The Enigma of Light Reflection in Mirrors

If you've ever pondered why the light in a mirror behaves the way it does, you're not alone. As an experienced optical design engineer with 41 years of experience, this question has been among the most fascinating in the realm of physics. In this article, we'll delve deeper into the complexities of light reflection and explore why it often defies our ability to visualize it.

Understanding Light Reflection

The nature of light and its reflection can be quite challenging to comprehend, especially given that light behaves in ways that are both physically and mathematically complex. When a physicist, such as Richard Feynman, provides an explanation, it typically is rooted in a mathematical description rather than a simple, visual one. Feynman, a renowned physicist and professor at Caltech, often discussed these phenomena in his lectures. For instance, his detailed explanations in his Yale lectures have been invaluable in these areas.

The Complexity of the Interaction Between Photons and Electromagnetic Fields

The interaction between photons and the bound electric fields of atoms within materials is known as "optics." When it comes to reflecting light off a surface, there are two primary factors to consider:

The kinetic electromagnetic (EM) energy content of the photon. The oscillations of the receiving electric field.

These factors determine the kind of optical behavior we observe, which can include reflection, refraction, absorption, diffraction, or polarization. For instance, the amount of kinetic EM energy in the photon and the oscillations of the receiving electric field dictate whether the photon will be reflected, refracted, or absorbed by the material.

Visualizing Photon Behavior

Visualizing the behavior of photons can be quite difficult as they do not follow the same physical laws as objects we are familiar with. In the classic example of a billiard ball bouncing off a table, the interaction is elastic, meaning the balls simply bounce off each other without deforming. However, photons do not interact in this way. Instead, they interact with electromagnetic fields.

Think of a mirror's surface in this context. The surface does not need to be perfectly smooth depending on the kinetic EM energy content of the incoming photons. If the energy level is that of visible light photons, the resulting wavelength will determine the required smoothness of the surface for a coherent image to form. Even powerful microscopes would reveal that what appears smooth to the human eye is actually bumpy with hills and valleys. The billiard ball analogy simply does not apply in this case.

Richard Feynman's Explanations

If you want to deepen your understanding, I highly recommend watching Richard Feynman's lectures on this topic. His mathematical and diagrammatic explanations provide a much clearer picture of the complex processes involved. These lectures are available on YouTube and are a valuable resource for anyone interested in the science of light and optics.

Conclusion

The behavior of light in mirrors is a fascinating but complex subject. While it may seem straightforward, the detailed interactions between photons and the electromagnetic fields of materials can be quite intricate. As an optical design engineer, I encourage you to dive deeper into the subject and explore the mathematical models that describe these phenomena. You may find it is worth the time and effort to get the light inside your head to work, as understanding these concepts can provide a profound appreciation for the physical world we live in.