The Most Complex System in the Universe

The human brain consists of about 86 billion neurons, which are interconnected through synapses and form a neural network. Each neuron receives input from approximately 10,000 other neurons and outputs to about 10,000 other neurons. The number of connections per neuron varies greatly, leading to a broad distribution. The total number of synaptic connections is estimated to be around one quadrillion. Only about one in 10 million theoretically possible connections is actually realized. The exact number of possible connectomes, which represent the totality of all connections in an organism’s nervous system, is difficult to calculate. However, for simplicity’s sake, if we assume that each connection is binary, we already get the absurdly high number of \({{2^{10}}^{22}}\) . However, it is unlikely that each of these connections leads to a powerful and viable nervous system. Assuming that each neuron is either active or inactive, there are purely combinatorially  \({{2^{10}}^{11}}\) . different activation patterns per millisecond. Since it is assumed that the experienced present lasts about three seconds, a sequence of 3000 of these patterns roughly corresponds to a mental state. The number of possible mental states is so large that it cannot be put into words, let alone grasped. The complexity of the human brain is thus unsurpassed.