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Microwave oven myths?

Anders W. Bonde

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While working on a little write-up that will be used to counter an e-mail-circulated Danish local newspaper comment full of anti-microwave woo, I've come across two topics I havn't managed to get a handle on so far.

1) It is claimed that microwave ovnes have been banned in the former Soviet Union since 1976. Is this ban still in force in any of the former Soviet republics, and if so, why was the ban introduced - and eventually lifted, if that's the case?

2) Cecil Adams, IIRC, on the Straight Dope, mentioned (although I can't find the link at the moment) that some laboratory processes using microwave oven heating rather than other (convective) heating techniques speed up some chemical ractions by orders of magnitude. Is this true?

I've searched this site and Google, but found nothing, on these two issues.

Help would be much appreciated!
 
Funny you should mention it, but the Skeptoid podcast just did an episode on Microwave Oven woo and he addresses both of these claims. You can find a copy of the the transcript here, or take a listen, here.
 
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Thanks, Mark.

I've read the transcript, but it doesn't appear to address the 'Straight Dope', IIRC, issue of increased reaction levels when using microwave heating as opposed to, say, the good ole' Bunsen burner. I'm sure some of the real scientists on this Forum can say something about this.

I haven't seen any evidence that Russia has banned or lifted a ban on microwave ovens, but as it's such an extraordinary claim, the woo should be the one who provide the evidence of a ban. Do we have any Russian members on the Forum who might help out here?

BTW, is the actual podcast longer than the transcript? There may be stuff on it which isn't on this fairly short transcript, I suppose.

We have a local academic, Sianette Kwee, who's deeply into the "EMF cause cancer" thing - any Danes on the forum here familiar with her "work" (I'm biased, I do assume she's on the Dark (aka woo) side).
 
I can't cite any specific sources, but it would be rather amazing if microwaves didn't speed up some reactions, particularly endothermic ones. It is a much more direct form of heat transfer than convection, so sans a dedicated study I'd believe it.

I mean, it's been known for a while you can induce chemical reactions that don't occur spontaneously using microwaves, and it even made the news this year.
 
Even one of my college physics professors was guilty of relating some "bad science" about microwave ovens to us.

He claimed that microwave ovens worked because the microwaves they emitted at the food were the exact resonant frequency of water molecules -- thus, the water in the food heated up, but everything else in the food only heated up because it was exposed to those now-hot water molecules.

Turns out, he was full of a certain sausage meat produced in the Bologna region of Italy. If the microwaves WERE at the resonant frequency of water molecules, they would get absorbed by the water at the surface of the food and wouldn't reach the center.
 
Organic chemists were interested in microwaves in the late 1970's. The rationale seemed to be that dipolar molecules would line up in the alternating field and increase reaction rates. I looked at it for our work in immunochemistry but concluded the heating effects would be too much to bother with.

This site seems to concentrate on this effect but the registration wants too much information for my liking and may be just a selling point.

http://www.microwavesynthesis.net
 
tracer said:
Turns out, he was full of a certain sausage meat produced in the Bologna region of Italy. If the microwaves WERE at the resonant frequency of water molecules, they would get absorbed by the water at the surface of the food and wouldn't reach the center.
Click to expand...

It's true that microwaves are not resonating with water molecules just agitating them and other dipolar molecules. But they still work from the outside inwards. That's why many microwaveable foods recommend stirring halfway through the heating process.
 
One I heard just the other day: If you put your cellphone in the microwave and it rings when you call it, this means that the protection the oven offers against radiation is not adequate.
 
Thanks, guys.

I suppose the real test of whether something 'bad' happens to the cooked food or not lies with clinical studies. I have found none that are reputable and support the woo viewpoint. In the end, it all seems to boil down to the effects of heating, regardless of the source of heat. But I can see how the microwave interaction in some chemical processes can set the woo thinking 'this must be bad'.

Mojo,

no the de-bunked water "study" wasn't referenced. That would've been an easy one to refute, though.

El Greco,

Whether a cellphone is shielded in a microwave oven or not will depend on the aperture sizes in the door seals and in the shielding mesh in the window versus the wavelength used for the cellphone. I suspect that the aperture sizes are well less than half a wave length, so I doubt the cellphone will be able to transmit signals. Has anyone here tried this?
 
Anders W. Bonde said:
El Greco,

Whether a cellphone is shielded in a microwave oven or not will depend on the aperture sizes in the door seals and in the shielding mesh in the window versus the wavelength used for the cellphone. I suspect that the aperture sizes are well less than half a wave length, so I doubt the cellphone will be able to transmit signals. Has anyone here tried this?
Click to expand...

I did, with two different microwaves. The cellphone rang both times, as expected.
 
I've also seen the claim that microwaving is an effective way of remove all antioxidants from a substance - any link to reality in this?

Other claims: Sianette Kwee and 'Japanese research' has demonstrated links between dementia and Alzheimers - but I can't find any sources for that claim.
 
Anders W. Bonde said:
El Greco,

Interesting. Have I got something wrong with respect to shield aperture sizes and wavelengths?
Click to expand...

Have no idea. I just thought that since the two waves have different wavelengths then it wouldn't be safe to assume that shielding for the one would also blcok the other. I also don't know the energy threshold above which a cellphone rings. BTW, here we have GSM 1800 and microwave ovens work at 2450MHz, which would result in wavelengths of about 12,2 and 16,6cm respectively.
 
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tracer said:
Even one of my college physics professors was guilty of relating some "bad science" about microwave ovens to us.

He claimed that microwave ovens worked because the microwaves they emitted at the food were the exact resonant frequency of water molecules -- thus, the water in the food heated up, but everything else in the food only heated up because it was exposed to those now-hot water molecules.

Turns out, he was full of a certain sausage meat produced in the Bologna region of Italy. If the microwaves WERE at the resonant frequency of water molecules, they would get absorbed by the water at the surface of the food and wouldn't reach the center.
Click to expand...

He's half-correct: the wavelength energzes the O-H bond. Water is affected, but so are fats, oils, sugars, starches, &c.

The distribution of heating intensity through an object is complex, and actually depends as much on resonance in the oven volume as it does penetration from the surface.
 
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