I'm part of a games studio who is currently building a game about high energy particle physics (essentially you control a quark and have to try not to get annihilated by anti-quarks), and we're thinking of setting it just after the Big Bang.
One idea we've been toying with is that you're...
What does this mean for missions like Voyager? If NASA uses GR to compute planetary positions, then I'd assume that they'd use it for these longer missions, but you've also stated that they wouldn't use it unless they were going to Mercury... unless there's a difference between using GR to...
I'm fairly sure not. As far as I'm aware, the bending of space is purely a gravity thing which acts on a mass. Mass itself, however, effects how all forces (EM, Gravity, Strong and Weak) are applied to a body.
You can mimic a massive object with your magic wand and things would be...
Aren't we at a point where we're pretty sure that the universe is flat (ie. unbounded), rather than closed (bounded)? While it's true that things like String Theory predict small, bounded dimensions, it's very unlikely that the big 4 (space and time) are modular.
In terms of mathematics, then...