Superluminal Signaling and Relativity

Steven Weinstein

Special relativity is said to prohibit faster-than-light (superluminal) signaling, yet controversy regularly arises as to whether this or that physical phenomenon violates the prohibition. I argue that the controversy is a result of a lack of clarity as to what it means to `signal', and I propose a criterion. I show that according to this criterion, superluminal signaling is not prohibited by special relativity.