To create a user from nothing, the time turner would have to acquire negative mass equal to that of the transported user. To destroy the user at the moment of transport, the time turner would have to have had negative mass prior to the use. In short, user mass + time-turner mass = 0 at all times. Which would mean that a time turner is much more useful as a levitation aid.
In general, negative mass behaves weirdly. The Newton’s laws still apply, so the gravitational force acting on the negative-mass time turner is mg (upwards if m < 0). However, if you let it go, it will fall down, not up (F=ma, so a=g, since m cancels). If you push on a negative-mass object, it tends to accelerate toward you. This makes carrying one quite hazardous: you can only pull it (in which case it gets pushed). If you even touch it, it will snap your hand.
Given the above, I think it is safe to say that time turners have positive (and small) mass and don’t change their mass when activated.
To create a user from nothing, the time turner would have to acquire negative mass equal to that of the transported user. To destroy the user at the moment of transport, the time turner would have to have had negative mass prior to the use.
No it doesn’t.
The time-turner just has to contain more mass-energy than the user at all times. Pretty simple, really. See it as a magical container and beamer for all that mass that gets displaced (and while creating the user-copy or deleting it, it also removes/generates an appropriate amount of air to equalize the pressure effects).
The process would, by the clock, look like this:
Time-turner is created, has a mass of 5000 (the mass is not apparent for the same reasons that wingardium leviosa makes objects float / less heavy, whichever reasons those might be).
Time-turner removes some air (mass 5000 + 2) and simultaneously generates a copy of the user (mass 5002 − 80)
Time-turner later removes the “old” / time-turned user (mass 4922 + 80) and generates some air to fill in the space (mass back to 5000).
As for how the time-turner itself moves places, well, it presumably either shares the mass among copies somehow (entanglement? wormholes? exotic space geometries?) or just teleports the mass reserve where appropriate, or perhaps the “enchantment” is contained in a separate “server” of sorts (which would be most coherent with the Atlantis hypothesis).
This explanation conserves mass—the mass is just taken from a big rock or something at the creation of the time-turner, and then redistributed/refilled as appropriate to create the apparent effect of creation-from-nothing.
I agree that if you allowed to screen a fixed amount of energy from GR by magic, you don’t have to have negative energy, as you can add an arbitrary and undetectable amount of it to whatever object you want. But then why stop there, GR is already broken.
GR was (apparently) broken by changes in mass; suppose instead that animagi convert between magic, energy, and mass in an analogous manner: When in a smaller form, they are more magical, and vice versa. Brooms convert magic to a combination of energy and/or something which is anti-mass but not anti-inertia, and/or something else which is not directly analogous to anything in GR.
The time turner then remains no harder than apparation combined with future prediction; future prediction is easy enough that it’s provided in novelty drinks.
or perhaps the “enchantment” is contained in a separate “server” of sorts (which would be most coherent with the Atlantis hypothesis)
This also provides a possible mechanism for the 8-hour limit on multiple time turners; the servers can predict up to eight hours in the future, except they cannot accurately predict their own future prediction. Things which do not depend on their future prediction can mostly still be predicted “Do not mess with time” could have originated from there as well.
To create a user from nothing, the time turner would have to acquire negative mass equal to that of the transported user. To destroy the user at the moment of transport, the time turner would have to have had negative mass prior to the use. In short, user mass + time-turner mass = 0 at all times. Which would mean that a time turner is much more useful as a levitation aid.
In general, negative mass behaves weirdly. The Newton’s laws still apply, so the gravitational force acting on the negative-mass time turner is mg (upwards if m < 0). However, if you let it go, it will fall down, not up (F=ma, so a=g, since m cancels). If you push on a negative-mass object, it tends to accelerate toward you. This makes carrying one quite hazardous: you can only pull it (in which case it gets pushed). If you even touch it, it will snap your hand.
Given the above, I think it is safe to say that time turners have positive (and small) mass and don’t change their mass when activated.
No it doesn’t.
The time-turner just has to contain more mass-energy than the user at all times. Pretty simple, really. See it as a magical container and beamer for all that mass that gets displaced (and while creating the user-copy or deleting it, it also removes/generates an appropriate amount of air to equalize the pressure effects).
The process would, by the clock, look like this:
Time-turner is created, has a mass of 5000 (the mass is not apparent for the same reasons that wingardium leviosa makes objects float / less heavy, whichever reasons those might be).
Time-turner removes some air (mass 5000 + 2) and simultaneously generates a copy of the user (mass 5002 − 80)
Time-turner later removes the “old” / time-turned user (mass 4922 + 80) and generates some air to fill in the space (mass back to 5000).
As for how the time-turner itself moves places, well, it presumably either shares the mass among copies somehow (entanglement? wormholes? exotic space geometries?) or just teleports the mass reserve where appropriate, or perhaps the “enchantment” is contained in a separate “server” of sorts (which would be most coherent with the Atlantis hypothesis).
This explanation conserves mass—the mass is just taken from a big rock or something at the creation of the time-turner, and then redistributed/refilled as appropriate to create the apparent effect of creation-from-nothing.
I agree that if you allowed to screen a fixed amount of energy from GR by magic, you don’t have to have negative energy, as you can add an arbitrary and undetectable amount of it to whatever object you want. But then why stop there, GR is already broken.
GR was (apparently) broken by changes in mass; suppose instead that animagi convert between magic, energy, and mass in an analogous manner: When in a smaller form, they are more magical, and vice versa. Brooms convert magic to a combination of energy and/or something which is anti-mass but not anti-inertia, and/or something else which is not directly analogous to anything in GR.
The time turner then remains no harder than apparation combined with future prediction; future prediction is easy enough that it’s provided in novelty drinks.
This also provides a possible mechanism for the 8-hour limit on multiple time turners; the servers can predict up to eight hours in the future, except they cannot accurately predict their own future prediction. Things which do not depend on their future prediction can mostly still be predicted “Do not mess with time” could have originated from there as well.