Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Difference between de Broglie waves and the normal waves which transfer energy?

  1. Aug 13, 2011 #1
    Alright, as this wikipedia article states that, "A wave is a disturbance that travels through space and time, usually accompanied by the transfer of energy. Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the medium—that is, with little or no associated mass transport." So basically a wave transfers energy.

    So what is the difference between these waves and de Broglie waves. Is "wave" used in a different sense in Quantum mechanics? When we say an electron acts as a wave (wave-particle duality), what exactly is oscillating in the electron?

    Is there a stricter definition of "wave" in physics? And does it differ between classical and quantum physics?

    Thank You
  2. jcsd
  3. Aug 13, 2011 #2
    (I don't know much about quantum mechanics, so my answers may not be correct)

    Did you read the article completely?
    Which type of wave are you referring to?
    De-broglie wave is a matter wave and comprises of all the characters that a wave has. Its a type of wave. So you can't distinguish between a wave and a de-broglie wave.
  4. Aug 13, 2011 #3
    The way I understand it, a wave is characterised by the periodic change of some specific property of a point in space over time. For example, an ripple on the surface of water can be called a wave because the distance between a specific point in space within the volume of the water body and any given water molecule is changing periodically, varying between a maximum and a minimum value. Similarly, an electromagnetic wave is a wave because at any point in space through which the ray passes, the intensity of the electric and magnetic field vectors periodically change or oscillate.

    So my question is, if we consider a particle a wave, what is it in that particle, that oscillates or changes periodically with time? In addition, does wave mean something else or is it different from what I have in mind in the above paragraph, in Quantum Physics?
  5. Aug 13, 2011 #4
  6. Aug 13, 2011 #5
    I have seen that page (hyperphysics is often the first place to visit for such things). The question asked is pretty much the one I asked as well, however I didn't get a satisfactory answer. Thanks for the help anyways.

    Nah, quantum mechanics is beyond the scope of our syllabus. It requires understanding of certain mathematics which unfortunately I am not well versed with.
  7. Aug 16, 2011 #6
  8. Aug 18, 2011 #7
    A de Broglie wave is associated with something we usually think of as a moving particle that has mass - an electron or a neutron, for example. We have no problem thinking of a moving particle as something having energy and momentum, and therefore able to transfer energy and momentum. A photon is usually thought of as a wave, but despite having zero mass it it can also be thought of as a moving particle, having energy and momentum and therefore able to transfer energy and momentum. So, in both cases, you can think of energy as being transferred by a wave.
  9. Aug 18, 2011 #8
    Thanks for the reply.
    So what physical significance does the de Broglie wavelength of a massive particle have? Is it actually length that we are measuring (just like in EM radiation) or is it something else?
  10. Aug 19, 2011 #9
    Yes, it's a wavelength - you can measure it with a classical slit experiment, or by diffraction off a crystal. The "waving" is the wavefunction solution to Schroedinger's equation for a free particle, which you can use to calculate expectation values in the usual way.
  11. Aug 19, 2011 #10
    The best way to consider this is to think of energy as a series of balls and sticks that are all connected, that way the wave or particle become irrelevant or trivial to the model.

    At no point in space is energy 0 and the wave is infinite essentially.




Share this great discussion with others via Reddit, Google+, Twitter, or Facebook