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Lagomorph
So the thread on invis+silence brought up a point for me that I thought would be best spun off into a different thread.

Does levitate just break the laws of physics (conservation of mass/energy) or is there a way to get it to make them work together?

Here's a question for you to illustrate the point:
A 100kg mage is in a 100kg cage on a scale, when the mage is at rest the scale shows 200kg, when he levitates does the scale read 100kg or 200kg?
JBlades
The scale would read 100kg, as the levitate spell is the application of energy to cause lift, hence while the mage still weighs 100kg, he no longer exerts that force on the scale, it has become potential energy because he's been lifted exactly as if a troll came along and picked the little guy up. No violation of physics has occurred.
pbangarth
Let levitate work within and against the magnetic/gravitational field of the Earth and there is no problem. the scale would measure 100 kg. because the weight of the mage is pressing against the gravitational field directly, via the effects of the magic spell.

As a similar example, say you had a plastic (or any other non-magnetic substance) balance on one side of which was a magnet, countered by an equal weight on the other side. Now, bring an opposite pole magnet underneath the balance arm and magnet on the first side.

The magnet in the balance would lift, and the scale would no longer feel it at the same weight it did to begin with.
Buster
QUOTE (Lagomorph)
Does levitate just break the laws of physics (conservation of mass/energy) or is there a way to get it to make them work together?

Here's a question for you to illustrate the point:
A 100kg mage is in a 100kg cage on a scale, when the mage is at rest the scale shows 200kg, when he levitates does the scale read 100kg or 200kg?

Don't forget that there's a difference between weight and mass. The mage doesn't change mass, only his force on the scale changes (i.e. measurable weight). It's just like standing on a scale and having someone lift you up with a rope. Just in this case the rope is magic.
Hank
If levitate lets you float across pressure plates, that scale had best read 100kg.
Gelare
Forgive me, but I can't help but point out...it's magic. biggrin.gif
But if you're looking for a challenge as far as ways to reconcile magic with physics, everyone always loved those threads about the Movement power. Conservation laws? Bah! Bah, I say!
Ol' Scratch
It just breaks the laws of physics. Just like Fireball creates a huge ball of flame out of thin air that goes hurtling wherever you wish, Shapechange temporarily destroys or creates matter out of thin air, and Turn to Goo does... whatever it does out of thin air.

Magic follows its own rules and only interacts with our world and our universal rules on a secondary level.
Lagomorph
QUOTE (Buster)
QUOTE (Lagomorph @ Nov 16 2007, 03:46 PM)
Does levitate just break the laws of physics (conservation of mass/energy) or is there a way to get it to make them work together?

Here's a question for you to illustrate the point:
A 100kg mage is in a 100kg cage on a scale, when the mage is at rest the scale shows 200kg, when he levitates does the scale read 100kg or 200kg?

Don't forget that there's a difference between weight and mass. The mage doesn't change mass, only his force on the scale changes (i.e. measurable weight). It's just like standing on a scale and having someone lift you up with a rope. Just in this case the rope is magic.

I understand the difference between weight and mass.

If you use the rope (or troll) example, if you extend the scale to a size to include the troll, or where ever the rope is attached, you haven't changed the mass of the system just transferred the mages mass to another object. With magic, where can you extend the scale to include where the mages is taken into account?

QUOTE (Dr Funk)
It just breaks the laws of physics. Just like Fireball creates a huge ball of flame out of thin air that goes hurtling wherever you wish, Shapechange temporarily destroys or creates matter out of thin air, and Turn to Goo does... whatever it does out of thin air.

Magic follows its own rules and only interacts with our world and our universal rules on a secondary level.


Yeah, I'm just trying to see if any one can figure out a way to stop that, but I think it's probably just a hand-wave type things which magic tends to be. Magic being inconsistent with physics is hard for me to grasp since I'm a physics geek at heart.
kzt
Ok, you levitate into an elevator. Elevator zooms up at 10 meters per second (it's a FAST elevator). This (we'll say) exceeds the max speed of the levitate spell of 6 meters per second. Does the levitate guy bounce off the floor, or is he fine because the elevator isn't moving relative to him?
Paradigm
KZT, that's a brilliant question. One I'd be inclined to rule over against the players and say that it'd likely catch up to them. After all, they could've always taken the stairs rather than the deathtrap on a wire.

I suppose that magic fudges the rules enough to support either ruling, but it'd be a nice example of incompatability of tech and magic in my eyes.
GryMor
Like most magical effects, Levitate, as written, presumes a preferred frame of reference. Normally the preferred frame of reference is the Earth's surface on a large scale, possibly even the astral shadow of the Earth.

The question then arises as to when an alternate frame of reference can be substituted for the Earth, and how transitions between these frames of reference occur. There is, additionally, the special case of when Levitate initiates while the subject is traveling at a velocity in excess of that which levitate can sustain with respect to it's current frame of reference.

Observations:
1. The frame of reference of a levitate spell need not be (and usually won't be) an inertial frame of reference. Specifically, the Earth's surface is under a 1g acceleration.
2. It is probably for the best that levitate not provide a corrective impulse to assert it's velocity restraints, otherwise, at weak force, it becomes an absurdly effective means of converting drivers into chunky salsa.
3. Levitate probably SHOULD assert it's velocity restraints in some manner, otherwise it isn't particularly useful as a parachute and opens up the door for very long range heavy projectiles (accelerate car towards target, levitate 600kg lance braced on the car, stop car allowing lance to continue onwards).
4. If there are frames of reference besides the Earth (a airliner in flight or ship in high seas for instance), it should be possible to acquire the Earth's frame of reference by means of getting far enough away from the alternate frame of reference's associated body.

Other note:
With regards to where you put the scale to include the 'weight' of the levitating mage, the question makes as much sense as asking where you would put a scale to measure the weight of the earth. The answer is, that the weight of the Earth mage system is not a well defined concept, the system is in free fall around the sun, and thus, from a certain perspective, has a weight of 0.
Kyoto Kid
...I've learned trying to rationalise magic with physics is a quick ticket to either a cerebral hemorrhage or drinking a half bottle of cheap whiskey to forget why you tried to do so. I've banged my head against the wall too many times on this topic (the whiskey at least helps to dull the pain) grinbig.gif

I'll let someone else say it for me...
QUOTE (Gelare)
Forgive me, but I can't help but point out...it's magic. biggrin.gif


Mercer
QUOTE (kzt)
Ok, you levitate into an elevator.  Elevator zooms up at 10 meters per second (it's a FAST elevator).  This (we'll say) exceeds the max speed of the levitate spell of 6 meters per second.  Does the levitate guy bounce off the floor, or is he fine because the elevator isn't moving relative to him?

Its even worse if the mage is on a jet. Does he float relative to the aircraft or does he suddenly go flying backwards hundreds of kilometers and hour and shoot out the back of the plane?

What about a mage putting an immobile barrier inside a jet? Does it move relative to the craft or does the plane hit it? What if the mage is in the cabin and casts the barrier into the air in front of the craft? What if a mage in the plane wants to put a physical barrier over one wing to protect it flak? What if the mage is standing still on the ground and casts a physical barrier into something that's moving, like a subway car? Does the subway car smash the barrier or take it with it, and would it matter if the mage casting the spell was in the subway car, or in the subway car casting out?

I generally go with the movement or immobility of spells is relative to the aura of the thing they are being cast inside of, unless the result is ridiculous, and then I go with the next less ridiculous thing. That's my rule of thumb. A barrier cast inside of a moving vehicle moves with that vehicle. If its cast outside the vehicle, it stays where it is.

A mage casting levitate inside of an elevator might bump into the floor, because his movement would be relative to the building. (I wouldn't give each room its own aura, for example.) If the elevator freefalls, the mage will slam into the roof. A mage levitating inside of a plane levitates relative to the plane. When the troll sammie fires his grenade launcher and blows the side of the fuselage off, the mage is sucked out of the plane and will slow until his levitation speed is relative to the earth, similar to a skydiver. (I like the idea of magically active leva-troopers. Sue me.)

Where physics and magic diverge, I try to go with common sense and failing that, blind guesses.
GryMor
There is precedent for using the containing objects aura as the frame of reference. Wards work this way (allowing for warded vehicles but not uncontained mobile ward bombs of magey destruction/
DTFarstar
I generally go with the intent of the caster. If you want it to move with the object it does, if you don't it doesn't. Generally they could get either effect if they thought about it anyway, and dumbing things down a little bit speeds up gameplay a lot.

Chris
Critias
QUOTE (DTFarstar)
I generally go with the intent of the caster. If you want it to move with the object it does, if you don't it doesn't. Generally they could get either effect if they thought about it anyway, and dumbing things down a little bit speeds up gameplay a lot.

Chris

+1

Where are times I hate to hear it (*cough* LA and the ocean, for instance *cough*) but the simple fact is...it's magic. Yes, it can break the fucking laws of physics. That's what magic does. That's why we call it magic.
JBlades
QUOTE (Lagomorph)
With magic, where can you extend the scale to include where the mages is taken into account?

Yeah, I'm just trying to see if any one can figure out a way to stop that, but I think it's probably just a hand-wave type things which magic tends to be. Magic being inconsistent with physics is hard for me to grasp since I'm a physics geek at heart.

If you must find a rationale for these things, my gut answer to your question would be astral space, and I would answer the shape changing question the same way. The mass is converted to energy (mana) and stored in astral space, then converted back when the spell is ended (or drawn from energy in astral space which is converted to mass in the case of growing larger from a shape change spell).

Remember that a mage has access to energies from another dimension of space, and that most magic is a manipulation of those energies. You'll generally find your answer there if you look for it hard enough and squeeze your brain in the right way. twirl.gif
Fortune
QUOTE (DTFarstar)
I generally go with the intent of the caster. If you want it to move with the object it does, if you don't it doesn't. Generally they could get either effect if they thought about it anyway, and dumbing things down a little bit speeds up gameplay a lot.

I agree as well.
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