Q&A: Quantum Theory
Quantum Theory
Question
I’m reading the book The Science of Freedom, and I didn’t understand what makes an electron different from just an ordinary wave.
Why is it only with regard to the electron that you can’t check where it will be, whereas with another wave you can?
Is it because the electron can also behave like a particle? After all, if you don’t check it with a detector, it behaves like a wave, so in a situation where it isn’t checked by a detector, can’t you know its location like any other wave?
I’d appreciate an explanation.
Answer
In this respect, there is no fundamental difference between an electron and a photon. Both behave as particles or as waves, depending on the measurement setup. The position of a wave is, by definition, not defined. Position is a property of a particle. The question is whether the photon (the electromagnetic wave) or the electron behaves like a wave (in which case it has no position) or like a particle (in which case it does).
Discussion on Answer
Hello Israel.
If you want to learn about quantum theory, that requires study, or at least reading popular material. I can’t give a course in quantum mechanics here.
A. A pure wave has no position, not even on average. It has no position at all. Its glory fills the whole world. If there is an average position, that means our object is not a pure wave but something in between.
B. We can know position precisely, provided that the object is in a particle state. But then you do not know the velocity. And vice versa. With macroscopic bodies, you can know the position precisely even though they are made up of electrons, because of the law of large numbers (just as when rolling a die, you have no way of knowing what will come up, but if you roll billions of times, you know exactly what you’ll get).
A. So the position of a light wave also isn’t really defined ontologically? Is it also defined by us only in some average sense?
B. What exactly does quantum theory leave us with that we know completely and not only on average, if everything in our world is made up of electrons?