Definition
Plain language
How fast something is moving compared to the speed of sound — Mach 10 means ten times the speed of sound.
As stated in the literature
The ratio of an object's speed to the local speed of sound; values above 1 are supersonic and above ~5 hypersonic, as in the Apollo Mach-10 re-entry CFD case study.
Also called: Mach 10, Mach-10, Mach ten
Why it matters: It tells engineers which physical effects dominate at a given speed, since flight below, at, and far above the speed of sound behaves very differently.
For example, a jet flying at Mach 2 is moving twice as fast as sound travels through the surrounding air.
Heard on the show
“Someone hands an AI system a scanned NASA report from nineteen-sixty-eight — a post-flight aerodynamics study of the Apollo command module re-entering at Mach ten.”Episode 042 — An Agentic Scientific Computing System That Actually Remembers What It Learns