I'm trying to understand quantum physics. I'm pretty familiar with it but I can't decide what counts as observing to cause particle behave (at least when it's about lights). So the question is what do we see with our eye-balls?

  1. We point a laser (or any kind of light source) to the wall. We see its way from point A to B. Do I "see" a particle or a wave?

  2. Let's see an average object. It pretty much looks like their "pieces" a observing that influences their behave. Does this means while we're watching a light it acts like particle in quantum level?

  • $\begingroup$ Isn't it just the energy in light rays that gets detected by our eyes? $\endgroup$ – user3459110 Nov 22 '14 at 17:15
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    $\begingroup$ The answer is "yes". $\endgroup$ – Hot Licks Nov 22 '14 at 23:02
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    $\begingroup$ "We see its way from point A to B" -- We see light reflecting off dust particles in the air. In a vacuum you would not see anything along the path. $\endgroup$ – Jim Garrison Nov 23 '14 at 7:22
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    $\begingroup$ One needs to remember that "waves" and "particles" are just terms we humans must use to "visualize" concepts that our poor brains cannot otherwise comprehend. $\endgroup$ – Hot Licks Nov 23 '14 at 15:27
  • $\begingroup$ We can't "see" particles or waves literally. The sensation of "seeing" is the perception of phenomena and objects by the light they emit or reflect. Light is only a medium of perception regardles of its characterisation as wave or particle. This does not answer your question, I know. $\endgroup$ – Ariser Nov 23 '14 at 21:16

You are seeing particles. However there's more to this than meets the eye so I need to explain exactly what I mean by this.

Light is neither a particle nor a wave. Instead it is a quantum field. As a general rule while light is travelling it appears as a wave, but when the light quantum field is exchanging energy with anything it does so in quanta that appear as particles i.e. photons.

You see because light excites electrons in rhodosin molecules in the cells in your retina. Since this is an energy exchange (from the quantum field to the rhodopsin molecule) the interaction looks like absorption of a photon.

So you are seeing particles.


It would be physically impossible to be able to "see" light as anything other than a particle (photon). The only time photons, or any other subatomic particle for that matter, can be described as a wave is when we are NOT looking at them.


This is misconception that light is some kind of 'mix' of waves and particles. Instead, It actually IS both waves and particles at the same time, you can't separate them from each other. So probably, the answer could be: you see particles as well as waves.

  • $\begingroup$ So you disagree with what @John Rennie said in his answer: "Light is neither a particle nor a wave. Instead it is a quantum field". Can you provide some arguments for your case? (I'm genuinely interested) $\endgroup$ – Marc.2377 Apr 16 '17 at 18:42

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