Mild evidence against is that Time Turners were (apparently) used to save a life in canon, namely Buckbeak’s. Stronger evidence is that no use of a Time Turner in HPMoR has actually altered the timeline; to the extent that there are rules I would expect them to be much more general than that. “Can’t save a life” is a deeply inelegant rule. It doesn’t cut the universe at its joints.
Can’t tell by your phrasing here whether you’re aware of this or not, but no use of a Time Turner in canon altered the timeline, either. Everything that Harry and Hermione did while time-turned was exactly what the trio saw the first time through. That part of HPMoR’s time travel rules are identical to canon’s, just more thoroughly explained.
Yes, that’s what the (apparently) was for. The point is that this is a canon example where a character thought someone was dead and used a Time Turner to rescue them, but the timeline ended up working out so that they were never dead in the first place (as it had to).
Stronger evidence is that no use of a Time Turner in HPMoR has actually altered the timeline
They can be used to control the timeline. It’s Parfit’s hitchhiker. If Harry was willing to use the Time Turner, he’d never have gotten into that situation. Just like when he was willing to use it to escape a locked room.
Perhaps one of the rules of Time Turners is that they can’t be used to save a life.
Mild evidence against is that Time Turners were (apparently) used to save a life in canon, namely Buckbeak’s. Stronger evidence is that no use of a Time Turner in HPMoR has actually altered the timeline; to the extent that there are rules I would expect them to be much more general than that. “Can’t save a life” is a deeply inelegant rule. It doesn’t cut the universe at its joints.
Can’t tell by your phrasing here whether you’re aware of this or not, but no use of a Time Turner in canon altered the timeline, either. Everything that Harry and Hermione did while time-turned was exactly what the trio saw the first time through. That part of HPMoR’s time travel rules are identical to canon’s, just more thoroughly explained.
Yes, that’s what the (apparently) was for. The point is that this is a canon example where a character thought someone was dead and used a Time Turner to rescue them, but the timeline ended up working out so that they were never dead in the first place (as it had to).
On-screen deaths have happened, and thus cannot be altered. Off-screen deaths might not have actually been deaths, and thus can be altered.
They can be used to control the timeline. It’s Parfit’s hitchhiker. If Harry was willing to use the Time Turner, he’d never have gotten into that situation. Just like when he was willing to use it to escape a locked room.
Better would be that it cannot interfere with the creation of a prophecy, since that is also ‘backwards’ causation.