Do Evocation Spells Create Matter?

[asnys]

For example, consider the spell burning hands. It creates a 15-foot-long, 30-foot-wide cone of flames. If I cast that in a hermetically-sealed chamber whose air pressure had been reduced to zero, would the "flames" - hot gas, presumably - still be there the round after I cast the spell? The spell does say that "a cone of searing flame shoots from your fingertips", so I don't think it's just heating up the matter in front of you, it's actually shooting fire at people. And the explanation of the Evocation school does include the line "create something out of nothing."

I've always assumed that evocation spells create matter that is only "pseudoreal", and it winks out of existence after the spell effect is finished. That's why evocation blast spells are generally SR: Yes but conjuration blast spells are generally SR: No. But I can't seem to find that actually in the rules anywhere. Some evocation spells do include specific lines saying the matter doesn't stick around after the spell expires, but not all of them. If anything, that would imply that the matter would otherwise remain, since otherwise they wouldn't need to specify it.

This isn't something I'm planning to use in actual play, it's for a theoretical exercise (designing a rocket in D&D - burning hands spell traps make a better thrustor than a decanter of endless water steam rocket). So I'm only interested in strict RAW, not what a DM would actually rule. Does it actually say anywhere in the rules one way or the other?

Edit to Add: To be more explicit, the idea is to place burning hands spell traps inside a "combustion chamber" to capture the gas and then channel it out of a nozzle.

[lunar2]

regardless of whether burning hands creates matter or not, it doesn't create any kinetic energy. it doesn't move you or anything else. you'd want an explosive spell with a long line for that (target the line upwards into the hardened rocket cone, activate the trap that's attached to the rocket, the blast goes off shooting the rocket to the end of the line. repeat with extra traps for faster speed.)

[asnys]

regardless of whether burning hands creates matter or not, it doesn't create any kinetic energy. it doesn't move you or anything else. you'd want an explosive spell with a long line for that (target the line upwards into the hardened rocket cone, activate the trap that's attached to the rocket, the blast goes off shooting the rocket to the end of the line. repeat with extra traps for faster speed.)

I'm planning to catch the gas in a "combustion chamber" and channel it through a nozzle (assuming it's actually real). I considered explosive spell, but it appears to create only pseudovelocity, not actual velocity.

[Deophaun]

First of all, a burning hands trap would produce zero thrust. How do we know this? Because there's nothing in the spell's description that says it does. This is why people build rockets out of decanters of endless water, because the description there does produce thrust.

Second, you're dealing with a reality where fire exists on its own, independent of combustion. Considering that, why would there be any hot gas left over? Experiments similar to the one you describe are partially responsible for disproving aristotelian physics, which holds true in the 3.5 setting. So the fictional result should instead disprove chemistry and uphold the idea of earth, fire, air, and water as fundamental elements.

Now, you want to know what strict RAW says? Strict RAW says it doesn't happen, because strict RAW does not say that it happens. Just because burning hands does not explicitly rule out the possibility of a herd of dinosaurs popping into existence at the end of the spell's duration, it does not mean that you wind up elbow deep in a pile of camposauri every time you cast it. The rules don't work that way.

[nedz]

Evocation Spells Create energy: Raw elemental stuff.

3.5 does not do Momentum, so forget that stuff.

Evocation Spells can also create Forcefields.

[jedipotter]

Does it actually say anywhere in the rules one way or the other?

Not that I have ever seen. But Evocation spells do create matter. Plenty of evocation spells make ice or water (both matter). Some can make salt or sand (again both matter).

Though if your just making a magic item, you can modify the spell effect a bit. After all, if you look at magic items, they don't all do the exact spell effect that created them.

[Slipperychicken]

Instantaneous magic fire doesn't need or use fuel IIRC, though it can ignite objects and creatures.

[JaronK]

Decanters actually create thrust back, but Burning Hands doesn't. I'd actually guess it pulls fire straight from the Plane of Fire and launches it at your target, almost as though through a portal. It should be able to launch in space just as well. But no matter is created... if done in a vacuum, you wouldn't have soot or anything afterwords.

I'd think of Evocation as magically pulling that fire into the world, and when the spell ends that pull ends so the fire bounces back to the plane of fire like a rubber band snapping back. Conjuration, meanwhile, actually pulls it over permanently.

JaronK

[asnys]

Decanters actually create thrust back, but Burning Hands doesn't. I'd actually guess it pulls fire straight from the Plane of Fire and launches it at your target, almost as though through a portal. It should be able to launch in space just as well. But no matter is created... if done in a vacuum, you wouldn't have soot or anything afterwords.

I'd think of Evocation as magically pulling that fire into the world, and when the spell ends that pull ends so the fire bounces back to the plane of fire like a rubber band snapping back. Conjuration, meanwhile, actually pulls it over permanently.

I thought about using blast of flame or other conjuration blast spells instead of burning hands, but the explanation of the Conjuration (Creation) descriptor - which is where all the conjuration blast spells I'm aware of fall under - says it "manipulates matter" rather than creating it. So it may look like minor creation is making that wineskin out of nothing, but it's actually taking microscopic bits of matter from everything around it to make it. I did look into "feeding" blast of flame spell traps using decanters or the like, but it proved to be logistically prohibitive.

[Talya]

Death to catgirls!

[JaronK]

I thought about using blast of flame or other conjuration blast spells instead of burning hands, but the explanation of the Conjuration (Creation) descriptor - which is where all the conjuration blast spells I'm aware of fall under - says it "manipulates matter" rather than creating it. So it may look like minor creation is making that wineskin out of nothing, but it's actually taking microscopic bits of matter from everything around it to make it. I did look into "feeding" blast of flame spell traps using decanters or the like, but it proved to be logistically prohibitive.

It being conjuration, I'd assume it's actually conjuring that wine skin from parts of the elemental planes of water and earth and such.

It still won't blast you. If you want a rocket, you want a Decanter of Endless Water piped through a tiny Riverine tube with some ability to force that water to become steam. That'll give you plenty of thrust.

JaronK

[nedz]

But changing water into steam is just a case of turning an element into a para-element. This never causes an increase in volume.

[JaronK]

If you do it through heat, it should work just like in the normal world, and with the decanter it's real water, not just evocation pulled temporary water. Steam has MUCH higher volume than water when the same amount of H2O is involved.

JaronK

[asnys]

It being conjuration, I'd assume it's actually conjuring that wine skin from parts of the elemental planes of water and earth and such.

<shrug> That's not what the descriptor text says.


It still won't blast you. If you want a rocket, you want a Decanter of Endless Water piped through a tiny Riverine tube with some ability to force that water to become steam. That'll give you plenty of thrust.

My plan at the moment is to capture the gas from burning hands in a conical "combustion chamber" with a nozzle. I'm modeling the thermodynamic properties of "fire" on the flame from a propane blowtorch, so it's basically a propane-oxygen rocket with an infinite massless fuel tank. By my numbers, the marginal thrust/cost ratio of that system should be about three times that of a decanter steam rocket. If the gas from burning hands is pseudoreal or otherwise unsuitable, then I'll go for the steam rocket, probably using permanent wall of fire as a heat source.

I'm going to post it on my blog when it's done, but right now I just want to determine if there's anything in the actual rules that says the flame from a burning hands spell vanishes. Because I've always assumed it does, but I can't find it anywhere in the SRD. :smallconfused:

[Psyren]

I'd think of Evocation as magically pulling that fire into the world, and when the spell ends that pull ends so the fire bounces back to the plane of fire like a rubber band snapping back. Conjuration, meanwhile, actually pulls it over permanently.

Tome of Magic supports this interpretation:


For every action, an equal and opposite reaction exists. The reaction is not visible in most forms of magic. The wizard who casts a fireball into the midst of his enemies neither sees nor cares about the brief amount of flame that vanishes from the Elemental Plane of Fire to power that spell.