It's hard to metaphorically put a finger on exactly why "invisible" polymer water balls are so appealing, but what we do know for sure is that we want our literal hands all over them right now and maybe we want to take a bath with them too a little (a lot).
Reddit user BlackBox recently posted a GIF of these wobbly bobbly jiggle balls, and even if you've seen them before—perhaps in the IncredibleScience video above which has a whopping 41 million views—it's still important to stop for a moment and think about the science behind this optical magic.
First off, these balls are, as implied by their name, made of a polymer—a material with a repeating molecular structure (like plastic or even DNA)—that does a super good job of absorbing water. One pound of water beads can absorb up to 50 gallons of water, which is usually the kind of ratio reserved for Homer Simpson and a Squishee machine.
The reason the polymer balls disappear when placed in water is due to the fact that, as Reddit user TheEpicaricacy points out, they develop the same index of refraction as water. This means that lightwaves, which are refracted (or slowed down and thusly bent) in different mediums, treat the water and the watery jiggle balls as essentially the same substance. Both the polymer balls and the water have an index of refraction of 1.333, meaning that light travels 1.333 faster in a vacuum than it does in the balls or the water. And voilá, you have yourself some big disappearing balls.
And now, what you've all really come here for, GIFS of all the jiggling:
What do you think of these disappearing water balls? Do you want to jiggle and bounce them right now and maybe eat them? DO NOT EAT THEM. But do let us know what you think of them in the comments below!