You know the infinitely long tunnel that appears when you look into two mirrors that are pointed at one another? Have you ever noticed that the tunnel becomes more and more green, the deeper you go?
YouTube personality Vsauce has a fascinating new video titled “What Color Is A Mirror?”. In it, Mr. Sauce explains that this is due to the fact that there is no such thing as a perfect mirror (i.e. a mirror that perfectly reflects 100% of light). The fact is, a typical mirror best reflects light in the 510nm range, which we perceive as green light.
Each mirror is a tiny, tiny, tiny bit green — a tint so insignificant that we don’t notice it. However, when you point two mirrors at one another and have them reflect light back and forth, this green tint is magnified until it becomes very noticeable.
Here’s the video in which Vsauce explains the phenomenon (among other things):
This raises the question: doesn’t that mean the mirrors inside DSLR cameras are every-so-slightly green? In other words, objects in the mirror are be less-green than they appear…
Luckily for DSLR users, shots are framed through a couple of mirrors rather than in a mirror tunnel.
Update: The paper that Vsauce references deals entirely with mirror tunnels and mirror color. You can read it here (warning: it’s pretty technical).