...theoretical availability of bitcoins? A Florida man bought a Tesla Model S car from a dealership in California, using bitcoins. The parties agreed on a third-party intermediary who converted the bitcoins into US Federal Reserve Notes.

Got me thinking: The originators of Bitcoin have said there's a cap on the maximum number of bitcoins that can be created. But if a holder of bitcoins chooses to trade them for another currency, do those bitcoins "go away" forever once they are converted into dollars, kroner, baht, what have you?

Anyone know?