This experiment fascinated me ever since I read about it and ultimately made me not pursue a degree in physics on my last year. I could understand majority of quantum mechanics in terms of particles, or photons, but the official explanation that was given to us on the university (of the double slit experiment) was always that it was an electron (photon) manifesting it’s wave properties with it’s minima and maxima. I could never comprehend this, because – after all – what is a wave if not a group of particles? Furthermore, I always knew (as it was verified by the experiment) that in the end, only a single particle hits the projector screen. After you wait long enough, these particles just happen to appear in places that would be explained by the wave theory. However what stuck to me was that only a single particle hits the screen. Therefore, how can we be sure that it is the very same particle that we have started with? Or in case of photon (and laser) are we absolutely sure that the photon that hits the screen has the exact same frequency? (and thus – energy). If not, then it could mean that the electron (photon) that was shot interacted with something, and produced a different photon (electron) which in the end hit the screen, right?
In: Physics
> after all – what is a wave if not a group of particles?
This is a classical view of waves. In QM we cant describe anything as just a particle.
>Therefore, how can we be sure that it is the very same particle that we have started with?
By being careful. We can fire 1 electron, or photon when using light, at a time at the slit and let the results build up over time.
>could mean that the electron (photon) that was shot interacted with something,
This is exactly what is happening. The only part you are missing is the electron(or photon) is interacting with itself. Again by being careful we can be sure there isn’t anything else around for the electron to interact with.
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