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TobyBartels comments on Harry Potter and the Methods of Rationality discussion thread, part 6 - Less Wrong Discussion
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Has anybody unscrambled Harry's secret message?
(To avoid spoilers, please give your answer in rot13.)
thx!
On a slightly more serious note....
Flitwick: "Yes, Harry, what is the matter?"
Harry: "I have been instructed to deliver a message to you, Professor. "Silver on the tree"."
Flitwick: "I... see. May I ask who sends this message, Harry?
Harry: *pause*
Flitwick:"...the Headmaster? Prof. McGonagall? Prof. Snape?"
Harry's inner Hufflepuff: Next time maybe let's not be so lazy with doing a few extra Caesar shifts, eh?
Harry: I don't know if I'm supposed to say.
Remember, Innocent!Harry has no idea what's going on.
I'll fix it.
Good point! Since Harry's ruse seems to have succeeded, this looks like an oversight on Eliezer's part.
Which reminds me: While this cypher may be the kid-brother type, it used to be the major-governments type. So for unEnlightened Wizards, maybe it still is enough to fool major governments!
In Order of the Phoenix, Sirius Black seems to know that codes exist, at least. Although he dismisses them as "breakable" and decides to communicate over a floo network connection instead (which makes me wonder if wizards know about one-time pads, and if there are any spells which can break them).
Given that the magical community didn't seem to get into mathematics much, and provably strong crypto needs a ton of math, I could see how they never went beyond Caesar Ciphers.
He would have guessed and any timeline where he would have guessed wrongly would have been inconsistent, since he sure as hell would have remembered to include the relevant information then. So either the note would have included that information or he would have guessed correctly and not have bothered to include the information because he remembered guessing correctly. If you are willing to risk paradox to force a resolution you know with absolute certainty to be possible you never actually have to go though with it (compare Harry's first, third and fifth time travel escapades).
But this is essentially a less systematic variation of the trick he tried with factoring prime numbers. "I'll guess, and since guessing wrong would lead to paradox, it guarantees that I have guessed right" should have ended with another DON'T MESS WITH TIME note.
Besides, it costs him absolutely nothing to add a few more details to the letter. The only reason I can think of for not doing so is if he somehow evaded Flitwick's obvious question without arousing suspicion, (and so found himself needing not to know to replicate the feat).
The difference is that the factoring trick involved several thousand other timelines that had to be resolved while adding any information he lacked to the message involved one. Spontaneously generating timeline stabilizing random data that only requires resolving a low number of timelines to calculate being preferred over having to calculate thousands makes sense, being preferred over a stabilization that requires calculating at most one other timeline does not.
It's not really any different from any other trick that involves him observing the results of his time travel before he carries it out. The difference between a) resolving to use time travel to get himself out of the empty class room and b) just having thought of it and being willing to get himself out of the empty classroom if he observes it actually having happened is that in a) he would do it even if he had not observed the results, there is no other potential behavioral difference between a) and b) for the difference in outcome to correspond to.
It could have been a compressed code - maybe if Minerva had sent the message to Dumbledore there would have been no prefix.
Also, as the Time-Turner goes back in hourly increments, some additional security could have been achieved by making Harry use it in front of Minerva, and monitoring the room in question at 8PM, 7PM etc. It's possible that might cause or be purposely made to cause paradox, though.
I went through the trouble of finding a tool to brute force the Caesar cipher before I realized that of course it would be in rot13. I feel silly now.
Har har.
I tried that and I still don't get it. What is it?
Consider what the earlier version of Harry needs in addition to the secret message. (You did click Unnamed's link, right?)
I can't tell if you're being clever here or are just suffering from compartmentalization.
I liked your original message better, where it wasn't clear whether you knew that I was joking or not.