Magic smoke

From Wikipedia, the free encyclopedia

Magic smoke being released

A computer chip rendered useless after the magic smoke escaped through a hole blown in the top.

"Blue smoke" redirects here. For the nickname for aerogels, see Aerogel.

The magic smoke (also called blue smoke or magic blue smoke, and sometimes prefixed with the definite article) theory is a running in-joke that originated among electrical engineers and technicians, and has more recently been adopted by computer programmers. The magic smoke hypothesis is based on the empirical observation that any microchip will stop working if heat or extreme electrical current leads to the chip's producing smoke.

According to the theory, the factory puts a little bit of magic blue smoke in every electronic component — in each integrated circuit, resistor, transistor, and so forth — and it is this smoke which makes the device work. The humorous proof of the theory is that once the magic smoke has been released, the device no longer works. The smoke must therefore have been essential to the device's function.

It is often noted that once you let the magic smoke out, it can no longer be put back in. In some variations, it is alleged that the major microchip production companies (especially the large microprocessor manufacturers) are involved in a conspiracy to keep the true nature of their products under wraps.^[1]

This has led to use of the phrase "escaping of blue smoke" as a euphemism for the destruction of a processor (or other integrated circuit) by overheating. When a device is powered on for the first time, it is often called a "smoke test".

A variant on the magic smoke theory is the idea that the magic smoke also travels through wires, and in the event that wires get too hot, they too will leak some magic smoke, again making the circuit no longer work.