I'm very unfamiliar with them, just curious about the subject, so maybe you can help me out. I know that the speed of a (hypothetical) tachyon increases as its energy decreases, and that it can't go v <= c. Assume that by natural processes, the tachyon loses energy, as most things we know that interact do (even if it's interacting with other, similar particles, and not the ones we are familiar with). If would therefore gain speed. What if the energy goes to 0? Would it have infinite speed? Or is there a limit to how low the energy can go, or how high the speed can get?