This is necessary for most space dramas but has, apparently, become cliche in the eyes of some publications. That being said...

Is it possible for two spaceships flying alongside each other at FTL speed to see each other through their windows?

(Also let's assume the windows are some kind of tough material instead of glass)
 

The only thing that matters is if you can convince me that it is possible.

Or not.
~Sheena
 

Larry Niven's Known Space universe had space ships built out of a material mined from a white dwarf star. It was impervious and the only thing that could pass through it was visible light, which made its hull invisible to the naked eye.
 

(The inherent problem in your question is that our current physics says that the speed of light is constant, and independent of the speed of the observer. Thus, if you could somehow go faster than light (which the theory says you can't but anyhow) then, since you're going, er, faster than light, how would you ever see anything? The light bouncing off the thing you're looking at would never catch you up, so you'd, er, never see the thing you're looking at. Even if you're looking at another ship going FTL, makes no difference; the light still travels at the same constant speed, slower than you and therefore invisible. I think you'd see black out the window, not the streaks-for-passing-stars you see out of the Enterprise window when it's going where nobody went before at Warp speed. The idea we often see in movies that in FTL space everything goes bendy and psychdelic colours has no scientific basis, methinks.)

In Melissa Scott's "Dreaming Metal", for example, ship's pilot needed special hardware that was AI-enhanced to navigate space at FTL speed; I believe that in her universe it wasn't possible to see out of a ship at all.

I think that, without entirely contradicting current physics, today's SF can posit wormholes -- connections between 'folds' of space, through which ships travel. Although they move at sub-light speeds, ships get the appearance of FTL by taking short cuts through the wormholes from one region of the galaxy to another.

Then it would depend on your imaginary physics; even if a wormhole were large enough for two ships side by side, it might be necessary for a ship to be exactly in the middle of the wormhole for it to transport the ship accurately and safely; then, the windows would need to be fore and aft so that ships could travel one after another in the wormhole yet see each other.

Another factor would be the length of the wormholes. If they literally just connect folds in space, they might be quite short and a ship might not spend enough time inside to observe anything.

[This message has been edited by TaleSpinner (edited May 05, 2009).]
 

Of course, two ships going faster than light, would have an light reflecting off them, to pass behind them. The other ship would not be seen.

One thing that is used for interplanetary travel, is to also use a quirk in physics that we have not solved, to allow faster than light communications and faster than light vision.

I have heard theories that light does not actually travel at the same speed. They have seen signs of evidence that shows that different wavelengths do move faster than others. That might be something that can be used. At faster than light speed, they might be under the speed of certain wavelengths and not others. The computer could correct the images so things have some normalcy to them when looking at the screens and for navigating.
Exotic particles could move faster. One might be seeing by gravitational waves, or some quantum effect.

For faster than light travel, I prefer digging a hole in the fabric of the universe and then traveling in another dimension to the destination.

The main reason that any kind of faster than light travel is needed, is for things to happen on two or more different planets within a person's life time.
Generational ships don't make for the same person being alive when they reach the new world.

 

Once you can go faster than the speed of light, of course, there's no limit to how fast you can go, so the chances of two FTL objects matching speeds and directions exactly would be almost infinitesmal, I'd think.
 

Second, we have recently discovered that light is not the speed limit of the universe. We have found that the universe is expanding faster than the speed of light, which has the entire scientific community wringing their hands. So faster than the speed of light is apparently possible, but I couldn't imagine anyone surviving it unless their was something on the other end to reform the energy into matter, such as a transporter from Star Trek.

Third, warp technology (folding space and traveling at sublight speeds) and wormhole technology (creating tunnels connecting folds in space) are two ways science fiction gets around the problems with the speed of light. Interdimensional travel is another. Two ships traveling on the same warp wave should be able to see each other if they are generating a warp field together but not if they were chasing each other, because folded space would be three (possibly four) dimensional.
 

For example, imagine that you can, in fact, travel through normal time/space above the speed of light, and the light from your pair of ships travels at a fixed velocity. Consider that this light may then describe a cone - a 'light' shockwave inside which your ship can be seen, outside which it cannot - observers behind you can see your ship (with some artifacts of its motion) but observers ahead cannot.

The light cones don't intersect in the present - you can't see the ship next to you now.

Because you're travelling faster than light, the neighbour's light cone cannot catch you and you can't see them in the past either (which is what you can do with stars, let's say).

But, I wonder, can you see the neighbour's light cone in the future? For example, if you are one light-second away, do you in fact see their ship ahead of you, one second in the future? Could you build a technology around this, firing a probe ahead of a ship, and then following the probe in its wake, monitoring the probe's progress to counter events before they've happened?

Yes, it ignores some physics conventions, but isn't that half of the fun of speculation

[This message has been edited by BenM (edited May 05, 2009).]
 

As an adherent to relativity I would opt for space folding or wormholes rather than FTL. And in that case I would stay away from waving at each other through windows. Warp spaced should be an opportunity to describe something much less mundane.

You guys rock. What a fun conversation!!!

(And special shout-out to Pat for giving the clearest and most amusing parenthetical explanation of relativistic effects of FTL travel that I've seen.)

I don't have anything to add to this conversation but a book recommendation. I'm reading a book right now called Physics of the Impossible by Michio Kaku (by way of a recommendation from @MaryRobinette, who interviewed him for a sf pub recently.) It's a rocking good read so far. I'm on the chapter about force fields. Yet to come are Invisibility, Phasers and Death Stars, Teleportation and a number of other fun bits that are frequent guests in my stories. I would recommend you check it out as it's written by a theoretical physicist as a way to explain what science there is currently for these crazy things we think of as sci-fi, and where he thinks we might be going.

He divides the book into Class I, II and III Impossibilities. Class I Impossibilities are things that are impossible today but don't violate known laws of physics. Class II are technologies that sit at the very edge of our understanding of the physical world. Class III are things that violate the known laws of physics, which he points out is a very small group of things (perpetual motion machines and precognition are in this section.)

I've only just started, but it's very interesting and very well-written, I highly recommend it if you're looking for some scientific ideas to jump off.
 

[This message has been edited by Zero (edited May 06, 2009).]
 

If, on the other hand, it is not key to the story.

You could have the character working in the cabin, and a friend comes back from the meeting where it was explained to the passengers.
"How was the meeting."
"They talked about plank theory, quarks, time differencials, phase shifts."
"I thought so." He opens a case.
"Did they use any english?
"No, just a few words here and there, and then not the way we use it."
"I do wish they would speak english when they explain these things rather than scientific. It would make understanding how this works, a lot easier."

The ship, locally, is not moving. It's the local area of space that is moving and taking the ship with it. This bypasses some areas of relativity and solves problems like inertia. You would not feel the acceleration tug as your craft sped up because you are not moving.

Wikipedia has a very nice article about much of this theory:
http://en.wikipedia.org/wiki/Alcubierre_drive
 

Nope, they most definitely are not.

 

Regarding atoms, they can actually be sped up very very close to the speed of light, but their mass increases when they are. An electron's normal orbit is about 1% of the speed of light. Now our bodies are not only made of atoms, but also molecules. When molecule are sped up (as in boiling), they tend to fly apart (as in steam). Plus, since electrons orbit the nucleus of an atom, they could never be going in the same direction at the same time.
 

I found that answer unacceptable so I postulated my own reason. I am guessing this has been given before, but in this short amount of time I haven't seen it. So all you physics brainiacs out there let me know how this sounds, and let me down gently if this is common thought:

The faster you travel, whether on a planet or in a spaceship, the slower your personal experience of time is (it is relative). When you look out in space, whether up in the sky or out of your spaceship, everything appears to be speeding up due to your personal experience of time slowing (the faster you go, the slower your own time seems) versus the rest of the universe. Therefore the light actually catches you "faster" because you are experiencing slower time (the two negate each other, creating a constant speed of light). Inflation affects neither of these, but creates the red-shift.

This is very similar to gravity. The mass of an object increases its attraction (speed), but the greater the mass, the slower its acceleration (the two negate each other and so all objects fall at the same rate). Galileo proved this by dropping two objects of different masses from a great height and showing that they landed at the same time. 350 years later we proved it again on the moon with the famous feather and lead ball experiment.
 

I personally find the animated example on wikipedia helpful in understanding this problem.

I find this comment interesting: The lightpulses that are emitted by the reds at a particular frequency as measured in red time are received at a lower frequency as measured by the detectors of the green fleet that measure against green time, and vice versa. ie, frequency (redshift, blueshift) is measured in and so dependent on the local time.
 

"A Briefer History of Time", by Hawking and Mlodinow, might help. It's more accessible than Hawking's original book and when I read it some while ago I thought I got it. But I can't explain it now, so if my children ever ask, I'll lend it to them.

(The only thing I remember is that the idea of curved space, which means more than four dimensions, helps to explain why the speed of light is constant regardless of the observer's speed.)
 

Slower-than-light travel is possible...but the problem is that reports will never get back to the home planet, and wherever they wind up, that'll be it. Time and distance will ensure it.
 

quote:

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...but it's the only way to get some people to some exotic location beyond our solar system and still be able to have some link to the rest of the universe...

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I have ideas that fulfill this without resorting to FTL travel--not that I am against using FTL--I'm not. It was just your statement that it was 'the only way'.

Absolutism is absolutely flawed.(my own quote!)
 

quote:

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...but it's the only way to get some people to some exotic location beyond our solar system and still be able to have some link to the rest of the universe. That's what I use it for---the worlds I usually write about are Earthlike-with-a-few-differences...

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Obviously FTL doesn't and will likely never exist...your comment seemed to suggest that it was the only way (in a story) to get people to some exotic location beyound our solar system.

Apologies if I got the wrong end of the stick.

[This message has been edited by skadder (edited May 07, 2009).]
 

Another idea: when a jet flies overhead faster than the speed of sound, you don't hear it until after it passes. Perhaps if you fly faster than the speed of light, you'll see some sort of afterimage?

With this sort of thing I'd rather not degenerate into debates over theoretical physics. It usually doesn't even matter, so long as it sounds good, all the characters believe it, and the physics remains the same throughout the story. So there's my two cents.
 

The question of what an audience might willingly believe in an SF story is quite a different one. While I know that FTL cannot be done using known physics, I'm quite happy to go on believing in Star Trek's Warp Drive and its anti-matter crystals, because it's a good yarn.

Interestingly, such stories have been acceptable to SF audiences despite Einstein publishing his theory of relativity at around the same time as SF's Golden Age, if not a little before. (So it's possible to persuade SF audiences to accept science they know is whacky.) I suspect that as more of us grok relativity, and more writers depict FTL in cliches of bright flashes and streaky stars, it becomes less acceptable.

For example, in contrast to Star Trek and Star Wars, we never see Firefly's Serenity entering or exiting FTL. She quickly traverses lightyears, but the writers don't explain how; all we know is that she has an engine, so we can enjoy the drama of the -- single, for heaven's sakes! -- engine failing, without the challenges of getting a modern audience to accept FTL, or some other complicated physics which doesn't move the story along and only risks confusion.

[This message has been edited by TaleSpinner (edited May 07, 2009).]
 

Or did I misunderstand the opening?
 

I doubt you'd get more than one planet with temperate weather in a system.
 

You can't, I presume, terraform sunlight.

 

In the show, they are also referred to simply, though somewhat less properly, as "worlds". During the short television run of the Firefly series, it was not made clear whether the planets and moons depicted were located in one planetary system or many (however, creator Joss Whedon, as well as all licensed products, confirm that there is no faster-than-light travel in the Firefly universe). The opening narration of the film makes it clear that the planets and moons are in one system with "dozens of planets and hundreds of moons." This is supported by production documents published in Serenity: The Official Visual Companion.
 

However the science was not Firefly's strong point, nor was it intended to be.
 

-Fahrion Kryptov

Thus men, extending their inquiries beyond their capacities, and letting their thoughts wander into those depths where they can find no sure footing, it is no wonder that they raise questions and multiply disputes, which, never coming to any clear resolution, are proper only to continue and increase their doubts, and to confirm them at last in perfect scepticism. -John Locke
 

And I submit that there are lots of so-called "science fiction" writers who do exactly the same thing.