FTL Part Two

[Frenetic Pony]

So, random thoughts going through my head, and part of a science fiction novel I'm trying to wrap my head around involves FTL in the future.

Now, according to several papers it appears that the fine structure constant in the universe might not be so, well, constant. A tiny variation to sure, but there. Now, since the whole neutrinos going FTL appears to be all but buried, this is the only viable (however unlikely) appearance of something not going exactly right with C being a constant universal speed limit.

So assuming the results aren't a fluke of statistics/gremlins in the code/etc., AND that the mechanism behind this variability could be manipulated by humans, to produce, in practical effect, an FTL drive my question is this: What would the effects of this look like/work like? And yes, I am assuming that the speed of light is being changed which is what is changing the fine structure constant. It's science fiction after all, the barest hint of plausibility is good enough

[legend]

The difference between alpha and c is that alpha is dimensionless, c is not. So changing alpha does have some physically measurable effect, while by changing c you just change the definition of a meter.

[starslayer]

Um, no, he's talking about the meter being the same length as it is today, while the speed of light changes (i.e., c is now a different number of meters per second). This has very large effects, none of which are very good/conducive to life. Messing with c changes the strength of the electromagnetic interaction, and by extension chemical bonding characteristics of all the elements for a start. You may notice that these are things which life depends on being almost exactly what they are today.

[legend]

My point is that if you want to change a dimensional constant you have to exactly define what things does it effect and what not. E.g. choose some dimensionless parameters that are effected.
For example the current definition of a meter is "the length of the path travelled by light in vacuum during a time interval of 1⁄299792458 of a second". We can easily change this definition to "the length of the path travelled by light in vacuum during a time interval of 1/599596916 of a second", effectively doubling the speed of light without anyone noticing anything.
Another interesting idea is that you take a look at the FLRW metric d\tau^2=dt^2-c*a(t)*dx^2 that describes the expansion of the universe (a is basically a dimensionless relative size of the universe here) and replace the term a(t)*c by c(t). This gives you a universe that has a constant size, but the speed of light gets lower over time. This is a somewhat unconventional interpretation of the expansion of the universe, but mathematically it's exactly the same thing.