What is an electron?
Asked by
ETpro (
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August 27th, 2013
Back when I went to high school just at the dawning of the crazy 1960s, the model we were shown of an atom’:http://www.sr.bham.ac.uk/xmm/images/atom/atom_350_234.gif was that of an object with a dense nucleus made up of little balls called neutrons and protons, with tiny balls orbiting the nucleus much as the planets of the solar system orbit the Sun. Of course, even at that time particle physicists knew that the atom looked nothing remotely like that simplified representation. In fact, if we had eyes that could see at the Planck scale, what an atom would really look like would truly blow our minds. When they developed the tools to look, what they saw blew the minds of the nuclear physicists studying it. Words just seem inadequate to describe everything that’s really going on at the quantum mechanical level.
The now famous double slit experiment gives us a hint that electrons are unlike anything we know of in the medium-scale world in which we evolved. When we add in a measurement and then see what happens if we do or do not record the data of the measurement, the double slit experiment becomes hugely bizarre. Our consciousness controls the reality of subatomic particles. The wave of potentialities of an electron or photon does not collapse simply because a measuring device looked at it. It is only affected if WE look at what the measuring device recorded, or if we set up a data recorder so that we COULD look at some point in the future.
We have senses finely tuned for survival in this world, where our hunter-gatherer ancestors needed to avoid lions and tigers and crocodiles, find food and shelter, seduce mates, nurture offspring, etc. We didn’t evolve needing to interact with things that are measured in angstrom units or Planck lengths, or things at the scale of billions of light years, and so we can’t even begin to see things at those levels. And when you begin to use instruments to measure and report what’s going on at those levela, you might be thankful we don’t see it.
How electrons really behave defies common sense and is difficult to put into words. Electrons are definitely not particles. They aren’t waves in our understanding of that word. Yet they behave somewhat like a particle and somewhat like a wave. So what the heck are electrons? And, as Dr. Quantum asks, what the bleep does an observer have to do with any of that?
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25 Answers
Well I don’t know.
But I’ve been told that electrons are negatively charged sub atomic particles. So what does that mean? To me it means that electrons power transistors. Transistors make our modern world spin in greased grooves now and into the future. Electrons allow our bodies to function. Also basic chemical elements as well as the entire universe would not exist as we know it without elections. In fact you would not likely have black holes without electrons. You have to just love electrons.
Hence both the Heisenberg Uncertainty Principle and the observer effect. I wrapped my head around it by realizing an electron is not a very very tiny bit of matter but a bit of energy, and behaved like a photon, both particle and wave.
“The wave of potentialities of an electron or photon does not collapse simply because a measuring device looked at it.”
That’s not actually true, they do collapse based on the measuring device. Part of the heisenberg uncertainty principle is that any measurement must interact with the observed, because there’s no way to get information without interacting with the object in some way (for example, if you had a plane of glass so clean that light passed through it unaffected, you’d have no way of knowing it’s there until you ran into it). The fact that consciousness exists doesn’t change that, it’s just that it so happens that that’s the viewpoint we’re working from. That’s one of the reasons that quantum computing is so hard to do (though we’re making great strides): error-checking requires a measurement of a given state, and the measurement would kill the quantum effects allowing the computer to function. Doesn’t matter if a person is staring at the error readout or not, the effect still exists (we have gotten around this with some clever work I won’t go into, but it basically obviates the need for external checks).
Now, the second thing with electrons that might make it easier to understand is the fact that they’re not anything particularly special. Which sounds like a stupid thing to say but hear me out. The only reason they seem different is their size. They’re much lighter than any other atomic particle, and thus the effects of quantum mechanics are more pronounced. But everything acts that way to one extent or another. A rather silly but good example from Colin Bruce in the great book Schrodinger’s Rabbits points out that you could, in principle, do the same double-slit experiment by firing frozen chickens through doorways, if you had appropriate amounts of time and good enough measuring devices. The math is the same, it’s just that the scale is different. Everything is a particle and a wave, everything is energy made manifest. Protons and neutrons act as waves, too, it’s just that they’re so much more massive and thus their wavelengths are so much smaller. Everything acts like an electron, everything has wave-particle duality. You could easily tunnel through a wall just like an electron if you had several billion times the current age of the universe to wait. It’s just that we live in the macroscopic world that has allowed us to ignore this fact until recently.
Particle man, particle man…
Electrons are weird because they act like particles when observed, but waves when not observed (WTF?). Honestly, I think electrons have been fucking with us and chuckling the past 100 years
@BhacSsylan As this link explains, (watch it all the way through, the first part is about Young’s experiment) it is not the interaction of a detector that collapses the wave function, it is either directly observing what the detector sees, or recording the data so that it can be observed at a later date. Even stranger, while the detector and recorder collapses the wave function, if you erase the recorded data without ever observing it, the Quantum eraser effect kicks in. The interference pattern reappears. How does that fly with our understanding of causality?
Sorry, I can’t watch videos now, so I can’t comment on that. But I can comment more generally on the eraser effects. It’s a particularly striking but ultimately concordant result of quantum mechanics. If it were really true that the delayed choice effects of a quantum eraser were working backwards in time and influenced by our consciousnesses, we would be able to do things like send messages backwards in time and a quantum computer would be able to hum along just fine with no issue by computational error checking. But it doesn’t actually work that way. While the math is quite difficult (and way above me, I’m just a chemist), it does actually work out that it is the particles, not the viewer, that is causing the effects. Beware drifting into Chopra territory. You may want to have a gander at this article, linked from your link: Demystifying the Delayed Choice Experiments
Again, the math is intense, but the concise conclusion is, from that paper, that “The (well-known) point stated in the introduction was to distinguish correlation from causation. The lesson we draw here is that this very correlation between distant measurements does not feel their relative time ordering: it does not distinguish between future and past. This implies backwards correlation but still precludes backwards causation or any other tension with relativity, effectively demystifying the delayed choice experiments. It is important to note that arriving at our conclusions did not require introducing new physics. We only relied on elementary quantum mechanics: not on novel ‘backwards time’ concepts, nor on any particular interpretation: we only used the Born rule ‘as is’. And it better be so, since a careful quantum optical analysis of any of the delayed choice experiments is in perfect concordance with experimental results – without any auxiliary/new input. Only, these quantum optical analyses are slightly less transparent, and may leave some conceptual issues unclear and confusing. It is precisely this gap that we intended to fill with this note. With the remarks and intuition presented here, there really is no mystery whatsoever in any of the discussed experiments.”
Emphasis mine.
Things used by Schrödinger’s cat to juggle with (or swim in, when the mood dictates).
Human beings are curious, and so your question is poignant.
Nobody really knows what an electron is.
But when they do, it will change nothing. Human beings, if they are acting in accordance with their nature will heroically struggle to achieve their individual existence and happiness. Dictators will still take slaves, heroes will fight and attempt to destroy the dictators. Just like it has always been.
But I am as curious as anybody. I wish I knew.
A lot of people think that the Heisenberg Uncertainty Principle (we cannot know both position and momentum with extreme precision) is simply due to the Observer Effect (we cannot measure a particle without affecting it).
They are not the same.
The HUP is not a result of our technological inability to measure objects with high precision. It is a fundamental property of matter.
An example of this is the Bose-Einstein Condensate, which forms when material are cooled down to just above absolute zero. When atoms are cooled down to this extreme low, they almost stand still. This is where stuff gets weird.
Since we now know the momentum with extreme precision (it is almost zero), the HUP states that we must know almost nothing about the atom’s position. As a result, the atom transforms from a single point into a large probability cloud. The various atoms in the material morph together to form the condensate, which exhibits quantum properties on a large scale.
^^^ You still expect me to believe that you are 17?
You’ve been 16 then for several years, or so it seems?
I must say that while I tried not to imply as much, my answer above may be seen as supporting simply the observer effect, and as @PhiNotPi has said it’s not just that. My answer has to do with whether a consciousness vs a machine makes an observation and the resulting change, which does have to do with the ability to measure without perturbing the system, but that is not the whole story.
Along those lines, this is also tied up with a ‘hidden variable effect’, which is the belief that quantum mechanics would be deterministic if we simply understood the hidden variables better, but from what we currently know that is not the case, and the randomness of the system is an inherent quality of the math, challenging that means abandoning quantum mechanics. Which may happen, but not without a major overthrow of current physics.
Or according to quantum physics, 15, 16 and 17 at the same time perhaps.
@gailcalled don’t envy the poor boy’s youth quite so visibly (or at least wait till he turns 18 to vamp him! Is it hot in here or just me?)
I have no idea what an electron is.
@drhat77: That’s just it. Is he or is he not visible? And if this is your idea of vamping, you ain’t seen nothing yet.
@gailcalled heading towards a cold shower. don’t tell my wife
Damn. Until better evidence comes along, I will remain agnostic about the idea that electrons even exist.
@ETpro don’t look at them too hard, otherwise they may just cease to exist.
This reminds me of the old philosophical dilemma…
If a tree falls in the forest and there is nobody to hear it fall, is it then still something to blame your husband?
If a wife cannot find a way to blame her husband for something (anything), she doesn’t deserve to have him.
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