Talk:Quantum fluctuation

Completely wrong statement
'' the field's lowest-energy or ground state, often called the vacuum state, is not, as one might expect from that name, a state with no particles, but rather a quantum superposition of particle number eigenstates with 0, 1, 2...etc. particles.'' This is absurd. The vacuum state is always the eigenstate of the number operator with exactly zero particles,. There is no uncertainty in the number of particles, since it is an eigenstate. See also https://www.physicsforums.com/insights/vacuum-fluctuation-myth/ — Preceding unsigned comment added by 131.130.16.23 (talk) 09:13, 13 December 2016 (UTC)


 * You are also right.
 * And it can not be an igenstate of energy (the lowest energy ground state [of Hamiltonian]). If so, "nothing ever happens in a stationary [energy] state", as pointed out by Griffiths. But we have Casimir effect, which demands energy (uncertainty principle is NOT a font of energy), and vacuum fluctuations.
 * The article must be rewritten to suppress inaccuracies.
 * Anonimo Oculto (talk) 00:50, 8 May 2022 (UTC)

Article is Plagiarized
From the first words, through the first equation (although the original has 2pi in the denominator, not 4pi) then continuing. As per the discussion below, some changes were made relating to energy conservation. The plagerizing seems to end after the table of contents. The original, plagiarized text is on page 85 in "The Two Cultures: Shared Problems", 2009, by Ernesto Carafoli (Editor), Gian Antonio Danieli (Editor), Giuseppe O. Longo (Editor), published by Springer, available at Amazon.

I'm not a lawyer, but I doubt this can be retained. Whoever entered the text should be banned from future entry.

Incidentally, had the original text been read carefully, it would have been noted that conservation of energy is fixed, but is violated by the uncertainty principal. This may be hand waving, but it's accurate enough for Wikipedia.

Time span within which conservation can be violated
When you say conservation of energy can appear to be violated, but only for small times. Can't a minute be stretched or shortened? How long can you really say a fluctuation takes place? —Preceding unsigned comment added by 24.109.219.47 (talk • contribs)
 * The time span within which conservation can be violated cannot be longer than what's permitted by the uncertainty principle. It's an immensely small period of time; minute fractions of a second. A minute? Nowhere near. PsiCop 00:15, 15 June 2006 (UTC)

"conservation of energy can appear to be violated, but only for small times."

THIS IS WRONG

dE*dt>h/2pi

DOES NOT say that. That relation does not mean that energy is 'very uncertain for very small times'. Rather if you actually study the derivation of that equation, it's mathematical and physical meaning is different (see here for example: http://en.wikipedia.org/wiki/Uncertainty_principle#Robertson.E2.80.93Schr.C3.B6dinger_uncertainty_relations).

Basically the E-t-uncertainty means that "the uncertainty in the energy is related to how long the (mean) expectation value of another observable of the quantum system changes in time" or in simpler terms: "the energy uncertainty is related to the stability of the system: if a system never changes in time, the energy is perfectly known, while if the system changes rapidly, the energy value is quite indeterminate"

The important thing to realise is that in QM time is NOT an operator, but a parameter or independent variable as in newtonian mechanics was, since a time operator would contradict the Stone–von Neumann theorem.

Quantum fluctuations DO NOT rise from time uncertainty in relativistic qM (QFT) but because fields, even empty fields (ie in vacuum) are treated as (harmonic) oscillators (see http://www.mathematik.uni-muenchen.de/~schotten/qftcs/QFTCS_Notes-Drews.pdf)

At VERY SMALL distances (implying a small Dx) there corrisponds also a (large) uncertainty in the (four) momentum and thus energy. This however does not violate any conservation laws at all.

Not clear
This relates the the previous comments. In QM, a state that only exists for a very short time does not definite energy. Over such a brief period, the state's frequency can't be accurately defined. A particle that decays very fast has greater uncertainty in its mass. — Preceding unsigned comment added by BriCoil (talk • contribs) 22:25, 30 July 2016 (UTC)

How much energy is required to separate a quantum fluctuation
How much energy is required to separate a quantum fluctuation so the virtual pairs do not annihilate? I am aware that around the event horizon of a blackhole this is theoretically observed. One part of the virtual pair falls into the blackhole and the other part moves away from the blackhole into the observable universe. This creates the appearance of radiation coming out of blackholes, known as Hawking Radiation. Is there a way to measure the minimum amount of energy needed to separate the virtual pairs of a quantum fluctuation? —Preceding unsigned comment added by Skysunny7th (talk • contribs)

This article is very poor
THe section under the title "Quantum Fluctuations of a field" does not speak about quantum fluctuations per se, but about what seems a rather arbitrary choice of subject related to this topic, which would be the distinction with thermal fluctuations. Also, in general, the probability to observe a certain state in quantum mechanics depends on the "linear combination" that adds up to form that state; this would be what the second part of the article is about (?). Shouldn´t the article be about only the first part? At least, there should be more evidence in support for the need to speak about "quantum fluctuations".--190.188.0.22 (talk) 14:30, 17 May 2010 (UTC)
 * Agreed. The problem is that the second part is actually the best here. The first part has a reference to a New York Times article written by a baseball photographer. If you look at the early editing history you'd see an attempt to say this is !!! but there were too many exclamation marks there and the addition has been edited to look as if it were in compliance. I'd advice to consider deletion, but it is up to  you.  --93.73.19.163 (talk) 04:17, 13 April 2012 (UTC)

seriously their are lot of mis representative information like the law of conservation " apears to be " violated !! ? hope it is not turning more into hopefully, apears to be ..., probably, mostly etc things in physics !! Shrikanthv (talk) 11:29, 24 April 2012 (UTC)

People are saying that energy can come from the vacuum and many scientist have been killed for trying to develop energy independent of oil. Because oil supplies will not keep up with consumption there should be more effort to better define Quantum flucuations in order people have time to develop alternatives. I feel this article is only written for people who have been educated in quantum science. — Preceding unsigned comment added by 209.36.14.68 (talk) 08:31, 10 May 2015 (UTC)

A nice review of this article: "Almost everything from the wikipedia page you link is just false, or at best very misleading. IMHO, that page was written by someone that doesn't know anything about quantum mechanics beyond what one could find in TV documentaries. 'Not even wrong' came into my mind many times as I was reading the article." Continued at: https://physics.stackexchange.com/a/257700/85443 Keith McClary (talk) 02:32, 16 March 2018 (UTC)

Recommendation
I recommend that this article be renamed to quantum vacuum fluctuation, as the terms quantum fluctuation and vacuum fluctuation would then be obvious simplifications. A redirect from quantum vacuum fluctuation would be a good starting place. 70.247.166.5 (talk) 02:58, 18 June 2012 (UTC)

Quantum fluctuations claimed to be linked to the creation of the baby universe
The paper Spontaneous creation of the universe from nothing which appeared recently on ArXiv links quantum fluctuations with the baby universe. Maybe the article should be updated to take a note of this analysis, but I'm not sure if the analysis is correct or whether it is significant or reliable. Hoz do ze decide whether an ArXiv paper is significant for mention in the encyclopedia? It appears there are some press reports about the paper, but I'm not sure whether this means anything. Absinthia Stacy (talk) 15:24, 15 April 2014 (UTC)

"h"
What does "h" refers to in the equation in the first paragraph?

t is time, E energy, but h? — Preceding unsigned comment added by Zethradon (talk • contribs) 19:03, 6 September 2014 (UTC)

chronology
"This was proposed by scientist Heisenberg's study in 1916 at Harvard's Laboratory."

To what event are you referring? Uncertainty Principle? This doesn't make any sense. Wikibearwithme (talk) 07:32, 2 September 2015 (UTC)

Expansion of the Universe?
"Vacuum energy may also be responsible for the current accelerated expansion of the universe (cosmological constant)."

Shouldn't that be edited to say accelerating rather than accelerated?

(I would make this edit myself to the article right now, but I'm not even nearly familiar enough with this area of subject matter to know whether I would be helping or harming by doing so.) — Preceding unsigned comment added by 69.62.255.118 (talk) 09:16, 30 March 2016 (UTC)

"Popping into existence out of nothing"
There should not be a link from quantum fluctuation, to the Universe popping into existence. This article occurs in the context of not "nothing", but rather, space (which is not nothing) 1.144.97.72 (talk) 09:22, 14 April 2016 (UTC)

Nothing pops in and out of existence in a quantum fluctuation. See https://www.physicsforums.com/insights/vacuum-fluctuation-myth/ and references there.

Zitterbewegung
A derivation of quantum fluctuations has been demonstrated from purely classical Maxwell’s electrodynamics and published recently in a high impact factor journal (https://doi.org/10.1007/s11071-020-05928-5). I am the author of the paper, and therefore I am not the person allowed to upload the reference, since a COI is at stake. But perhaps, if someone finds it interesting, he could introduce a section entitled “Zitterbewegung” with something similar to this:


 * Charged extended particles can experience self-oscillatory dynamics as a result of classical electrodynamic self-interactions \cite{}. This trembling motion has a frequency that is closely related to the zitterbewegung frequency appearing in Dirac's equation. The mechanism producing these fluctuations arises because some parts of an accelerated charged corpuscle emit electromagnetic perturbations that can affect another part of the body, producing self-forces. Using the Liénard-Wiechert potential as solutions to Maxwell's equations with sources, it can be shown that these forces can be described in terms of state-dependent delay differential equations, which display limit cycle behavior. Such analysis points to fundamental particles as electromagnetic topological solitons arising from Einstein-Maxwell equations, and allow to interpret vacuum fluctuations as having an electrodynamic origin. Alvaro12Lopez (talk) 14:11, 3 October 2020 (UTC)

This article is very poor
I agree with some of the other comments. From Griffiths: "It is often said that the uncertainty principle means that energy is not strictly conserved in QM – that you are allowed to borrow energy ΔE, as long as you pay it back in a time Δt ≈ ℏ ⁄2ΔE; the greater the violation, the briefer the period over which it can occur. There are many legitimate readings of the energy-time uncertainty principle, but this is not one of them. Nowhere does QM license violation of energy conservation, and certainly no such authorisation entered into the derivation of Eq 3.151 (ΔE Δt≥ℏ/2)". --Wikiwert (talk) 19:52, 30 December 2021 (UTC)

You are right
Uncertainty principle is NOT a font of infinitely or inexhaustible energy; it is even not a merely font of any energy to be precise. So, it does NOT imply possible violations of conservation of energy, even momentarily. The problem resides in understand what "Δt" means in uncertainty relation. It is not a "free or random selectable" interval of time, As exposed by Mandelstam, "it is the shortest time during which the average value of a certainty quantity is changed by an amount equal to standard deviation of this quantity". So "Δt" shows to be linked to another physical quantity on problem, other than energy.

The article must be rewritten to suppress inaccuracies.

Anonimo Oculto (talk) 00:26, 8 May 2022 (UTC)

ARMY. MMSC.
HKI:AN 2001:FB1:11C:8DF4:B43F:D96:CD51:D229 (talk) 14:33, 23 September 2022 (UTC)