I'm not so keen on the calculations needed, but with current technology, how long would a light-year-long trip take? 1500 years? 200?

Depends on how fast you're going. If you're travelling at light speed, 1 year, by definition.

Figure it out yourself.
Assuming you're undergoing constant acceleration, the formula is s=ut+a/2*t^2 .
Let's make a couple of assumptions:
You start with zero speed.
You're undergoing constant acceleration of 10m/s (gravity on Earth, more or less (well, more actually)).
Half way there, you're going to turn around and undergo constant deceleration of 10m/s. This way you'll have zero speed when you get there.

So: for the first half lightyear, s (distance) = (a/2) * t^2 = 5 t^2.
So when you know s in meters (c=299792458m/s), divide by 5, take the square root and there's your time in seconds. There's half the journey; double it for the whole one.

None of this takes time dilation into account, of course.

I did a bit of a calculation and came up with this, I hope I got it right;)


Light travels 9,454,254,955,488 Km per year.

Spacecraft travels at around 50,000 Km per hour 438,000,000 Km per year

Just over 21,585 years to cover the distance.


Here's some refs. for a bit of thought.


240,000 miles - Distance from Earth to Moon

93,500,000 miles - Distance from Earth to sun

3,695,000,000 miles - Distance to Pluto at its most distant point

19,000,000,000,000,000 (19 quadrillion) miles (3,200 light years) - Approximate distance to nearest black hole candidate A0620-00

See this is why I'm majoring in English. :)
Seriously, there's a vague awareness of anything as far as my left brain is concerned.
That and I have no effort.. INSTA-PHYSICS!
I guess I shouldn' hang out in SCIforums then, eh?

you should stay, this place seems cool:) if you believe that you cant accelerate past the speed of light then you can go up to it but not beyond it. time dilation is when as you approach the speed of light time slows down for you. if someone was watching your craft leave they would see it going infinitely slow and stretch out then it would seem to "snap" and seem to accelerate all at once. from inside the ship you would see everything else going infinitely slow also.if you acheived the speed of light or beyond it then even light would seem to stretch out and slow down. if you ask me i say damn the acceleration and just use some sort of ftl drive or some sort of "insto-travel" device. this is how I understand it. i may be wrong but their are many theories as to what would really happen as you started to accelerate to and past teh speed of light.

As I understand it, one of the things that happens when mass approaches light speed is that it [Mass] approaches infinity, hence it would take infinte energy to accelerate any mass to the speed of light. I think that is one of the reasons why light speed is seen as the limit (i.e. never go faster than the speed of light).