what does it mean to say that light can be modeled as both wave and particle?

Question

explain the implications for scientific theory..

Answer 1

In classical physics, we found that light behaved like both particles and waves. The photo-electric effect, where electrons are bounced off a photosensitive material by photons, is an example of light behaving like particles. This is something like a cue ball (the photon) colliding with the eight ball (the electron).

The split slit experiment, where alternating light and dark rings are cast through two slits upon a flat surface, is an example of light behaving like waves. The dark rings appear where there is destructive interference; the light rings show up where there is constructive interference. These are characteristics of all waves.

With the advent of quantum mechanics, we fundamentally combined the wave and particle concepts by saying light is nothing more or less than waves of particles called photons. Thus, light is something like the molecules of water rippling on the surface of a pond. The molecules are like the photons and the ripples are like the waves of photons traveling through some medium (like air or space).

One of the implications of combining the two modes through quantum mechanics is that we have been able to validate QM over and over again. Light is relatively easy to use in the labs; so it makes an excellent tool for testing various aspects of quantum mechanics. Thus far, QM theory has proved to be remarkably accurate and valid.