So in some fanfics dodging spells is a key part of defense. But in my mind spells, since they are presented as being colored light, would naturally travel at the speed of light. This would mean that dodging would be near impossible. In order to dodge, spells would have to travel relatively slowly, like somewhere around baseball speed. What do all of you think?

 

I'm a big fan of fast spells but I think the speed of light is pushing it a bit. The problem with spell velocity is that there's very little to go on in the books. The nature of writing is that you must write things in a certain order - it's very difficult to present simultaneous action or very rapid successive action.

So the text under-determines the actual physical situation. A duel where the spells travelled almost instantaneously would read much the same as one where they travelled like tennis balls. In either case you would have to write the person casting the spell first, followed by the reaction of the defender, be that blocking, parrying, shielding or attempting to dodge. It's worth noting, however, that we have no real examples in canon of any duellist dodging a spell that is already mid-flight. Dodges are rather almost always initiated as wild leaps out of the way of a wand pointed in their direction, not a controlled movement to avoid a spell that is already on its way. That could indicate relatively rapid spell movement.

The best information we have, however, is Snape's duel with Harry in HBP. That more than anything illustrates to us the mechanics of a duel as it's the only duel where we get a proper look at blocking, parrying etc. What that duel seems to indicate is that the nature of blocking and parrying spells - a fairly standard and important technique - is doing something to interfere with the spell mid-way through the incantation. That in turn suggests that doing it after the incantation may be too late to block, which also points towards rapidly moving spells.

That HBP duel really changed the way I visualised spells in HP. In the past I had imagined them as exiting the wand at the end of the incantation, fully formed, then moving towards the target. Since reading HBP I have rather viewed spells as forming during the incantation, not after it, with defensive actions being taken largely during the incantation of your opponent. That formation process is itself not really a matter of exiting the wand like a bullet, but rather forming in the air around the wizard and particularly focused around the wand.

 

Too fast to effectively dodge but slow enough to be seen. Nowhere near the speed of light.

We don't really see anyone athletically dodging a bunch of spells in a duel. But spells have to be aimed and can miss. Mostly it's blocking/countering mid-cast (Snape) and shields.

I think a fast baseball comparison is apt. Something like 60-120 kmph.

 

So we can agree that a gunshot could theoretically hit a wizard before he has time to block or evade it. In Philosopher's Stone Hagrid took the gun from Vernon before he was able to actually use it, and just be clear this isn't meant to be a wizard Vs. Muggles just a statement from the evidence we have here.

 

On the other hand we have Voldemort's killing curses traveling slow enough for animated statues (and Fawkes) to have enough time to move in front of the spell (OotP). In DH Bellatrix is said to be "capering" around Molly's spells, before she's hit by one.

Also I never liked the Snape vs Harry "duel"; it just feels extremely unnatural for Harry to stop mid-word when saying a short word like "Crucio" or "Stupefy". Sure, Snape may well block Harry's spells, but the way he's doing it feels simply badly written.

Really the Harry Potter magic works on the rule of cool. The moment you set any solid rule on any of the magic, tons of game-breaking ways of abusing that rule emerges and everyone not exploiting those ways looks stupid. So, don't set rules on your magic, just make it as magical as possible.

 

Spells are magic, not light. I don't see why spells couldn't have variable speed, but thinking magic travels the speed of light is kind of crazy. Looking like light, and actually being light, is two completely different things. Unless it's the lumos spell, which I guess travels at the speed of light because it is light.

 

I don't think that spells can travel even remotely close to the speed of light and be blockable/dodgeable or even remotely defensible.

Like, for comparison, light from the moon hits Earth 1.28 seconds after it is reflected off its surface. That means that light traveled the distance from the moon to Earth (~239000 miles) in 1.26 seconds.

Wizards are going to be battling within 1 mile of each other in all but the unlikeliest of situations. That means that spells starting from the wizard/witch's wand will hit his/her target in approximately 0.00000535 seconds.

Yeah, good luck trying to defend against that.

 

B-but legilimency in combat to predict and pre-emptively defend!

 

Taure's example of the Snape vs Harry fight is a pretty good one, I think. It means there is at least some way of blocking a spell in the middle of the incantation, even if it will still have to travel after that.

I think another instructive fight would be Voldemort vs. Dumbledore. Neither of them actually attempts to dodge a spell even once, not physically anyway. Both apparate out of the way, but they don't try to leap aside or sidestep any spells. Since they're the two most powerful wizards in the series, they're presumably using a fairly optimal fighting strategy. This seems to suggest that dodging spells once they've already left is difficult. Dumbledore does animate a statue to jump in front of a killing curse, but for all we know, he had already directed it to do so before the spell left Voldemort's wand.

Of course, there is also the possibility that Dumbledore and Voldemort were just not agile enough to dodge. Although Dumbledore was described as fast for his age, he usually wore long robes -- presumably not very good for quick movement. Who knows what Voldemort's body was like after the resurrection, but he was also over 70 years old and also seemed to favor robes.

 

I think you can dodge a spell the same way you dodge a bullet. Not by seeing the bullet come towards you and move. But by seeing the barrel of the gun point towards you and dodge that. You dont dodge the spell, you dodge the wand direction.

I think in the battle in Hogwarts when Dumblredore died, Ginny had some luck potion and was said to be dodging around most of the spells.

 

The problem with determining the velocity of a spell is that's simply impossible to determine and despite some of the holes in how Rowling wrote, it was the one thing she did right. The movies kind of scappered anything that she may have imagined for speed of spells with making the Killing Curse an instantaneous bolt of green lightning but you have to imagine it yourself and how you write it. Maybe the force put into casting the spell effects velocity, maybe the over-all power of the spell changes it's speed. Fact is, we don't really know and it can break how a writer works with the content.

Just for an example, the speed of light is 186,000 miles per second and the Earth is 24,901 miles in circumference. Your thought of a spell going the speed of light is impossible as the spell would be moving fast enough to circle the entire planet 7.5x before coming to a stop within the span of one second. So let's break this down further; it takes a human (on average) 0.25 seconds to respond to visual stimuli. If you were to break that down, the spell would still be traveling 167,654,157.25 miles per 1/4 of a second. Even if you knew what was coming through using Legilimency, you would never have the chance to escape from the spell.

Let's take in the rules of how duels work in Harry Potter, their rules and how that effects the reality of it all. For distance between participants, it is not really clear as duels apparently can start formally (I.E. The Dueling Club in Year 2) or informally, like damn near every other duel that takes place in the series. So let's choose an arbitrary distance, say ten paces each starting from a back to back standing position. Average stride distance for adolescent males (study I found was nonspecific on age) is roughly 2ft (24 inches, 0.9 meters). For a total of 20 paces, for a rough distance of 40-59 feet (dependant on length of individual stride).

To have spell light remain visible and react-able, it has to remain visible from that distance over the course of (using movie travel time based on average distance of stride) 2 seconds. Each spell would be traveling at around 13.6 MPH or roughly 6 meters per second. Any faster and the spell becomes closer to impossible to react to unless the distance is greater.

What does all of this mean? That I over think the physics present in a fictional universe created for enjoyment? Probably. What it does mean is that the movie contradicts basic physics based on pre-existing evidence in the same movie series between the Second Year with the Dueling Club, Fourth Year in the Graveyard, Fifth Year between the Death Eaters and the Order, Sixth Year when Harry tried to Curse Snape and Seventh Year in the 'Final Duel' between Harry and Voldemort.

 

Well, there are instances where they cast Protego after the spell was already on its way. That will give us a relative estimation on how fast spells go.

My question is that how it applies to transfiguration and conjuration. There's no indication of light. It happens instantly. Dumbledore transfigures something and it happens immediately. It almost feels like telekinesis or pyrokinesis when Dumbledore casted that inferno in HBP.

In lieu of that thought, it must mean that transfiguration and conjuration is almost unblockable. What if you conjure a knife on top of the person and drop it on his head? Transfigure the ground behind him to a spike through the heart?

There's not a bolt of light that hits the target and then transforms it.

 

Fireballs emit light; they don't move at the speed of light.

Plasma emits light; it doesn't move at the speed of it.

I can throw a flashlight, but it won't move at the speed of light.

Then there's magic. Spot the pattern.

Vernon is a dick, but not a killer. Not many people can pull the trigger. That Hagrid wrecked his shit before he fired the shotgun isn't a surprise; he was never going to use that shotgun.

 

I'd also like to point out that if the spells were travelling at the speed of light, then you wouldn't actually be able to see them before they hit you. (Unless my physics is wrong)

 

Perhaps it comes with being a Star Wars fan, but I imagine spells to go roughly the same speed as blaster bolts. Still a projectile, but Jedi have the time to deflect with their lightsaber

 

Can you give examples? I can't really remember where this happened. Usually, it seems extremely unclear to me at what point the protego was cast.

 

GOF, Harry casted it and Hermione blasted it off with a jinx. OoTP, when they were being chased inside the Ministry of Magic, Harry used it a couple of times to a great effect. HBP, Harry used it to redirect Legilimens back to Snape etc. etc.

You are right however, that it is unclear whether or not Protego was cast before or after the offensive spell was cast already. It would happen in the chase in OoTP if it happened and I think during the Legilimens, Harry cast the spell as soon as Snape did his Legilimens and redirected it back.