Theoretical Physics discussion

I'm making this, mostly, because a staff member asked for me to make a proper thread for this, but also because the other one was getting a little cramped.

In here, do the title.

Also remember that Iam not all knowing on this type of thing; Ionly read about it. Alot about it.

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So we left off here, with this question.

"Question time!

So, let's say we put a person on a space craft which is 30 years old and let that space craft travel around at or near light speed. If 50 years would pass on earth how old would he be on the space craft? And what age would he have when he'd go back to earth, after? Would he be 80 then, or that age that he'd have on the space craft?

Also, how would that effect the human body? (Not the years in the space craft, but the time thing). Would the body age slower, too?" -Carpesir

So to find the amount of time dilated we would use the Lorentz (time dilation) equation which is:

t=to((1-(v^2/c^2)))

(t) is the time dilated. (to) is the time outside of dilation. v is the speed. and c is the speed of light.

A note to make while using this equation is that if you are traveling light speed you will get 0, which means you do not age, but if you do a speed more than light, you will get a negative number, resulting in an unreal answer (which is one of the reasons why FTL travel appears impossible).

That being the case, lets use a speed a little slower than light - say 279 792 458 m/s

So, using this we get:

t=50((1-(((279792458)^2)/((299792458)^2))))
t=17.955
Which would mean, even though the earth experienced 50 years of time, the person in the spacecraft going at the speed 279 792 458 m/s would only experience about 18 years of biological change.