What do empty thoughts look like? According to the artist Gustav Metzger, they look like the weird blobby object above. Metzger hooked up his brain to a robotic sculpting machine that carved away at a piece of Portland Stone based on the stimuli it received from Metzger's EEG readings as he tried to think of nothing at all. Titled "Null Object," the work is now on display at London's Work Gallery.
In other words, this is Gustav Metzger's Stay Puft Marshmallow Man, empirical proof that even when we try our hardest to think of nothing, there's always something going on up there.