After studying de Broglie's hypothesis we can very well say that every particle is just a localised wave packet and not a particle in the sense of the word. A particle would be like a point in space as far as I understand. Is it accurate to specify all quantum objects as wave packets? Or is it only a theoretical concept employed to explain interference/diffraction?

Edit: For a particle at rest I guess this wave packet picture fails.

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    $\begingroup$ They're neither, they're quantum objects which aren't classical particles and aren't classical waves, see e.g. physics.stackexchange.com/q/46237/50583, physics.stackexchange.com/q/193325/50583 and others. $\endgroup$ – ACuriousMind Dec 13 '15 at 14:07
  • $\begingroup$ But wouldn't a wave packet be an appropriate candidate for a quantum object? $\endgroup$ – Weezy Dec 13 '15 at 14:09
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    $\begingroup$ It's one description of it that's often possible, but there are situation where you can't have a "wave" description, e.g. for finite-dimensional quantum systems. See Lubos' answer - the wave and particle picture are both valid descriptions of a quantum object in some cases - you can't say one is "more correct" than the other. $\endgroup$ – ACuriousMind Dec 13 '15 at 14:12
  • $\begingroup$ @ACuriousMind that first comment should be an answer $\endgroup$ – David Z Dec 13 '15 at 14:24
  • $\begingroup$ On a side note could anybody point out if my "edit" is correct? $\endgroup$ – Weezy Dec 13 '15 at 14:26

Electrons - like all other fundamental "particles" - are as much "wave packets" as they are "particles", which is to say: They are neither, but in many situations you can get away with describing them as one or the other without knowing that the actual description of them in modern quantum mechanics is by states in a Hilbert space, which you may often model by "wavefunctions" as long as you accept that in cases where the particles are not free, those "wavefunction" may not look very much like a wave, and, in any case, this "wavefunction" only gives a way to compute the probability of detecting the object "as a particle", so its amplitude has a very different meaning from that of a classical wave.

For more on this, see Is the wave-particle duality a real duality?, my answer here, or other questions in the tag.


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