New theory may explain the ‘music of the meteors’

originally posted by: Bedlam
a reply to: mbkennel

A few big issues- that's a lot of power density- I assume you meant 10E8 W per square meter at the ground. 1 billion Watts per square meter seems a bit much. Hopefully I just misread that.

Yeah, it's 10^-8 of course. (minus eight). 10 nanowatts. Might be higher locally.

Yet, no. Also, and it's filtered through journalists, but they seemed to be claiming they were replicating it in the lab. There's no way to be out of the near field. Propagating EM works differently than bare E or H fields.

Which is why I try to find the original paper source, as I did here. Geophysical Research Letters is a top journal in planetary physics.

originally posted by: mbkennel

Yeah, it's 10^-8 of course.

Sorry - was writing that as I was falling off to sleep. Seemed sort of wacky.

However, pending resolution of that article I read, I still don't believe the guy replicated the sound in the lab. Made a sound with something, sure, but it wasn't a propagating VLF radio wave.

And I've been at Holt when they were radiating over a megawatt, nada. No weird sounds, no sounds coming from my sunglasses or hair etc.

Which is why I try to find the original paper source, as I did here. Geophysical Research Letters is the top journal in planetary physics.

I agree...

The generation and propagation length scale is over planetary size distances because of the wavelengths of course.

...which brings up the next protest. Of course it is. So why do only people under the meteor/aurora hear it? The footprint for an essentially uniform power density should be YUUUGE.

originally posted by: Soylent Green Is People
a reply to: Caver78

It should also be noted that meteors burn up 60 miles up -- so they are AT LEAST 60 miles away from you (if the are right overhead), and possibly 100+ miles from you if it is somewhere between the horizon and right over head.

Therefore, sound could take 4 or 5 minutes to travel 60 miles (and that's assuming a constant density of air between the meteor and you -- which by the way is NOT the case because the air is thinner at altitude and sound would carry more slowly).

So if people really are hearing anything, it isn't sound waves, because how in the world would they know a faint hiss they hear 4 or five minutes after a meteor was from that meteor? That's where this radio wave hypothesis comes into play -- because the radio waves would move at the speed of light, so there would be no noticeable time delay.

However, I think it is much more likely that people are not really hearing a hiss, but just think they are, due to their brain picking up the visual clue of the meteor, and the brain adding a sound that isn't really there.


Edit to add:
mbkennel types up his thoughts much faster than I do.

Sorry if some of my explanation seems to repeat idea he said above, but I just took longer to type and post.

Thanks for this tutorial! I'm sure I'm not the only one who is trying to grasp the material and understand the topic.

Same to you MBKennel!!

...which brings up the next protest. Of course it is. So why do only people under the meteor/aurora hear it? The footprint for an essentially uniform power density should be YUUUGE.

The first thing that struck me about this was usually when you can see the Aurora it is also mind numbingly cold out. Dunno about you but here every winter we get a few brief nights of -20F and on those nights if it's clear out sound "seems" to travel much further. IE I can hear a vehicle MUCH further away out here than I can on a night that the humidity is higher. Wouldn't this also apply partially to the spectrum of sound the human ear is capable of hearing from the Aurora?

The downward angle of hearing, as you said "why do only people under it hear it" could be that as the sound hits the earth, the ground under our feet, its travel is abruptly stopped and were are more standing in the reverb than hearing the original sound wave?

I'm sure this fishing around is painful to you guys who know more, so THANKS!!!

a reply to: Caver78

One of my issues here is that the Geophysical article ascribes the "sound" to an extremely low power VLF radio signal causing mechanical shaking of objects. I don't think you get this with propagating radio waves, nor do I think the power level would produce audible sound if it did, and since the wavelengths of radio waves in the frequencies he discusses are very long, many miles at the low end, you should be able to hear this anywhere in a ring of several hundred miles radius. Yet you don't. More, VLF transmitters with MUCH more local energy density do NOT produce "electrophonic sounds".

I have had two meteor experiences in my life that made real time sound.
The first was when I was very young was a famous large meteor that skipped back out to space.
It was a large day time fireball, that took a fair amount of time to cross the horizon, it essentialy roared and you could feel the heat on your face as it passed.
The other was about 20 years ago, it was dark already and it crackled and there was a sort of "rumble/vibration" you could feel as it passed. At the time I had the impression that the crackling and the "flashy/pulsey" green light it was giving off were some what in time.
When it exploded, likely 100-120 miles down range,
there were two "bangs",one more of a thud just after the flash, then a few seconds later there was the loud bang that shook the fence and i thought it was going to break a window.
Ive never thought about the lack of time lag with the sound as they passed overhead

a reply to: Bedlam

As far as localization---it comes from the ionization in front of the meteor causing a major charge gradient, so that's not everywhere. I guess we'd have to read the paper for the actual model.

But really, random background sounds aren't memorable unless you correlate it with something else, like a sudden bright light at night, and probably when you are in a quiet area of the countryside.

originally posted by: mbkennel
a reply to: Bedlam

As far as localization---it comes from the ionization in front of the meteor causing a major charge gradient, so that's not everywhere. I guess we'd have to read the paper for the actual model.

But the wavelength is so long that if you're proposing it's not a near field effect, it's going to be spread all over the state and beyond, depending on the frequency involved.

However, maybe you're right in reverse on the other thing - it could be a psychoacoustic phenomenon where people are correlating background noise with visual input.

Personally, I'd never notice it, my tendency to hear flashes or rippling lights as sounds would make me ignore real sounds that were similar.