"Ground Zero"
Testing of an atomic blast, 1953
Public DomainTesting of an atomic blast, 1953 - Credit: United States Department of Energy

This reference is another inaccuracy, though most likely a deliberately ironic one. The term Ground Zero here refers to the hypercentre of an atomic explosion, and was first used by those involved in the Manhattan Project. It was therefore not in use before 1945, making it anachronistic at this point in Gravity's Rainbow.