 random points A & B are chosen on the circle. A straight line is drawn between those two points. You are not shown the whole circle. All you can see is A, B the straight line and an arc representing an unknown number of degrees. You know the length of the...
34. ### A Calmet & Hsu: Quantum hair and black hole information

https://www.bbc.com/news/science-environment-60708711 Scientists claim hairy black holes explain Hawking paradox https://arxiv.org/abs/2112.05171 Quantum Hair and Black Hole Information Xavier Calmet, Stephen D.H. Hsu It has been shown that the quantum state of the graviton field outside a...
35. ### How can I properly study Information Systems without adequate resources?

IS stands for information system. here's the syllabus-: https://ioesolutions.esign.com.np/contents/information-systems-ct-751 here's the notes that are available for this subject-: https://ioesolutions.esign.com.np/notes/text-notes/information-systems-ct-751and there is 1 badly written book...
36. ### Comp Sci Why should we plan Information Systems?

So this is what given in book-: This is not just slide. This is exactly what is written in my book. I don't understand any of this. What I understand a bit-: Information System plan describe the structure of information system, content, of information system, how IS should be developed. IS...
37. ### Comp Sci 1 example of information system in real life?

I am studying IS but I am yet to find an example of IS. Is database IS? Is expert system IS? What is example of IS? And this question came to me while studying about this issue-: is security policy same as security methods? justify your argument with appropriate example of Information system...
38. ### Comp Sci Not getting anything in this subject Information system-:

no resources to study except 2 slides and 1 badly written unauthentic book. Teacher was extremely bad. He just read one of those slides. But no complains. It is pretty normal where I live. I am not getting an overview of what are these slides trying to tell to me. Application control means...
39. ### Comp Sci Where Can I Find Gas Properties for Argon and Neon?

Hello my friends. I would like to know if you guys are aware of some site or paper that provides informations about gas. That is, i would like to know the energy band in which the ionization of a gas is high, and also the energy in which multiple scatter is high. The gas need to be Argon of Neon.
40. ### A Double double slit experiment and path information

Hi Pfq My question is about this experiment: https://www.nature.com/articles/s41598-020-68181-1 (the link was given by DrChinese. If all the impacts are conserved no interference can be seen on the screens. but if we only take the impacts (Y, yi) where Y is always at the same position on the...
41. ### I What is the physical meaning of concurence (quantum information)?

Hello, I am currently studying about entanglement on spin-1/2 chains and I was able to find some information about the mathematical point of view of concurrence but I can't understand the physical meaning of it . Can somebody help me, please?
42. ### I Information content in electromagnetic or gravitational waves

Electromagnetic or gravitational wave carries energy and momentum from place to place as,I understand.Does it imply that such waves only can carry information and if their energy gets dissipated as heat, the information contained is lost. Is this information content is to be decoded by human...
43. ### B Quantum Entanglement information transmission idea to knock down....

I work in IT and am a layman in the quantum world. I have obviously misunderstood something in my amateur reading of quantum, but if someone could explain my mistake in the above scenario it might be very insightful for me! Forgive me if the terminology is not correct - or if indeed lay folks'...
44. ### Looking for Pneumatic control valve information

I am looking to find out if there is a control valve type that will move a duel port cylinder in both directions but then the current to the valve is turned off the cylinder will NOT be locked up. I thought a 5/2 double coil valve would do this but it holds cylinder when current is removed...
45. ### Comp Sci What are the steps for performing audits on Information Systems?

https://ioesolutions.esign.com.np/notes/text-notes-show/Control,-Audit-and-Security-of-Information-System Here are what I have researched but both of these don't cover what are information system audit steps. Then here is sth that I am not sure of...
46. F

### How should you find reliable information?

Where is the best place to find reliable information? What is the best way verify the reliability of information found online?
47. ### I Is Information Really Preserved in Quantum Systems?

I don't know what category this fits in but how conclusive is it that information can't be lost or destroyed? Is this mostly just Stephen Hawking talking or do others support this idea?
48. ### How to prove the chain rule for mutual information

Hi, I was attempting the following problem and am a bit confused because I don't quite understand the structure/notation of how mutual information and entropy work when we have conditionals (a|b) and multiple events (a, b). Question: Prove the chain rule for mutual information. I(X_1, X_2...
49. ### I Merging black holes: gravitational waves and information

A popular theory is that black holes gradually leak information because of black hole evaporation due to hawking radiation. When black holes merge, a significant portion of their mass is converted into gravitational waves. If it's true that black holes leak information due to hawking radiation...