I think it makes more sense to hypothesise that HPMOR-universe is a simulation being run in some meta-universe, and that time turners (and magic in general) are examples of complicated, explicit case rules that are hard-programmed into the simulation program.
To quote EY’s story “The Finale of the Ultimate Meta Mega Crossover”...
“Vg npghnyyl qbrf fbhaq zber yvxr zntvp guna culfvpf,” fnvq Unebyq Furn, jvgu n frevbhf ybbx ba uvf snpr. “V’ir orra guebhtu rabhtu jbeyqf gb xabj gur qvssrerapr—jul, onpx va zl rneyl qnlf, V hfrq gb geniry nebhaq orgjrra jbeyqf ol qrfpevovat gur ehyrf hfrq gb guvax nobhg gurz! Gur Ynjf bs Fvzvynevgl naq Pbagntvba, gung fbeg bs guvat. Riraghnyyl V jbexrq bhg gur ynjf bs gubhtug juvpu qrfpevorq gung jubyr zhygvirefr, juvpu vf ubj V tbg bhg… ohg bhe fgbevrf pna jnvg hagvy yngre. Naljnl, Znevn, gur ybtvp bs gur riragf lbh’er qrfpevovat vf bar jurer pbafpvbhfarff unf rssrpgf gung gnxr cerprqrapr bire gur ynjf bs culfvpf—jurer ybjre yriryf bs betnavmngvba tvir jnl gb uvture yriryf bs betnavmngvba. Gurer ner havirefrf jurer gur ivfvoyr ehyrf ner fvzcyr, zngurzngvpny, naq shaqnzragny, naq rirelguvat gung unccraf, unccraf jvguva gurz. Naq gurer ner havirefrf jurer gur ivfvoyr ehyrf ner pbzcyvpngrq naq unir rkcyvpvg fcrpvny pnfrf sbe fhesnpr curabzran—naq hfhnyyl fbzr bs gur ivfvoyr ehyrf ner nobhg zragny curabzran, naq qba’g ivfvoyl erqhpr gb ehyrf nobhg aba-zragny cnegf. Jr pnyy gur sbezre fbeg bs havirefr ‘angheny’, naq gur ynggre fbeg ‘zntvpny’. Ol bhe pbairagvbaf, Znevn, lbh jbhyq or pbafvqrerq gb pbzr sebz n zntvpny havirefr—be zntvpny zhygvirefr, engure, fvapr lbh’ir nyernql zbirq nebhaq vafvqr vg naq qvfpbirerq fbzr bs gur ehyrf sbe geniryvat.”
This explains why magic is so difficult to explain in terms of physical laws—it’s irreducibly complex. Things like being able to sustain human-level cognition even after being transformed into a cat and time turners only counting it as information if you’re consciously aware of some specific fact from the future (instead of knowing that there’s something you might want to know, as Dumbledore does when Bones asks him if he wants to hear the news from six hours in the future) are products of the fact that that magical rules pay special attention to things like the brain states of humans. Similarly, the laws of thermodynamics are irrelevant because magical laws are just as fundamental and operate as exceptions to these rules—“energy cannot be created or destroyed except when someone waves a wand and says “fridgerio”.”
If I’m right, the simulation probably either:
a) selects between possible time-paths on the fly, calculating the most probable path within a given, bounded probability space for any given moment. Most of these tend to not actually be loops at all (they’re linear and don’t include time travel), but when time turners get involved the universe has to chew through the numbers until it settles on the most probable, stable loop. In this case, the six hour limit may stem from a processing limitation, i.e. the computer can only handle a certain number of calculations at once. This version doesn’t inherently explain kooky messages like don’t mess with time, so they must be the product of specific, complicated rules too—“allow people to fool around with time unless they try to find primes or otherwise buck the system”.
or b) calculated all of time from start to finish in one giant flop. In this case, there are no contingent time-paths, everything happens because it had to happen that way in order for the next thing to happen. In this case, the simulation had to choose not between different possible momentary time paths but different possible universes, and the six-hour limit is probably just a number that the simulators picked to keep things relatively simple. In this case, kooky messages are necessary because that’s just what happens to happen in this universe.
Perhaps there is a set of meta-rules governing what the magical laws are, allowing people to invent new spells if they delve deep enough into the mysteries, I think we probably need more information to decide on that point. If such meta-laws do exist then we can expect Atlantis to have been a real civilisation in HPMOR-universe, which formulated most of the magical laws we see today by action of the meta-laws. If there aren’t any such meta-laws, Atlantis is probably the civilisation/individual/planet/universe/computer running the HPMOR simulation (or else a previous situation which was used as a test-run for the current one), which would explain how it seems to have been “erased from time”. It was never in the universe to begin with, so of course you can’t see it by looking into the past.
I think it makes more sense to hypothesise that HPMOR-universe is a simulation being run in some meta-universe, and that time turners (and magic in general) are examples of complicated, explicit case rules that are hard-programmed into the simulation program.
To quote EY’s story “The Finale of the Ultimate Meta Mega Crossover”...
“Vg npghnyyl qbrf fbhaq zber yvxr zntvp guna culfvpf,” fnvq Unebyq Furn, jvgu n frevbhf ybbx ba uvf snpr. “V’ir orra guebhtu rabhtu jbeyqf gb xabj gur qvssrerapr—jul, onpx va zl rneyl qnlf, V hfrq gb geniry nebhaq orgjrra jbeyqf ol qrfpevovat gur ehyrf hfrq gb guvax nobhg gurz! Gur Ynjf bs Fvzvynevgl naq Pbagntvba, gung fbeg bs guvat. Riraghnyyl V jbexrq bhg gur ynjf bs gubhtug juvpu qrfpevorq gung jubyr zhygvirefr, juvpu vf ubj V tbg bhg… ohg bhe fgbevrf pna jnvg hagvy yngre. Naljnl, Znevn, gur ybtvp bs gur riragf lbh’er qrfpevovat vf bar jurer pbafpvbhfarff unf rssrpgf gung gnxr cerprqrapr bire gur ynjf bs culfvpf—jurer ybjre yriryf bs betnavmngvba tvir jnl gb uvture yriryf bs betnavmngvba. Gurer ner havirefrf jurer gur ivfvoyr ehyrf ner fvzcyr, zngurzngvpny, naq shaqnzragny, naq rirelguvat gung unccraf, unccraf jvguva gurz. Naq gurer ner havirefrf jurer gur ivfvoyr ehyrf ner pbzcyvpngrq naq unir rkcyvpvg fcrpvny pnfrf sbe fhesnpr curabzran—naq hfhnyyl fbzr bs gur ivfvoyr ehyrf ner nobhg zragny curabzran, naq qba’g ivfvoyl erqhpr gb ehyrf nobhg aba-zragny cnegf. Jr pnyy gur sbezre fbeg bs havirefr ‘angheny’, naq gur ynggre fbeg ‘zntvpny’. Ol bhe pbairagvbaf, Znevn, lbh jbhyq or pbafvqrerq gb pbzr sebz n zntvpny havirefr—be zntvpny zhygvirefr, engure, fvapr lbh’ir nyernql zbirq nebhaq vafvqr vg naq qvfpbirerq fbzr bs gur ehyrf sbe geniryvat.”
This explains why magic is so difficult to explain in terms of physical laws—it’s irreducibly complex. Things like being able to sustain human-level cognition even after being transformed into a cat and time turners only counting it as information if you’re consciously aware of some specific fact from the future (instead of knowing that there’s something you might want to know, as Dumbledore does when Bones asks him if he wants to hear the news from six hours in the future) are products of the fact that that magical rules pay special attention to things like the brain states of humans. Similarly, the laws of thermodynamics are irrelevant because magical laws are just as fundamental and operate as exceptions to these rules—“energy cannot be created or destroyed except when someone waves a wand and says “fridgerio”.”
If I’m right, the simulation probably either:
a) selects between possible time-paths on the fly, calculating the most probable path within a given, bounded probability space for any given moment. Most of these tend to not actually be loops at all (they’re linear and don’t include time travel), but when time turners get involved the universe has to chew through the numbers until it settles on the most probable, stable loop. In this case, the six hour limit may stem from a processing limitation, i.e. the computer can only handle a certain number of calculations at once. This version doesn’t inherently explain kooky messages like don’t mess with time, so they must be the product of specific, complicated rules too—“allow people to fool around with time unless they try to find primes or otherwise buck the system”.
or b) calculated all of time from start to finish in one giant flop. In this case, there are no contingent time-paths, everything happens because it had to happen that way in order for the next thing to happen. In this case, the simulation had to choose not between different possible momentary time paths but different possible universes, and the six-hour limit is probably just a number that the simulators picked to keep things relatively simple. In this case, kooky messages are necessary because that’s just what happens to happen in this universe.
Perhaps there is a set of meta-rules governing what the magical laws are, allowing people to invent new spells if they delve deep enough into the mysteries, I think we probably need more information to decide on that point. If such meta-laws do exist then we can expect Atlantis to have been a real civilisation in HPMOR-universe, which formulated most of the magical laws we see today by action of the meta-laws. If there aren’t any such meta-laws, Atlantis is probably the civilisation/individual/planet/universe/computer running the HPMOR simulation (or else a previous situation which was used as a test-run for the current one), which would explain how it seems to have been “erased from time”. It was never in the universe to begin with, so of course you can’t see it by looking into the past.