On Wed, Aug 22, 2007 at 01:08:32PM +1000, Evan Beaver wrote:
> Birds are mostly made of iron aren't they?
Bird do have light-mediated magneto-receptors so the device's claims
aren't impossible but the basic physics make the claim extremely
hard to believe. Magnetic fields drop off steeply with distance.
As I rember first year physics at the claimed 6 metres, the device's
magnetic field will be 6^6 = ~50000 times weaker than it is at 1 metre.
Apart from MRI machines which birds probably don't encounter much,
railway overhead wiring springs to mind as having a strong artificial
magnetic fields. Don't know if birds avoid railway wiring.
The hefty fields around AC power lines unfortunately don't stop bird
collisions. It'd be interesting to know if there was difference in
the collision rate between AC lines (time-varying fields) and DC lines
(static fields).
Andrew Taylor
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