For 10 points, name this physicist whose number equals velocity divided by the speed of sound.
For diatomic ideal gases, a quantity named for this man roughly depends on the impact pressure over the static pressure all raised to the one-seventh power. This scientist's son popularized an interferometer that uses two detectors and is co-named for Ludwig Zehnder. This physicist criticized Newton's thought experiment involving a bucket full of water by arguing that rotation is relative to the entire universe, an idea that influenced (*) Einstein. If a quantity named for this man is less than 0.2, then a flow is incompressible. That constant named for this man determines whether or not pressure increases or decreases down a streamline, and equals one for air moving at 343 meters per second. For 10 points, name this physicist whose number equals velocity divided by the speed of sound.
For diatomic ideal gases, a quantity named for this man roughly depends on the impact pressure over the static pressure all raised to the one-seventh power.
Ernst  Mach 