Why isn’t there a microwave for cooling things instead of heating them up?


There are only 3 ways to transfer heat into or out of something: radiation, conduction, and convection. A microwave, not surprisingly, uses microwaves (radiation) to transfer heat. It’s very easy to add energy through radiation. You just blast whatever it is you want to heat up with microwaves. The microwaves are absorbed by water, fats and sugars. Once absorbed, they’re converted directly into atomic motion, meaning heat.

To cool something down this way is another story entirely. Instead of just blasting something with microwaves, you have to hit it with very specifically tuned and timed microwaves to counteract and dampen the atomic motion. This is a very nice analogy: it’s easy to throw something at a bell to make it ring, but it’s a lot harder to hit it with something to make it quiet.

A “reverse microwave” would undoubtedly be an amazing invention. Right now, we waste a great deal of energy on cooling items, and keeping them cool. With a reverse microwave, you could cool that same item in a fraction of the time, using only a fraction of the energy. Though I’m afraid something like a reverse microwave might never exist. Active radiative cooling just isn’t very practical.

You might come across products that claim they can do it (e.g. http://www.ohgizmo.com/2013/10/29/reverse-microwave-chills-drinks-in-seconds/), but don’t be fooled. This impostor doesn’t use radiation at all. Instead it uses ordinary conduction & convection.


3 thoughts on “Why isn’t there a microwave for cooling things instead of heating them up?

  1. The biggest difference between ringing a bell and heating up something is that the vibration of the bell is directive while the movement of the atoms of a heated up object is non-directional. Therefore to make it quiet is not that hard from my perspective, as you can refer to the Bose’s QuietComfort series using active noise cancelling tech. So we can still believe some microwave-like technology may be created that can slow down the movement of the atoms in a active way besides conduction and convection. _(:з」∠)_

  2. I know for heating up, radiation cannot make things cooling. This is the way of heating up and this is the function of microwave. Could you explain detailed how microwave works? It is heating up the cell of the things inside or another way?

  3. Indeed, compare with cooling a thing with heat up a thing cost much more. I think the reason is the average temperature on earth quite high, and some times the temperature we need is lot lower than that. There is a theory said that”after infinite long time, everything in the universe will be in the same temperature”.
    If you can image, we are living in a world which is in absolute 0 degree, then we just cost 0 to cool a thing, and need to pay to heat up a thing.

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