I have a thought experiment that i need a answer to. In my experiment, I am in a bathroom with a mirror along one wall. I also have a laser that emits a single file line of photons. The laser is attached to the ceiling and emits a line of photons parallel to the mirror. What property of light makes it so i can see the photons in the mirror? A normal laser that doesn't emit just a single file of photons can be seen reflected in a mirror while it's pointed parallel to the mirror. So how is this possible? How do the photons get out of the line if the laser and reflect off the mirror to my retina? How do the photons go in a different direction than the laser is emitting them? I hope i presented my question in a answerable manner, and please excuse my lack of knowledge.