Exploring Reflection of Light: What is the Path of an Individual Photon?

[PhilipF]

I have been reading Feynmanns 'QED' and am trying to understand what happens when light is reflected from a surface. I would be grateful if someone could answer the following question. I am not sure which of these views (if any) is correct.
1) When light is reflected from a surface a photon bounces of that surface
2) When light is reflected from a surface a photon is absorbed and another is emitted
3) It is not meaningful to talk about the path of individual photons , they can only be said to exist at the point of detection by some instrument.

 

[Danger]

#2 is correct.

 

[quicknote]

I can provide some insights into the concept of reflection of light and the behavior of individual photons. First, let's start with the basics. Light is a form of electromagnetic radiation that travels in waves, and it can also be described as a stream of particles called photons. These photons have energy and momentum, and they interact with matter in different ways.

Now, when light is reflected from a surface, what happens to the individual photon? The answer is not a simple one, as it depends on the perspective and the level of detail we are looking at. From a macroscopic perspective, we can say that the photon bounces off the surface, following the law of reflection, which states that the angle of incidence (the angle at which the photon hits the surface) is equal to the angle of reflection (the angle at which the photon bounces off). This is similar to how a ball bounces off a wall.

However, from a microscopic perspective, the behavior of individual photons is more complex. According to Feynman's Quantum Electrodynamics (QED), when a photon hits a surface, it interacts with the electrons in the material. This interaction causes the photon to be absorbed and then re-emitted by the electrons. This process happens very quickly and at a subatomic level, making it difficult to observe. So, in a sense, both views 1) and 2) mentioned in the question are correct, depending on the level of detail we are looking at.

Finally, it is true that it is not meaningful to talk about the path of individual photons in the traditional sense. This is because photons do not have a definite trajectory like a physical object, and they can also exhibit wave-like behavior. So, while we can describe the behavior of photons using mathematical models, it is not possible to track the exact path of a single photon.

In conclusion, the behavior of individual photons when light is reflected from a surface is a complex phenomenon that can be understood from different perspectives. Both the bouncing and absorption-emission views have some merit, but ultimately, it is important to remember that photons do not follow the same rules as physical objects and their behavior cannot be fully described in terms of a traditional path.