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Aaron Slepkov, a Trent University physics professor, has published a paper describing why grapes spark when heated in a microwave.
The team found that a microwave -- with a wavelength of 12 centimetres in air -- is the exact same size of a grape in water due to what's known as water's high index of refraction, Slepkov explained. That's when something interesting happens, he said.
Microwaves accumulate and become trapped inside the grape, he said, and those light microwaves pack themselves in the centre and the grape begins to heat up. When a second grape comes in, or the other half of a cut grape, the microwaves concentrate at the sides near each other creating an intense electrical field.
The electric field becomes so high, he said, that it begins stripping electrons off sodium and potassium molecules, creating ions.
"Once you have an ion of sodium or potassium, then all hell breaks loose and the rest of microwave oven is feeding that spark, ionizing the air and turning it into ball lightning," he said.
Professor Slepkov pointed out that there are potential applications in antena design for cellphones or wireless routers:
"We're hypothesizing maybe you can change antenna design because the grapes are acting as a concentrator for wireless radiation or cellphone radiation -- effecting how we design antennas to help act as a signal booster," he said.
I suppose such a product could be considered a grape concentrator.
(Score: 2) by urza9814 on Tuesday March 12 2019, @12:11PM (6 children)
So, grapes are mostly water, and humans are mostly water. Seems like a brain is potentially a similar water content and therefore similar refraction of a grape.
If we assume the size of the grape is 1cm, and the average human brain is 15cm long, then presumably you'd need a wavelength of 12*15=180cm to reproduce the same effect in a human head, which would be around 1.6GHz.
Oddly, it seems a lot easier to find the length of a brain rather than the width, although I think for grapes it relies on width...but if we go with 10-11cm (which seems potentially reasonable based on my own head and tape measure) then the frequency comes to 2.4GHz.
Don't get me wrong, I'm not trying to say the "wifi sensitivity" stuff is legitimate, pretty sure it's been pretty thoroughly debunked...but if one wanted to do some trolling.... :)
(Score: 1) by rst on Tuesday March 12 2019, @02:58PM (1 child)
A microwave oven uses 2.4 GHz, so either your math is wrong or the article's is.
(Score: 2) by urza9814 on Tuesday March 12 2019, @03:19PM
Ahh shit, you are correct, I did 180mm instead of cm...
So what operates at 24GHz...?
Looks like it's amateur radio and point-to-point network links. Not aware of any conspiracy theories around those. Damn... :(
(Score: 2) by Muad'Dave on Tuesday March 12 2019, @04:14PM (3 children)
Your math is off by a factor of 10. If the ratio of grape to head is 15, then the resonant frequency would be 2.45 GHz / 15, or 163.3 MHz.
(Score: 2) by urza9814 on Tuesday March 12 2019, @04:51PM (2 children)
Jesus, I should not be trying to math that early...I even posted a correction in which I went the wrong damn direction. Thanks. Good thing my ham license expires this year, I probably don't deserve that anymore ;)
So, 163 MHz...I see nothing of interest (particularly to conspiracy nuts) around that frequency...damn...
(Score: 2) by deimtee on Tuesday March 12 2019, @05:24PM (1 child)
The article states that the RI (refractive index) is very frequency dependent. At microwave freqs, for some reason the RI goes up over 10 and the resonant wavelength approaches the size of a grape. It's not just a matter of scaling the sizes to headsize, at the new wavelength the RI will be different. You need to find the frequency that has a wavelength the size of the human head, while the wave is in the head.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by Muad'Dave on Tuesday March 12 2019, @07:29PM
You can do the math using the data here (see page 53): https://apps.dtic.mil/dtic/tr/fulltext/u2/a312143.pdf [dtic.mil]
According to that site the 'n' portion of the complex RI of water at 2.45 GHz and 160 MHz are both very close to 10.