No, backing implies that someone has a legal obligation to supply something in exchange for the thing backed. Gold originally backed USD because paper dollars were literally a contract to pay the bearer a certain amount of gold. Gold and USD now have the same sort of relationship that USD and bitcoin do: neither USD nor bitcoin is backed by anything.
Both are still worth something, at the moment, though, which is all you need for an exchange to be possible.
Both are still worth something, at the moment, though, which is all you need for an exchange to be possible.