1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A Why are vibrations so common?

  1. Apr 6, 2016 #1
    Vibrations are everywhere and the question is if there is some fundamental reason for this. Per example, symmetries and the least action principle are behind the conservation laws. What is the reason that vibrations are so common?
  2. jcsd
  3. Apr 6, 2016 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Because the temperature around you are not at absolute zero.

  4. Apr 6, 2016 #3
    I don"t mean vibrations of atoms. I mean sound propagation, water waves etc
  5. Apr 6, 2016 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Then you should have been more explicit in the very beginning.

    These "sound propagation, water waves, etc..." are not THAT common. These are just "physical waves". How many ARE there? They are certainly not "everywhere" in terms of different sources that generate these things.

    Intrinsic vibrations, on the other hand, ARE almost everywhere.

  6. Apr 6, 2016 #5
    I admit my question is badly written . I wanted to say that harmonic oscillators can describe nature. I have read that this is because strength of fields weaken with inverse square. Is this intuition correct? ( english is not my mother tongue, i apologize )
  7. Apr 6, 2016 #6


    User Avatar
    Science Advisor

    At the risk of being stupid...

    If you have particles and approximate conservation of kinetic energy then there are two general possibilities. Either you have particles scattering to the winds or you have particles staying in clumps. If you have particles staying in clumps then the kinetic energy will manifest as "vibrations". No need for an inverse square principle.

    Edit: Rigid rotational motion or linear motion would also be possible, I suppose.
  8. Apr 6, 2016 #7
    So you say that conservation of energy dictates that potential and kinetic energy must be interchanged?
  9. Apr 6, 2016 #8


    User Avatar
    Science Advisor

    I think that I posted at cross-purposes. You are contemplating patterned vibrations and my response was not.
  10. Apr 6, 2016 #9
    All vibrations are patterned, please explain more your insight about kinetic energy
  11. Apr 9, 2016 #10
    There is a branch in math where we can decompose any function(either periodic or non-periodic) into sine and cosine functions called fourier analysis. The intuition which I understood was that any vibration can be modelled as superposition of sine and cosine componenets. Each sine and cosine component has an amplitude and frequency.
    let f(x) be a function
    then f(x)= summation of(sine terms)+summation of(cosine terms).
    In physics, any natural phenomena can be modelled( if not, we should solve differential equation for the system) as a function and this function can be decomposed into vibration(sine and cosine) components.
    So, thus we can definitely say that any phenomenon in nature can be modelled as vibrations.
  12. Apr 9, 2016 #11
    Harmonic oscillations occur if the potential energy increases quadratically with distance from an equilibrium position. If you expand any analytical potential as a taylor series to second order, you can do away with the constant and linear (by redefining the coordinate origin) terms, ending up with only the quadratic term which leads to harmonic oscillations. Often (e.g. in solid state physics) it seems to be easier to start from here and introduce higher order terms as perturbations.

    Not really. Above doesn't work for 1/r-potentials because of the pole at 0, i.e. because they are not analytic at r=0.
  13. Apr 10, 2016 #12


    User Avatar
    Gold Member

    It is because mechanical systems tend to have a resonance when energy can be stored either in their inertia, or mass, and their springiness. Energy can transfer between these two properties by changing between PE and KE. In many cases, objects have distributed mass and springiness, and then they behave like a transmission line. This also promotes vibrations, and can have numerous modes and frequencies of vibration. In the electrical world, conductors have inductance (involving magnetic fields) and capacitance (involving electric fields). Each of these can store energy, and vibrations occur as an exact parallel with the mechanical world. When a light switch is operated, vibrations occur in the wiring until things settle down.
  14. Apr 10, 2016 #13
    I guess that periodic oscillation between known states is the most primitive kind of ongoing change or process that can occur in any system.
  15. Apr 10, 2016 #14
    Vibrations are so common because restoring forces which accompany equilibrium positions are so common.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted