I am nearly finished a grade 12 physics course, and am loving it, however there is one theory from the entire course that is making me go insane. And as you may have guessed (since it is the subject) is the lovely dilated time theory (or law, or whatever you want to call it).

So, from what I've read, it can be solved through a mathematical equation that someone on a moving object, could essentially witness the birth and death of a solar system because they are moving so fast in their space shuttle? Let's look at the twin paradoxs: You leave earth at some amazing, incrediable speed. You start traveling when you are only 10, and travel across the universe. When you return, you are now 90 years old, while the earth may have passed near 400 years. (those being extreme conditions/speeds)

How exactly is this possible? You can live your entire life on a spaceship, traveling at immense speeds and return to possibly find your race extinct (I say that because at the rate our civilization is going, +400 years is probably not going to happen :P).

I have been running this through my mind. Here is how I look at it:

E = Earth, S = Spaceship, P = Planet

E ====> S ====> P

While traveling on a spaceship, from earths reference, it takes you 5 years to travel to a nearby planet.

E <==== S <==== P

While returning on a spaceship, from earths reference, it takes you another 5 years to return.

Thus, Earth has passed 10 years, and you have passed 10 years.

From your reference on the spaceship, would it not also appear to take 10 earth years for the entire journey? (365 days, 24/7, etc.)

Second, if all measurements have been on Earth for recording this data/mathemathical equations for physics over the past millenia, how is it possible for us to create a time dilated equation if it is saying something that we cannot test (ie. spaceflight time dilation)?

Can anyone explain this to me without going deep into physics termology. I mean, it is hard enough figuring this out with all the physic terms. Is it possible to define any other way? :)

Thanks for any input, hopefully this is the last hurdle I have to think about :)