Weaponized FTL in ST or SW?

[Borgholio]

That assumes that ramping the mass back up doesn't drop the velocity back down, or that it's possible to ramp the mass up to ridiculous levels, or so on.

Rapidly increasing the mass of an object won't immediately decrease it's velocity if it's already in motion in space...there is no drag or rolling resistance to worry about.

So if it were possible, rapidly increasing the mass of a projectile after launch would be a powerful tool. But I don't recall seeing any mass INCREASING tech in Star Trek, just mass lightening.

[Q99]

Rapidly increasing the mass of an object won't immediately decrease it's velocity if it's already in motion in space...there is no drag or rolling resistance to worry about.

Still, I'd expect some side-effects. After all, they keep the mass lightning on while traveling for some reason.

[Imperial528]

That assumes that ramping the mass back up doesn't drop the velocity back down, or that it's possible to ramp the mass up to ridiculous levels, or so on.

Rapidly increasing the mass of an object won't immediately decrease it's velocity if it's already in motion in space...there is no drag or rolling resistance to worry about.

So if it were possible, rapidly increasing the mass of a projectile after launch would be a powerful tool. But I don't recall seeing any mass INCREASING tech in Star Trek, just mass lightening.

By conservation of momentum it has to.

[Elheru Aran]

If you have mass lightening... you have mass increasing, sort of. You take a large mass, lighten it, and then bring it back up to its original mass, which is an increase

So you could, I don't know, take a slug of depleted uranium the size of a photon torpedo, strap a couple of warp engines, some guidance and a mass-lightener on it, fire it in the desired direction after lightening it. Shortly before impact, restore the original mass.

Or something. I don't really know how that would work.

[Q99]

If you have mass lightening... you have mass increasing, sort of. You take a large mass, lighten it, and then bring it back up to its original mass, which is an increase

So you could, I don't know, take a slug of depleted uranium the size of a photon torpedo, strap a couple of warp engines, some guidance and a mass-lightener on it, fire it in the desired direction after lightening it. Shortly before impact, restore the original mass.

Or something. I don't really know how that would work.

What of the answer to that is as simple as, rather than simply being a switch one can turn off, it taking as much energy to restore the full mass as it'd take to do the full acceleration to begin with, for no net gain?


With such a fantastic future tech, I'm normally hesitant in assuming 'easy' cheats.

[Borgholio]

By conservation of momentum it has to.

The momentum will be the same, the mass will just change.

What of the answer to that is as simple as, rather than simply being a switch one can turn off, it taking as much energy to restore the full mass as it'd take to do the full acceleration to begin with, for no net gain?

Well any change from the status quo should require energy. So to lighten the mass, energy must be expended. To increase the mass, energy must be expended. Like EA suggested, it might be most energy efficient to take a large slug of some dense material, lighten the mass, launch it, then simply cut the power shortly before impact...as opposed to taking a light material and increasing the mass.

[Imperial528]

By conservation of momentum it has to.

The momentum will be the same, the mass will just change.

A change in mass requires a change in velocity in order to conserve momentum. The object gaining mass from nowhere is just the same as the object smacking into a second object equal to the gained mass via a perfect inelastic collision. In both cases the acceleration of the additional mass up to speed causes the net velocity to decrease. The only way this could work with magic mass increases is if the mass lightening device puts just as much energy into the projectile as would be required to accelerate the additional mass. At that point, it's better to forgo the mass lightening all together because you're still inputting the energy at some point. Well, it's better because it doesn't break conservation of energy, but it does break conservation of momentum still, because the final resulting projectile will be impact at a higher momentum than it was fired.

In order to obey conservation of momentum, when the mass lightening is disabled, the projectile must slow down.

[Borgholio]

In order to obey conservation of momentum, when the mass lightening is disabled, the projectile must slow down.

Would that not be the same as taking an object and breaking it in half? The two halves aren't suddenly going to accelerate since the velocity is the same but the mass is suddenly cut in half.

[Imperial528]

In that case you get two objects with the momentum split between them. Mass is divided, but so is momentum, so it comes out with the same total. In this case you have an object suddenly gaining mass. The only way for momentum to be conserved in this case is for velocity to decrease. Note that momentum can't increase because the new mass is not external to the system.

[Q99]

A change in mass requires a change in velocity in order to conserve momentum. The object gaining mass from nowhere is just the same as the object smacking into a second object equal to the gained mass via a perfect inelastic collision. In both cases the acceleration of the additional mass up to speed causes the net velocity to decrease. The only way this could work with magic mass increases is if the mass lightening device puts just as much energy into the projectile as would be required to accelerate the additional mass. At that point, it's better to forgo the mass lightening all together because you're still inputting the energy at some point. Well, it's better because it doesn't break conservation of energy, but it does break conservation of momentum still, because the final resulting projectile will be impact at a higher momentum than it was fired.

In order to obey conservation of momentum, when the mass lightening is disabled, the projectile must slow down.

Supporting this, when engine glow goes off, the ship slows.

Also, if something seems like a super-easy way to do something overpowered, but no-one does it or suggests it's possible, that's a sign it's not so super easy.

[Mr Hugh Mann]

As far as weaponized FTL systems go I think the Co-axial warp drive from “VOY: Vis a Vis” has great potential. While the episode never discussed its application as a weapon of war, the general properties of its malfunctions might allow it serve in that capacity, supposedly if the drive fails catastrophically it collapses space within a radius of a billion kilometers. If the drives are brought out of the experimental phase and can be forced to fail catastrophically in a predictable fashion then a modified co-axial warp drive could serve as a weapon of mass destruction, with its faster-than-warp delivery system also serving as the payload.

Admittedly this drive system only appears in one episode so it is very much a technology of week, however the properties seem interesting enough for at least some consideration.

[Q99]

Yes, one of the most potentially destructive tech of the weeks there is!