Chalam:
If you look at matter on the quark level, its composed of very little actual "stuff" (quars, etc), and pretty much entirely of energy. Notice that E=mc^2. So jamming up the speed of light (and you got to jam it up GOOD) will totally change the mass of all kinds of stuff. Its difficult to say what effect this will have. Will Atoms be possible? how about stars; one would think the gravitational confinement would be a little off, and the energy gained from each fission event would at any rate be WASTLY different, speaking of staller formation, the momentum of massless particles would be different to, this again would have a huge influence on the gravitational equilibrium of a star.
Another thing - the diraq equation (relativistic equation for the electron in electro-magnetic field) would change. That might be detectable, but i dont know by how much.
In short, just jamming the speed of light up will lead to a whole cascade of changes to physics, most of which we simply dont understand. Each of these changes might have to be balanced out by other changes to other parts of reality by God to make everything work, and you get a mess where God is jumping around fixing stuff all because he want the universe to look very old, but not be very old.
Im not saying this is impossible. Im just saying it seem far more easy to explain this by keeping the speed of light fixed, and accepting that the universe is pretty old. Alternatively, while it might seem more silly, it would seem to have been easier for God just to create rays of light from the old galaxies to our eyes so the light "looks" old. Its a horrible theory, but at least we are no longer in cowboy land in terms of physics.
