Quantum Mechanics: The 2 slit experiment

My beginner's book described this.

If photons or electrons are directed at a sheet with, say, 2 slits each of 1 mm width then on a screen behind, an interference pattern develops. Like water waves interacting - some adding to size and some cancelling whereby a typical 'interference pattern' is formed. This shows electrons acting as waves, not as particles. Apparently electrons have 'duality'. This means they can be in a state of being both a wave and a particle. It seems that this superposition state is natural for them because even after collapsing to a particle (wave function collapse) they can recover their superposition if not interfered with.

My comments:-

The strangeness arises because if you observe the electrons at the slits the interference pattern stops and the electrons act as particles hitting the screen in two patches. This is called wave function collapse. It seems as if human beings have 'powers' untold.

However, the words used can mislead lay people like me. After investigation "Observed" is really 'interacted with". The interaction can be a collision with another particle/ electric field or any number of things including people trying to measure the electron. No special powers are needed. So, particles are chameleons. Ish. It seems that electron duality (having the form of a wave and a particle) is hard to grasp and seems to be presented as if the electron is undecided as to what it is. To me, there is no mystery in that the electron is conditioned by its environment. In superposition it is not a decision awaited it is just a thing with duality.

One thing that does stretch the imagination though is the ability (of a photon say) of a single electron say to go through both slits and produce an interference pattern - but then we have already established it has duality and a wave can do this. Just because we like objects ie solid things, is no reason to get upset about its preference for a waveform on occasion.

An analogy that may be useful (or not) might be that water consists of molecules and loves to form waves when windy or other disturbances. Maybe sand after low tide. I have to think that waveform collapse occurs constantly everywhere and instead of wind, we have Time.

The end of the chapter mentions the 'Copenhagen interpretation'. This says that some things are undecided until they are decided. Seems reasonable to me - unlike the many worlds theory which suggests that the future divides after each intervention (collision or whatever of particles having wave collapse) into 2 universes. This is the same as the Copenhagen interpretation except they add the complication that maybe the wave did not have to collapse and that this would give a different universe. Odd because if it collapsed then that is the way our universe goes. No need to get mystical (?)
This desire to have infinite this and infinite that should be set aside until we really need it. If ever (in endless time, lol)

Now for the next chapter....
 
Last edited:
Sep 11, 2020
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The fascination with electrons began after reading a report about electrons moving faster than light. It seemed that electrons disappeared and reappeared at distances and time periods that meant that they had to move faster than the speed of light which physicists said was impossible. The most logical answer was that it was not the same electron. Vacuum energy appears and disappears all the time. It all had to come from somewhere.The obvious answer was that there was a soup of the building blocks of matter outside of spacetime. Unfortunately we have yet to figure out how to see it. Is it a wave or a particle? Quantum mechanics makes more sense to me if there are actually waves of particles outside of space time that pop in and out when we do a measurement . Outside of spacetime they could instantly be where they need to be, as there is no space between the pieces that fit so they can be there in no time.
 
The obvious answer was that there was a soup of the building blocks of matter outside of spacetime. Unfortunately we have yet to figure out how to see it. Is it a wave or a particle? Quantum mechanics makes more sense to me if there are actually waves of particles outside of space time that pop in and out when we do a measurement . Outside of spacetime they could instantly be where they need to be, as there is no space between the pieces that fit so they can be there in no time.
Or let's equate 'spacetime' with the universe. Time forces the universe through the Quantum landscape interacting as it goes. Like a shockwave passing through embedding space as it expands.
 
So,
One thing that does stretch the imagination though is the ability (of a photon say) of a single electron say to go through both slits and produce an interference pattern - but then we have already established it has duality and a wave can do this. Just because we like objects ie solid things, is no reason to get upset about its preference for a waveform on occasion.
Apologies for replying to my own comments but-

In the 'entanglement' thread the possibility of particles being strings extending from history which in the Quantum World is real - still exists - is considered. This idea gives a common sense reason why an interference pattern might arise as individual particles hit the screen. They are part of a growing band of strings happily acting together even if 'fired' individually.