- #1
rlinsurf
- 25
- 0
So I'm having a problem actually visualizing what close to light speed travel would look like, both from the viewpoint of an observer on Earth and from the viewpoint of an on-board traveller.
It doesn't seem that any of the visualizations in the movies fit my understanding of it, so maybe I've just done something wrong.
Anyway, here goes.
By my understanding, the classic thought experiment is of two twins, one of whom leaves Earth in a spaceship flying close to the speed of light, the other staying on earth. When the first returns, he appears only a few hours older, while his twin has aged many years.
But as the ship always flies off into space, we never see how each perceives the event itself, only the final outcome.
So I tried changing it a bit. There's a hyper-space Concorde, and it's going from NY to London. It'll be traveling at 2.998 x 108 m/s and will take 15 min. to complete it's journey (ok, so it's a thought experiment. I had to artificially slow it down just to be able to see it. Actually, it would of course take less than a sec.). At the end, about 1000 years will have passed on earth. There are observers at both ends of the journey, one in the middle of the Atlantic, as well as on-board.
Since the on-board clocks will only show 15 min. have passed, but by standard Earth time, it will have been 1000 years, to me, it looks like the ship should continue to appear in the sky for all those 1000 years, going at a rate of, say, 2 feet per minute. In fact, to my mind's eye, the trajectory should be something like:
The Concorde takes off from JFK. From the point of view of the observers on earth, the plane would at first appear to accelerate, then hit some "magic point" where relativity effects would kick in. At that point, the plane would seem to be moving slower and slower, the closer it gets to light speed. At some point, it would hit cruise speed, and continue on, clearly visible in the sky to the mid-Atlantic observer, say, for most of the next 1000 years, going about 2' per minute.
At Heathrow, as the plane decelerates, the observers on Earth would see the plane accelerating faster and faster. Again, a "magic point" where relativity effects would no longer be apparent would come into play, and the plane would then seem to decelerate normally until it came to a stop.
On-board, starting from JFK, the observers would at first see normal acceleration. As the effects of relativity would kick in, the world outside would seem to suddenly slow down, getting slower and slower, until it seemed the world was, again, only moving about 2' per minute. Most of the 15 min. would pass, with the observers seeing only about 30' pass by their windows.
Then, as they approached Heathrow, and began their deceleration, the world would suddenly start to speed up around them. As they decelerated further, the world would begin rushing at them, faster and faster, catching up with the "real" time around them, a thousand years of history in the blink of an eye. Finally, as relativity no longer had an apparent effect, they would see themselves actually decelerate to normal (earth) speed, and stop, now a 1000 years in their own futures.
But let's go even further. Let's say this was a really awesome Concorde, and could actually decelerate beyond the speed of the rotation of the Earth and and even further, slowing down further and further relative to the speed of light (sorry, I couldn't think of how this would work -- just a thought experiment again
.
From the perspective of the observers at Heathrow, the plane would suddenly seem to accelerate as it hit the apparent relativity effects. It would go faster and faster, until finally, it disappeared altogether. A mere few seconds later, a fast moving Concorde would suddenly appear, going slower and slower, hitting that magic point, and then seeming to accelerate again. Finally decelerating to actually slow, and coming to a stop.
From the point of view of the on-board observers, the world would seem to accelerate as they slowed, faster and faster, until it was just a frenetic rush of history. Their on-board clock would show many years as passing. Finally, as they started to accelerate to reach normal space/time, the world would appear to slow down, until they finally reached the point at which there was no apparent relativity effect, and they would appear to accelerate normally, then decelerate and come to a stop, now just 15 min. into their world's future, but their ship an ancient 1000 year-old ruin full of corpses.
This is like nothing I've ever heard of before. Have I just got this all wrong?
Thanks.
It doesn't seem that any of the visualizations in the movies fit my understanding of it, so maybe I've just done something wrong.
Anyway, here goes.
By my understanding, the classic thought experiment is of two twins, one of whom leaves Earth in a spaceship flying close to the speed of light, the other staying on earth. When the first returns, he appears only a few hours older, while his twin has aged many years.
But as the ship always flies off into space, we never see how each perceives the event itself, only the final outcome.
So I tried changing it a bit. There's a hyper-space Concorde, and it's going from NY to London. It'll be traveling at 2.998 x 108 m/s and will take 15 min. to complete it's journey (ok, so it's a thought experiment. I had to artificially slow it down just to be able to see it. Actually, it would of course take less than a sec.). At the end, about 1000 years will have passed on earth. There are observers at both ends of the journey, one in the middle of the Atlantic, as well as on-board.
Since the on-board clocks will only show 15 min. have passed, but by standard Earth time, it will have been 1000 years, to me, it looks like the ship should continue to appear in the sky for all those 1000 years, going at a rate of, say, 2 feet per minute. In fact, to my mind's eye, the trajectory should be something like:
The Concorde takes off from JFK. From the point of view of the observers on earth, the plane would at first appear to accelerate, then hit some "magic point" where relativity effects would kick in. At that point, the plane would seem to be moving slower and slower, the closer it gets to light speed. At some point, it would hit cruise speed, and continue on, clearly visible in the sky to the mid-Atlantic observer, say, for most of the next 1000 years, going about 2' per minute.
At Heathrow, as the plane decelerates, the observers on Earth would see the plane accelerating faster and faster. Again, a "magic point" where relativity effects would no longer be apparent would come into play, and the plane would then seem to decelerate normally until it came to a stop.
On-board, starting from JFK, the observers would at first see normal acceleration. As the effects of relativity would kick in, the world outside would seem to suddenly slow down, getting slower and slower, until it seemed the world was, again, only moving about 2' per minute. Most of the 15 min. would pass, with the observers seeing only about 30' pass by their windows.
Then, as they approached Heathrow, and began their deceleration, the world would suddenly start to speed up around them. As they decelerated further, the world would begin rushing at them, faster and faster, catching up with the "real" time around them, a thousand years of history in the blink of an eye. Finally, as relativity no longer had an apparent effect, they would see themselves actually decelerate to normal (earth) speed, and stop, now a 1000 years in their own futures.
But let's go even further. Let's say this was a really awesome Concorde, and could actually decelerate beyond the speed of the rotation of the Earth and and even further, slowing down further and further relative to the speed of light (sorry, I couldn't think of how this would work -- just a thought experiment again
.From the perspective of the observers at Heathrow, the plane would suddenly seem to accelerate as it hit the apparent relativity effects. It would go faster and faster, until finally, it disappeared altogether. A mere few seconds later, a fast moving Concorde would suddenly appear, going slower and slower, hitting that magic point, and then seeming to accelerate again. Finally decelerating to actually slow, and coming to a stop.
From the point of view of the on-board observers, the world would seem to accelerate as they slowed, faster and faster, until it was just a frenetic rush of history. Their on-board clock would show many years as passing. Finally, as they started to accelerate to reach normal space/time, the world would appear to slow down, until they finally reached the point at which there was no apparent relativity effect, and they would appear to accelerate normally, then decelerate and come to a stop, now just 15 min. into their world's future, but their ship an ancient 1000 year-old ruin full of corpses.
This is like nothing I've ever heard of before. Have I just got this all wrong?
Thanks.
Last edited: