Science

So for the new study, scientists at MIT set out to investigate what might be happening. After a few basic experiments, they suspected that light itself was causing the excess evaporation. The idea is surprising because water doesn’t really absorb light – hence why you can see through it to a decent depth if it’s clean.

To really check their hypothesis, the scientists placed a hydrogel sample in a container on a scale, exposed it to different wavelengths of light in sequence, and measured the amount of mass it lost over time to evaporation. The equipment was carefully controlled and the lights shielded to prevent any heat being introduced to the system and messing with the results.

One possibility: The hydrogel is absorbing the light and emitting it as heat to the water thus increasing the evaporation.