Sound (moving faster than the speed of)

Cecil's Columns/Staff Reports
1

This is comment on Cecil’s column.

Ok, here’s what I want to know…

I drive my convertable at mach 1.1. Sound from my rear speakers is carried away from me and I don’t hear it, right? Cause I’m going faster than the air can propogate it.

Ok, so let’s say it’s 1:00pm. I, driving mach 1.1, blast someone saying the word “One!” from my stereo. I keep driving.

Then, one minute later, I blast someone saying the word “Two!” from the speakers. One minute later. . .“Three!” One minute later, I stop.

Would would I hear?

Since, at 1:01pm, I had out distanced the sound of the “One!” and then made the “Two!” sound, wouldn’t the “Two!” arrive before the “One!” Ditto the “Three!”

Also, technically, since at each instant I was outdistancing the sound of my speakers, wouldn’t I hear whatever I had been listening to backwards? as each sound was spit out of my speakers after and therefore ahead of the earlier sound?

2

In an idealized case, I think that you’re actually right on this. In any practical situation, though, you’re going to have enough other noise that you won’t be able to distinguish the radio at all.

3

You’d hear the sound backwards, but only after you’ve slowed down for the waves to catch up to you. Now just a few technical details to be solved, and a whole generation of kids with only CD players can hear The Beatles say “turn me on dead man.”