This one's for scientists

I didn't get this until it was explained to me, but if you have a scientific mind, you might get it. Speaking of not getting it, the thing I like about this drawing the most is it's the first cartoon I've drawn after finally figuring out how to work with transparencies and gradients in Photoshop. Adobe has some incredible software, but I find their manuals sometimes to be extremely hard to follow and understand. Thank you for letting me vent.