StarDestroyer.Net BBS

Okay, I think I get what you're saying now. It's still a very weird field under space-time. From what I can see, your propellant mass stays the same, but dry mass is released from the ship to this field. You now have a higher mass ratio and therefore can achieve a higher relative velocity. The weird part still seems to be slowing down. It doesn't look like you're using propellant to decelerate, so that means that you must be able to interact with the field such that it has an energy-momentum that decelerates the ship for you. Am I on the right track?

Perhaps these mass/energy "shunt" ideas rely on the field in question being of immense scale and arbitrary access, so you can dump off mass/energy at some point and then pick it back up elsewhere without having to actually drag it along with you (which would hence make the whole exercise moot) or create a moving field that possesses mass/energy yet lacks inertia. As long as the field is thought of as a conventional field generated by the ship rather than some universe-sized phenomenon they tap into, then all of these problems crop up. Of course, if it's a universe-sized phenomenon they tap into, then why not just use it for free energy?

Darth Wong wrote:Perhaps these mass/energy "shunt" ideas rely on the field in question being of immense scale and arbitrary access, so you can dump off mass/energy at some point and then pick it back up elsewhere without having to actually drag it along with you (which would hence make the whole exercise moot) or create a moving field that possesses mass/energy yet lacks inertia. As long as the field is thought of as a conventional field generated by the ship rather than some universe-sized phenomenon they tap into, then all of these problems crop up. Of course, if it's a universe-sized phenomenon they tap into, then why not just use it for free energy?

That's exactly what Wyrm and Jason Hinson are proposing, a chart between space-time and some scalar field (subspace) that you can dump rest mass (not of your propellant, apparently) into. To solve the free energy problem, consider that the generator warps both space-time and subspace such that you can draw a connection between the warp field and the interface of these two manifolds with a large enough content to contain the shed rest-mass. Then postulate some energy condition that requires at most on average that subspace's energy content remain constain. This means that the warp field has to remain intact while the shed mass is resident in subspace. As soon as the connection evaporates, the universe pays you back your inertial mass. The cost, of course, is the energy needed to sustain the field throughout its operation.

To be honest, this solution really doesn't seem any less arbitrary than simply proposing a "field" that cancels out conservation laws, as kuroneko mentioned. The idea of a field that exists in connection to spacetime but with no energy costs of moving its mass/energy about seems to perform the same function anyway.

Darth Wong wrote:To be honest, this solution really doesn't seem any less arbitrary than simply proposing a "field" that cancels out conservation laws, as kuroneko mentioned. The idea of a field that exists in connection to spacetime but with no energy costs of moving its mass/energy about seems to perform the same function anyway.

It's not a very clever solution, but that's what you get with Star Trek and it actually does abide by conservation laws An observer would essentially see an interaction through this chart from space-time to subspace in which rest mass departs every single particle of the ship (except, of course, the propellant). So locally, which is the only condition that seems to matter right now to physics, energy-momentum is conserved. Globally is a different matter. You either have to chose conservation or the principles of relativity. Subspace as Wyrm and Hinson describe it throws out the latter by proposing a chart that to some field that is not even locally isotropic. There is some amount of mass-energy at some point in subspace that must be given up somewhere else.

Kuroneko's proposal for extracting and depositing four-momentum extraction has the same issues, only in reverse.

metavac wrote:Subspace as Wyrm and Hinson describe it throws out the latter by proposing a chart that to some field that is not even locally isotropic.

Why is local isotropy important in a field? The electrostatic field of a Vann de Graf generator sure as hell isn't isotropic. That's why you have a potential in the first place.

metavac wrote:Kuroneko's proposal for extracting and depositing four-momentum extraction has the same issues, only in reverse.

Though, again, I'd like to see how that works.

Wyrm wrote:Why is local isotropy important in a field? The electrostatic field of a Vann de Graf generator sure as hell isn't isotropic. That's why you have a potential in the first place.

I should be less ambiguous about this. I meant anisotropy the smooth scalar field that charts both to space-time and to subspace.

metavac wrote:Though, again, I'd like to see how that works.

In this case, at every point in space-time there exists a chart to some bundle of 4-momentums. You somehow transport a desired 4-momentum out of subspace and accelerate to the appropriate velocity relative to your previously comoving observer. Then, when you get to where you're going, you turn off the bubble or whatever you call it and the 4-momentum you gained is transported back. By the way, the interest you pay on this would be from the mass-energy you're using to support the bubble/whatever.

In both cases, there is some sort of strange manifold coincident with space-time that has some notion of an absolute frame of reference.

metavac wrote:

Wyrm wrote:Why is local isotropy important in a field? The electrostatic field of a Vann de Graf generator sure as hell isn't isotropic. That's why you have a potential in the first place.

I should be less ambiguous about this. I meant anisotropy the smooth scalar field that charts both to space-time and to subspace.

Get away from Wikipedia and learn some real math. Scalar fields, smooth or otherwise, cannot "chart" a manifold, coordinate systems do. And to describe a coordinate system as "anisotropic" is silly. Of course moving a certain way changes the coordinate system in a definite way — that's the point of a coordinate system: to give distinct points of the manifold different coordinates. Furthermore, different coordinate systems assign different coordinates to the same point. A physical field, on the other hand, always has the same value at the same point.

And I'm still waiting for an explanation of why local isotropy is important in fields. Vector fields (for instance, an electrostatic field) are manifestly locally anisotropic: they definitely single out one direction in preference to any other — the direction in which the field points. The spacetime metric about the Earth also has local anisotropy — worldlines tend to be deflected toward the local large source of stress-energy (that is, the Earth's mass, which is why we have gravity). Any field associated with a non-constant potential has anisotropy.

metavac wrote:

Though, again, I'd like to see how that works.

In this case, at every point in space-time there exists a chart to some bundle of 4-momentums. You somehow transport a desired 4-momentum out of subspace and accelerate to the appropriate velocity relative to your previously comoving observer. Then, when you get to where you're going, you turn off the bubble or whatever you call it and the 4-momentum you gained is transported back. By the way, the interest you pay on this would be from the mass-energy you're using to support the bubble/whatever.

In both cases, there is some sort of strange manifold coincident with space-time that has some notion of an absolute frame of reference.

Except in my example, I never use the mass reservoir as such a frame of reference. Indeed, I never stated the frame of reference of the mass reservoir at either of the relevant points, and in the final answer, the reference frame of the mass reservoir was completely irrelevant, insofar as the figures go.