1pSec Jitter

magnetoencephalography (MEG), functional brain imaging, by measuring the magnetic field form active neurons with squids. Stef

Ok, that *is* a bit more high-tech then recording and playing a bit of music, I guess :) Interesting technology !

Poor squids!

I didn't know that Radboud University was collaborating in the gravity wave detector experiments ....

-- Bill Sloman, Nijmegen (even if I'm in Melbourne, Australia at the moment).

Working for Peter Hagoort?

I think that's Leiden, we're just looking for brain waves. Stef

Heavy thoughts ?

No, at the ID Stef

I'd think that when you get to a rocket launch or a large bomb blast, you probably won't need to worry too much about preamplifying the signal... ;-)

Cheers! Rich

Stef probably means SQUIDs. ;-)

Cheers! Rich

It'd be interesting to do an experiment where you sense magnetic fields in the body during emotional stimulation - i.e., like watching a good movie, or listening to some good music, or picking a fight...

Cheers! Rich

All shock waves are supersonic. That's why it's a shock wave and not an ordinary sound wave. There's a big increase in entropy in its wake, too.

Cheers,

Phil Hobbs

Years ago, I saw a satellite video of Mt. St. Helens going off, and it sent out what must have been a shock wave all the way to the next-door states. In the vid, it happened in seconds, but I have no idea what the time-scale was compared to real-time. But it looked like the sort of condensation wave that you see with shock waves. I've done a little searching, but haven't really found out anything about it, and I guess MSH is pretty much old news these days.

Thanks, Rich

Then you'd have to buy the amp and speaker to reproduce the recording!

Tim.

"ID" ? The Donders Centre does have an MEG

but I guess you'd have to be tied up to the Radboud hospital

but none of the departments listed there seem to qualify as "ID"

Is a supersonic shockwave the explanation of the effect one sometimes notices with a nearby lightning strike: see the flash, & hear almost simultaneously a sharp crack, like a stick snapping. A second or so later, comes the boom. So that crack must have been supersonic?

Did the "sharp crack" come out of your radio?

In article , Rich Grise wrote: [...]

If you are measuring the field in the body, you have to insert the magnetometer. I don't think we'd hear the music over the "OUCH".

BTW: The heart pumping makes some magnetic noise you'd have to filter out before you could start looking for other stuff.

Much simpler explanation. The speed of sound varies with frequency.

Or more likely that the audio attenuation is frequency (and temperature dependant).

If you have a lightning that hits close to you, it might still be 1-2 km long. You will hear the local hit immediately with all high frequency components present.

However, the sound from the tail of the lightning will arrive 6 seconds later with all high frequency components attenuated and you will just hear the rumble.

Paul