Mach Memes

Left side: The Mach number - a simple ratio of speed to sound that even undergrads can calculate without crying. Right side: Mach's principle - that bizarre cosmological concept suggesting inertia exists only because of all other matter in the universe. The kind of thing that makes physicists stare at walls for hours questioning reality. Both named after Ernst Mach, who clearly enjoyed watching future generations suffer through his intellectual legacy. Thanks, Ernst.

Physics textbooks: casually asking if you've witnessed objects traveling at 158 times the speed of sound like it's a normal Tuesday activity. For context, Mach 158 is approximately 121,000 mph or 54 kilometers per second . At that speed, a golf ball would circle the Earth in about 12 minutes and have enough kinetic energy to level a small city. The textbook's follow-up question is basically asking "Would you like to experience a thermonuclear explosion with a side of atmospheric reentry burns?" Sure, right after I finish my coffee.