March 24, 2017 at 6:15 pm #76
For the last few months I’ve been working on a little pet project on refraction, trying to explain it similarly to that of Feynman’s explanation of reflection as I’ve had a decent look around and can’t seem to find a reasonable answer as to why (as a photon) light refracts!
Yes it makes sense as far as a wave goes I have absolutely no quarrel with that however I can not seem to convince myself that we can just allow some things to be only explained as waves and some things only as photons and embrace the duality of light.
So this may just a) be just my issue and b) not actually be an issue with a perfectly more reasonable answer however I had fun either way brainstorming everything around my project!
Whilst coming up with a basis to work on, I started by asking myself “what makes particles change direction?”. Fortunately this question only really took a few clicks to answer, that and thanks to the very few correct answers GCSE physics gives.
Newton’s first law of motion states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. Hence this leads me to believe that a force from the boundary of the medium the light is entering exerts a force on the photon to cause it to change direction. Such as a reaction force, however I realised this would be near negligible considering the virtual mass of your typical photon and that since a photon itself doesn’t have a definable size it would most likely not interact with most ions/atoms in the first place of a solid let alone a gas or liquid.
So with that notion out the window I considered how light can be manipulated further afield. Such as around a black hole light can be caught in what’s called an event horizon, where the light falls into this spacetime dip which is so great causing it to never come out. So if denser and “heavier” mediums cause curvature of light than possibly when it goes through one of these mediums like glass it curves in a small dip of spacetime. Now since this is both not my field to say anything about and considering how gargantuan a black hole is comparatively which bends light a glass block seems also negligible.
Now this is where my imagination decides to stretch a little bit for something that can make sense of my conundrum. With limited knowledge and no actual experience in either QED or physics in the real world outside my education and the books I’ve read that was the only thing I could turn to. After reading up about Neil Bohr’s and Richard Feynman’s work on QED, I had an inkling of an idea.
So going back to forces, we understand photons to be carriers of electromagnetism, which leads me to believe that it can interact with other photons or electromagnetic fields from particles.
Using this notion, I’ve tried to outline the change in direction in refraction due to the conservation of momentum and path integrals (to which I will elaborate if it isn’t evident what I mean).
As something of a history lesson in QED, 3 physicists worked together(ish) to finalise the QED theorem; American theoretical physicists Richard Feynman and Julian Schwinger, and Japanese physicist Sin’Ichiro Tomonaga. However arguably more notably Feynman for making the theorem easier for the ‘average Joe’ to understand with his famous Feynman Diagrams.
In his lectures, Feynman outlines the Quantum explanation of reflection. In which there is an infinite number of paths light can take between a source and a detector across a mirror, however the reason we observe a single ray of light is because that path is the most probable hence light is most intense along that path.
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