The nature of light can indeed be described by wave-particle duality, and it can exhibit both wave-like and particle-like behaviors depending on the experimental setup or observation. This can sometimes lead to the perception of light behaving as an "obvious wave" or a "not-obvious wave."
In classical physics, light is often described as an electromagnetic wave, characterized by properties such as wavelength, frequency, and amplitude. These wave characteristics explain phenomena such as interference, diffraction, and polarization, which are typically associated with waves.
However, in the early 20th century, experiments such as the photoelectric effect and the Compton scattering revealed that light also exhibited particle-like behavior. This led to the development of quantum mechanics, which introduced the concept of photons as discrete packets of energy. Photons are considered the fundamental particles of light and can be thought of as quantized excitations of the electromagnetic field.
Quantum field theory (QFT) provides a theoretical framework that combines quantum mechanics and special relativity to describe the behavior of particles, including photons. According to QFT, particles, including photons, are manifestations of quantum fields. These fields permeate all of space, and particles are understood as excitations or oscillations in these fields.
So, is light fundamentally a wave or a particle? It's important to note that light does not conform to our everyday classical intuitions. Light is best described as an entity that exhibits both wave-like and particle-like characteristics, depending on the context of observation or experiment. In certain situations, light can be described more easily using wave concepts, while in others, particle concepts are more appropriate. Both descriptions are essential to fully understand the behavior of light.