I'm taking on an interesting task: explaining to an extremely advanced 11 year old that much of what he hears and reads from the "popular physics" videos and TV programs isn't accurate, and some of it is just wrong. I know I have a problem here however - once he moves on to high school physics he's going to come across many of these same incorrect explanations from his teachers. I need to decide if I go so far as to explain that there is ZERO evidence showing or theorizing that an electron (for instance) is ever a wave.

He's bright as heck, and I can certainly explain a probability function, and can explain that it's a solution to a wave equation. And I can explain that this probability function is NOT the electron itself. And that this probability function can be plotted in a way that it can look like a wave or a superposition of waves. But do I stop there or continue and say simply "this does not in any way imply that the electron itself is a wave!"


If I was that kid I would have LOVED it if someone explained this to me at an early age. But I know I would have upset some teachers. Maybe only once or twice though. I'd like to know what everyone else thinks.


From the comments I realize there's a need to modify my question with the following statement:

The probability function (or superposition thereof) has meaning because it is the solution to a very special wave equation that has proven to glean incredible meaning. The electron is and never has been a solution to such a special wave equation. We can learn things about electron behavior from the solutions to this wave equation, but it makes no sense to say that the electron is a solution to this same wave equation.

Furthermore, to posit that ANY localized entity is a wave is disingenuous and misleading: Propose any thing which can be plotted and/or described as a function, and I will show you a superposition of orthogonal solutions of SOME equation that will describe it to whatever precision that seems reasonable (let's say "measurable" for these purposes). If I choose that equation to be a wave equation then I allow myself the right to call the thing a wave and give it a wavelength which quantifies some average spatial distribution. Is that meaningful? Does that help us to understand an electron? I say no.

Yes - I do strongly believe that there is NO reason to call the electron a wave ever, because there is no evidence and no theory showing it to be such a thing. There IS however much evidence showing that an electron is a particle, and that's because we measure it to be such a thing. To state that it is also a wave is nothing but disingenuous babble. If it's an electron then it's measured always as a particle.

So do you think the electron IS ever a wave? If so please state your evidence and/or theories which prove it to be such a thing.


closed as off-topic by AccidentalFourierTransform, tpg2114, WillO, By Symmetry, tparker May 24 '17 at 22:35

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    $\begingroup$ This site is about physics, not the teaching of physics, so this might go better somewhere else. My personal opinion is that one should never make strong statements either way ("the electron is / is not a wave") because "wave" is just a vague word. It's better just to say what electrons do, i.e. give a solid introduction to the math. That will also allow the kid to evaluate other peoples' claims himself, later in life. $\endgroup$ – knzhou May 24 '17 at 20:48
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    $\begingroup$ I'm voting to close this question as off-topic because questions about physics pedagogy are not in the scope of the site. $\endgroup$ – tpg2114 May 24 '17 at 20:49
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    $\begingroup$ If you went so far as to explain there is zero evidence showing that an electron has wave-like properties, YOU would be telling him something patently false. Also in my experience most introductory physics classes taught by good teachers haven't gone so far as to do the same. $\endgroup$ – IntuitivePhysics May 24 '17 at 21:12
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    $\begingroup$ Er ... electrons can (and do if you rig the experiment correctly) diffract. While there is an ontological argument that the electron fails to be a wave, it's wave-like properties are of non-trivial physical consequence. As a greasy-handed, soldering-iron and wrench physicist I always figure that ontology can take a flying leap if it obscures consequential behaviors. $\endgroup$ – dmckee May 24 '17 at 21:16
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    $\begingroup$ I'm voting to close this question as off-topic because the OP wrote "A great part of the reason for posting my question was to OUT the misconceptions so often perpetuated." In other words, this was apparently never intended as a question in the first place. $\endgroup$ – WillO May 24 '17 at 21:39

And electron is not a wave. However, describing matter with the use of wave functions has proven to be very effective in giving a mathematical framework for quantifying empirical observations regarding the probabilistic nature of interactions of small particles, and our uncertainty of their momentum/position, or energy/time relationship.

To say "an electron is not a wave" is not going to clear up any misconceptions - it is likely to perpetuate them in the same way that you seem to be having some misconceptions (and strongly held opinions masquerading as facts).

If this 11 year old is so bright, you might want to take him through some of the experimental work that has been done to explain optical diffraction (is a photon a particle or a wave?), the photoelectric effect, and electron diffraction. Three beautiful experiments that cannot, between them, be explained unless you accept that particles "sometimes are like particles, and at other times are like waves". Note - I don't say "are waves"; I say "like waves".

At the age of 11, having a clear and well grounded intuition for the behavior of the world (including some of that "fuzzy duality") is appropriate; telling a child something "absolute" when you are not actually an expert is likely to set them back.

I applaud your desire to help this child grow; please consider the advice given in the sense it was given - we both want the next generation to be equipped to deal with the challenges of their time, and we'll need some first class scientists...

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – ACuriousMind May 25 '17 at 21:58
  • $\begingroup$ dude. i think it's really uncool the way you blew me off. you aren't qualified to do that to me. instead of stopping to figure out why I might be right on with my post, you took the easy route and chose to assume i meant something incorrect. You were incorrect to do that. I'd be tremendously embarrassed if I was you. $\endgroup$ – John Ahearn Nov 14 '17 at 23:46
  • $\begingroup$ @Floris - I am SO SORRY. My comment was for ACuriousMind. It seems to me that you are the only one that understood my points here. My post wasn't given the chance to see an entire day's worth of responses from people across the globe that were never allowed to read it - many were still at work or sleeping when it was voted down! What's incredible to me is how you and I are trying to be careful with our words, while others are just incorrect with regard to their logic AND their physics. You and I are saying the SAME things written by some of the most esteemed members on S.E! $\endgroup$ – John Ahearn Nov 18 '17 at 15:37
  • $\begingroup$ @JohnAhearn no worries and thank you for the clarification. I will delete my earlier comment. Civility seems to be in short supply on the internet... best to just move on. Be the change you want to see. $\endgroup$ – Floris Nov 18 '17 at 17:33
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    $\begingroup$ @Floris FWIW I just visited a "page" about you specifically and was about to type the following "My interactions with Floris have proved him to be an invaluable PSE member. Very knowledgeable and very patient. Always fair and unbiased. Keep it going Floris;-)". However, I'm not allowed to post because of some rule related to my overall "score". Good luck to you regardless. $\endgroup$ – John Ahearn Feb 7 '18 at 23:30

Whether an electron's probability function should be thought of as distinct from the electron itself is pretty much a completely philosophical question with very little physical content, and so saying that its "DEFINITELY NOT" true is wrong. (Note I'm not saying that it's true that an electron is the same thing as its probability function. I'm saying that it's not true that an electron is definitely not the same thing as its probability function.) Presenting this as a "common misconception" is just going to confuse him and set back his physics understanding.

In fact, based on the confidence with which you present the incorrect statement in your question, I would recommend thinking twice about clearing up the "misconceptions" that his physics teachers are spreading and letting the professionals do their job.

  • $\begingroup$ Physics.SE comments are not the place to discuss ontological convictions, and I've removed a comment thread that did not really try to address or improve this answer. I'd also remind everyone that we try to be nice even to people with which we disagree. $\endgroup$ – ACuriousMind May 25 '17 at 22:02
  • $\begingroup$ @ACuriousMind Thank you. Of course I walk a fine line here, but your comment begs the question "with respect to Q.M. where does ontology begin and where does it end?". Bohr stopped a lot of this speculation, not because of the ontological nature of it, but because it wasn't useful and it didn't appear to go anywhere. And yet he was too late - cat was out of the bag and everyone started calling electrons (for instance) waves. But isn't THAT the very ontological conviction which I'm attacking with my non-ontological approach? $\endgroup$ – John Ahearn May 25 '17 at 22:20
  • $\begingroup$ @tparker - you write "I'm saying that it's not true that an electron is definitely not the same thing as its probability function.". You would be alone here. A prob function is useful to present expectation values for what might be measured when some effect due to an electron's presence is measured. You seem to misunderstand that the electron may be a solution to the Schrodinger's Eq? Regardless, there is no evidence that electron is or ever has been a wave. Expectation values would need to imply fractional mass/charge in that case. $\endgroup$ – John Ahearn May 29 '17 at 20:45

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