Listening to the Radiolab Bit Flip episode. If you haven’t listened, then you really should first.
Cosmic rays bombard the Earth. Electrical engineers are finding that these rays can trigger an electrode in a computer chip. The electrodes are bits. The cosmic rays changing a bit is a bit flip. Almost all the time these flips are benign. The wrong flip, though, can cause out of control behavior in automated systems.
Think the Toyota sudden unexpected acceleration or the Boeing 737-MAX’s autopilot dropping the plane a thousand feet. As electrical engineers discover these behaviors, they are building in redundancies. Instead of depending on a single sensor, there will be multiple and the computer will act on the majority, aka a quorum.
The episode didn’t say this, but it reminded me of the Boeing 737-MAX issue where the planes had a single pitch sensor light unless a buyer opted for the multi-sensor package with a light saying the two sensors disagreed. Given what is known about bit flips, I would think it would be typical airplane safety to have these redundancies built into an autopilot.
Now, I don’t expect microprocessor quorums everywhere. There will be too many sensors to affordably do this everywhere. But, I do expect them in systems designed to preserve human life.
From Micro Quorums published June 26, 2019 at 07:22AM.