I was trying to think of a reason for a rebounding Killing Curse to make Voldemort’s body disappear (no luck so far) when I thought of an entirely different question: with no body and no witnesses (other than Harry, who probably didn’t know more than a few words), why was the wizarding public so quick to believe Voldemort had been defeated?
McGonagall was staking out Privet Drive in cat form by the time Vernon left for work the next morning, and she already knew that “everyone” was saying Harry had defeated Voldemort. Even if we’re generous and say that the attack happened at 6:00 p.m. (after dark, trick-or-treaters are out) and Vernon left at 9:00 a.m. (wizards gathering in the streets), that’s only fifteen hours. And the attack could have happened as late as 10:00 p.m., and Vernon could have left for work earlier. Maybe it was only ten hours.
Now, ten or fifteen hours might be enough time for word to spread that something had happened at Godric’s Hollow, but it’s a very short window for everyone to be so confident of what had happened. Why was “everyone” already saying Voldemort was gone for good?
Consider what the Ministry could have known from the scene and whatever Dumbledore told them: James and Lily were dead, probably from the Killing Curse; something blew a hole in the house near Harry’s crib; Harry had an unexplained curse scar and was alive. Voldemort didn’t leave a body. What made them think he was mostly dead? He could have killed James and Lily, inexplicably failed to kill Harry, blew a hole in the house to vent his frustration, and left without sending up the Dark Mark because he was too embarrassed to claim his work when he couldn’t finish the job. Maybe he didn’t even try to kill Harry, just cursed him as a warning. (The general public doesn’t know about the prophecy, so they have no reason to think he was targeting Harry rather than Lily and James.) If they didn’t track down and question the one child who saw under Voldemort’s hood, they might not even be sure that Voldemort rather than one of his Death Eaters was the attacker. How did they know he wasn’t torturing that Death Eater for botching the assignment at the same time the Ministry was examining the scene?
Did he maybe leave bits of his body behind? But we have no evidence that he did, and you’d think it would come up during one of the discussions Harry heard about whether Voldemort was really most sincerely dead. Umbridge probably would have used it as “proof” that Voldemort hadn’t returned, for example.
Did some Death Eater stop in the middle of a public attack and start shrieking that he’d felt the Dark Lord cry out in terror before being suddenly silenced? That would be very dramatic, but we have no evidence of that either. And it’s so dramatic that it would be weird that we didn’t hear the story, if it happened.
Or did everyone take Dumbledore’s word for it? “I didn’t witness any of last night’s events, haven’t spoken to anyone who did, and can provide no evidence whatsoever, but my mysterious sources tell me that Voldemort was suddenly weakened nearly to the point of death, and that whatever remains of him is currently fleeing the country. No, I couldn’t possibly explain why I’m claiming that young Harry was responsible. No, I really can’t offer any reason you should believe any of this. But I am absolutely certain that Voldemort won’t be resuming his campaign of terror after a week to recuperate.”
And that’s enough for the Ministry to make a statement for the Daily Prophet so that everyone can start planning parties by breakfast time? Trusting bunch, wizards.
Okay, maybe Dumbledore told them he saw some of the events in Harry’s memory via Legilimency. Maybe he showed Ministry investigators Harry’s memory in the school Pensieve. At least that supports part of the story.
On the other hand, Dumbledore might not have wanted anyone to see that memory. The more people knew that Lily had jumped in front of a Killing Curse meant for Harry, the more risk there was of someone wondering whether there wasn’t some old magic they thought they’d heard about once, something about love and sacrifice, and maybe Lily was really the one somehow responsible for Voldemort’s disappearance? Dumbledore had several reasons not to want the rumor mill getting ahold of that idea, starting with “’Harry did it’ is good protection for Harry against any vengeful Death Eaters, and I can’t be sure that one of these Ministry investigator isn’t secretly a vengeful Death Eater.” If Dumbledore showed or even told these details to anyone, he must have made really sure that they couldn’t talk.
Which just kicks the problem down the road, because then the public would be taking some Ministry official’s word that a baby semi-killed Voldemort. Why would they do that? Especially when they were all sure that Death Eaters could be anywhere, including working at the Ministry? That’s even less believable than everyone taking Dumbledore’s word for it. At least he had first-hand experience with defeating Dark Lords.
Am I missing something? What convinced everyone within hours of Voldemort’s defeat that he was gone, and made them so confident enough to celebrate rather than waiting and seeing?