Science of Microwave Ovens (2016) • Hacker News Board

Re: Science of Microwave Ovens (2016)

#11

Post by KineticLensman » Thu, Feb 06, 2025, 7:00 PM UTC

> My father was a radar officer in WWII, and recalled warming his hands on cold British mornings in front of the beam emitted by a "magnetron" inside his primitive radar transmitter. Then he went back to work detecting Nazi aircraft. But, it is a short distance from warming to cooking- in 1946 engineers at the military contractor Raytheon noticed microwaves could not only warm, they could heat and cook food.

In the 1990s I was a contractor at DRA Malvern in the UK, which was one of the successor organisations to the WW2 radar research establishments. The greybeards I encountered always felt that they had invented microwave cooking even if Raytheon got the credit later. Sausages cooked using the lab magnetrons, they said, although unfortunately there were no photographs.

The future of cooking was something that famous futurist Arthur C Clarke got wrong. He might have predicted geostationary communications satellites but in his short story The Sentinel - which was the inspiration for the film/book 2001 - the crew of a small lunar rover fry their sausages in a conventional frying pan.

Re: Science of Microwave Ovens (2016)

#12

Post by slt2021 » Thu, Feb 06, 2025, 7:07 PM UTC

cstrahan wrote: post #10

newfocogi wrote: post #4

Earlier quoted context omitted.

I understand the physics of microwaves but haven't taken the time to understand when metal is dangerous — I tend to just always avoid it. Do you know of any resources that explain what scenarios belong in the "harmless" category?

My (limited) understanding is that the shape is a large factor. Something about sharp edges or points concentrating the electric field induced by the microwaves, leading to a high voltage buildup. So forks are a bad idea, while spoons will likely not result in any sparks.

I once put food covered with alumnium foil (that had ton of creases) to heat up. That was fun show

Re: Science of Microwave Ovens (2016)

#13

Post by whycome » Thu, Feb 06, 2025, 7:12 PM UTC

Cheer2171 wrote: post #8

This last part is such pseudoscience that it makes me suspicious of everything I was nodding along with before: > Of the 70,000 chemicals in widespread commercial production, only around 500 have been competently screened for human toxicity. Since most products are a blend of numerous ingredients, it is axiomatic that all products contain at least one ingredient that is untested and not known to be safe. This include…

> at least one ingredient that is untested and not known to be safe

This seems kinda okay though. It’s very different to saying “known to be unsafe”. There are tons of untested (or insufficiently tested) things.

Re: Science of Microwave Ovens (2016)

#14

Post by dole » Thu, Feb 06, 2025, 7:27 PM UTC

bell-cot wrote: post #2

(2016), FWIW. The article doesn't mention issues with putting metal - dishes, silverware, twist ties, whatever - in the microwave. IF you know what you're doing, that's pretty harmless. (If not - sparks, fire, and other excitement often results.)

Alton Brown used to have a recipe (I'm Just Here for the Food?) for homemade microwave popcorn where you can use a typical metal staple and it won't spark, something to do with the amount of metal, and also actual size of the microwave wavelengths used being bigger than a staple, iirc.

Re: Science of Microwave Ovens (2016)

#15

Post by anotherhue » Thu, Feb 06, 2025, 7:27 PM UTC

You can put some thermal paper, or a sufficiently large chocolate bar in there (without the turntable) to see the interference patterns yourself without any fancy gear.

You can then eat the chocolate.

Re: Science of Microwave Ovens (2016)

#16

Post by rhodescolossus » Thu, Feb 06, 2025, 7:31 PM UTC

I wonder if there’s a market for a microwave with an IR camera and AI to estimate food weight and thermal conductivity.

With accurate heat tracking, it’d only need a button to open the door and no knobs.

Re: Science of Microwave Ovens (2016)

#17

Post by nimbius » Thu, Feb 06, 2025, 7:38 PM UTC

anotherhue wrote: post #15

You can put some thermal paper, or a sufficiently large chocolate bar in there (without the turntable) to see the interference patterns yourself without any fancy gear. You can then eat the chocolate.

processed cheese will visualize the waveform well.

Re: Science of Microwave Ovens (2016)

#18

Post by ssl-3 » Thu, Feb 06, 2025, 7:48 PM UTC

rhodescolossus wrote: post #16

I wonder if there’s a market for a microwave with an IR camera and AI to estimate food weight and thermal conductivity. With accurate heat tracking, it’d only need a button to open the door and no knobs.

We can measure weight using a scale.

We can make a solid guess at volume using visible light and a rotating view (already provided by the unfortunately-common carousels), with a bit of CV and math.

We can therefore deduce density.

We can measure outside temperature using IR.

And we can measure the power put into the things being microwaved.

And we can also measure the temperature and humidity of the air that is exhausted from the microwave chamber.

With all of that data, we can do some cool things.

But with only single-button input, there's a lot we can't do:

We can't know if the user is cooking a hamburger from raw meat (yes, raw meat can be used in the science oven), or reheating one that was already cooked, or finishing one that was par-cooked.

We can't know if they're softening butter to spread onto toast, or melting it to pour over popcorn

We can't know lots of things. So we need more than one user input.

The slope to getting back to where we started is very short: Some preset buttons that most people will never understand, a speed control that most will never use, and a keypad for a timer.

Re: Science of Microwave Ovens (2016)

#19

Post by bell-cot » Thu, Feb 06, 2025, 7:50 PM UTC

dole wrote: post #14

bell-cot wrote: post #2

(2016), FWIW. The article doesn't mention issues with putting metal - dishes, silverware, twist ties, whatever - in the microwave. IF you know what you're doing, that's pretty harmless. (If not - sparks, fire, and other excitement often results.)

Alton Brown used to have a recipe (I'm Just Here for the Food?) for homemade microwave popcorn where you can use a typical metal staple and it won't spark, something to do with the amount of metal, and also actual size of the microwave wavelengths used being bigger than a staple, iirc.

Good memory! He also says to use a turntable microwave, to keep the staples several inches apart, and away from the microwave's walls.

Re: Science of Microwave Ovens (2016)

#20

Post by crazygringo » Thu, Feb 06, 2025, 7:58 PM UTC

rhodescolossus wrote: post #16

I wonder if there’s a market for a microwave with an IR camera and AI to estimate food weight and thermal conductivity. With accurate heat tracking, it’d only need a button to open the door and no knobs.

I want an IR camera and I want to input my desired temperature. That's all.

Then I want the microwave to cycle on when the camera says everything is below temp, and cycle off as soon as any hot spot hits temp. Then wait for the hot spot(s) to dissipate before cycling back on.

Seems like a foolproof way to cook evenly without overcooking.

I kind of approximate it now by cooking something frozen on high for a couple minutes, then on 20% power for five minutes, then 10% power for another five minutes. But it would be nice to have it all automated.