To date, there is no experimental evidence that definitively proves that light is neither a wave nor a particle. The wave-particle duality of light is a fundamental concept in quantum mechanics and has been extensively supported by numerous experiments and observations.
Various experiments have demonstrated the wave-like behavior of light, such as interference and diffraction patterns. For example, the famous double-slit experiment shows that light exhibits interference patterns similar to other types of waves. This experiment provides strong evidence for the wave nature of light.
On the other hand, there are also experiments that demonstrate the particle-like behavior of light. The photoelectric effect, which I mentioned earlier, is one such experiment. It shows that light can transfer discrete amounts of energy (quanta) to electrons, supporting the idea that light consists of particles called photons.
Additionally, experiments like the Compton scattering and the observation of the photon's momentum in the momentum-space wave function also provide evidence for the particle nature of light.
While these experiments and observations strongly support the wave-particle duality of light, it's important to note that quantum mechanics provides a mathematical framework to describe and predict the behavior of light and other particles. The wave-particle duality is a fundamental aspect of this framework and has been validated by numerous experiments, but it's also possible that our current understanding may evolve or be refined as scientific knowledge advances further.