I have an older Panasonic microwave with a turntable. I’ve noticed that when I stop, then start it it reverses the rotational direction of said turntable.
Cool, huh? 
Does your’s?
They all do that. The type of motor–a synchronous induction motor–will start randomly in one direction or the other. There’s no particular reason for it, except that the motors are cheap and it’s one of the few motor-driven applications where direction is unimportant. Another neat trick: Nearly all of them complete one full turn every ten seconds, so if you put your coffee cup in the front and set the timer for a multiple of ten seconds, it will always return to the front in easy reach.
I’d often wondered about that. Not enough to look into it, but I noticed.
I’ve noticed that about microwaves, too; one revolution every ten seconds. It’s handy if I put a mug in, handle facing the door, and hit it for 30 seconds or so.
I also have a fan that uses a synchronous induction motor for the oscillation function. If you turn on oscilation (it’s keypad-driven) it’ll randomly pick a direction to start in.
I wonder if that holds true here (UK) , where the frequency of our AC is 60Hz. Will test this later.
Mine (an old model) doesn’t seem to start in a random direction each time, but reliably reverses every time I open the door, then close it again in the middle of a cycle. I’ve never known this to NOT happen, in 15 years of using it.
It’s the other way around, US is 60Hz, UK is 50Hz.
Nope. My microwaves are commercial and do not have a turntable. 
Boring. I thought by “reversing microwave” you meant you could use it to chill a warm bottle of beer in 20 seconds. 
As Og is my witness, I’ve had it in my mind to invent the mirror twin to the microwave for years. Just as you describe: Put something in that’s warm, set the timer for an appropriate length, and within seconds (or a few minutes if it’s hot) you’ll come out with a nicely chilled (possibly even frozen) item.
I just have to figure out a way to get the magnetron to work in reverse so that instead of exciting particles, it progressively bores them into a state of relative inactivity without the need for gases like freon or liquid nitrogen. I’m certain it’s possible, but my experiments – which thus far have only involved installing the magnetron backwards – have not quite been the successes I had hoped for.
Not only does my micro reverse directions, the turntable slides from side to side as well. ::adopts look of smug superiority::
Oops. Yes.
So mine might be expected to make a circuit every 12 seconds (I think it’s faster than this, but we’ll see later.)
I don’t watch it. It would be so hypnotic it would . . .
it would
it would
it
If it is an old microwave I hope you have checked it’s output recently. I just checked mine after a couple of heating “disasters”. Bought a new one for $99.
Anyhow this is how you do it:
Put 1 litre of 20 degree C water in the microwave.
Heat for 63 seconds.
Stir.
Measure the temperature.
Take off 20.
Multiply by 70 = wattage.
I’ve often wondered why someone doesn’t invent the “reverse microwave.” A product that would instantly chill would be so useful.
We also need a microwave clothes dryer.
I think entropy gets in the way, unfortunately.
Start with inventing something simpler, such as the darkbulb, then work up to the anti-microwave, would be my suggestion.
Of course if this were a B movie, you’d just have to reverse the polarity. For a Doctor Who (3rd Doctor, at least) episode, it would be reversing the polarity of the neutron flow.
On Iron Chef, they use a thing called a Blast Chiller. Now I’m going to have to look that up and see how close that comes to a reverse microwave. I’m guessing there are no waves involved. Or neutrons.
Ye’s - mine doe’s.
And once you’ve perfected that, get to work on the Ginster’s anti-pasty, which will make me slimmer and healthier as I eat.