What is the nature of light – is it a particle or a wave?

Question

This question has perplexed scientists for centuries and led to the development of quantum mechanics. Historically, debates revolved around whether light behaved like a particle (as suggested by Isaac Newton) or a wave (as argued by Christiaan Huygens). The breakthrough came with the understanding that light exhibits properties of both particles and waves, a concept known as wave-particle duality. Experiments like the double-slit experiment demonstrated that light can show interference patterns (a wave property) but also can be quantized into photons (a particle property). This dual nature of light is a cornerstone of quantum physics and has profound implications for our understanding of the fundamental nature of reality.

Answer 1

This question is frequently asked almost daily (it seems) on online physics forums. The reason why it keeps coming up is that humans are not able to form an adequate model for light. One model might be "particle". Well, yes, but that doesn't explain diffraction. The model might be "wave". OK, I can understand diffraction that way, but I don't see how it can explain the fact that interactions occur one at a time, and in specific locations. So what am I to think? The problem is that light is neither. It is something altogether different, something that has no analogue in everyday experience. And that is indeed a problem. Our brains evolved in an environment of everyday phenomena. Our consciousness has formed interpretations of observations. It doesn't know what to do with pheneomena that it has never experienced, and in the case of the true nature of light, can't. The best our brains can do is "Sometimes it looks like a wave, sometimes a particle depending on how the observation is done." Physics has a mathematical description of light. Actually, more than one description. They all turn out to be equivalent. Ambiguity about its nature exists even in our detailed theories. What we usually do is what everyone else does: sometimes one, sometimes the other. But sometimes we need something closer to the actual thing. In those cases, alternate interpretations are used! Something other than a wave or particle. To wit: "a one-quantum exitation of the quantum electromagnetic field that pervades space."