system
Given the following post, respond as if you're commenting on Reddit:
human
With sunglasses on, one of my computer monitors is almost unaffected, only slightly darker, and the other one turns entirely black. What about monitors or sunglasses makes them react differently?
gpt
Most monitors have a polarization layer on the screen that helps to greatly reduce any glare on the monitor. The effect is that light emitted by the screen itself is also polarized in a certain direction. If you then pass this light through another polarizer, such as polarized sunglasses, then depending on the orientation it may cause the light to be blocked (almost) completely.

The reason the other monitor doesn't have this effect is either because it has no polarization layer or because the direction of its polarization lines up with that of the sunglasses.

You can play with this by rotating your sunglasses (or the monitor, but that's less practical). If both the sunglasses and monitor have a polarization filter, then depending on their respective orientation the light from the monitor will be blocked or let through or anything in between.