What is Quantum fluctuations: Definition and 57 Discussions

In quantum physics, a quantum fluctuation (or vacuum state fluctuation or vacuum fluctuation) is the temporary random change in the amount of energy in a point in space, as prescribed by Werner Heisenberg's uncertainty principle. They are tiny random fluctuations in the values of the fields which represent elementary particles, such as electric and magnetic fields which represent the electromagnetic force carried by photons, W and Z fields which carry the weak force, and gluon fields which carry the strong force. Vacuum fluctuations appear as virtual particles, which are always created in particle-antiparticle pairs. Since they are created spontaneously without a source of energy, vacuum fluctuations and virtual particles are said to violate the conservation of energy. This is theoretically allowable because the particles annihilate each other within a time limit determined by the uncertainty principle so they are not directly observable. The uncertainty principle states the uncertainty in energy and time can be related by




{\displaystyle \Delta E\,\Delta t\geq {\tfrac {1}{2}}\hbar ~}
, where 1/2ħ ≈ 5,27286×10−35 Js. This means that pairs of virtual particles with energy


{\displaystyle \Delta E}
and lifetime shorter than


{\displaystyle \Delta t}
are continually created and annihilated in empty space. Although the particles are not directly detectable, the cumulative effects of these particles are measurable. For example, without quantum fluctuations the "bare" mass and charge of elementary particles would be infinite; from renormalization theory the shielding effect of the cloud of virtual particles is responsible for the finite mass and charge of elementary particles. Another consequence is the Casimir effect. One of the first observations which was evidence for vacuum fluctuations was the Lamb shift in hydrogen. In July 2020 scientists report that they, for the first time, measured that quantum vacuum fluctuations can influence the motion of macroscopic, human-scale objects by measuring correlations below the standard quantum limit between the position/momentum uncertainty of the mirrors of LIGO and the photon number/phase uncertainty of light that they reflect.

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  1. S

    I Electrons keeping dynamical quantum fluctuations?

    I was thinking about this paper (https://arxiv.org/abs/1405.0298) where the authors argue that there wouldn't be dynamical quantum fluctuations in a De Sitter space as fluctuations would be static once all perturbative radiation escapes the horizon (in the case that the Universe has a finite...
  2. S

    I Could entropy be reversed eventually in the far future?

    In the far future there will be most likely a point where a maximal state of entropy will be reached in the universe and after the last black hole evaporates there could be no more structures and no more work could be done. According to the Poincaré recurrence theorem for a closed universe...
  3. J

    I Quantum fluctuations & 'virtual particles'

    I've been reading about how language around virtual particle fluctuations is metaphorical. This is helpful: https://www.physicsforums.com/insights/vacuum-fluctuation-myth/ I'm just trying to understand a bit more from a layman's point of view. I found Matt Strassler's article 'Virtual...
  4. S

    I Is it a fact that vacuum energy exists?

    I have always read that vacuum energy and zero point energy are established facts of physics supported by various observations of their effects both indirectly and even directly. But I have also read some comments from various physics discussion sites where they say that it is not a fact that...
  5. TheHeraclitus

    Particle ontology and quantum fluctuations

    I have been reading about ontologies in quantum physics recently and I came across Bohmian mechanics. If I understood it correctly BM endorses Particle ontology. Particle ontology claims that point-like particles that move continuously in time are the fundamental building blocks. I know some...
  6. R

    Working on my scientific script on quantum physics (sources for the Casmir effect)

    Summary:: Any good english or german sources for Casimir effect, quantum fluctuations or zero point energy Hello, fellow quantum physicists I am currently writing a detailed physics script for my quantum physics project and I wanted to ask if you know some good internet sources on the theme of...
  7. Vanilla Gorilla

    B Could Quantum Fluctuations exist W/out the presence of Spacetime?

    I want to know whether Quantum Fluctuations could exist without the presence of Spacetime. Would it be possible, in the event of a Big Rip scenario, and if Spacetime really would get ripped apart, that quantum fluctuations could still occur? And if Spacetime is ripped apart, does that mean the...
  8. A

    A Quantum vacuum fluctuation in BEC

    Hi, I have some problems with visualization (I'm trying to understand Jeff Steinhauer's experiment, but my questions are general). Why the quantum vacuum fluctuations are guaranteed by the underlying pointlike atoms composing a BEC? And if vacuum fluctuations generate excitations (i.e...
  9. TheQuestionGuy14

    B Do quantum fluctuations actually occur in De Sitter space?

    A little while back I asked a question about quantum fluctuations, and I got some great answers. Just recently, I stumbled upon a paper by Sean Carroll, which states that there isn't quantum fluctuations after all, in a De Sitter space in a vacuum state. He used this to argue against Boltzmann...
  10. D

    Quantum Quantum Fluctuations & Virtual Bosons for Amateur Physicists

    I am searching for anything on quantum fluctuations and virtual bosons for someone who is a serious but amateur physicist ie. I have completed undergrad physics/math and some graduate level math at university. I am having a hard time finding anything that isn't beyond pop science. Not really...
  11. Cathr

    I On Hubble's constant, the expansion of the Universe and vacuum energy

    Recently I was thinking about the Hubble's constant (which, actually, is not Hubble's and not constant...) and wondering: if the universe is expanding at 70 km/s each Mpc, then there's possible to calculate some expansion of space, say from me to a person 1 meter away from me (theoretically)...
  12. MJM

    I When exactly did 'quantum fluctuations' in the early universe occur?

    I came across this video today: Which summarizes this new paper from University of Tokyo: https://arxiv.org/pdf/1907.02273.pdf I get that the video is just an explainer for primordial black holes, but I was hoping to get a better explanation on exactly when conventional wisdom says density...
  13. S

    I Is the holographic principle based on fuzzy logic?

    Physicist Craig Hogan has proposed that the universe is based on holographic principle. To prove that the universe is a "hologram" he (and other physicists) have designed an experiment named "The Holometer" to measure quantum fluctuations that would become fuzzy at Planck scale...
  14. A

    B A little logical doubt on Hawking radiation

    Summary: As hawking radiation is based on quantum fluctuations, can they cancel out each other due to equal probabilities of a particle remaining in or drifting away? I recently learned how hawking radiation actually works. It is based on quantum fluctuations which happen randomly in space...
  15. T

    B So Quantum Fluctuations don't exist?

    Is it true that when we dig deep into the math, we realize that Quantum Fluctuations and virtual particles are just a heuristic way of explaining certain phenomena to lay public?
  16. M

    A Quantum fluctuations of the metastable false vacuum

    I have been trying so hard to get some answers to a few questions I have in regard to this paper: https://arxiv.org/abs/1404.1207 I think those questions can best be summarized this way: 1) A metastable false vacuum is a field and fields are just the changing value of a parameter in...
  17. nomadreid

    I Do quantum fluctuations mean metric fluctuations?

    I suspect the following reasoning is faulty, but I am not sure why. Hence I would appreciate someone pointing out the errors. That is, which, if any, of the following statements are incorrect, and why? 1) Theoretically, albeit not practically due to the large numbers involved, the laws of...
  18. M

    I Virtual Particles: Speed & Impact on Rocket

    Hi, quantum fluctuations enable virtual particles in space. If a rocket travels through space, these particles (real ones of antiparticle-particle pairs) could impact it. Is the effect of an impact dependent of relative speed of such particle and the rocket? For example rocket could be warmed...
  19. A

    I 'Localization,' particle motion, and quantum fluctuations....

    Hi all, Some time ago I was reading about Anderson localization (posted a question about it was well) - this got me thinking about vacuum fluctuations. I think I have the wrong idea in my mind - so wanted to ask the great community here about it: Quantum (vacuum) fluctuations must have an...
  20. Doctor Strange

    A How do quantum fluctuations become gravity wells?

    How do quantum fluctuations become gravity wells? I thought the whole idea of the fluctuation was that it had to happen so quickly that the universe didn't notice. I see how a field could have a random, but non-zero value, but I don't see how that momentary variation in the field can stick...
  21. S

    A Quantum fluctuations in early universe

    Why do quantum fluctuations of fields arise at high energies and temperatures? What is the mathematical formulation of these quantum fluctuations? Why are the sizes of these quantum fluctuations approximately the Planck size?
  22. F

    I Relation between quantum fluctuations and vacuum energy?

    As far as I understand it, the non-zero vacuum energy attributed to a quantum field (at each point in space-time) is precisely due to the Heisenberg uncertainty principle (and the fact that the energy of the quantum field at each space-time point is quantised). Accordingly (in order to satisfy...
  23. M

    I Some questions regarding quantum fluctuations

    First of all, would I be correct in using the following explanation? Quantum fluctuations are not actually events but properties of the quantum vacuum, they don't have a physical cause but they are not an example of creation ex nihilo, they are created from other things. I think of it like a...
  24. J

    Quantum fluctuations within an electromagnetic field

    hello, I was wondering what caused quantum fluctuations within an electromagnetic field as i recently accepted that there are no virtual particles what causes the energy to fluctuate. here the quantum fluctuations are said to be caused by virtual particles. essentially I'm asking for an...
  25. D

    Quantum fluctuation and quantum mysticism

    Hello, searching for information about debunking quantum mysticism I stumbled upon this article: http://www.csicop.org/si/show/quantum_quackery/ , where one of the main arguments seems to be based on quantum fluctuation to explain Einstein´s famous "spooky effect on a distance". You can check...
  26. Dr. Strange

    Why do Quantum Fluctuations need Inflation?

    The general logic of Inflation is that some field popped into existence just long enough to flatten out the universe, then disappeared again. Before the field, the universe had tiny fluctuations in the plasma. Inflation blew these up from the size of an atom to the size of a grapefruit (If I...
  27. goat-on-a-stick

    How can quantum tunneling create Big Bang after heat death?

    Wikipedia states that, after he heat death of the universe: "Random quantum fluctuations or quantum tunneling can produce another Big Bang in years." How would this work?
  28. DeathbyGreen

    Quantum fluctuations and order

    Is there a good explanation for how we can explain an ordered universe arising from an inherently uncertain quantum world? I'm aware of the conflict between special relativity and quantum vacuum fluctuations, but is this the only issue? The correspondence principle would seem to imply that...
  29. A

    Quantum fluctuations at critical point

    According to wikipedia: "As for a classical second order transition, a quantum second order transition has a quantum critical point (QCP) where the quantum fluctuations driving the transition diverge and become scale invariant in space and time." I am confused about what this means. Why do the...
  30. P

    Quantum fluctuations at radio frequencies

    Hi. I'd like to learn how to calculate the probability of a photon being emitted from a radio antenna where the energy per wavelength is below the threshold to emit photons. Let's assume the electrical thermal noise is insignificant. The antenna temperature could be sufficient low or the...
  31. M

    Quantum Fluctuations: Origins Explored

    How do quantum fluctuations originate?
  32. B

    Quantum Fluctuations and Big Bang

    Hi, I have read that quantum fluctuations have created our universe through the Big Bang. The issue that I didn't understand is that as far as I know quantum fluctuations are properties of space. How could these fluctuations exist before the Big Bang while there was no space before the Big...
  33. maverick_starstrider

    Thermal AND Quantum Fluctuations?

    Hi all, I know how if a statistical partition function is written as a path integral in imaginary time (Wick's rotation) the fluctuations around the mean-field represent thermal fluctuations. If the path integral is instead done in real time then fluctuations from the...
  34. H

    Do quantum fluctuations come from nothing ?

    Do quantum fluctuations come from "nothing"? Hello, I have two questions regarding quantum fluctuations. Do the particle (and its' anti-particle) appear from nothing? I know it happens in a Quantum vacuum. But do the particles themselves appear from nothing? Where do they get their energy...
  35. Teichii492

    Optoelectronics: Dark current caused by Quantum fluctuations?

    Hello Physics Forums, This is my first time posting so apologies for any mistakes or misunderstand of forum etiquette here. I am having difficulty understanding a phenomenon known as "dark current" I've tried for a few hours to research it but most of what i find is very vague on the...
  36. R

    What is meant by being driven by quantum fluctuations in QPTs

    What is meant by "being driven by quantum fluctuations" in QPTs Hello all, I'm reading a bit about quantum phase transitions, and in almost every description out there one will find the following mysterious phrase: "quantum phase transitions are driven by quantum fluctuations rather than...
  37. NATURE.M

    Quantum Fluctuations: Virtual Photon in Feynman Diagrams

    Contrary to a classical vacuum, particles tend to pop into and out of existence in a quantum vacuum. When analyzing a Feynman diagram (such as Moller scattering), is the virtual photon that mediates the electromagnetic interaction considered to be a quantum fluctuation? (Any feedback will be...
  38. A

    What are quantum fluctuations ?

    What are quantum "fluctuations"? We get to know that vacuum is not really empty but that its energy ground state is non zero. Is this what is represented by quantum "fluctuations"? As far as I understand QM this seems to me a very misleading representation of things. If we believe that...
  39. e2m2a

    Quantum fluctuations and momentum

    The Lamb shift showed that quantum fluctuations could have a real, measurable effect on the orbits of electrons. Since these fluctuations can impact the momentum of mass, is it possible that quantum fluctuations could impact electro-magnetic momentum, such as the momentum of photons...
  40. D

    Quantum fluctuations and Spacetime

    Hi there. I am a layman, and I have a question. As far as I have gathered, the prevalent view in cosmology is that the universe appeared as a result of the Big Bang, which in turn occurred due to expansion of singularity. Ok. Some go further and propose that singularity appeared through...
  41. E

    Quantum fluctuations at different height.

    has quantum fluctuations and the Wand der walls force that they produce been measured at different heights? Are there any results? Would there/ should there, according to accepted theories, be any difference?
  42. C

    Lack of quantum fluctuations rules out holographic principle ?

    Recent searching of the light from the quasars indicate lack of the quantum fluctuation of the spacetime. http://arxiv.org/PS_cache/arxiv/pdf/1108/1108.6005v1.pdf Does it mean the lack of quantum foam rules out the discretness of the spacetime too ? How to explain Casimir effect and...
  43. M

    Quantum Fluctuations: Meaning & Universe Creation

    I want to get some opinions on quantum fluctuations what they mean, and how they could have created our universe. Thanks!
  44. M

    Why are quantum fluctuations amplified when viewed on a smaller scale?

    Why are quantum fluctuations amplified when viewed on a smaller scale? I read about this in 'elegant universe' but the book never answered my question.
  45. S

    Quantum fluctuations and space

    Hi PF Can quantum fluctuations create space? And if so, could quantum fluctuations have created the universe and therefore spacetime we live in? \Schreiber
  46. R

    Quantum fluctuations and Inflation

    Wikipedia defines quantum fluctuations as: "In quantum physics, a quantum fluctuation is the temporary change in the amount of energy in a point in space,[1] arising from Werner Heisenberg's uncertainty principle. According to one formulation of the principle, energy and time can be related by...
  47. Z

    Quantum fluctuations = gravity?

    Since spacetime bubbles with quantum fluctuation energy, and energy is equivalent to mass, and mass generates gravity, wouldn't spacetime be awashed with gravity?
  48. p764rds

    Quantum fluctuations in a vacuum

    Some physicists are giving up on physical particles and talking about quantum fluctuations in a vacuum. So, what exactly is a quantum fluctuation in a vacuum?
  49. S

    Quantum Fluctuations and Curved Space

    There is a new theory being put forth that gravity may amplify vacuum energy to the point that the amplified vacuum energy may predominate over classical vacuum energy, which would cause it to influence astrophysical processes: http://www.physorg.com/news193330592.html It's just a...
  50. G

    Gravitationally amplified quantum fluctuations

    http://www.physorg.com/news193330592.html In the above article, a mechanism is suggested whereby a massive body gains mass from quantum fluctuations. This seems to contradict Hawking Radiation, where interaction with virtual particles result in a (very) massive body radiating away energy! Why...