i understand about the differing frame of refrence Punoqllad. But Earth and Alpha Centuri are real points (a and b) seperated by a distance 4.5 lightyears. it would take light 4.5 years to get from one system to another. If I took one of those slow ships traveling at lets say 0.1c it would take me about 45 years. now we know from an observers point of view nothing can exceed the SoL, and only light itself can travel at the SoL. fine
As the ship is aproaching c, time slows down for the ship’s crew and space itself contracts in the direction of flight. time and space are vastly diffrent from 2 frames of ref. but time still goes on on the ship. when the ship decelerates at Alpha Centuri back down to its velocity it was at when it started the trip (at real point a) it would be at the real point b. The time for the trip as seen by the observer on earth would have taken many years (would that be 4.5+ yrs at 0.999c?), but how long has it taken for the crew, in other words how many years have they aged since they left? now this is open ended, it depends on the speed relitive to the start or destination point, but it seem like the crew could make the trip aging only 3 yrs
Yeah, k2dave, you could reach Alpha Cen in three years, as measured by a person on the ship. Of course, we don’t currently have any hope of a spacecraft that fast, but as long as it stays below the speed of light, it’s a problem of engineering, not physics.
k2dave:
Yes, you could travel to Alpha Centauri in a month of shipboard time, if you traveled at a high enough fraction of c. But it would seem to the people back at earth that it took you 4 years. You can lower your ship-board time to whatever you like, as long as you can increase your velocity to an arbitrarily close fraction of c…the closer to c, the shorter the trip. You can’t travel faster than c, but from the perspective of an observer on a ship, it seems as if you can…you can travel 4.5 light years in what seems to be 3 months, say.
So, if you set out for the the Zaxulbrtz galaxy in your arbitrary ship, and set engines for .999999c, you could cross millions of light years in what seems like years, weeks, days, or seconds, depending. Of course, when you get back to Earth, everyone will have green tentacles and you’ll be put in a zoo as a sub-human life form.
Heinlein’s classic novel, “Time for the Stars” explores this. Tom sets out on a relativistic ship to explore the local stars, in telepathic contact with his twin Pat. He crosses dozens of light years, but he only ages a few years himself, while his twin gets older and older. Of course, we have the problem that Heinlein’s torch ships wouldn’t be able to carry enough reaction mass to continuously boost at 1.25 g for several years, and of course telepathy doesn’t happen, and if it did, it wouldn’t be FTL. But everything else makes sense.
Or Ursula K. LeGuin’s novels, postulating Nearly As Fast As Light travel…you can get to other planets in a few seconds, but everyone back home will have aged as many years as the distance you traveled. This is fine if you don’t want to come back.
[Yeah, k2dave, you could reach Alpha Cen in three years, as measured by a person on the ship]
that’s what i wanted to know, now the next step is calculating the mass of fuel required to do this
Thanks