Quantum mechanics joke on TBBT?

I heard this joke on the latest episode of the Big Bang Theory today Penny tells the four guys this joke to pull their attention away from a new girl that just moved into a flat above them, and here it is: (A physicist goes to an ice cream parlour every week and orders an ice cream for himself and offers an ice... show more I heard this joke on the latest episode of the Big Bang Theory today Penny tells the four guys this joke to pull their attention away from a new girl that just moved into a flat above them, and here it is:

(A physicist goes to an ice cream parlour every week and orders an ice cream for himself and offers an ice cream for the empty stool sitting next to him. This goes on for a while until the owner asks him what he is doing.
The man said “well I’m a physicist and Quantum Mechanics teaches us that it is possible for the matter above this stool to spontaneously turn into a beautiful woman who might accept my offer and fall in love with me”
The owner says” well there are a lot of single beautiful woman come in here every day, so why don’t you buy an ice cream for one of them and they might fall in love with you”.
And the physicist says “yeah, but what are the odds of that happening”!)

What does it mean spontaneously turn into a beautiful woman? What exactly does quantum mechanics teach us? That matter can suddenly change and take a different form?
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