Disturbances of Warp Drives

[recon14193]

I have seen some news about development of warp drives and watched some videos about them. I see how they bend the space in front of and behind them and that made me think. Could this disturb the orbits of planets and celestial objects if it is used because the force I know of in the universe that can bend the fabric of space is gravity, or at least how i see it is demonstrated in videos I see when they show a fabric to represent space and gravity.

[K^2]

Outside of the warp bubble, the space-time is flat. So there is no gravity generated by warp drive out there. There is also the interior region which is flat. The space ship is located in the interior and also does not experience any gravity. And then there is the boundary region in between. That's what actually makes the warp bubble a warp bubble, and space-time there is very much distorted. That does result in quite a bit of gravity acting on anything that passes through the warp bubble boundary. The boundary could extend quite a bit around the ship, in which case, you can run risk of damaging something or throwing it out of the orbit, but to shift something as big as a planet, or even a small moon, you need an enormous amount of energy. If we need that much to make the warp drive work, we might never get that far with it.

At any rate, any safe operation of the warp drive would be such where there are no objects within the bubble boundary. In which case, you do not run any risk of affecting orbits of planets or the like.

[Scotius]

I wonder if it would be possible to use Warp Drive as a normal, sub light engine? Set it to low power mode, aim at a point somewhere near Mars and let'er rip without going FTL.

[K^2]

Warp drive isn't really a propulsion device in the traditional sense. You can use it to get somewhere faster, even without going FTL, but you can't use it as your only drive.

[Scotius]

So it just gives you a lift, and then leaves you in space, with only the speed you already had. As a result you have to use another, conventional engine to match your speed with your target. For example: Warp gets you from Earth's orbit into general vicinity of the Mars, and when field drops you still have only Earth's orbital speed which is higher than martian. So you have to use your NERVA engine to do correct insertion burn into martian orbit. Did i got it right? Still, it seems to save a lot of dV, not to mention time. You don't have to reach escape velocity, then do translation burn - you only have to brake yourself into orbit around Mars.

[K^2]

You know... I have no idea how a warp drive would affect orbital flight. It might be that you'd follow the same trajectory you would without it, only faster. And I don't even know how to do the math required to check that. I can do very basic math with the warp metric and I can do very simple math with the Schwartzschild metric, which would describe gravity around the star. But combining the two? That requires solving Einstein Equation for the combination, and while there is probably a good way to do this approximately, I wouldn't know where to start.

[nyrath]

Alcubierre's warp drive would totally ignore orbital trajectories, it would move along a direct geodesic. Since it is making a pocket universe to cut off the effect of relativity, it would also cut off the effect of gravity.

Problems include:

• There does not seem to be any way for the ship inside the warp to stop the warp
  
• creating the warp takes about 12 times as much energy as is contained in the entire universe
  
• When the warp is released, a huge blast of radiation vaporizes anything in its path
  
• 
  

[OdinYggd]

In Star Trek lore, they always tried to avoid using warp drive while within a planetary system precisely because of the risk of disrupting a planet's orbit or damaging it directly.

Though more than once it was done anyway, once they were sure that they had safe distance to any major bodies so as to not damage them with spacial distortions.

[architeuthis]

Alcubierre's warp drive would totally ignore orbital trajectories, it would move along a direct geodesic. Since it is making a pocket universe to cut off the effect of relativity, it would also cut off the effect of gravity.

Problems include:

• There does not seem to be any way for the ship inside the warp to stop the warp
  
• creating the warp takes about 12 times as much energy as is contained in the entire universe
  
• When the warp is released, a huge blast of radiation vaporizes anything in its path
  
• 
  

I wonder how momentum is conserved through the warp. It seems to me that even if you have this warp drive you would still need 30-50km/s of delta-v to match Hubble velocities with other star systems (unless you didn't mind hurtleing past them post-warp).

[nyrath]

I wonder how momentum is conserved through the warp. It seems to me that even if you have this warp drive you would still need 30-50km/s of delta-v to match Hubble velocities with other star systems (unless you didn't mind hurtleing past them post-warp).

As far as I know it is conserved. So yes, you will need an auxiliary propulsion system to match Hubble velocities with your destination.

In the old E.E. "Doc" Smith Lensman novels, this was called a ship's "intrinsic" velocity.

[Spacial_Anomaly]

I wonder how momentum is conserved through the warp. It seems to me that even if you have this warp drive you would still need 30-50km/s of delta-v to match Hubble velocities with other star systems (unless you didn't mind hurtleing past them post-warp).

I'm not so sure about that, since the Hubble velocity is a property of the space-time and not of the object within, so I'd guess you'd move in comoving coordinates, which aren't affected by the expansion. Also the expansion of the universe doesn't affect gravitational bound objects (much), such like galaxies. The far greater source of differences in velocity would be plain gravity (e.g. Andromeda rushes with 300 km/s in our direction).

[nyrath]

Perhaps not Hubble velocity. But certainly you'd have to match the "peculiar velocity"

http://en.wikipedia.org/wiki/Peculiar_motion

in the same way a Kerbal has to match velocity with the destination planet.

[Spacial_Anomaly]

Yes. But the peculiar velocity is caused by gravitational interaction. And I agree with you: there's no way around matching your velocity with the target.

[Pugspaceprogram]

Perhaps not Hubble velocity. But certainly you'd have to match the "peculiar velocity"

http://en.wikipedia.org/wiki/Peculiar_motion

in the same way a Kerbal has to match velocity with the destination planet.

Do you have a wiki link for everything?!

[Spacial_Anomaly]

Do you have a wiki link for everything?!

That's because there is a wiki link for everything. Also:

http://en.wikipedia.org/wiki/Wikipedia:Researching_with_Wikipedia

[K^2]

Alcubierre's warp drive would totally ignore orbital trajectories, it would move along a direct geodesic. Since it is making a pocket universe to cut off the effect of relativity, it would also cut off the effect of gravity.

The ship in the bubble is in flat space-time. But the energy that generates warp bubble is not. The bubble would interact with other masses. It will most certainly not go in "direct geodesic," because there is no such thing. "Direct line" is a very relative concept in GR. It is all a matter of metric.

The other argument is from conservation of energy. If your ship gets off the orbit, where does the energy for it come from? Energy in the bubble does not change in the process.

creating the warp takes about 12 times as much energy as is contained in the entire universe

Rubbish.

[Nuke]

Do you have a wiki link for everything?!

the google is strong with this one.

[Pugspaceprogram]

that's because there is a wiki link for everything. Also:

http://en.wikipedia.org/wiki/wikipedia:researching_with_wikipedia

bwaaaaaaaaaaah!!!