Does Light Behave Differently Observed?

When a quantum "observer" is watching Quantum mechanics states that particles can also behave as waves. ... Once an observer begins to watch the particles going through the openings, the picture changes dramatically: if a particle can be seen going through one opening, then it's clear it didn't go through another.

Does light change when observed?

To be clear, having observed something doesn't change anything, but the nature of how something is observed is what is causing the observer effect. So in short, the equipment we use is perfectly capable of distorting our results, but we can expect a baseline of error simply by observing it in the first place.

Does matter change when observed?

While the effects of observation are often negligible, the object still experiences a change. This effect can be found in many domains of physics, but can usually be reduced to insignificance by using different instruments or observation techniques.