Do not try this at home!

Mike MacDonald mmacdon at ll.mit.edu
Fri Nov 6 09:55:44 EST 1998



jwill at pacbell.net wrote:

> Minor technical point, unrelated to hearing:
>
> In article <3640DBF3.65587DF8 at ll.mit.edu>,
>   Mike MacDonald <mmacdon at ll.mit.edu> wrote:
>
> > It doesn't come from radar.  I know of no physical mechanism in the human body
> > (other than heating, and most radars use pulses which would minimize heating
> > effects due to the small duty-cycle) which is capable of  detecting radar
> > signals.  In any case, wrapping your head in tinfoil (or placing it in a large
> > metal pot) would reflect the signal and you'd notice the sound vanish
> > immediately.  As some have pointed out, low-frequency fields can penetrate
> > thin conductors.  Radar is not low-frequency.   Wrapping a potato in tinfoil
> > and placing it in your microwave oven should amply demonstrate its (the
> > tinfoil's) lack of transparency.
>
> You probably didn't study the effect of a conductor on the standing
> waves in a microwave oven.   As Eistein once said (paraphrased
> and adapted), "A good explanation should be as simple as possible.
> But no simpler."
>
> If you did the above, you'd be lucky just to blow a fuse.
>

Having re-read my post, I must apologize for the above section.   Aluminum foil is a
near-perfect reflector of microwave radiation (the point I was trying to make) which
makes it the last thing one would want to place in a microwave oven.  There was a
hoax some years back in which a physicist writing for a social-science journal
implied that physical laws are subjective and without rigor.  After he revealed the
hoax, he suggested to those who had believed the paper that if they wanted to prove
the "reality" of gravitation to themselves, they might try stepping out a
third-story window.   Few people would do that, of course.  What I regrettably
failed to consider was that someone might actually place a foil-wrapped potato into
a microwave oven.  I've never tried this myself, but I understand the fireworks
within the oven are pretty impressive.  Again, I apologize for attempting a "stupid
human tricks" approach to making a point.


--
Mike MacDonald, MIT Lincoln Laboratory  mmacdon at ll.mit.edu
** The views expressed here are not those of Lincoln Laboratory. **





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