I Feynman's summing arrows for photon amplitudes applied to LIGO?

[Spinnor]

In Feynman's The Strange Theory of Light and Matter the simple technique for calculating quantum amplitudes for simple optical phenomenon by adding arrows is given. Could that same technique in principle be used to calculate the amplitude for a photon to arrive at the detector port of the LIGO interferometer? Because light gets stored in Fabry-Perot interferometers and also recycled there are an infinite number of possible paths to the detector and all paths need to be added?

With LIGO adjusted for a detector null can you just argue that for every path to the detector by the left arm there is by symmetry an identical path to the detector by the right arm with opposite phase, all paths must pair off and add to zero amplitude?

Thanks for any help.

 

[weirdoguy]

the simple technique for calculating quantum amplitudes for simple optical phenomenon by adding arrows is given

But is this technique something different than just a graphical dumb-down representation of what we're actually doing, that is, adding complex amplitudes?

 

[Spinnor]

But is this technique something different than just a graphical dumb-down representation of what we're actually doing, that is, adding complex amplitudes?

But is this technique something different than just a graphical dumb-down representation of what we're actually doing, that is, adding complex amplitudes?

I don't think it is, I think he represents this technique as basis of quantum electrodynamics but to be sure I would have to watch his Auckland lectures again.

 

[weirdoguy]

I think he represents this technique as basis of quantum electrodynamics

Ok, but in QED we either work with Feynman diagrams, or with path integrals. "The Strange Theory of Light and Matter" is a pop-sci book in which he presents a layman-friendly* version of the latter technique, or mixture of both.


*Which for me wasn't friendly at all xD And I read this book after passing classes on QED, QFT, and operator methods in QFT. I don't know, there is something about Feynmans way of lecturing that I don't like and it makes it hard to read everything. I'm not that big fan of "Feynmans lectures" either...

 

[Spinnor]

But is this technique something different than just a graphical dumb-down representation of what we're actually doing, that is, adding complex amplitudes?

Ok, but in QED we either work with Feynman diagrams, or with path integrals. "The Strange Theory of Light and Matter" is a pop-sci book in which he presents a layman-friendly* version of the latter technique, or mixture of both.


*Which for me wasn't friendly at all xD And I read this book after passing classes on QED, QFT, and operator methods in QFT. I don't know, there is something about Feynmans way of lecturing that I don't like and it makes it hard to read everything. I'm not that big fan of "Feynmans lectures" either...

I think most of his students that sat through the Feynman lectures on physics would agree with you, I think he points this out in the last lecture?

 

[Herman Trivilino]

I'm not that big [a] fan of "Feynmans lectures" either...

That seems almost like sacrilege in the physics teaching profession, but there has been a fair amount of professional criticism to support it. I remember reading an article in that vein many years ago, probably in TPT although it may have been in Physics Today or AJP. I believe the author was present in the early 1960's at Cal Tech when Feynman did his now-famous "experiment" teaching the freshman class using that series of books.

As the semester progressed there were fewer and fewer students present in the lecture hall, and more and more professors! It was a "view from above" and a grand one at that. But the novice is the intended audience, and the purpose is not to impress them, but to teach them. While certainly well-intentioned, Feynman missed the mark. And when he agreed to perform this "experiment" it was under the condition that he do it only once. I think the appeal of the "Feynman Lectures in Physics" over these many decades has been largely driven by professional physicists who see the series as a neat way to present the subject. So it's a nice theory, but it fails experimental verification.

Edit: IIRC even Feynman himself felt that his "experiment" in teaching the freshman sequence had been a failure. And keep in mind that he did it at Cal Tech where of course the caliber of student is well above average,