So, I was thinking about tachyons, and I started wondering about what it would be like to be one. How would the universe look from a superluminal vantage point? Tachyons (should they exist) travel faster than the speed of light. But according to the principle of relativity, a tachyon in a superluminal inertial frame must observe light travelling at speed c. However, if the tachyon is travelling away from a light source at a speed > c, then surely the light can never reach it? What about if it was travelling towards a light source at > c - how would the received light appear to the tachyon? What kind of time dilation/length contraction effects would be observable in the tachyon's frame? Also, I've heard that tachyons travel backwards in time. Or rather, that there is always some subluminal observer that observes the tachyon travelling backwards in time. Does the reverse hold true: In the tachyon's frame of reference, does the observer appear to be moving backwards in time? Would a tachyon on a fly-by past the earth 'see' (hypothetically speaking) us going about our lives in reverse?