# Talk:Quantum fluctuation

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## 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 (talkcontribs)

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 underterminate"

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

Quantuim 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.

## References

The author made non referenced claims. —Preceding unsigned comment added by 70.81.162.66 (talkcontribs)

## 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 (talkcontribs)

THe section under the title "Quantum Fluctuations of a field" does not speak about quantumn 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)

## 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 (talkcontribs) 19:03, 6 September 2014 (UTC)