The horcrux technology uses the ghost phenomenon. Specifically, by causing the violent death of a wizard under controlled conditions (i.e., murder)
Some of the horcruxes in canon are made from murdering Muggles, though.
In chapter 45, the Dementor recognized Harry as Voldemort and addressed him by name: "Riddle".
I don't see anywhere that this happens in Chapter 45.
Very early in the chapter: "He had regained an impossible memory, for all that the Dementor had made him desecrate it. A strange word kept echoing in his mind."
And later: "Harry glanced in the Dementor's direction. The word echoed in his mind again. All right, Harry thought to himself, if the Dementor is a riddle, what is the answer? And just like that, it was obvious."
Once Harry figures out what Dementors are, he stops being able to hear their "voices", because he no longer sees (hears) them as sentient. But if "the word" was actually coming from the Dementor, I don't know what would've kept everyone else from hearing it.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 88-89. The previous thread has passed 500 comments.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: