Impulse speeds and time dilation

[Penta]

Okay, this has been bugging me for a bit.

Somewhere, deep in the recesses of my brain, I remember seeing something that stated that full impulse was only 0.25c, in a bid to not hit the worst of relativistic effects.

Of course, now that it matters for some writing I'm doing, I can't find a canon (or even Memory Alpha) reference to that effect.

So:

1. Has anybody else ever heard that? If so, where?

2. If not, how might one go into higher sublight speeds while not being hit by time dilation and the other relativistic effects?

 

[sojourner]

Not sure about 1, but the answer to 2 is "you don't". Physics pretty much controls that. Though the time dilation isn't severe until you get above .7c or .8c if I remember correctly.

 

[Christopher]

Okay, this has been bugging me for a bit.

Somewhere, deep in the recesses of my brain, I remember seeing something that stated that full impulse was only 0.25c, in a bid to not hit the worst of relativistic effects.

Of course, now that it matters for some writing I'm doing, I can't find a canon (or even Memory Alpha) reference to that effect.

It's not canon; it's from the TNG Technical Manual, p. 78. And it tends to be misconstrued in fandom. It's a mistake to say that "full impluse equals 0.25c," because "full impulse" isn't a speed, it's a power level, an acceleration. At full impulse, you'd be accelerating as fast as you could, not traveling at a "maximum" speed.

The actual statement in the TNGTM is merely that normal impulse operations are limited to 0.25c and below to avoid time-dilation effects -- not because the effects are significant at those speeds, but because they're enough to throw off the ship's clocks relative to other clocks, which is an inconvenience. Also because impulse drive efficiency drops off above about 0.5c.

To be specific, at 0.25c, shipboard clocks would be about 97% as fast as external clocks. At 0.5c, it would be 87%. At 0.75c, it's 66%. At 0.9c, it's 44%. At 0.99c, it's about 1/7.

2. If not, how might one go into higher sublight speeds while not being hit by time dilation and the other relativistic effects?

By employing a warp drive at less than 1000 millicochranes, if we assume the ST warp principle is along the same lines as Miguel Alcubierre's theoretical model. An Alcubierre warp drive is free of time dilation effects at any effective velocity, because time dilation cancels out of the equations when you compare shipboard time to an external observer's time.

 

[Mister_Atoz]

I've never liked the idea of an "intergalactic speed limit" and until someone writes it into a script, I tend to ignore it. I'm sure there are many sitautions where you would want to travel faster than .25c without going to warp, and frankly reducing the relative travel time for your crew seems like a good idea.

My guess is us 21st century audiences are just a little uncomfortable with the idea that time is relative, and that passage in the TM is intended to excuse the writers who tend to ignore it.

 

[sojourner]

^Well, time dilation does make story telling difficult when the crew of the ship outlives everyone.

 

[Christopher]

I think the TM reference was just about plausibility. It takes vast amounts of energy to accelerate to high relativistic velocities. If you have a magic-tech shortcut that lets you actually go faster than light for a reasonable output of energy, it just makes more sense to use that for high-speed or long-distance journeys, so it stands to reason that impulse drive would be used mainly for travel at the kinds of speeds you'd use for interplanetary journeys. I mean, don't make the mistake of assuming that 0.25c is in any way "slow." That's better than 2 AUs per hour. It's fast enough to get from the Earth to the Moon in six seconds. For an interplanetary journey within a single system, it's really quite fast.

Also, the faster you go at sublight, the greater the danger you face from space debris and radiation. At high relativistic speeds, the kinetic energy of oncoming dust grains becomes comparable to a nuclear explosion, and the light of the stars in front of you becomes blueshifted into deadly gamma and x-rays. Traveling at really high sublight velocities isn't only unnecessary and inefficient, it's just plain undesirable. If you have the option of using warp drive instead of relativistic impulse speeds, you'd be insane not to.

So it really makes perfect sense to say that impulse operations would normally be below a quarter of lightspeed except in unusual or emergency situations. Especially since it was never stated as a "speed limit" despite the way fans misconstrue it. It was merely said that normal impulse operations don't exceed that range. And really, there's no reason why they would.

 

[JarodRussell]

It's not canon; it's from the TNG Technical Manual, p. 78.

lol, I hope you actually had to look that up. Would be kinda scary if you knew the page numbers.

At high relativistic speeds, the kinetic energy of oncoming dust grains becomes comparable to a nuclear explosion, and the light of the stars in front of you becomes blueshifted into deadly gamma and x-rays. Traveling at really high sublight velocities isn't only unnecessary and inefficient, it's just plain undesirable. If you have the option of using warp drive instead of relativistic impulse speeds, you'd be insane not to.

What happens if a ship at warp hits a dust cloud?

 

[Basill]

What happens if a ship at warp hits a dust cloud?

That's where the navigational deflectors come into play, sweeping said matter out of the ship's way.

 

[JarodRussell]

What happens if a ship at warp hits a dust cloud?

That's where the navigational deflectors come into play, sweeping said matter out of the ship's way.

But they wouldn't work for ships moving at high relativistic speeds?

 

[Shazam!]

Wasn't there a whole bit about time dilation and impulse speed in one of the Destiny books?

 

[sojourner]

What happens if a ship at warp hits a dust cloud?

That's where the navigational deflectors come into play, sweeping said matter out of the ship's way.

But they wouldn't work for ships moving at high relativistic speeds?

Why not?

 

[JarodRussell]

At high relativistic speeds, the kinetic energy of oncoming dust grains becomes comparable to a nuclear explosion, and the light of the stars in front of you becomes blueshifted into deadly gamma and x-rays. Traveling at really high sublight velocities isn't only unnecessary and inefficient, it's just plain undesirable. If you have the option of using warp drive instead of relativistic impulse speeds, you'd be insane not to.

What happens if a ship at warp hits a dust cloud?

That's where the navigational deflectors come into play, sweeping said matter out of the ship's way.

But they wouldn't work for ships moving at high relativistic speeds?

Why not?

The answer to this question depends on what difference is there between

1. What happens if a ship moving at warp hits a dust cloud?

and

2. What happens if a ship moving with impulse power at high relativistic speeds hits a dust cloud?

Christopher already answered question 2. And so we have come full circle and returned to my original question 1.

 

[Ronald Held]

Which is why the time dilation effects on the USS Columbia seem suspect, since impulse engines and its associated fields are not governed by Special Relativity.

 

[Christopher]

One can assume that the warp metric (the spacetime geometry that generates the warp field) would be shaped to shunt incoming matter away from the interior of the warp bubble.

 

[Ronald Held]

I agree with that Christopher, except for a head on collision of matter or radiation

 

[timelord1010]

I was under the impression that a starship's warp field actually "warped" the space around the ship so the ship and the immediate space around the ship had zero velocity while the ship was in the warp bubble and this bubble traveled faster than light.
Another option is when the ship goes to warp it travels thru subspace. But then the subspace idea doesn't work with Riker ordering the Enterprise-D to warp into the Borg cube in Best of Both Worlds part 2.

Either way the ship would avoid a high speed impact with particles or radiation and also avoid the power problems of the ship's mass increasing as it got closer to the speed of light. This could be a reason why Starships are limited to .25c since the closer you get to the speed of light the greater your mass becomes and more energy is needed to move your ship and light speed is infinite mass and the only thing that can travel at the speed of light are photons. Then on the other side you have tachyons that travel faster than light but can't slow down to the speed of light.

I always liked the Starblazers or NuGalactica jump engine technology that was used in TNG episode "nth degree". Your ship creates a Einstein/Rosen bridge and jumps from one place in space/time to another but then that takes the drama of racing across the galaxy out of the stories.

 

[SoM]

Another option is when the ship goes to warp it travels thru subspace. But then the subspace idea doesn't work with Riker ordering the Enterprise-D to warp into the Borg cube in Best of Both Worlds part 2.

I tend to think that "warp ramming" involves either (a) getting close at sublight then going to warp in such a way as to partially envelop the enemy ship, ergo your warp field tears them to bits or (b) timing your coming out of warp so you "land" inside the enemy ship.

Either way, it's notable that TNG-era ships are discouraged from warping into or in planetary systems, but it's a "Should Not" rather than "Must Not", meaning that there's a significant risk, but not certain disaster from it.

 

[Scout101]

I always liked the Starblazers or NuGalactica jump engine technology that was used in TNG episode "nth degree". Your ship creates a Einstein/Rosen bridge and jumps from one place in space/time to another but then that takes the drama of racing across the galaxy out of the stories.

Makes more sense, but less drama in the 'traveling from place to place', plus makes it difficult to run into new things if you're just popping in and out.

Also, the way BSG used it make the show kinda look retarded. Untraceable, large radius every time, but somehow they get chased across space for years! Even allowing for the tracking devices and such, the math after even a couple jumps makes chasing someone almost impossible. Every time they jump, you've got a huge sphere of space to search. And from any point in that sphere, they can jump again, and again, and your search radius becomes an entire galaxy very quickly.

The story meant they had to be chased, but it felt dumb to me with the tech...

 

[Christopher]

I was under the impression that a starship's warp field actually "warped" the space around the ship so the ship and the immediate space around the ship had zero velocity while the ship was in the warp bubble and this bubble traveled faster than light.

That's basically the idea, yes. The geometry of spacetime is changed around the bubble so that its distance from its origin point increases while its distance from its destination point decreases. In a sense, it's "surfing" on a spacetime distortion.

Either way the ship would avoid a high speed impact with particles or radiation and also avoid the power problems of the ship's mass increasing as it got closer to the speed of light.

The warp field itself would still be impacting with those particles and radiation. I've read a research paper or two saying that they could penetrate to the interior of the warp, but I'm not sure how reliable they are. (Although the problem of impinging radiation from ahead of the warp field would be trivial next to the problem of the runaway stress-energy tensor generated by the field itself, which would tend to vaporize anything inside the warp field. If that problem could be solved, the problem of navigational hazards would be a relative snap.)

This could be a reason why Starships are limited to .25c since the closer you get to the speed of light the greater your mass becomes and more energy is needed to move your ship and light speed is infinite mass and the only thing that can travel at the speed of light are photons.

Once again: starships are not "limited" to 0.25c. That is a myth, a misreading of the TNG TM. What it says is that normal impulse operations tend to remain below that velocity, because if you need to go faster than that, it's safer and more efficient to go to warp. But it's not a strict limit, just a convention.

And once again, you'd need to get far, far closer to c than 25% before the mass increase became a noticeable problem.

 

[Ronald Held]

The Phoenix was travelling nowhere close to c when it went into warp.