Cary L. Brown wrote:
It doesn't matter if you accelerate due to a field interaction, or due to expulsion of mass. You're still accelerating, and you're still subject to relativistic effects. Anything else, no matter how convenient for storytelling, is nothing more or less than "make-believe."
I've always understood it to be a compression of space fore of the vessel and expansion aft, like Juan said. Thus, neither of your Newtonian scenarios fit. You don't have multiple fields interacting but rather space itself changing dimensions, thus allowing the ship traveling at sublight within the confines of the dimension changed space to appear to travel faster than light since the surrounding space hasn't changed dimensions.
That's exactly my point. "Warp drive" isn't a "field drive." It's something else entirely. Warp drive is "none of the above." A "field drive" is still a Newtonian system. It just creates acceleration through the interaction of two fields (one internally generated, one external and, almost always, natural), rather than through expulsion of highly-accelerated mass.
Warp drive is something else entirely. It's just "warp drive," not a subclass of some other category.
Warp drive is all about perspective. It's like if you take a tablecloth and scrunched up the left hand side but left the right hand side fully extended across the table. Take two Matchbox cars and have them travel from one end of the tablecloth to the other on each side at the same rate of speed. While both cars travel over the same amount of cloth, the car on the left side gets from one end to the other more quickly due to the tablecloth being scrunched up.
Now that's an obvious oversimplification of my understanding of it, but it gets the point across. A ship traveling at warp doesn't compress all of space as such but manipulates it as it travels via a subspace field.
It's kinda like you're not really traveling faster than light but rather shortening the distance that you have to travel. It just seems like you're traveling faster than light because light itself can't shorten the distance it has to travel.
That's a fairly good explanation of how my hypothetical "FTL impulse" would work... albeit that everything is based upon local frame-of-reference. You might say that the "local speed of light is greater, relative to 'real space/time'." But, by the same argument, you might say that "real space/time is compressed, relative to your local frame of reference." So a Newtonian propulsion system becomes plausible for interstellar travel, because the distances your "sublight," Newtonian system requires you to move are (effectively) tremendously reduced.
But "warp drive" isn't even like that. It's not about "shortening the effective distance between two points" or "increasing the effective speed of light" or anything like that. The best way to describe "warp drive" is that you're creating a wave in the fabric of the universe, and "surfing on subspace."