Probably a stupid question, but will we ever have something like a microwave to make things cold? Is there a reason this can't exist?
All you need to do, is figure out a way to use electro magnetic radiation to slow down particles.
It's just a small technical challenge.
Technically that's already a thing. It is pretty expensive compared to a normal refrigerator though...
Easy, just invert the polarity of the microwaves
i turn the microwave upside down
There’s something called blast freezer, which is basically a freezer with fans inside, like what convection ovens have. It cools down food much faster than a standard freezer.
It's on my list when I have fuck you money. Next to a pacojet
Basically like a blast furnace right?
The problem is that cold is merely the absence of heat, you can't inject cold into something or generate cold, because there is no such thing as cold. It's kind of like how we can make a light bulb, but we can't make a dark bulb.
Maybe we could start manufacturing mini black holes to build the dark bulbs!
We have that, it's called a fridge, and then there's a freezer for making things frozen.
But a fridge is the opposite of an oven. Some kind of flash freezing would be like the unmicrowave.
The reason we shrink heating devices down but not cooling devices is a combined consequence of economics and the laws of thermodynamics.
First an analogy: Making a boat that moves downstream a river is easy. Take any buoyant material like a log or a branch and drop it in water. Presto, you've got a mode of transportation of any size. Want to go upstream? Now you need motors to fight the current. Putting a motor on a large piece of wood, (a boat) is economically viable. Putting one on thousands of sticks? Ain't nobody got time for that.
As a consequence of the laws of thermodynamics, the the universe naturally converts all potential energy (fuel, electricity) into heat. The universe will do this basically on its own, over time, constantly. This is called entropy.
Doing the reverse, taking heat and putting it back into potential energy, i.e. cooling, is difficult. You basically have to pay a price to the universe in some other way, kind of like how a motorboat has to push more water downstream than the current would have naturally moved on it's own. This is what heat pumps (AC, fridge) do. Heat pumps put some of that heat back into potential energy, in exchange for also releasing potential energy into heat... The trick here is to do these two things in different places. The fridge's motor converts some electrical energy into heat in exchange for being able to move some of the heat in the fridge outside of the fridge. The consequence of this is that the room the fridge is in is now hotter. Mostly because you took the heat in the fridge and moved it into the room, but also because the fridge's motor also added some MORE heat to the room in the process in order to fight entropy. So to actually make this useful, you need to insulate what you are cooling (or it will just get warm again, warmer than it was before, because you added heat to the room), and you also want to dispose of the heat in the room. So you pump that out into the atmosphere...
Anyway, long story short, you need insulation, refrigerant, motors, heat changers, lots of power to fight the universe's tendency to spread heat everywhere. Technically you could miniaturize these things, but they become less efficient as you shrink them down, to the point where things smaller than a fridge are just not practical to make compared to the benefit you get from having them.
Making small heating devices is easy. You don't need to fight the universe. You just need an apparatus that will "go with the flow".
There are blast chillers that are closer to a microwave
Liquid nitrogen
Air Frozer
>unmicrowave
I'm laughing more than I should at this
Go ahead, report the mods, they can't unmicrowave this post
Depending on where you live and the season, that could be called stepping outside.
Blast freezer is a better analogy
They meant quickly. A fridge nor a freezer can make things cold or frozen in a minute or two.
Flash freezer exists
Those devices are very slow at transferring heat, unlike the microwave.
Temperature is average kinetic energy. It is very easy to put kinetic energy into an object and much harder to take it out. Microwaves do it by shining a “light” tuned to microwave frequencies on objects. So you can imagine the problem is about as hard as shining a lamp on something and having it get colder. Laser-based cooling methods do exist but they’re quite expensive and mostly operate on the atomic scale. For now, the best way we know of to cool large items in bulk is to put them next to something that’s even colder—in short, a refrigerator.
Fridge?
There are devices that will cool a drink (can of soda or a beer) to 'ice cold' ( I assume something like 5°) in 60 seconds. I guess this sort of answers your question? The full answer is probably not that it is technically impossible, but that the practical use is largely limited to drinks.
In a few seconds.
Refrigerator
You can dump energy into something by blasting photons at it, because photons carry energy. You can't do the reverse because you'd need to use particles with negative energy. Either that, or you'd need to suck photons out of the food, but it doesn't work that way; things radiate photons at a specific frequency and intensity (called blackbody radiation) depending on how hot they are, and you can't make them emit more energy except by getting them hotter.
Allow me to introduce you to this
Funny note- the way we actually get things to near absolute zero, is by shooting it with lasers.
A common misconception. Take the so called "light bulb" for instance. People think they emit light. They do not. They ingest darkness. They are dark suckers. They pull in all the darkness around them, but objects get in the way, and that's why there are shadows. And when they're full, they stop working. That's why they have a brown spot when they stop working, they are full of dark.
Don't fall for the light emitting conspiracy. LONG LIVE THE DARK SUCKERS!!!
Considering room pressure and temperature, things are not cooling at their fastest possible rate. Blackbody radiation isn't the only way things cool down. You are forgetting conduction and convection. Liquid nitrogen can cool things down super quickly.
Refrigeration Tech here. See: Traulson Blast Chiller. I imagine there'd be a consumer version if enough people wanted them.
But isn't the cooling method an airflow and steady temperature decrease of the chamber?
Seems more like a reverse convection oven than a microwave.
But thanks otherwise. I never knew these existed. Was an interesting read.
Without breaking the laws of thermodynamics, I'm not sure how you'd accomplish that. Being you can't "make" something cold. You can only remove the heat...
Blast Chillers can make 160°F Poultry 34°F quite fast. Mind you that's internal Temps. As far as I know, airflow is the best, maybe only way to carry the heat away...
if you see a dark area you can turn on a flashlight to emit light towards the area and make it not-dark.
If you see a lit area and you want it unlit, there is no anti-flashlight you can point towards it to suck the light out.
Similar kind of thing, heat can only be given, not taken. heating stuff up is easy, but for cooling the best you can do in most cases is to make it easier for the thing to give you its heat (ex by the atmosphere colder), but you can't force it.
This is fundamentally not true.
Light is made of electromagnetic waves. If you can control the timing of those waves precisely enough, you can add another light with the opposite phase (an inverted wave) that will cancel out the other light.
This is what happens in the famous "double slit experiment". It's also the same principal as noise cancelling headphones albeit with sound pressure waves instead of EM waves.
Scientists have actually cooled atoms very close to absolute zero by shining a laser at them
Laser cooling exists, but I don't suppose you can afford one or want your beer on 2°K
it also helps to be cooling a single atom at a time
My god where does it end with you beer snobs??
A lot of laser coolers were built exactly for cooling single atoms (to do scientific research)
How does that work?? Genuinely curious.
It's unintuitive, but super cool! There's a great video by Physics Girl and Veritasium that explain it better than I ever could here.
First, the wavelength of the laser (think of it as the "color" of the laser) is chosen such that the energy of the photons is just under the energy state of the atoms that you are trying to cool.
Now, when the atom is moving toward the source of the laser, this causes the atom to "see" a higher energy. This is called Doppler shift and is a very well-known effect in anything that emits waves and is moving. In fact, you've experienced it before when you hear a car horn -- as it moves towards you it has a higher pitch and as it moves away from you it has a lower pitch.
So, for atoms moving toward the source the see the energy rise just enough to absorb the photon and move to a higher energy state. Inevitably, the atom will want to move to a lower energy state (as all matter does) and will end up ejecting a new photon in a random direction. In order to maintain the conservation of momentum, this means that the photon will likely be ejected in a way that counteracts the direction it was previously moving, effectively slowing it down. Since heat is a measure of how fast atoms are moving, this means that atom has cooled down.
For atoms moving away from the laser source, they are unable to absorb the photons because the Doppler shift acts in the opposite direction, and they are completely unable to absorb the photons.
So as a result of all this, it is possible to slow down atoms moving in a very specific direction, without affecting the other atoms. This means you can systematically slow atoms down which means you can systematically cool things down.
Edit: Here's a piped link to the youtube video above in case you're privacy-conscious, however, Dianna (aka Physics Girl) has been bed-ridden with Long COVID for a while now so it would be great if you could contribute to her Patreon in lieu of the ad revenue
Basicly photons are shot against an atom to slow it down (the slower the elements move the "colder" something gets)
This is a bit like asking if we could build a flashlight that emits a beam of darkness I think
It's not. A device that rapidly cools things down placed inside it isn't implausible. He's not asking for a beam of absence, he's asking for an enclosed space that subtracts heat.
I have that device
It is my phone
Very much so, and equally possible in theory (interference patterns with light exist, light cancellation could work somewhat like noise cancelling) but also equally impossible to do at anything much above an atomic scale.
That's a fog machine
There are actually two ways to do this. One is a heat pump (like a small ac or an electric cooling plate) the issue is that it would heat up on the other side, so not great.
The other option is actually really interesting as just like a microwave it uses radio waves (in this case lasers) to cool things by shooting the atoms in a way that negates their current movment and slows them down.
Oh, so that's why when I shot someone they got cold! Silly me. I'm a reverse microwave, not a murderer duh
the victim was having a fever, your honor!
Came here to mention laser cooling; glad someone else got there first.
peltier cooler
In reductively simple terms heat is really easy to generate. In fact pretty much everything we do creates extra heat entirely on accident, so a device than make things hot on purpose is actually surprisingly simple. It's much harder to get rid of. The only economical way we've found of managing it is by using to phase change of refrigerants to pump it out of enclosed spaces, which is how refrigerators and air conditioners currently work. Everything else would be more complex, less efficient, or both. So if such a thing is even possible it would almost certainly be much more expensive
It's called a freezer and it just takes a bit longer.
Liquid nitrogen is kinda dangerous for consumer appliances.
The simple answer is entropy. It's much easier to poor a bunch of energy into something and have it express itself as heat than it is to retrieve spent energy out of an object. You can burn down a forest and make a lot of light and heat, but you can't spend light and heat to turn smoke into a dark, cold forest.
We cant do it now thats true. But isnt the process you described called photosynthesis? Using Sunlight (heat in form of UV Waves) to turn Smoke (CO2 and bunch of other stuff that isnt used) with Water into sugars which build the structure of plants?
There's a lot of posts here not answering the question or saying it's impossible.
A reverse microwave is possible.
The 1997 Nobel Prize in physics was awarded for the development of methods to cool and trap atoms with laser light.
It's just very hard to do and no one has successfully cooled a large complex object with laser-based cooling.
TIL, that's cool.
Push heat into something is easier than pull heat out of something
That's not how a microwave works.
It pretty much is. It bathes your food in intense radio waves that get absorbed and turned into heat.
Pushing energy into a thing is easier than stopping it
Make something vibrate fast easier than make something vibrate slower
This is technically possible. The cosmic microwave background, i.e. space, is extremely cold (barely above absolute zero) so it basically acts as a heatsink you can pump infinite amounts of heat into. It turns out that if you can make the food radiate heat out into space and prevent it from absorbing more heat from sunlight, it's possible to cool it below ambient temperature. This is also a completely passive process so it requires no electricity or other form of active energy input.
The problem with this is that doing it with food might be impossible. At the moment, we can only really do it using objects with special coatings that have been optimized for this purpose.
Here's a couple interesting videos that explain how it works:
Put a heat sink into your scrambled eggs
I always did enjoy a high protein, high copper diet
Cool question. I‘d imagine the easiest way I can at least think of is spraying it with liquid nitrogen. The challenge will be to get the nitrogen back in the bottle and keep it liquid in the meantime.
I think that'd shake out to being an air conditioner with nitrogen as the "air." You'd lose some nitrogen every use, but nitrogen is cheap.
The problem is your piece of pizza would become as brittle and sharp as ice, and likely to injure you if you handled it.
I‘m baffled our usernames only differ by one letter. My idea was, if you „sprayed“ the item from afar, it would cool the surrounding air and only ever so slightly touch that item. I don’t think this would flash freeze it. Feel free to correct me.
There's commercial equipment called blast chillers but it still takes like 10-15 minutes
Part of the problem is if you want to chill something, like a warm beer or bottle of wine, you dont want to freeze any part of it. Sure you could dubk it in superchilled liquid nitrogen at -255 or whatever, but the heat energy leaves the object from the outside, and the liquid nearer the edge would freeze before you got the middle cold. You might also thermally shock the glass and break it.
The fastest way to chill a wine or beer would probably to put it in an immersion bath fully submerged in a dense, thermally conductive liquid like salt water, kept at a temperature of -2 degrees C or so, and a pump to circulate it around, like a cold sous-vide where maximum surfacearea is being exposed to the chilling liquid. If you left it in long enought it might eventually freeze, but you could optimise immersion time and bottle temperature to ensure that its inner heat energy and thermal transfer rate is enough to prevent the liquid at the outer edge from freezig.
If your wine or beer had a magnetic stir bar or something inside to keep the temperature of the inner liquid circulating and thermally consistent, your saltwater bath could go even colder, but that would introduce other problems like nucleating the carbon dioxide in the beer or wine.
There are cheap household gadgets that rotate a can or bottle in a [salt] ice water bath to chill it rapidly. https://www.amazon.com/Chill-Matic-Automatic-Beverage-Chiller/dp/B0148K37K2?th=1 etc
Also more expensive ones with better temperature control for wine bottles.
It is called liquid nitrogen and it is too expensive to store.
It's not just too expensive to store, it's thermodynamically impossible to store indefinitely at room temperature.
Flash freezing is how frozen foods are made.
Blast freezer. It's about as close as we'll get any time soon. Not an affiliate or anything, just googled and found this bugger (about microwave sized).
https://www.nisbets.co.uk/polar-countertop-blast-chiller/ck640
Lemmy sure has gotten popular, bunch of comments that doesn't understand how microwaves work
Commercial kitchens sometimes have blast chillers and blast freezers. Some of the cooking shows use them.
Flash freezing things is a thing.
Well, it does exist, it's called laser cooling, but it's only if you want to have things really cold
You just have to rotate the food the other way in the microwave like in Steins;Gate.
Call it Macrowave!
It's a lot easier to generate heat from electricity than to transfer them out. Closest bet would be just blasting cold air but heat transfer will be slow so it's still quite limited.
Probably not. Nice choice of pic to illustrate the need, though 😄
There is! It's called a blast chiller and just takes a dumby amount of energy proportional the amount of energy removed from the food. It's easier to add than subtract.
Liquid nitrogen bath, works opposite of a microwave, freezes it from outside and towards the middle.
You would need to find a way to make food spontaneously emit microwaves so it loses energy and cools off. That probably involves altering the strength of one of the nuclear forces or something.
What I would like to know is if we will ever have microwaves that stop the spinning plate in the same place that they started. It's XXI century, I want to take out my cup as easily as I've put it in.
It's a pretty specific patent that says you delay the cooking by couple of seconds while spinning the plate to 'synchronize' the start and stop positions. There are more ways to do it so it would be fairly easy to avoid this patent. I don't know why it's not a standard feature.
It could easily be done, but would only work if: you don't stop the cycle manually by opening the door, or you are ok with the microwave quickly spinning your food (or liquid filled cup) to the starting position as soon as you do open the door.
No, what it should do is:
This way you can stop the plate manually at any position but when operating microwave in the usual way you get the benefit of the cup always pointing the right way.
You should try to build a chamber that sprays liquid nitrogen or other cryogenic liquids at the food.
Idk, good luck.
I believe that the problem with this method is that the nitrogen will expand in contact with the hot object, and this being a chamber means that there's risk of explosion.
Yea, but it'd be a really cool explosion.
I'll see myself out.
They never said the chamber had to be pressure tight ...
Win win in my book.
that thumbnail
Yeah, seriously lol
There is a drink chiller that chills drinks in about a minute. You could use the same idea for other things.
The Chill-O-Matic is smaller, cheaper and probably easier to clean as it doesn't seem to have tubing.
The design of that machine in your link is a lot of overkill for something simple.
This was a b plot on the Bam Margera movie haggard.
Falcone wants his royalties
I’m talking about GNAR KILL!
WWWAAAAAAGGGGGHHHH WWWWAAAAHHH WAAAAAHHH WAAAHHH
WOOBADOO
In beer brewing there's a point where you want to cool your beer down as quickly as possible.
A chiller is dropped into the just cooked wort. (wort is the beer before fermentation).
It goes from steaming hot to room temperature very quickly.
It's just a spiral pipe that you run cold water through.
Sounds like you need something like that for a potato.
some kinds of fire extinguisher could accomplish this. bit expensive though.
It occurs to me that you could get some really high-speed cooling with liquid nitrogen (or dry ice and alcohol) but the reality of working with cryogenic fluids is that they're pretty dangerous so I don't think anyone would do that. Unlike a microwave where the dangerous part (the waves) is all self-contained and turns off the instant you open the door.
That's an air conditioner. Or a fridge.
You just need to adjust the output and input sizes. Do to like... physics. It is easier to add heat to a system than to remove it.
To be fair, those are more akin to an oven. As they use convection to cool.
Good point.
https://youtu.be/MHm3fHVZitI?si=mkUIGlaqUUt2NPKs
Furze did it... kinda
I present the Macro Wave!
I don’t know if it’s a stupid question or not but I have been wondering this myself for years. :)