Skip to main content

How Fast do Spells Travel in the Harry Potter Universe?



We've discussed if spells travel in a straight line and about blocking spells. We know spells don't just happen. They have to be directed by a wand and they can be blocked, so there's every indication that most attack spells travel from the end of a wand to the object in question.


Is there anything to indicate how fast a projectile-style spell travels?



Answer



Well, from the books we know that when wizards duel (like in the dueling league) they face each other at a range where normal spoken communication is easy.


Beyond ~30 feet, you have to put in a lot more effort to be heard, which the books do not demonstrate happening - Harry and Draco, for example, exchanged threats just fine.


Therefore, we can assume that it is reasonable for an experienced duelist to react to their opponent's spell at a distance of ~30 feet.


The casting time of a spell seems to average around one second (verbal and motion casting). We can further assume that the common attack spells in duels can be distinguished by an experienced duelist from the first motion (so within a half second of the start of casting).


This leaves the opponent a half second to choose a defense and cast it before the spell is headed their way. They need to then cast their defense or counterattack, which will take approximately a second.



  • At time 0 the attacker (A) begins casting a spell.


  • At time 0.5, the defender (D) begins casting a defense or counter.

  • At time 1, A's spell launches towards D. D still needs a half second to finish casting.


Therefore, if the spell can cover 30 feet in half a second, D will never be able to counter, and the duel will likely end with the first spell every time.


Spells can't move too slowly, either, or even an inexperienced duelist will have plenty of time to summon a defense - attacking will never hit.


I would therefore estimate that the spell takes between .75 and 1 second to travel a distance of up to 30 feet.


That works out to ~37.5 feet per second to 30 feet per second (I would expect that different spells travel at different speeds, but this works for an average range). This is fast, but not so fast that a prepared defender won't have time to defend himself and/or dodge.


For comparison, a quick google search suggests that most bullets from a handgun travel at a minimum of 1,000 feet per second (up to around 1,500 fps) when they exit the barrel. A spell travels, then, at ~2% the speed of a handgun bullet (rifle bullets are considerably faster).


These are back-of-the-envelope calculations, and may be off by a factor of two or three (if duelists stand 40 or even 60 feet apart, instead of 30). Even a worst-case scenario, though (60 feet apart, at which distance you MUST yell to be heard) has a spell traveling at less than 80 feet per second.


Comments

Popular posts from this blog

harry potter - Did Dolores Umbridge Have Any Association with Voldemort (or Death Eaters) before His Return?

I noticed that Dolores Umbridge was born during the first Wizarding War, so it's very likely she wasn't a Death Eater then (but she is pretty evil -- who knows?). After that Voldemort was not around in a way that could affect many people, and most wouldn't know he was planning to rise again. During that time, and up through Voldemort's return (in Goblet of Fire ), did Umbridge have any connection with the Death Eaters or with Voldemort? Was she doing what she did on her own, or was it because of an association with Voldemort or his allies? Answer Dolores Umbridge was definitely not a good person. However, as Sirius points out, "the world isn't split into good people and Death Eaters". Remember that he also says that he doesn't believe Umbridge to be a Death Eater, but that she's evil enough (or something like that). I think there are two strong reasons to believe that: Umbridge was proud to do everything according to the law, except when she trie...

What is the etymology of Doctor Who?

I recently decided to watch Doctor Who, and started viewing the 2005 version. I have the first two episodes from the first season, and I can't help but wonder what is the etymology of the name "Doctor Who"? And why does the protagonist call himself "the Doctor" (or is it "the doctor")? Answer In the very first episode of Doctor Who (way back in 1963), the Doctor has a granddaughter going by the name "Susan Foreman", and the junkyard where the TARDIS is has the sign "I.M. Foreman". Barbara, who becomes one of the Doctor's companions, calls him "Doctor Foreman" (probably assuming that is his name given his relationship to Susan), and Ian (another early companion) does the same in the second episode, to which the Doctor says: Eh? Doctor who? What's he talking about? "Foreman" is most likely selected as a convenient surname for Susan to use because it happened to be on display near where the TARDIS landed....

story identification - Animation: floating island, flying pests

At least 20 years ago I watched a short animated film which stuck in my mind. The whole thing was wordless, possibly European, and I'm pretty sure I didn't imagine it... It featured a flying island which was inhabited by some creatures who (in my memory) reminded me of the Moomins. The island was frequently bothered by large winged animals who swooped around, although I don't think they did any actual damage. At the end one of the moomin creatures suddenly gets a weird feeling, feels forced to climb to the top of the island and then plunges down a shaft right through the centre - only to emerge at the bottom as one of the flyers. Answer Skywhales from 1983. The story begins with a man warning the tribe of approaching skywhales. The drummers then warn everybody of the hunt as everyone get prepared to set "sail". Except one man is found in his home sleeping as the noise wake him up. He then gets ready and is about to take his weapon as he hesitates then decides ...