for stronger uncreated, it's more or less used to aim the call you send out. For weaker entities, it literaly drags them into creation against their will, and if the summoner has enough willpower, allows for a (usualy temporary) binding to a set of rules given by the summoner.
So, it's kinda like a phone rune?
The reasoning is simply that the past is merely what a person recalls and thinks occurred, that is, it is merely perception and knowledge, there is no concrete past.
...Darn. You actually explained your point of view well there. Now I need to resort to higher physics to try and do this. And I have to hope that reversibility applies to all applicable laws of physics.
Emp, you're being dumb. Spacetime is a thing. This implies that time is quantifiable which implies that there is a concrete past in the sense of moving backwards along the time dimension. :I
Not necessarily, space-time is a thing, but it does not facilitate anything pertaining to the past. After all, it may be distorted to slow down time, but not even a blackhole reverses it.
Oh look, advanced science got involved without me.
You can't use one specific method to travel to the past. That's like saying that since you can't walk to London*, you can't get to London at all.
(For the sake of argument, assume you live outside the Brittish Isles.)
If you take all the particles in a system and simply reverse their velocities, it goes in the exact opposite direction than that it was before--ie, time effectively flows backwards. Mind, it's practically impossible to do so, but with magic, why can't you use such properties of physics to travel to the past? (Or effectively to the past, at least.)
I feel like people overuse Heisenberg on non-quantum stuff. These are macro-scale events. Sure, there's some indeterminability, but does it really matter for our purposes?
Depends. If you set things up right? Sure. *cough*RadioactiveIsotopeAndPoisonInABox*/cough*