system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5, the photoelectric effect, and how light can behave both as a wave and as a particle

If I tried explaining I would go on a long unclear explanation of this phenomena in quantum physics. If someone could explain to me simply what is happening it would be incredible!
gpt
Light behaving like both a wave and a particle is because it is neither of those things. In our macroscopic lives, we can observe waves and particles, but in the very small quantum world things are not exactly like either. They act somewhat like both.   
  
The photoelectric effect occurs when light is absorbed by an atom and causes it to emit ("kick out") an electron. The thing that is surprising about this is that you would think that this would be proportional just to the intensity of the light...."stronger" light, more electrons. But that isn't quite true. It is also proportional to the frequency (color) of the light, and if the light is the wrong color, there is virtually *no* emission.  
  
Einstein explained this by describing how light acts not just like a wave, but also as discrete particles. Some people describe this as the key discovery in kicking off what we now call "quantum physics", where we understand that energy (and matter) is by its nature in small, discrete amounts rather than a continuous range.  And that they act like both particles and waves.
  
Fun fact: Einstein won his Nobel Prize in physics for this discovery of the photoelectric effect. (Technically, for "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect").