Photo of the invisible.

On the photo my friend Nick.

I made few photos regarding this assignment because I couldn't decide. At first I made a picture of a glass filled with water but I felt as it was not enough. I chose this one because it shows happiness. It's a feeling, which is abstract and is not a physical object. You can't see happiness as a literal object. Smile and eyes only express happiness but how does it look like? Is it 5ft tall, is it as big as a building? Is it a hormone? Is it a set  of cells in the brain?