B Does the quantum vacuum have information?

[microatx]

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.

 

[PeroK]

I can't help you with the physics, but I can help with your English a little.

It should be "Does the quantum vacuum have information?" Or "Does the quantum vacuum contain information" is even better.

"or otherwise" is a good expression to learn and is better than "and the other ways".

It's "grammar". And "English" is capitalised.

 

[microatx]

Thanks buddy. In my main language, words are pronounced as they are written. My mistakes like ''grammer'' are caused by this.

 

[hutchphd]

words are pronounced as they are written

what a silly idea !

 

[Klystron]

English spelling is irregular. Spelling does not match pronunciation and words may not always be pronounced as spelled. Physics Forums (PF) software provides spell check, underlining misspellings. Touch or point to the word for suggestions.

English does contain a large vocabulary with many technical terms.

 

[Mike S.]

I'm not competent to answer this question, but I suspect this news story from today changes the answer one might give: Scientists may have solved Stephen Hawking's black hole paradox

 

[jim mcnamara]

To follow up with @Klystron 's nice post -- Biology has a large specialized vocabulary. Here is is an online dictionary:
https://www.biologyonline.com/dictionary
a medical one, too:
https://medical-dictionary.thefreedictionary.com/

Throw in the estimated number of plants species in the world. -- add another 311000 items. Then there are species names for animals, procaryotes, primitive eucaryotes,viruses, and prions (prions are not living). Now you are up near a million terms.

The point is there are more science terms than you can expect anyone human to be able to recall and use fluently. In my opinion, Biology verges on the absurd edge of this kind of extreme. And let's not even consider what is happening to taxonomy, the "science" of classification of living things -
because genomic data is rewriting a lot of this very stuff.

For example, some Mimiviruses (giant viruses that kill amoebas) were first classified as bacteria. Why? Because the people doing the research believed no virus could be so big.

 

[Demystifier]

Has quantum vacuum information ? And can we measure it with Shannon Entropy and the other ways.

It depends on what you mean by vacuum and what you mean by information.

By vacuum, one usually means a unique state with no particles. Since it is unique, it can only be in one state, there are no two or more different states called vacuum. As such, it cannot contain information in the sense of Shannon entropy.

Nevertheless, one often associates entanglement entropy with the vacuum. How can that be? The vacuum is an eigenstate of the Minkowski particle number operator. If you measure an observable that does not commute with that operator, you cannot predict in advance what will be result of measurement, there is an uncertainty. When there is uncertainty, there is entropy associated with that. A well known example is the Rindler particle number operator, which is defined only in a part of the Minkowski spacetime, so the entropy is associated with entanglement of that part of spacetime with the rest of it.

If all this is too abstract for you, here is a rough analogy: Can empty book contain information? It depends on what you mean by empty book and what you mean by information. In a most obvious sense, the empty book cannot contain information. Yet, there is a sense in which it can. For example, you can crumple some pages and leave other pages non-crumpled. This can be done in many different ways, so in this way you can encode information even in an empty book.

 

[Melbourne Guy]

That's a timely question, @microatx, as this recent paper suggests information could be tested as the fifth state of matter (there's a phys.org article as well that provides a summary). Potentially, we really do live in the Information Age!

 

[Mike S.]

as this recent paper suggests information could be tested as the fifth state of matter (there's a phys.org article as well that provides a summary)

This article makes much sense, except ... I was under the impression that it takes energy to erase a bit of information, but here the information in the electron has energy that can be converted into photon(s). Where am I confused?

 

[Melbourne Guy]

Where am I confused?

I took the situation to be 'erasure' as transformation of information from one form to another, and that the signature of this can be detected, @Mike S.. The delete still takes energy. (Or anti-information, perhaps, it's a pretty wild concept.)

 

[Mike S.]

I'm afraid I'm still confused. :) I can almost understand the idea of spending energy to get rid of energy - like the eraser is a heat pump, say. Except ... the information is gone after that! If your air conditioner spends energy to cool the room and the energy isn't seen again, the First Law would like to have a word with you.

 

[Oldman too]

Hi, I too am confused, albeit on another point. I notice references to candidates for a 5th state of matter... Am I mistaken, or isn't that title officially held by Bose-Einstein condensates? For me it gets more confusing, as I see BIC also referred to as a black hole analogue. At that point I could use a reality check, can anyone clarify this?
Thanks in advance.

 

[Mike S.]

Don't forget liquid crystals (nematic, smectic, hexatic... I've never even learned all the different 'phases'). Superfluids? Supercritical fluids? What about substances with a liquid-liquid phase transition? I'm afraid I gave up on counting these a long time ago, and I haven't even thought about ferromagnetic fluids, neutron stars, quark-gluon plasmas and so on. Imagine the list I could come up with if I had a reasonable knowledge of physics!

 

[mitchell porter]

This article makes much sense, except ... I was under the impression that it takes energy to erase a bit of information, but here the information in the electron has energy that can be converted into photon(s). Where am I confused?

You're not confused. You are correctly remembering Landauer's principle. But the author of that paper invented his own theory that mass has information and that information is the fifth state of matter.

 

[Melbourne Guy]

But the author of that paper invented his own theory...

Indeed, but it is an apparently testable hypothesis, at least, with predictions for the expected results even if it is not an easy experiment to conduct.

 

[Mike S.]

You're not confused. You are correctly remembering Landauer's principle. But the author of that paper invented his own theory that mass has information and that information is the fifth state of matter.

I'm getting the impression that you think it may be a crackpot theory. At the same time, it's published in AIP Advances, a journal that Wikipedia says has an impact factor of 1.5. I would think it was peer reviewed at least enough that he didn't just misremember the sign of the mass involved. But I don't see how peer reviewers accepted that information can have a positive mass, then you put mass into it to erase it, and after that it's gone!

 

[Lord Jestocost]

To my mind, one shouldn’t attribute greater importance to the term information as necessary. As Robert Alicki remarks in “Information is not physical“ (https://arxiv.org/abs/1402.2414):

“... It is true that, as Landauer wrote: ‘[Information] is always tied to a physical representation. It is represented by engraving on a stone tablet, a spin, a charge, a hole in a punched card, a mark on paper, or some other equivalent. This ties the handling of information to all the possibilities and restrictions of our real physical word, its laws of physics and its storehouse.’
However, the legitimate questions concern the physical properties of information carriers like ‘stone tablet, a spin, a charge, a hole in a punched card, a mark on paper’, but not the information itself.” [underlined by LJ]

 

[ohwilleke]

I agree that there is an inherent ambiguity here.

The vacuum as a whole (i.e. space between macroscopic particles in the Universe) certainly contains information, such as the cosmic background radiation from which we make many notable findings about the early universe and cosmology.

But, qualified as the "quantum vacuum", I am imagining something more along the lines of the notion that sometimes quantum physics expects spontaneous creation of pairs of fundamental particles (or at least virtual fundamental particles) and similarly the particle sea of something like a hadron which is full of valence particles of every imaginable kind in addition to the valence quarks of a composite particle.

Since the particle sea of a hadron has observable physical consequences, as does the existence of virtual particles, that can be described, I guess you could say that this is form of information. Quantum physics without virtual particles would behave differently than the world that we observe.

But as @LordJestocost notes, these are not "information carriers". You can't transmit information via a quantum vacuum.

 

[microatx]

Guys thank you for the answers. But ı think at this point ı should ı ask about that means of information conservation. Because when ı say that information conservation ı feel like information must be carried by somehow.

 

[Demystifier]

Guys thank you for the answers. But ı think at this point ı should ı ask about that means of information conservation. Because when ı say that information conservation ı feel like information must be carried by somehow.

Sorry for the offtopic, but how do you get letter "ı" instead if "i"?

Concerning your question, information is carried by the state in the Hilbert space. It is conserved because the time-evolution of the state (of the full system) is unitary, governed by the self-adjoint Hamiltonian.