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?
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?
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.
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.
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.
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.
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.
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:
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
Commercial kitchens sometimes have blast chillers and blast freezers. Some of the cooking shows use them.
Flash freezing is how frozen foods are made.
Lemmy sure has gotten popular, bunch of comments that doesn't understand how microwaves work
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!
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.
Probably not. Nice choice of pic to illustrate the need, though 😄
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.
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.
There is a drink chiller that chills drinks in about a minute. You could use the same idea for other things.
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.
I present the Macro Wave!
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Yeah there are those machines that like instantly cool your soda can or make ice cream instantly supposedly. They just bathe it in ice and salt water for some time basically
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https://youtu.be/MHm3fHVZitI?si=mkUIGlaqUUt2NPKs
Furze did it... kinda
Fridge, well. But now I'm wondering if that would be possible with electromagnetic radiation somehow. Would it be possible to direct infrared waves away from a closed chamber, making the inside cooler? Like a semipermeable membrane in shoes with water vapor?
I don’t know if it’s a stupid question or not but I have been wondering this myself for years. :)
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I've been wondering this for my entire life
yeah, not only microwave but heater in general... but reversed, i asked myself that question for a long time, i mean we pump an electricity into the wire and we get heat, why not reverse? why we can "magically" get heat from electrons but to get something cold we need to pump the heat elsewhere, like microwave basically make atoms vibrate generating heat, would be cool to be able to generate some field that makes atoms stop
If I read the question correctly, you mean refrigerator?
i would think not. unless waves can be tuned to cancel out background radiation, but that would only stop it from heating up more.
'projecting' energy is kinda easy... 'sucking' energy is difficult
a can of soda can cool faster in the freezer for ~30 min.
some people suggest adding an insulated sleeve.
i also use freezer to cool down coffee quickly.
< deleted. pls find info on fb/yt > ..Given how much about science we still have to learn, I would say it is a distinct possibility. If you want something cheap and easy to use like a microwave to do this though, I highly doubt we'd see that possible for the next 30-40 years at minimum.
A freezer?
https://m.youtube.com/watch?v=Cb_s_8aEVuQ
They trial'd something similar on the snowpeircer train instead of treats like ice cream for good behaviour they froze your arm off for being naughty lol
It's a good job they didn't have that when I was at school because I'd be just a head and torso now lol