[HN Gopher] Science of Microwave Ovens (2016)
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Science of Microwave Ovens (2016)
Author : comebhack
Score : 59 points
Date : 2025-02-06 12:09 UTC (10 hours ago)
(HTM) web link (www.genuineideas.com)
(TXT) w3m dump (www.genuineideas.com)
| bell-cot wrote:
| (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.)
| lawgimenez wrote:
| Especially don't forget to remove aluminum foils, sparks inside
| the microwave is a scary sight to witness.
| newfocogi wrote:
| 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?
| cstrahan wrote:
| 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.
| slt2021 wrote:
| I once put food covered with alumnium foil (that had ton of
| creases) to heat up. That was fun show
| Henchman21 wrote:
| My aunt did that with baked potatoes in ~1990 and burned
| down the entire house.
| EvanAnderson wrote:
| Optical disks produce fun, brief light shows in the microwave.
| Don't run them for more than a couple of seconds, though.
| dole wrote:
| 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.
| bell-cot wrote:
| Good memory! He also says to use a turntable microwave, to
| keep the staples several inches apart, and away from the
| microwave's walls.
| kbouck wrote:
| ElectroBOOM demonstrates this:
|
| https://youtu.be/OyTmJX_TC84?feature=shared
| foobarian wrote:
| jinx
| kbouck wrote:
| you win!
| foobarian wrote:
| Yeah, Mr. ElectroBOOM has a pretty informative video [1] trying
| a handful of different configurations of metal objects in a
| consumer microwave oven. Turns out it's hard to make
| "interesting" things happen with metal even if you intend to.
|
| [1]
| https://www.youtube.com/watch?v=OyTmJX_TC84&ab_channel=Elect...
| edoceo wrote:
| Put a burning candle in there
|
| https://www.experts-exchange.com/questions/24081775/Candle-i...
| JoeDaDude wrote:
| I read somewhere that you can place a candle under a bowl (with
| allowance for oxygen to get in) and you can capture the plasma
| given off by the candle.
| https://www.youtube.com/watch?v=x5BFIVDUQPE
| jurgenaut23 wrote:
| I cannot read this title without my brain bringing back memories
| of 30 Rock
| Cheer2171 wrote:
| 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
| includes everything from hand lotion to plastic water bottles to
| deoderizers.
| whycome wrote:
| > 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.
| Cheer2171 wrote:
| Do you not understand what the word axiomatic means? If there
| are 70,000 chemicals and only 500 have been tested, does that
| mean *every single product* *must* contain an untested
| ingredient? No, because products don't randomly pull
| ingredients out of a hat. Proof by counterexample: pure water
| in a bottle made of the many materials that have been tested
| for food safety. But hey, why bother with facts when you can
| just make shit up and call it "axiomatic"?
|
| Words have meaning.
| KineticLensman wrote:
| > 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.
| anotherhue wrote:
| 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.
| nimbius wrote:
| processed cheese will visualize the waveform well.
| rhodescolossus wrote:
| 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.
| ssl-3 wrote:
| 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.
| SoftTalker wrote:
| Agree. I think 90% if people use their microwave to reheat
| leftovers or cook pre-packaged meals. All they need is a
| timer. And I'd prefer a dial to a keypad.
|
| My wife bought a countertop convection oven that has nearly
| 100 pre-defined cooking programs and 10 different "quick set"
| buttons. How do we actually use it? Set a temperature and
| time. With a dial. Could have be so much simpler.
| ghaff wrote:
| >to reheat leftovers or cook pre-packaged meals
|
| There was some experimentation early on--I even have a
| microwave cookbook--but, outside of some vegetables, very
| few people actually try to cook using one. And, yeah, I
| don't know the last time I did anything other than set
| time. I rarely even do anything other than full power. I do
| use the popcorn setting from time to time but even that is
| pretty much unnecessary if you listen to the popping.
|
| I have to replace my microwave because it caught on fire in
| the middle of the night and I'll probably get a 4-in-1
| Panasonic which will also replace my second oven which I
| basically never used.
| ssl-3 wrote:
| My parents used to cook taco meat and bacon in the
| microwave.
|
| It worked OK-ish.
|
| It's hard to actually get the Maillard process going in a
| microwave with a couple of pounds of ground cow, so
| proper browning wasn't a thing.
|
| They'd just put the moo into a glass mixing bowl, turn
| the machine on, and give it rigorous toss with a wooden
| spoon every couple of minutes. Ground beef crumbles were
| the result.
|
| For bacon, we had a special angled plastic tray with
| drainage slots for the grease. They'd layer up bacon
| separated by paper towels, and start the machine.
|
| This worked better than the taco meat did, in my opinion,
| but it still sucked because picking little bits of
| greasy, stuck paper towels off of hot bacon is annoying.
|
| I've never done either of these methods myself, because I
| naturally want to do things better than they did. In my
| adult life, ground taco meat goes in a skillet on the
| stove (and uses a cheap wire potato masher to break it
| up), and bacon goes in the oven on a sheet pan.
| ghaff wrote:
| I actually have one of those bacon tray things. It's just
| very messy as you say and doesn't really save effort
| overall. Probably better using a standard oven for big
| batches.
|
| re: ground beef or meat in general, slow cookers have
| sort of the same problem with respect to Maillard
| reactions. You're generally better off using a dutch
| oven, browning, and then cooking in the dutch oven--
| unless you want to do prep and then toss in a pot and
| forget for the day. I have a slow cooker but wouldn't buy
| one today.
| ssl-3 wrote:
| I use mine mostly for warming up shitty frozen burritos.
|
| It has an inverter and a humidity sensor and 20 or so
| different preset buttons that use them, with sub
| permutations.
|
| None of them work well at the job of warming up two shitty
| frozen burritos.
|
| What does work well is this: One minute at power 10, and 3
| minutes at power 3.
|
| When others see me programming this in they think I'm a
| madman, and sometimes they even audibly question my sanity.
|
| And I'm not sure that they're wrong.
|
| ---
|
| The microwave I grew up with had a mechanical timer knob
| (with a simple mechanical bell), a second knob to set duty
| cycle (probably borrowed from an electric range), and a
| start button.
|
| It worked fine. I like being able to program things, but
| I'm usually standing right there anyway so I'm perfectly
| capable of turning the duty cycle knob down after about a
| minute passes and getting the same results that I do today.
|
| (And that method did in fact work fine back then, too, even
| though people also thought I was crazy when they'd see me
| doing that)
|
| And for bonus nachos: The timer also worked perfectly as a
| simple mechanical kitchen timer. Just give it a twist,
| avoid the start button, and it spins down until it goes
| "Ding!".
| crazygringo wrote:
| 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.
| 01100011 wrote:
| When I was a kid(~1980), I remember our microwave had a
| removable temperature probe you could insert into the food. I
| don't know if it was just for informative purposes or if it
| controlled the cooking however.
| xp84 wrote:
| I think a probe would be really great, because knowing the
| surface temp doesn't tell you how hot the thickest part of
| the food is. Although GP has an interesting point that if
| you cycle it for long enough, I guess the heat should
| approach equilibrium and the surface and insides should
| match.
| crazygringo wrote:
| Yup that's exactly the idea, for it to approach
| equilibrium.
|
| And the microwave should be able to deduce how close it
| is by the rate of cooling of non-hotspots while the cycle
| is off. If it's cooling quickly, the inside is still
| frozen. If it isn't cooling at all, the inside is nice
| and warm.
| crazygringo wrote:
| Those disappeared, though, because they're solving the
| wrong problem.
|
| Those would tell you when the center of your food was
| cooked, but by then the outside of your food was insanely
| over-cooked. Most of your chicken breast has turned into
| dried-out rubber.
|
| The real problem isn't to get the center hot enough, that's
| easy. It's to prevent the outside from getting _too_ hot.
| And you need a camera for that.
| glitchc wrote:
| The only problem is that the camera would not survive the
| first time you use that oven. High power microwaves happily
| destroy all manner of electronics.
| crazygringo wrote:
| Surely it can be shielded?
|
| IR and microwave wavelengths are nowhere even close to each
| other.
|
| The grill in my microwave door lets through visible light.
| And the electronics already present in my microwave seem
| just fine.
| snarfy wrote:
| If it's going to take 10+ minutes to cook, why not use
| something like a toaster oven?
| crazygringo wrote:
| Because if the microwave can do it in 10-15 min, the
| toaster oven is going to take 40-60 min or worse.
|
| Waiting 10-15 min to reheat something evenly is doable for
| me. I can make a side salad, toast some bread, empty the
| dishwasher or whatever while I wait.
|
| Waiting 40-60+ min requires real advance planning, which is
| often just not feasible.
|
| If you've ever used a toaster oven to warm up a frozen
| personal-size lasagna, sometimes it can take as long as an
| hour and a half.
| MisterTea wrote:
| I know someone who worked at a failed startup that attempted
| almost exactly this minus the AI. It used an IR camera paired
| with a secret method to beam form the microwaves to uniformly
| heat the food no matter how it was dispersed across a plate.
| This means you could have a pile of water rich vegetables and a
| steak on a plate and it would heat evenly. It worked great nut
| IIRC the issue that caused it to fail was calibration of the IR
| sensor took a ton of effort and they could not scale that to a
| production scenario. Edit: should mention it let you dial in a
| temperature so the method is workable, just needs to scale to
| production.
| FuriouslyAdrift wrote:
| This one?
|
| https://www.eater.com/2015/2/11/8022235/never-burn-
| popcorn-a...
| MisterTea wrote:
| No, but that is a neat idea!
| xp84 wrote:
| Wow. I envy the guy who got to take the prototypes home. What
| a device that would be to have in your kitchen!!
| FuriouslyAdrift wrote:
| From all the way back in 2015
| https://www.eater.com/2015/2/11/8022235/never-burn-popcorn-a...
| HPsquared wrote:
| IR sensors aren't reliable if there is a lot of water vapour
| coming off the food (it measures the temperature of the water
| vapour). Great for oil and other dry heat (but again beware,
| with shiny metal they tend to measure the mirror image of
| what's reflected by the metal, not the metal itself). These
| effects are more visible using an actual thermal camera.
| Terr_ wrote:
| Some microwaves take a useful shortcut with a sensor for water
| vapor, so they know when something has started to steam and can
| reactively change the amount of time remaining.
|
| Obviously this is great for things like soups, but not-so-much
| for things which don't reach 100C in an even fashion.
| NotYourLawyer wrote:
| Better microwaves existed. Nobody wanted them. Technology
| Connections:
|
| https://www.youtube.com/watch?v=UiS27feX8o0
| xp84 wrote:
| If even one person here doesn't yet have a fast-reading food
| thermometer I have to evangelize for them here. Good ones that
| instantly read used to cost like $75, and the cheap kind would
| take literal minutes to arrive at the real temp, but I think
| someone in China figured out the secret and brought the price
| down to like $14. Mine has a magnet and I keep it right next to
| the microwave and air fryer. It has made it tremendously easier
| to get food correctly heated through, in both devices.
|
| The other thing I believe in strongly is, for most things, using
| 40-60% power and heating the food about twice as long as your
| original instincts say, for more even heating.
| copypasterepeat wrote:
| Completely agree with the reduced power recommendation. That
| really helps evenly heat foods that start popping in the
| microwave or have hot spots when taken out. The few extra
| minutes are usually not a big deal anyway.
| Scubabear68 wrote:
| In particular, anything that has a lot of liquid benefits from
| using lower power for longer.
|
| Of course, putting a quart of spaghetti sauce in an open
| container and microwaving it at 100% will result in some very
| cool sauce explosions as localized steam in the source rapidly
| expands and blows giant sauce bubbles all over your microwave.
| anotherevan wrote:
| Our microwave oven died on Christmas Eve, and I ended up getting
| one of those newer flatbed ones. The novelty of putting something
| in there and watching it _not_ rotate has not worn off yet.
| beloch wrote:
| If you're screwing around with microwave sources, I'll pass on a
| warning I got from one of my profs.
|
| Microwaves will heat your body up, but in a relatively harmless
| way. e.g. If you microwave your hands a bit, blood flow will
| transfer that heat out and things will remain pretty okay unless
| you really overdo it.
|
| Your eyes are an exception. They're orbs of aqueous humor that's
| mostly water, but have relatively little blood flow when compared
| to most other tissues in the body. Microwaves will heat them up,
| but bloodflow won't distribute the heat away quickly. Protect
| your eyes around microwave sources.
| chiph wrote:
| If anyone has a school-age child needing a science experiment, my
| niece created a list of various items and what she expected their
| behavior to be in a microwave at different cooking times.
|
| And then tested her hypothesis in a cheap microwave (out in the
| yard in case of explosions), documenting what happened with
| photos and making a conclusion for each. She got top scores from
| the teacher for following the scientific method.
| craigmcnamara wrote:
| Put a whole uncooked egg in the microwave for a few minutes and
| call me in the morning.
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