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The wavefunction of the electron is “smeared” around the atom, which is not empty. The wave function may be smeared out over space, but that does not mean that

The wavefunction of the electron is “smeared” around the atom, which is not empty. The wave function may be smeared out over space, but that does not mean that there is an electron everywhere. Electrons are never at two places, never has anyone looked and found the same electron at two different places at the same time. What happens if nobody looks is up for debate, whether you think the electron has no position, whether you think it is guided along its path by a pilot wave, whether you think it split into zillions of copies in different universes, or whatever. But the electron or many electrons filling out its entire orbit is not compatible with any of that or any experimental evidence. At least as far as I know, I am not a physicist.

pvg 9y ago
never has anyone looked and found the same electron at two different places at the same time. https://en.wikipedia.org/wiki/Double-slit_experiment https://en.wikipedia.org/wiki/Double-slit_experiment
- danbruc 9y ago
  The photon - or electron or whatever - hits the screen in exactly one spot, not in several and not in any smeared out way.
  - pvg 9y ago
    I think the other comment addresses this somewhat and, of course, there is the endless verbiage online on all levels - you can't really explain the observed phenomena by treating the particle as little ball with a somewhat uncertain location.
krastanov 9y ago
> But the electron or many electrons filling out its entire orbit is not compatible with any of that or any experimental evidence. On the contrary, imagining the electron as a smeared cloud (a complex-valued wave function with a bunch of specific properties), is pretty much the only way to explain chemical bonds. The confusion stems from semantics. Sure, nobody claims that an electron has been detected at two spots simultaneously, not because it does not happen, rather because to say that you need the premise that the electron is a point particle with a position. Sure, it is useful to claim that the electron is a point particle - in plenty of circumstances it does look like one. But modern physics pretty conclusively has demonstrated that it is actually something described by a wave function, that is most certainly smeared over space. I am a physicist, so I will leave the discussion of whether "smeared" is a good word for it to the philosophers and linguists. It is a good enough word for me, when I try to derive properties of atoms.
- danbruc 9y ago
  I am not sure whether or not I want to agree with that, it sounds a bit like the claim that there are fields and not particles, just for single instead of many particle physics.
  - krastanov 9y ago
    The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). To some it sounds unsatisfactory, to others it sounds profound, and yet others are happy to just shut up and use the model to do calculation that just work.
    - danbruc 9y ago
      The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). Sure, but the crucial points is, quantum fields are just mathematical tools, the universe is filled with particles, not with quantum fields stretching across all of spacetime. The fact that it is under some circumstances convenient to mathematically treat a large collection of particles as a quantum field does not make that quantum field a real thing, just as describing the traffic flow on roads with fluid dynamics as a mathematical modeling tool does not mean there actually exists a car field spanning across all the roads. [...] yet others are happy to just shut up and use the model to do calculation that just work. This certainly seems to works in many circumstances, but I think it is not really good enough to treat the point raised in this thread. When you are discussing whether an atom is mostly empty space, you have to be more careful. Just because your mathematical model uses objects that fill the entire atom does not necessarily mean that this is true for the actual atom, it could just be an artifact of your mathematical model.
      - krastanov 9y ago
        I can not argue with you about that, because I consider it more a question for philosophers, not scientists. However, please also accept that for many people (me included) the model of quantum fields is much more real, and the model of point particles is the one that is just a mathematical illusion.

pvg 9y ago

never has anyone looked and found the same electron at two different places at the same time. https://en.wikipedia.org/wiki/Double-slit_experiment https://en.wikipedia.org/wiki/Double-slit_experiment

danbruc 9y ago
The photon - or electron or whatever - hits the screen in exactly one spot, not in several and not in any smeared out way.
- pvg 9y ago
  I think the other comment addresses this somewhat and, of course, there is the endless verbiage online on all levels - you can't really explain the observed phenomena by treating the particle as little ball with a somewhat uncertain location.

krastanov 9y ago

> But the electron or many electrons filling out its entire orbit is not compatible with any of that or any experimental evidence. On the contrary, imagining the electron as a smeared cloud (a complex-valued wave function with a bunch of specific properties), is pretty much the only way to explain chemical bonds. The confusion stems from semantics. Sure, nobody claims that an electron has been detected at two spots simultaneously, not because it does not happen, rather because to say that you need the premise that the electron is a point particle with a position. Sure, it is useful to claim that the electron is a point particle - in plenty of circumstances it does look like one. But modern physics pretty conclusively has demonstrated that it is actually something described by a wave function, that is most certainly smeared over space. I am a physicist, so I will leave the discussion of whether "smeared" is a good word for it to the philosophers and linguists. It is a good enough word for me, when I try to derive properties of atoms.

danbruc 9y ago
I am not sure whether or not I want to agree with that, it sounds a bit like the claim that there are fields and not particles, just for single instead of many particle physics.
- krastanov 9y ago
  The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). To some it sounds unsatisfactory, to others it sounds profound, and yet others are happy to just shut up and use the model to do calculation that just work.
  - danbruc 9y ago
    The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). Sure, but the crucial points is, quantum fields are just mathematical tools, the universe is filled with particles, not with quantum fields stretching across all of spacetime. The fact that it is under some circumstances convenient to mathematically treat a large collection of particles as a quantum field does not make that quantum field a real thing, just as describing the traffic flow on roads with fluid dynamics as a mathematical modeling tool does not mean there actually exists a car field spanning across all the roads. [...] yet others are happy to just shut up and use the model to do calculation that just work. This certainly seems to works in many circumstances, but I think it is not really good enough to treat the point raised in this thread. When you are discussing whether an atom is mostly empty space, you have to be more careful. Just because your mathematical model uses objects that fill the entire atom does not necessarily mean that this is true for the actual atom, it could just be an artifact of your mathematical model.
    - krastanov 9y ago
      I can not argue with you about that, because I consider it more a question for philosophers, not scientists. However, please also accept that for many people (me included) the model of quantum fields is much more real, and the model of point particles is the one that is just a mathematical illusion.