# Photons That Hit Tilted Glass

Individual photons directed at tilted glass have an option of being reflected or going through.  They can’t do both because they can’t be divided, or so we are told.  Yet some experiments seem to imply that they sometimes take both paths unless a detector is in place.

Tilted glass acts like a sort of beam splitter.  It either goes through or bounces off  (or sometimes absorbed).

QED can easily compute the probability dependent on the angle.  Some go through and some reflect and the angle makes the difference.  You can adjust the angle to get a 50-50 chance of reflect or go through.

If you use other beam splitters to put the two beams back together you can get an interference pattern, not unlike the one depicted in the double slit experiment.   The beam goes both ways, but one path is longer and so when they come back together, they interfere with each other.

However, if you turn the light down so only one photon at a time goes through you still see the same effect, implying the photons go both ways.   If you leave the single-photon-at-a-time beam on long enough and have a good film in an exceptionally dark room, the outcome will be a well defined interference pattern.

How can single photons being emitted minutes apart interfere with each other?   How can a photon that can only go one way or the other interfere with itself?   QED cannot explain this quantum weirdness for single photons.  It can predict the pattern but cannot explain it.  Every indication is that when no detectors are present, the individual photons somehow split.

There are some very sophisticated delayed choice experiments involving beam splitters.  There are super fast detectors that can be switched into the photon beam after it goes through the splitter. In other words, spit a photon at the splitter, calculate when it reaches it (about 1 nanosecond per foot of travel) and then switch the detector into the path behind the splitter.

The idea is to try to trick the photon into “thinking” there is no detector so it is ok to split, then turning on the detector at the last moment and try to catch the photon doing something it is not supposed to do, breaking laws along the way.  If it arrived at a detector in the reflected path and was also seen by the detector behind the splitter, some law has been broken and the mystery solved – figure out a new law. You do this randomly. If the photon goes both ways, it can be caught by the detectors.   It never does.

The physics says that if you try to make the measurement, it will disturb the experiment. And so every test seems to verify that fact. Whenever a detector is present there is no interference pattern. Whenever the detector is absent, the pattern reappears.

There is an argument that the photon must go through the glass whole since the photons transmitted through the glass are actually retransmissions within the glass, not the same photon that impacts it.  That argument then says that the other path has to either have had no photon or a whole one also (creation of energy not allowed).   It also says that the photon must retain a whole packet of energy.   Yet single photons seem to interfere with each other.  QED cannot explain why.   I hope to do so.

Next:  Entangled Particles

### One response to “Quantum Weirdness for Tilted Glass”

1. I removed two comments by OlderDan here at his request.