system
Given the following post, respond as if you're commenting on Reddit:
human
If sound can be cancelled by producing another sound-wave in anti-phase, and light is packets of waves, is it possible that light can be cancelled out using anti phase?
gpt
Yes, all waves, including sound and light, experience destructive interference when two coherent waves meet out of phase. This is what leads to optical interference effects such as the swirling colors on soap bubbles, the colors on peacock tails, the color patterns on the bottom of a CD, etc. The reason that you see color patterns when interference happens is because different colors have different wavelengths and experience destructive interference at different points. So at one point on the soap bubble, the green light has the right wavelength so that the reflection of the front surface of the bubble's thin film interferes with the reflection from the back surface of the thing film, destroying the green light, and leaving the red/blue light to reflect back into your eye. 

Note that in wave interference (true for both sound and light), energy is never really destroyed. Rather, energy is redirected by the interference effect to the areas of constructive interference (and/or absorbed by materials and turned into heat).

Also note that unlike sound-cancellation headphones, light cancellation goggles (i.e. sunglasses) don't use wave interference as the mechanism to block light since it is so much easier and practical to use simple absorption. 

UPDATE: As others have wisely noted, mostly only low-end optical filters use simple absorption, whereas high-end filters indeed use the interference that happens between the multiple reflections of the incident light off of the layers of optical coatings.