And then there’s your brain. Three pounds of the most complex
material we’ve discovered in the universe. This is the mission
control center that drives the whole operation, gathering
dispatches through small portals in the armored bunker of the
skull. Your brain is built of cells called neurons and
glia—hundreds of billions of them. Each one of these cells is as
complicated as a city. And each one contains the entire human
genome and traffics billions of molecules in intricate
economies. Each cell sends electrical pulses to other cells, up
to hundreds of times per second. If you represented each of
these trillions and trillions of pulses in your brain by a
single photon of light, the combined output would be blinding.
The cells are connected to one another in a network of such
staggering complexity that it bankrupts human language and
necessitates new strains of mathematics. A typical neuron makes
about ten thousand connections to neighboring neurons. Given the
billions of neurons, this means there are as man