He aged while travelling?
If he travelled at multiples of c then he'd actually be going back in time wouldn't he?! Just like when Superman rounded earth many times to turn back time. So how could he have aged seven years?
shareWell we have equations to calculate time dilation, that is a fact of life and has been proven correct over and over again and that has to be taken into consideration by gps satellites or they'd give us the wrong position.
Well if you use that equation on faster than light speed travel then you end up with i, an imaginary number. Your equation forces you to take the square root of a negative number to get a result if you input a number faster than the speed of light. There is no real number multiplied by itself that becomes a negative number, thus there is no real unit of time that passes by.
So essentially for every second of time we experience here on earth a multiple of an imaginary unit of time passes by for him. I have no idea what the implications of this would be in real life. I mean imaginary numbers are a mathematical construct (or so I believe) so you calculate things like the square root of negative numbers. For example, the square root of -64 = 8i, not 8 and not -8.