I thought sound required a medium that would support the waves - is there a speed of sound in interstellar space?
Never mind, I looked it up:
Speed of sound in interstellar space is 10 - 100 km/s (as opposed to .34 km/s in air at sea level and 1.5 km/s in water).
Seems like scientists would be more specific unless this one assumed the high end for his reference about it exceeding the speed by several magnitudes.
Caught my eye, too. A big “huh”?
Wiki: “The vacuum of intergalactic space is not devoid of matter, as it contains a few hydrogen atoms per cubic meter. By comparison, the air we breathe contains about 10^25 molecules per cubic meter.”
Not much of a medium to conduct sound, is it?