Electron flow. Computer model of electron flow in a 2-dimensional electrical landscape. The pattern observed depends upon both the initial conditions and the electric potential. The electrons enter at bottom left and spread out over the landscape. The tracks vary from dark (few electrons) to bright (many electrons). The electric potential can be considered the landscape's shape: its main slope (rising, bottom to top) has local bumps or hills (such as atomic nuclei). The main slope slows the incoming electrons, which fall to lower right. The hills at upper centre (holes) are revealed as slow electrons flow round them. This model was created as an artwork by Professor Eric Heller.