As I commented on a previous article of this series, everything gets clear when you understand that all the massless carriers we picture as travelling through the universe at the speed of light don't experience any spacetime intervals at all.
What we picture as emission-flight-absorption processes get "compressed" into a blink of existence for them. Any distance gets reduced to a point. Any duration to an instant. They can't "evolve" or "choose a path" because they don't know what time is. They know nothing about different times and places, because they literally don't have the time to move or change. For them, emission and absorption is one and the same thing, taking place at once. Their complete existence is just an instantaneous point-like event that simply "happens".
Seeing what happens from their perspective can help explaining the Quantum Eraser and the Delayed Choice experiment results.
In fact, it helps explaining all the puzzling behaviour that plagues Quantum Mechanics (nondeterminism, wave/particle duality, wave function collapse, Bell’s theorem, faster than light communication, Scrhödinger’s cat experiment, Many-worlds interpretation, double-slit experiment…):
Any massless carrier that pops into reality is a "collapsed" wave function already, because it is the whole history of conditions that made it appear at our detector.
The history of a massless quantum can be told only after detection, so the future you talk about is, in fact, always in the past.
This is the way they can know there's a beam-splitter in their future. They feel all the conditions of the journey at once. What we see as "spooky action at a distance" is "action at spooky distance" to them.
Massless carriers are only real at detection, when they fulfill an energy or information exchange between two matter particles. We picture this interaction as a process, but this view is an artifact caused by our spacetime perspective for what happens in the universe. We always experience a distortion of the true instant action/reaction events that really take place in the universe.
The true reality of any massless carrrier detected is the instant point-like existence it experiences, where every condition that contributed to its development happened at once.
