If relativity theory is correct, no object can travel forward in time at a speed greater than the speed of light. Yet quantum mechanics predicts that the tachyon, a hypothetical subatomic particle travels faster than light. Thus, if relativity theory is correct either quantum mechanics' prediction about tachyon is erroneous or tachyons travel backwards in time.
OA is Strong
Tachyon is a hypothetical particle. Can't the relatively theory be talking about non-hypothetical objects. That is the only loophole I observed in the argument and thought could be the sole hint.