Feynman on Reflection: Exploring Time & Direction

In summary, Feynman reviews the theory of reflection and its application to various situations. He discusses how the properties of the reflecting surface come into play, and how they can affect the transmission, reflection, and absorption of light.
  • #1
Saw
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I have been reading the explanation of reflection that Feynman provides in The strange theory of light and matter.

There are two things I do not understand:

a) How does he choose the directions of the little arrows below the diagram? I understand that each path is different in that it takes more or less time to get to the target (the detector). But on which grounds does he associate to this magnitude (time) one or another spatial direction for the arrows?

b) It seems as if the explanation applied regardless the nature of the reflecting surface, i.e., whether it is specular (a mirror) or not. But the fact is that depending on that factor the detector at point P will actually see or not a reflection of the object at point S...
 
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  • #2
Saw said:
a) How does he choose the directions of the little arrows below the diagram? I understand that each path is different in that it takes more or less time to get to the target (the detector). But on which grounds does he associate to this magnitude (time) one or another spatial direction for the arrows?
They all start at the source pointing in the same (arbitrary) direction, and they all rotate at a constant speed like the hands of a clock, so the direction they're pointing after traveling for a given distance and hence given time is completely determined.

b) It seems as if the explanation applied regardless the nature of the reflecting surface, i.e., whether it is specular (a mirror) or not. But the fact is that depending on that factor the detector at point P will actually see or not a reflection of the object at point S...
The properties of the reflecting surface come into the picture through the "shrink and turn" behavior of the interaction at the surface; differences here will affect the transmission, reflection, and absorption of the incident light.
 
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  • #3
Nugatory said:
They all start at the source pointing in the same (arbitrary) direction, and they all rotate at a constant speed like the hands of a clock, so the direction they're pointing after traveling for a given distance and hence given time is completely determined.

Thanks. That is very clear.

Nugatory said:
The properties of the reflecting surface come into the picture through the "shrink and turn" behavior of the interaction at the surface; differences here will affect the transmission, reflection, and absorption of the incident light.

More thanks. I was reading an extract and hence missing that part of the explanation. Will retake the full text now and try to understand...
 

1. What is Feynman's theory of reflection?

Feynman's theory of reflection is based on the idea that all electromagnetic radiation, including light, travels in both directions in time. He proposed that when light reflects off of a surface, the reflected light is actually the same light wave going back in time.

2. How does Feynman's theory of reflection explain the direction of light?

Feynman's theory explains that the direction of light is determined by the way in which it interacts with matter. When light hits a surface, it is absorbed and then re-emitted in a different direction. This process occurs in both directions in time, resulting in the direction of light that we observe.

3. Why is Feynman's theory of reflection important in physics?

Feynman's theory of reflection has been used to explain various phenomena in physics, such as the behavior of electrons in a magnetic field and the movement of particles in quantum mechanics. It also provides a deeper understanding of the fundamental nature of light and its interactions with matter.

4. How did Feynman develop his theory of reflection?

Feynman's theory of reflection was developed through his work on quantum electrodynamics, which is a theory that describes how light and matter interact at the subatomic level. He also drew inspiration from the concept of time symmetry in physics, which suggests that the laws of physics remain the same in both forward and backward directions in time.

5. What are the implications of Feynman's theory of reflection?

Feynman's theory has sparked debates and further research in the field of physics, particularly in the study of time and causality. It also challenges our conventional understanding of the arrow of time and raises questions about the nature of reality. Additionally, it has practical applications in technology, such as in the development of new materials and devices for manipulating light.

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