Phillip Huggan, the wikipedia article on tachyons answers your question. Extremely short version (granting tachyons exist): for a tachyon, there is no distinction between the processes of emission and absorption. The attempt to detect a tachyon from the future (and violate causality) would actually create the same tachyon and send it forward in time.
Phillip Huggan, the wikipedia article on tachyons answers your question. Extremely short version (granting tachyons exist): for a tachyon, there is no distinction between the processes of emission and absorption. The attempt to detect a tachyon from the future (and violate causality) would actually create the same tachyon and send it forward in time.