Vanishing point: the rise of the invisible computer

For decades, computers have got smaller and more powerful, enabling huge scientific progress. But this can't go on for ever. What happens when they stop shrinking?

In 1971, Intel, then an obscure firm in what would only later come to be known as Silicon Valley, released a chip called the 4004. It was the world's first commercially available microprocessor, which meant it sported all the electronic circuits necessary for advanced number-crunching in a single, tiny package. It was a marvel of its time, built from 2,300 tiny transistors, each around 10,000 nanometres (or billionths of a metre) across - about the size of a red blood cell. A transistor is an electronic switch that, by flipping between "on" and "off", provides a physical representation of the 1s and 0s that are the fundamental particles of information.

In 2015 Intel, by then the world's leading chipmaker, with revenues of more than $55bn that year, released its Skylake chips. The firm no longer publishes exact numbers, but the best guess is that they have about 1.5bn-2 bn transistors apiece. Spaced 14 nanometres apart, each is so tiny as to be literally invisible, for they are more than an order of magnitude smaller than the wavelengths of light that humans use to see.

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