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An additional refinement is that a fully empty glass empty of air, i.e. in a vacuum, would be full of quantum foam. If you are ever served a pint of a quantum foam of virtual particles in a bar pay the man with virtual money. Virtual money appears as money and antimoney before cancelling iteslf out in a time so brief as to render the money undetectable except as a solution to Schroedinger's equations irrespective of the Fermionic mode or Bogoliubov transformations. It's more widely known as, 'having a mortgage'.
Antimoney isn't all that rare as a substance. My bank account is full of it. I have no idea what happens when it meets real money, as this has never happened.
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