Isom said:
Hello
Is the interference pattern observable or just mathematical?
Thanks
It is just mathematical. The problem is that there is an implicit assumption that when stripes are seen that look like a mathematical interference pattern that some how it IS an interference pattern.
An interference pattern implies the classical situation of waves in a medium. The waves propagate toward a pair of slits, the waves go through both slits and coming out the other side they tend to interfere with each other according to the angle they make progressing toward the observer screen. So far so good. IF (and only if) your experiment is 1. dealing with waves in a medium, and 2. the medium exists. In such a case the mathematical formula you calculate based upon the wave interference pretty much matches the patterns you observe on your screens.
So classically the original idea was that light was an electromagnetic vibration that traveled though space as a wave. Hence all the optical phenomena made sense. But if light (and electrons) are particles which are simply painting a TV image on the face of a CRT that is in fact CONTROLLED by some kind of wave, we get closer to the truth. So there are particles and there are probably waves too. And the waves seem to control the particle motion because the statistics of the trajectories form the solutions to wave equations. [Yes, it might not be absolutely necessary to have waves to form such solutions but it may be probable.] So how does it all work? Nobody is quite sure.
Now here's where it gets tricky. You do this same experiment with light or electrons and it appears at first glance to give the same results. You shine the beam at the double slit and the "screen" (or detector) shows a mathematical double slit diffraction pattern. So, "problem solved" said physics. But not so fast. If you REALLY start to look closely, you find out that what is traveling to the screen are particles. You can see that they are only going through one slit at a time, and further you can lower the intensity until they are traveling to the screen one at a time. So where are the "waves"? Where is the medium for the waves to wave in? It's not there.
But wait. What about the diffraction pattern we observed so easily? Well careful examination shows that the pattern is made up of a statistical average of great numbers of particle impacts. There is no "wave" making it up. So now we have the problem of how single particles traveling to a double slit somehow ON AVERAGE are guided into a direction such that the statistical average of impacts is IDENTICAL TO a wave interference pattern?
Well, there is no model to explain this so a lot of "hand waving" is used instead. The theory that "works" involves probability waves. What are probability waves and what do they use for a medium? Who knows? The bottom line is that it's all mathematical, but nonetheless does work to predict results. So what exactly provides the "nudges" that move the stream of particles into mimicking on average the solutions to wave interactions? Nobody knows yet.
Now the theory that just looking at something causes "waveform collapse" so the thing suddenly exists is really just so much word salad. And it's arrogant as well. I don't think the universe needs me to look at it in order to exist. However, to really provide a cogent explanation of what is going on, would require a true understanding of just where the "probability waves" come from and how they operate. And that understanding does not exist. In fact it's a wonder that such an oddball theory was invented in the first place and actually fits observed phenomena to the degree it does.
