I've recently read Alastair Reynolds' sci-fi best seller, Redemption Ark, where he explored the concept of manipulating an inertial frame overlaid on the quantum vacuum like many of the other fundamental, underlying fields proposed by quantum field theory.
The method described in the novel was shown to work exceptionally for subluminal travel, wherein a device capable of manipulating the local inertial field would decrease the inertia experienced by particles in the field, thus decreasing the energy required to accelerate them; e.g., manipulating the inertia experienced in the local field by a factor of 0.5 would result in particles requiring 0.25 times the energy needed to accelerate to a given speed had the field been switched off. The upshot was that starships expended less energy by moving less mass, though that missing mass was not at all missing, it was just misrepresented from the norm, seen as having less resistance to changes in motion.
The physics and math behind the effect are, as far as I can tell, imaginary. Here in the real world, from what we have thus far ascertained, inertia is a property of matter and not a property of the local quantum vacuum imposed onto matter.
However, the idea was damned good, and so for my question, I will try to use a slightly modified version of this idea. Please keep in mind that I am not very educated in these matters, I am practiced at regurgitating ideas and concepts I have only flimsy understandings of.
Reynolds imposed guidelines to his inertial dampening effect. Straightforward guestimations at how the manipulation ought to work, given the fantasy science at hand. Should the local inertia be suppressed completely, such that particles in the field experience no inertia, they would become photonic, forced to move at the speed of light. If particles were to experience less than no inertia, they would become tachyonic, forced to travel faster than the speed of light and backward through time. This method seems like a viable approach to convenient, near-light speed travel, however, I believe Reynolds either overlooked an idea or had not and discarded it simply because it doesn't make sense. I hope it is the former because I'm shooting for a similar plausibility.
Try for a moment to imagine that a shift in the inertial "constant" is like a bulge on some film, like the classic presentation we all have seen to portray gravity. The shift may go in any vertical direction, positive or negative, much like the gravity analogy. It is basically analogous. Continue in this moment to imagine that a rising bulge in the film represents a decrease in the inertia experienced by all particles in the local field. In Reynolds' universe, this bulge may rise from units 1 (normal), to 0 (lightspeed), to -n (ludicrous speed), where the value may represent some multiplier of inertia experienced. Reynolds seems to allow this multiplier to be experienced by particles with mass, yet, mass in his system seems to be defined by the inertia they experience, which can be fluctuated. The mass of light, 0, doesn't change proportionally.
In my imaginary system, I propose that photons themselves are subject to this field and that decreasing or increasing the local inertial state has a proportional effect on all particles, tardyonic and photonic, in that field.
Now, if one was in a starship traveling in such a manipulated field, and one was to take a flashlight and shine it down a corridor directly in front of them, one would observe that the speed of light appears to remain consistent with what would be measured should the field be switched off, relative to oneself within the field. The increase is proportional to all particles. To an outside observer, they would observe the speed of the photons emitted from the flashlight within the traveling ship within the field to be traveling a proportion faster/slower than the speed of light.
It is important to note that this proposed field has a gradient-like drop-off whose function yields a range proportional to the distance apart from the origin of the field, like gravity.
That's basically what I had in mind for how it works.
Now, the question. The field certainly does not need to encompass an entire object. Nothing's that perfect. Some parts and pieces of an object can occupy the gradient-like region where the drop-off is significant, down to experiencing the field only nominally. Light, as it enters the significant region of the gradient, would be expected to lose some of its "inertia," increasing in velocity as a result. Based on the accepted answer of this, I know that "nuclear reactions would be much more energetic." (Though, the author of the answer did not elaborate on why that would be the case.) This question is irrelevant to mine anyway. This isn't an increase of the speed of light intrinsically, you see, because, within the field, an observer would observe light moving at what speed it appears to always move at, relatively speaking. So there is no true increase going on here, except in the differential space between the bulk of the field and the outside universe only marginally affected by the field. This is the region of interest to me.
How would energy and matter behave in this region?
Given the differential—objects further from the field feel its effects less than one nearer—perhaps some properties of matter may differ as one traverses the differential. If one soared headlong into such a field, one's head may experience less inertia than one's feet. Given different kinds of gradients, steep (perhaps mere atoms in thickness) to drawn-out (perhaps kilometers), to somewhere in between (meters or less), I want to know how matter would interact with itself and how embarking or disembarking matter and energy (photons) would behave. How would this thing look visually, anyway? That's always an important aspect if one's trying to illustrate something.
Bonus points if you give me an estimate or elaboration on how plausible this all is. That's what I was aiming for, but as I implied, I'm treading "unfamiliar" territory. I don't normally try to design these kinds of systems.
In a universe where inertia is a quantum field overlaid among other quantum fields, and also manipulable, imagine a hill of lowered inertia with some gradient-like drop-off from the peak of the hill. The inertial dampening effects all particles of mass and energy, so that particles entering the region experience less resistance to acceleration. Assume that light is bound to lightspeed by some inertial figure, which can be lowered and raised proportionally to particles surrounding it, such that an observer in any inertial frame always observes a constant speed of light. Across differing frames, however, this is not the case.
How would particles of matter and energy behave in this differential region, should it be steep or drawn-out?
I'm looking for the effects of a molecular bonded object entering the field, say, someone sticking a long pole into it, where the front of the pole experiences less inertia that the end.