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Travelling at the speed of light

 
author and iconoclast
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A story on Slashdot points to this website which has some computer-generated movies of what near-light-speed travel would look like. It shows the movies, describes them, but best of all, explains the physics very clearly. There's some wonderful stuff, especially the explanation of the fact that an observer near the speed of light can see behind herself. I just thought this was cool -- I've never seen a simulation like this one before. Why haven't any SciFi TV/movies used this? Instead we get those cheesy stretched-out stars on Star Trek. Bleah.
 
mister krabs
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Instead we get those cheesy stretched-out stars on Star Trek.

Because the Enterprise goes faster than the speed of light!
 
Thomas Paul
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Originally posted by Ernest Friedman-Hill:
Why haven't any SciFi TV/movies used this?

Simple reason... rarely does the Enterprise fly down streets. Think about it... what would this effect look like in space? Stars would still be points but they wouldn't be where they were supposed to be. And the viewer would tell this by...?
 
lowercase baba
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Well, Thomas...

Any TRUE Star Trek fans KNOWS how to read a start chart, and can tell when they are not positioned correctly...

 
Wanderer
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[Tom]: Think about it... what would this effect look like in space? Stars would still be points but they wouldn't be where they were supposed to be. And the viewer would tell this by...?

By the additional apparent angular motion of the stars during acceleration and deceleration. During acceleration the stars seem to shift angularly away from the direction the ship is accelerating; during deceleration they shift in the opposite direction. As can be seen in the video, yes?

I remember reading somewhere that back when the first Star Trek movie was made, the producers consulted with some PhDs from JPL to find out what warp drive "should" look like. (Ummm, inasmuch as warp drive "should" even be possible at all.) They got some detailed descriptions from their consultants, but ultimately decided it would be "too unbelieveable" to audiences if they saw that onscreen. Make of that what you will...
 
Thomas Paul
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During acceleration the stars seem to shift angularly away from the direction the ship is accelerating; during deceleration they shift in the opposite direction. As can be seen in the video, yes?

OK, so how would a star that is a pinpoint of light 300 light years away look different under warp drive?
 
Jim Yingst
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Under warp drive - who knows? Since it's essentially "magic" technology as far as we're concerned. It's not clear how they can see anything at all behind them, for example, if they're going faster than light. Attempting to invoke relativity at this point is probably too late to make any sense of it.

Warp drive aside, if we interpret this in terms of sub-lightspeed travel - stars would still look like distant points. Stars ahead would be blueshifted and stars behind would be redshifted - a significant effect ignored in the video. In terms of the distortion effects shown in the video, there would be little way for viewers to tell whether a starfield was relativistically distorted or not except during acceleration or deceleration, when we would see the distortion level changing. Of course that assumes the ship accelerates a significant fraction of lightspeed in the time it's shown onscreen, which takes an awful lot of energy and would proably crush the pilot and crew to jelly if they don't have some sort of spiffy "inertial dampeners". Ultimately, relistic space travel doesn't really fit in with most sci-fi films, as it seems too slow & boring by comparison.
 
Thomas Paul
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Originally posted by Jim Yingst:
It's not clear how they can see anything at all behind them, for example, if they're going faster than light.

Tachyons?
 
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Lets say you are in a ship that can travel up to the speed of light. Behind where you sit there is a light source. You accelerate up to light speed and hold there for a few hours. When you deccelerate aren't you going to get hit with all the light that his been building up for those few hours in the form of something like gamma rays?

Just a thought.
 
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this is definitely very cool, but i do not feel the speed is near light speed. it is more like 300 mile/hour or something, if you look at the building along the street, it takes ~1 second for each block to pass by

but of course, you will definitely get ticket for speeding.
 
Steven Bell
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Maybe that's due to the effects of near light speed on time.
It only seems to you that it takes ~1 second to pass each block.
 
Ernest Friedman-Hill
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No, if you read the explanation pages (which I thought were far more interesting than just the simulations themselves) it explains that what you're looking at is a simulation of near-light-speed travel, if light itself travelled at 30 kilometers per hour; they effect they're going for is lightspeed on a bicycle!
 
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Originally posted by Steven Bell:
Lets say you are in a ship that can travel up to the speed of light. Behind where you sit there is a light source. You accelerate up to light speed and hold there for a few hours. When you deccelerate aren't you going to get hit with all the light that his been building up for those few hours in the form of something like gamma rays?

Just a thought.



No. That wouldn't happen.
You say you can go up to lightspeed. That means that light is still faster than you are and therefore passing you
If you were to go faster, the light would still not form a massive wave front out to get you when you slow down again.

Anyway, anything that has mass cannot travel AT lightspeed. Travel at FTL speeds isn't theoretically impossible though.
If one could somehow get to FTL speeds without having to at some point travel AT lightspeed one would experience free accelleration but having to input ever more energy to slow down to lightspeed. This is the exact opposite from travelling at below lightspeed where the energy expense to accellerate to lightspeed increases as the speed nears lightspeed.

So the trick towards achieving FTL speeds is to find a mechanism by which is it possible to accellerate from non-relativistic speeds to speeds that are far FTL and decellerate again in the same realm without ever coming near lightspeed itself.
 
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Originally posted by Jim Yingst:
I remember reading somewhere that back when the first Star Trek movie was made, the producers consulted with some PhDs from JPL to find out what warp drive "should" look like.



From what I've heard, the Enterprise doesn't move faster than light itself, but creates a warp field thingy around itself, and then moves the field faster then light. While this handily gets around the whole needing infinite acceleration and accidentally turning into pure energy thing, it does seem to bring some other problems. As the Enterprise is merrily zooming around the galaxy, its going to be hitting all sorts of bits of floating crud. Although dust is quite widely spread out, at FTL speeds the Enterprise is going to be hitting tonnes of the stuff every second. It'd be a bit like trying to fly through wet concrete. Now I know it has a deflector shield doodah on the front, but how on earth can this be powerful enough to deflect the mass amounts of mass that it hits? We think the odd fly on the windscreen is bad enough, but that same fly would pulverize the Enterprise if it hit it at these kinds of speeds. Maybe the warp field somehow offers a kind of protection. Any Trekker-physicists out there with the answer?
 
Jeroen Wenting
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My idea is that the warp field itself intercepts those colliding particles and that that's in part why it needs so much energy.
If you follow the series a bit you'll notice that they usually fly at lower warp speeds or even on thrusters in or near planetary systems and gas clouds, probably to prevent the warp field from getting overloaded deflecting those collisions.
 
Ernest Friedman-Hill
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In a later season of TNG, you may recall that they discovered that warp drive contrails were damaging spacetime, although I don't know if there was a good explanation for that. Maybe it has to do with the disposition of those tons of dust!
 
Steven Bell
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Originally posted by Jeroen Wenting:

You say you can go up to lightspeed. That means that light is still faster than you are and therefore passing you



So would that mean in the situation I described, if you were traveling very near light speed, you would be subject to constant low dose radiation near the wavelength of gamma rays?

Although I suppose the question is irrelevant. My guess is that the answer to space travel beyond the local solar system would need to find means of travel other than moving at high rates of speed in our current understanding of dimentional space.
 
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Jim Yingst:

Warp drive aside, if we interpret this in terms of sub-lightspeed travel - stars would still look like distant points. Stars ahead would be blueshifted and stars behind would be redshifted - a significant effect ignored in the video. In terms of the distortion effects shown in the video, there would be little way for viewers to tell whether a starfield was relativistically distorted or not except during acceleration or deceleration, when we would see the distortion level changing.

You would get some visible effects. The starfield ahead would become denser, while that behind would become sparser.

If you take into account the wavelength shifts, which as you point out are a bigger effect, you get more interesting effects. The stars ahead are blue shifted out of the visible spectrum, and those behind are red shifted out of the visible spectrum, so you only see a ring of stars to the sides. This ring of stars in rainbow like, with the forward edge of ring blue, and the after end red.
 
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