Rolls eyes in disbelief at the staggering intellect:
Naz - Yes, I would be, but that would hardly refute the theory of time travel, would it? Rather, it would prove it because I'd travelled back in time (see what I've done there?) and my grandfather had killed me...
Bertie - Imagine I'd built a time machine and travelled back in time? See, the theory of time travel is actually proved there, because I'd built a time machine and travelled back in time.
The wheels on the bus go round and round...