Re: [GBlist] Microwaves - sorta off topic

[billc_lists@greenbuilder.com]

marilyn wrote:

>A few days ago there was some comment about using a fluorescent bulb
>for seeing if your microwave oven was leaking.  I passed this tip on to
>some women friends, who now wonder if microwaves bend or bounce.
>Specifically if your microwave oven was leaking at the back, how far
>back will they go, will they 'bounce' off a wall behind and come back at
>whoever is in front, or do they just kind of float around and go
>everywhere?  Do they 'wear out' after a certain distance or do they make
>the whole room/house unsafe?
>From now on, everyone on the list will be fully aware of my total
>ignorance of things scientific <G> Grade 12 science class was about 40
>yrs ago.
>

Well, I only have to go half the distance, back to my undergrad 
degree in Physics.  Let's see what I can remember.

Yes, microwaves can bounce.  They can bend too, from the 
gravitational force near a very massive object, but black holes (of 
that sort) are very rarely found in the typical kitchen.

The amount of "bounce" or reflection will depend upon the properties 
of the material that they're hitting.  Many metals tend to reflect 
radiation - that's why you don't wrap your potato in aluminum foil 
when you put it in the microwave... the radiation would be reflected 
off, and your potato would still be cold and hard.

Lead, on the other hand, is pretty good at attenuating radiation 
(absorbing or "wearing out", in your wording).  The glass on your 
computer monitor (assuming a non-LCD type) has lead in it to absorb 
stray radiation and keep it from cooking your brain and various other 
sensitive body parts.  That's why the monitors are so dang heavy.

Other materials vary in their ability to absorb or reflect radiation. 
And it depends upon the wavelength of the radiation, too.  Some 
wavelengths will pass right through solid objects (think x-rays) and 
others will not (think visible light).  In fact, if you think about 
the x-ray example, you can see some materials pass them through 
better (the fleshy parts) and others tend to absorb more (the bony 
parts).

Generally, microwave ovens are tuned to a particular wavelength that 
makes water molecules vibrate.  This vibration of the water is known 
as "heat", and gets transferred from the water molecules to the other 
molecules in the food you're heating.   That's one of the reasons 
you're told to wait 5 minutes before serving microwaved food - so 
that the heat transfers more or less completely.  It's also the 
reason that nuked food seems to cool down faster - basically, you 
have the equivalent of boiling water with ice cubes thrown in.  If 
you put it in your mouth immediately, it'll feel plenty hot, but if 
you wait a little until the heat transfers, you'll get something 
between reasonably hot and lukewarm.

These microwaves that are hopefully not bouncing around your house 
will lose some of their energy each time they hit something - walls, 
counter tops, cabinets, your dog, you, the couch, whatever.  If the 
thing they hit has a lot of water or other molecules that vibrate at 
that wavelength, they'll absorb more of the radiation than if they 
don't.

The good thing about radiation is that the power decreases as the 
square of the distance.  So if you're 10 feet away, you're getting 
hit with 1/4 of the raditation that you would at 5 feet.  Turn on the 
microwave and go clean the bathroom or something.


Getting farther off topic, I read an article by Dr. Andrew Weil some 
time ago - maybe 10 years or more - in which he described some 
anecdotal evidence about the effects of microwaves on taste and 
nutrition.  Seems some scientists were doing an experiment with some 
amino acid in a petri dish.  Now, an interesting thing about amino 
acids is that they are "handed" molecules - there's a couple of atoms 
in the molecule that can either be "up" or  "down", creating what is 
known as "left handed" and "right handed" molecules. It turns out 
that plants and animals on earth have evolved to use just one type - 
I can't remember if it's left or right, but since we're in the 
greenbuilding list let's say it's left.

Well these scientists had a petri dish of left handed molecules. 
Somehow, the stuff got some contaminants in it, and they decided to 
"disinfect" it by throwing it in the microwave for a couple minutes 
before going on with whatever their intended experiment was.  When 
the results of their experiment came back, the data was not what was 
expected.  To make a long story short, they found that the process of 
microwaving had switched the handedness of half the molecules to 
right handed.

Well, guess what probably also happens to your food?  So in 
microwaving food, it could be that you're turning half the 
nutritional value (and taste too, as handedness plays a part in taste 
as well) into useless filler that your body can't do anything with.

No, I don't use a microwave.  Take the above with a grain of salt, of 
course.  Weil's article was full of disclaimers, and I'm unaware of 
any further research to corroborate or rebuke the above claims.


-- 
Bill Christensen
billc@greenbuilder.com

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