We know Hermione didn't send herself a signal she could notice instantly on a second iteration. As of ch76, we do not know if she sent herself a signal not instantly noticable.

You might not want to use a signal that could be detected by yourself during an obliviation event in order to make sure the signal isn't telegraphed to the obliviator.

Harry might think that if one needed to signal obliviation, it might be best to detect it safely in the future, unless he thought he could make use of an instantly detectable signal and a tactical response would be worth risking interception. In Ch. 6 he risked interception of the signal (he told the potential obliviator McGonnagal about it) in order to forestall obliviation. I doubt that that tactic would work with Mr. Hat and Cloak/Ms. Veil/...

I doubt the Ch. 6 signal was magic, since he'd invented it and the recognition code before knowing about magic, and implemented during his first shopping trip. I don't think you'd need magic to signal obliviation or a full-on groundhog day attack.

Magic-wise, I'd suppose that obliviation would make a rememberall signal permanently, but then it seems like that would be important to for obliviators to counter somehow.

Magic leaves an armory worth of potential Chekov guns laying around. If owling hand grenades isn't enough to win the next war, it should be something interesting.

I'd think the chances are fair that Harry passed his Chap 6 obliviation signaling method onto his allies. If she is paranoid enough to key it for disorienting encounters with powerful wizards, the chances are high they might end up talking about encounter N.

What would signal would Harry think best? Something you could detect at the time of signalling, like a broken toothpick in your pocket, or a signal detectable safely in the future, like a penmark on the inside of your pocket? Probably both.

With a lever, and a place to stand, you can lift the barbell.

Defining omnipotence in respect to all possible beings seems more like "suprapotent" or "ultrapotent".

How is this the actual meaning of "omnipotence" and how does it relate to "a descriptor who's actual meaning makes an argument self-evidently bad, but which is sound if you do really think about it"

I'd taboo "actual" and "really".

Hams do this sort of thing already. If they could hook their G3 cell phone to a car battery and easily make it into a G3 APRS digipeater, they would do that too.

If the cell phone towers are down, maintaining a charge cell phone battery is near useless in current emergencies.

You need the distinct transmit/receive channels for full-duplex communication. The frequencies often only differ by <10MHz or so, with the uplink band being adjacent to the receiving band so they can share the same antenna an RF circuitry. The RF circuitry isn't the technical difficulty, it's in the software/firmware that is controlling the hardware. With some firmware/software changes, cell phones should be able to do some ham-APRS-like protocol.

The Hams have already solved this once using APRS at 144.39MHz, and it's dumb that we don't have a similar solution ported to cell phones at a convenient one of their working frequencies when not in reach of an on-line tower.

I think I saw a demo, or video a demo, about 15 years ago, of the ERICA gaze-tracking program at UVA where onlookers could see the screen change characters while the person whose gaze was being tracked couldn't see the changes. If I remember correctly, it was a screen of normal text in MS-Word or something that would mutate into gibberish where the user wasn't watching.

After reading that Bones and Dumbledore had timeturners, and remembering that if the ministry hands them out to schoolchildren, I thought probably any ministry official rating an iPhone, Blackberry, or Franklin Planner would have one as well. So, certainly the Dark Lord should/could/would have recognized their utility and gathered a few for his side.

A 6 hour simulation buffer would explain a T-6hour limit, but not that you couldn't go back into the same simulation buffer more than once, or that you couldn't operate on the 4 disjoint 6-hour segments of the 24 hour limit.

With an un-shelled Time Turner, could Harry go backwards from 23:59 to 17:59, then cover most of the same 6 hour interval again by jumping back from 00:01 the next day to 18:01?

Depending on how the 6 hours in 24 constraint is imposed, (Scotland's midnight-midnight, noon-noon, whenever the operator's variable 24-30hour days roll over, 9:00pm-9:00pm, a leaky-bucket token at 15sec/min, or whatever), what happens at 9 hours past lunch could be odd.

Any reasoning from Bella's apparent knowledge should take into account the Dementor-induced censoring of good memories, (e.g., sun, clouds).

Perhaps she can still remember parts of the plans that went wrong without remembering the successful parts.