I highly doubt he would do that as well, given that there is no known method to travel further than 6 hours back in time. He would not base his entire “save Hermione” plan on a hope that he could somehow find a way around this constraint.
What he does at this very moment should exclude as few plans to save her as possible, and not preserving her brain would exclude almost all of them.
Alternatively, he could have simply entered the room and watched the room for six hours, perhaps while random-walking. By doing so, he ensures that the only observer he needs to worry about himself, so that far-future Harry can plan a time travel trip in security.
Also, given how time travel works in this story, the only thing he would achieve with this is making it impossible for future Harry to do any changes at all to Hermione’s body in these 6 hours (since he can only “change” what he doesn’t know).
The former is granted; better to be sure. (Though any trick that can overcome information-theoretic death has a decent chance of allowing arbitrary time travel anyway.)
The latter, however, is easily dealt with: show up under the Invisibility Cloak, hit his past self with some variant of the Confundus Charm. Since he’s watched the entire 6 hours, he can be certain this will be sufficient.
… except he can’t, because someone else could’ve pulled the same trick. Nevermind; retracted.
Though any trick that can overcome information-theoretic death has a decent chance of allowing arbitrary time travel anyway.
I do not see how that would follow at all, could you please explain?
The latter, however, is easily dealt with: show up under the Invisibility Cloak, hit his past self with some variant of the Confundus Charm.
Dumbledore has already told Harry that he tried a variant of this once and that it didn’t work. “Time” didn’t like that. See this quote from chapter 90:
I asked the Headmaster to go back and save Hermione and then fake everything, fake the dead body, edit everyone’s memories, but Dumbledore said that he tried something like that once and it didn’t work and he lost another friend instead.
This should at the very least be considered weak evidence to not “mess with time” in the way you’re suggesting, and Harry will not go for a plan when he only has evidence against it being the best solution (this + time travel is constrained to 6 hours + not preserving her brain will make “easier” plans to save her impossible).
Since he’s watched the entire 6 hours, he can be certain this will be sufficient.
This is not how time-travel works in this story, he doesn’t need to watch her to do it. The less he knows about the situation the more he can “change” it, so the absolute smartest thing he could do if he planned this is to stay as far away from her body as possible.
I do not see how that would follow at all, could you please explain?
Reversing information-theoretic death is fundamentally the problem of taking a bunch of atoms in random configurations and getting a person out of it—and not just any person, a particular person about whom you no longer have any data whatsoever.
This problem is fundamentally equivalent to time travel: if you can time travel, you can just go back and copy the original, and if you can reverse information-theoretic death, you can “resurrect” the visible universe at whatever time and put yourself in, essentially, a simulation of a prior time.
Dumbledore has already told Harry that he tried a variant of this once and that it didn’t work. “Time” didn’t like that. See this quote from chapter 90:
Actually, there’s a stronger example from the Standford Prison Experiment arc, which is why I already retracted this point. (Though why it doesn’t work is still a legitimate and interesting question.)
This problem is fundamentally equivalent to time travel: if you can time travel, you can just go back and copy the original, and if you can reverse information-theoretic death, you can “resurrect” the visible universe at whatever time and put yourself in, essentially, a simulation of a prior time.
A person is a good bit smaller than the visible universe.
Well, yes. But that’s a practical/engineering problem. It is a useful and interesting fact that you can simulate any computer and execute any game by using a Conway’s Game of Life Board of sufficient size; this does not mean that making a square-kilometer Board and hiring a few million people to update it is at all practical.
The machine required to make the universe would be larger than the universe; the machine to make a brain or person need only be bigger than the person.
There’s a qualitative difference at some point along the line.
I think you meant to say that humans can operate machinery which can do those things. The crane must be taller than the skyscraper, but we can’t design a crane large enough to lift the counterbalance for a space elevator, much less actual stellar-scale engineering. There’s a qualitative difference somewhere between a skyscraper and the altitudes of stable orbits.
Intelligence and creativity can replace brute force. You don’t need a crane taller than a skyscraper, you just need to get taller than the skyscraper somehow—a skycrane, a ladder made of constructor robots, a collapsible crane taller than a single floor that you carry from floor to floor, so on. You definitely don’t need a crane for a space elevator, you use a rocket.
Now build a skyscraper with a rocket; the two are qualitatively different. Making a person is qualitatively different from making a planet, which is qualitatively different from making a galaxy, which is qualitatively different from making a universe.
Two things are qualitatively different if no amount of either one can serve as a viable substitute for the other; TNT and U-235 are qualitatively different explosives mostly because TNT does not generate neutrons.
The construction project that makes a planet be scaled down to make one person, and the project which makes a galaxy cannot be scaled down to make a planet even though creating galaxies involves creating planets: The process by which a galaxy is created cannot be scaled down to make a single planet.
When I say that two processes are identical, I’m talking about a theoretical or mathematical identity, not a practical identity. If you can reverse information-theoretical death, then, at least in theory, time travel is possible; he same device may not be able to do both, but the one implies the other.
This problem is fundamentally equivalent to time travel
I agree that if you solve time travel you can also solve death, but the other implication does not hold. A possible way for Harry to “resurrect” Hermione is to scan her brain, run it through an error-correcting algorithm (to reduce/remove errors introduced from decay and it being transfigured) and then “print out” a brain that is arbitrarily similar to Hermione’s brain at the moment of her death. This will of course depend on the amount of computing power available to Harry, but since he is already “destined” to tear apart the stars, that will probably not be a problem. It’ll also require some “minor” scientific breakthroughs.
Now, I am not at all saying that this is Harry’s plan to resurrect her (In fact I suspect his plan to be very different from this), I am merely providing an example for how you can “restore” someone who is dead without being capable of time travel.
By definition, however, an information-theoretic death means that such an error-correction scheme would be impossible; such a machine would require knowledge that, by the Uncertainty Principle, cannot be attained.
Thus, if you did have that capability regardless, it could then be used to rewind an arbitrary section of the universe to an arbitrary time, which is equivalent to time travel.
By definition, however, an information-theoretic death means that such an error-correction scheme would be impossible; such a machine would require knowledge that, by the Uncertainty Principle, cannot be attained.
Ok, now we’re just talking past each other. Just googled the term “information-theoretic death” and got the following definition from wikipedia:
Information-theoretic death is the destruction of the information within a human brain (or any cognitive structure capable of constituting a person) to such an extent that recovery of the original person is theoretically impossible by any physical means.
This is obviously the situation that Harry has to avoid. If his plan was:
Allow Hermione’s brain to decay so much that it becomes theoretically impossible to restore it.
Well, that would depend entirely on whether or not time travel beyond 6 hours into the past is possible. So, in other words, it’s time travel arbitrarily far back in time that would make this term nonsensical.
I highly doubt he would do that as well, given that there is no known method to travel further than 6 hours back in time. He would not base his entire “save Hermione” plan on a hope that he could somehow find a way around this constraint.
What he does at this very moment should exclude as few plans to save her as possible, and not preserving her brain would exclude almost all of them.
Also, given how time travel works in this story, the only thing he would achieve with this is making it impossible for future Harry to do any changes at all to Hermione’s body in these 6 hours (since he can only “change” what he doesn’t know).
The former is granted; better to be sure. (Though any trick that can overcome information-theoretic death has a decent chance of allowing arbitrary time travel anyway.)
The latter, however, is easily dealt with: show up under the Invisibility Cloak, hit his past self with some variant of the Confundus Charm. Since he’s watched the entire 6 hours, he can be certain this will be sufficient.
… except he can’t, because someone else could’ve pulled the same trick. Nevermind; retracted.
I do not see how that would follow at all, could you please explain?
Dumbledore has already told Harry that he tried a variant of this once and that it didn’t work. “Time” didn’t like that. See this quote from chapter 90:
This should at the very least be considered weak evidence to not “mess with time” in the way you’re suggesting, and Harry will not go for a plan when he only has evidence against it being the best solution (this + time travel is constrained to 6 hours + not preserving her brain will make “easier” plans to save her impossible).
This is not how time-travel works in this story, he doesn’t need to watch her to do it. The less he knows about the situation the more he can “change” it, so the absolute smartest thing he could do if he planned this is to stay as far away from her body as possible.
Reversing information-theoretic death is fundamentally the problem of taking a bunch of atoms in random configurations and getting a person out of it—and not just any person, a particular person about whom you no longer have any data whatsoever.
This problem is fundamentally equivalent to time travel: if you can time travel, you can just go back and copy the original, and if you can reverse information-theoretic death, you can “resurrect” the visible universe at whatever time and put yourself in, essentially, a simulation of a prior time.
Actually, there’s a stronger example from the Standford Prison Experiment arc, which is why I already retracted this point. (Though why it doesn’t work is still a legitimate and interesting question.)
A person is a good bit smaller than the visible universe.
Well, yes. But that’s a practical/engineering problem. It is a useful and interesting fact that you can simulate any computer and execute any game by using a Conway’s Game of Life Board of sufficient size; this does not mean that making a square-kilometer Board and hiring a few million people to update it is at all practical.
The machine required to make the universe would be larger than the universe; the machine to make a brain or person need only be bigger than the person.
There’s a qualitative difference at some point along the line.
Not at all. Humans are much smaller than skyscrapers, but we can design, simulate, and build skyscrapers.
I think you meant to say that humans can operate machinery which can do those things. The crane must be taller than the skyscraper, but we can’t design a crane large enough to lift the counterbalance for a space elevator, much less actual stellar-scale engineering. There’s a qualitative difference somewhere between a skyscraper and the altitudes of stable orbits.
… No?
Intelligence and creativity can replace brute force. You don’t need a crane taller than a skyscraper, you just need to get taller than the skyscraper somehow—a skycrane, a ladder made of constructor robots, a collapsible crane taller than a single floor that you carry from floor to floor, so on. You definitely don’t need a crane for a space elevator, you use a rocket.
Now build a skyscraper with a rocket; the two are qualitatively different. Making a person is qualitatively different from making a planet, which is qualitatively different from making a galaxy, which is qualitatively different from making a universe.
… Okay, so we’re talking past each other. Define “qualitatively different,” please.
Two things are qualitatively different if no amount of either one can serve as a viable substitute for the other; TNT and U-235 are qualitatively different explosives mostly because TNT does not generate neutrons.
The construction project that makes a planet be scaled down to make one person, and the project which makes a galaxy cannot be scaled down to make a planet even though creating galaxies involves creating planets: The process by which a galaxy is created cannot be scaled down to make a single planet.
Oh, I see. Fair enough.
When I say that two processes are identical, I’m talking about a theoretical or mathematical identity, not a practical identity. If you can reverse information-theoretical death, then, at least in theory, time travel is possible; he same device may not be able to do both, but the one implies the other.
I agree that if you solve time travel you can also solve death, but the other implication does not hold. A possible way for Harry to “resurrect” Hermione is to scan her brain, run it through an error-correcting algorithm (to reduce/remove errors introduced from decay and it being transfigured) and then “print out” a brain that is arbitrarily similar to Hermione’s brain at the moment of her death. This will of course depend on the amount of computing power available to Harry, but since he is already “destined” to tear apart the stars, that will probably not be a problem. It’ll also require some “minor” scientific breakthroughs.
Now, I am not at all saying that this is Harry’s plan to resurrect her (In fact I suspect his plan to be very different from this), I am merely providing an example for how you can “restore” someone who is dead without being capable of time travel.
By definition, however, an information-theoretic death means that such an error-correction scheme would be impossible; such a machine would require knowledge that, by the Uncertainty Principle, cannot be attained.
Thus, if you did have that capability regardless, it could then be used to rewind an arbitrary section of the universe to an arbitrary time, which is equivalent to time travel.
Ok, now we’re just talking past each other. Just googled the term “information-theoretic death” and got the following definition from wikipedia:
This is obviously the situation that Harry has to avoid. If his plan was:
Allow Hermione’s brain to decay so much that it becomes theoretically impossible to restore it.
Do something theoretically impossible.
Then his plan is just wrong.
Information-theoretic death implies the absence of time travel.
With time travel, the concept is nonsensical.
Well, that would depend entirely on whether or not time travel beyond 6 hours into the past is possible. So, in other words, it’s time travel arbitrarily far back in time that would make this term nonsensical.