What is the purpose of these other than making me want to touch them and own them.... Now I want to have a bath with them.
I don't know about it's scientific applications but it'd make one hell of a prop to fuck with people.
Basically the polymer balls have the same (or really similar) refractive index as water so they can't be discerned. I've seen people use it to make things appear suspended in water by lying it on a bed of these balls and then filling it up with water so it seams to be floating on it's own.
What kinda of witch craft is this? I went to fill my wife's bath with them and watch her surprise when she gets in.
I've seen a lot of gifs with polymer water balls and water... but this is the first time I've wondered what it would be like to swim with a pool filled with them.
There are two properties necessary for something to be invisible:
First, it must be transparent (and colorless, I suppose).
Next, it must have the same index of refraction as the medium that it is in.
This is why glass is transparent, but it's not invisible in air. You can see the difference in refraction as light passes through it differently than the air around it.
These balls have the same index of refraction as the water, therefore, in the water, they are invisible.
You can do the same thing with pyrex glass and canola oil. [You can check out a good example of that in this video.](https://www.youtube.com/watch?v=9Tj2KMZhfoc