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Lysander
2010-03-04, 05:11 PM
There was this argument I saw a while back proposing that Wall of Force could be used to destroy a planet, or at least cause major damage. Here's what you do. Become immune to cold/heat/vacuum, teleport somewhere in deep space in the path of the planet, then start throw up Walls of Force. The walls are immovable and invulnerable so when the planet hits them they should dig tunnels right through the core of the planet at thousands of miles per hour. If not outright destruction we're talking major earthquakes and volcanic activity as a result.

But Walls of Force aren't completely invulnerable. The Legendary Dreadnought epic prestige class has the Unstoppable class ability which lets it make a DC32 Str check to break walls of force. So, should we assume that a freaking planet also has the ability to smash walls of force apart?

Kobold-Bard
2010-03-04, 05:16 PM
There was this argument I saw a while back proposing that Wall of Force could be used to destroy a planet, or at least cause major damage. Here's what you do. Become immune to cold/heat/vacuum, teleport somewhere in deep space in the path of the planet, then start throw up Walls of Force. The walls are immovable and invulnerable so when the planet hits them they should dig tunnels right through the core of the planet at thousands of miles per hour. If not outright destruction we're talking major earthquakes and volcanic activity as a result.

But Walls of Force aren't completely invulnerable. The Legendary Dreadnought epic prestige class has the Unstoppable class ability which lets it make a DC32 Str check to break walls of force. So, should we assume that a freaking planet also has the ability to smash walls of force apart?

If it can make a DC120 Escape Artist check (http://www.d20srd.org/srd/epic/skills.htm#passthroughWallofForce) or has 1 Level of Legendary Dreadnought then sure it can.

But how many Class Levels do you think the Earth has? Probably not enough, it is inanimate after all.

ScionoftheVoid
2010-03-04, 05:18 PM
There was this argument I saw a while back proposing that Wall of Force could be used to destroy a planet, or at least cause major damage. Here's what you do. Become immune to cold/heat/vacuum, teleport somewhere in deep space in the path of the planet, then start throw up Walls of Force. The walls are immovable and invulnerable so when the planet hits them they should dig tunnels right through the core of the planet at thousands of miles per hour. If not outright destruction we're talking major earthquakes and volcanic activity as a result.

But Walls of Force aren't completely invulnerable. The Legendary Dreadnought epic prestige class has the Unstoppable class ability which lets it make a DC32 Str check to break walls of force. So, should we assume that a freaking planet also has the ability to smash walls of force apart?

I think it would be more funny to have Legendary Dreadnought-shaped bits of planet survive due to a DC 32 Str check (with circumstance modifiers for going at such a speed) where the Walls have been broken. As a rule, unless you want to deal with this kind of thing and Walls of Force whizzing about all over the place due to them being literally immovable, you could have "immovable" effects be relative to the nearest object over however much mass/volume. You can still do this, but it's much more difficult.

Thalnawr
2010-03-04, 05:23 PM
If it can make a DC120 Escape Artist check (http://www.d20srd.org/srd/epic/skills.htm#passthroughWallofForce) or has 1 Level of Legendary Dreadnought then sure it can.

But how many Class Levels do you think the Earth has? Probably not enough, it is inanimate after all.
Hmmm, what would be funny is having some epic wizard who's really bored cast Animate Object and Permanency on a planet.

The Glyphstone
2010-03-04, 05:25 PM
Hmmm, what would be funny is having some epic wizard who's really bored cast Animate Object and Permanency on a planet.

Needs more Awaken Construct. Now it can take class levels, and call itself Ego.

Thalnawr
2010-03-04, 05:26 PM
Needs more Awaken Construct. Now it can take class levels, and call itself Ego.

I knew I was forgetting something...

Dr Bwaa
2010-03-04, 05:31 PM
As a rule, unless you want to deal with this kind of thing and Walls of Force whizzing about all over the place due to them being literally immovable, you could have "immovable" effects be relative to the nearest object over however much mass/volume. You can still do this, but it's much more difficult.

That's why the proposed plan of action is to teleport into deep space first, so that the WoF is immovable with respect to that point in space, rather than the Earth.

I'd probably allow a planet to break a WoF, though. I'd also allow for the insane, and probably still catasrophic, damage that would result from such a collision. Consider--it's a meteor that's immune to the atmosphere, slamming into the Earth at the Earth's speed. As it passes through the atmosphere at several thousand mph, the air explodes; huge shockwaves (http://en.wikipedia.org/wiki/Tunguska_event) precede the shattering earthquakes that begin once the ground impacts the WoF. Still plenty of destruction, I think. :smallbiggrin: Consider: your WoF, at a very modest (since you're teleporting into the freakin' depths of space) CL 20, has surface area of 200 sq ft. This is about 1/3 to 1/5 the size of the Tunguska Event's (probable) meteor cause. And yours isn't going to burn up in atmosphere. Ouch.

Volkov
2010-03-04, 05:34 PM
Needs more Awaken Construct. Now it can take class levels, and call itself Ego.

No, he needs to use wish to turn it into a giant transformer.

Forever Curious
2010-03-04, 05:35 PM
Needs more Awaken Construct. Now it can take class levels, and call itself Ego.

...ladies and gentlemen, my next campaign setting :smallbiggrin:

Volkov
2010-03-04, 05:37 PM
...ladies and gentlemen, my next campaign setting :smallbiggrin:

Mine's better.

ericgrau
2010-03-04, 05:38 PM
Consider--it's a meteor that's immune to the atmosphere
Actually propelling a flat object at thousands of miles per hour through the earth's atmosphere will do considerable damage. If a level 32 character with a PrC can break it, then the atmosphere probably can too (if any object can). So there's a brief flash of light, the wall of force is torn to pieces a mile above the earth's surface, theoretical optimizers go back to finding ways to break the game using rules instead of physics and the DM gets on with his campaign. Unfortunately the catgirls still suffer.

Dr Bwaa
2010-03-04, 05:58 PM
WoF is immune to fire, and presumably won't heat up as it goes through the atmosphere, so unless it breaks on its initial contact with the upper atmosphere (which, arguably, could happen), it probably won't break until it hits the ground.

I'm just saying my interpretation of the situation, after all :p

Lapak
2010-03-04, 06:03 PM
... what is this 'outer space' of which you speak? And why would you assume that the world moves? Any fool can see that the sun and stars move about the world.

My standard response to 'I teleport X into the SUN!' would be to have the pissed-off Sun God come down in his chariot and smite the idiot who just popped a villain into the back seat of his ride. And the response to outer space shenanigans along these lines is for the caster to find himself adrift in the Astral plane, where he can sit until he gets a chance to prepare Plane Shift and get back to the completely-stationary Material Plane where he belongs. :smallwink:

Volkov
2010-03-04, 06:10 PM
... what is this 'outer space' of which you speak? And why would you assume that the world moves? Any fool can see that the sun and stars move about the world.

My standard response to 'I teleport X into the SUN!' would be to have the pissed-off Sun God come down in his chariot and smite the idiot who just popped a villain into the back seat of his ride. And the response to outer space shenanigans along these lines is for the caster to find himself adrift in the Astral plane, where he can sit until he gets a chance to prepare Plane Shift and get back to the completely-stationary Material Plane where he belongs. :smallwink:

Or the Sun says no, because the Sun is a sapient entity, a very, very, very large sapient entity.

Hand_of_Vecna
2010-03-04, 06:12 PM
Assuming you could make the wall immovable in outer space and outer space worked like real world outer space and the world couldn't destroy it (the world "attacking" something should have some impressve effects) a some wizard would have divined that this was going to happen even and would teleport in and disintegrate the wall.

Was this a serious question or am I being a wet towel?

Ravens_cry
2010-03-04, 06:12 PM
... what is this 'outer space' of which you speak? And why would you assume that the world moves? Any fool can see that the sun and stars move about the world.

My standard response to 'I teleport X into the SUN!' would be to have the pissed-off Sun God come down in his chariot and smite the idiot who just popped a villain into the back seat of his ride. And the response to outer space shenanigans along these lines is for the caster to find himself adrift in the Astral plane, where he can sit until he gets a chance to prepare Plane Shift and get back to the completely-stationary Material Plane where he belongs. :smallwink:
Depends on the setting. Golarian (http://pathfinder.wikia.com/wiki/Golarion), for example, is explicitly a spherical world that orbits a sun, as is Oerth (http://en.wikipedia.org/wiki/Oerth), while Hollow World is just that.
Creativity is something a DM should encourage, in my opinion.

Volkov
2010-03-04, 06:14 PM
Depends on the setting. Golarian (http://pathfinder.wikia.com/wiki/Golarion), for example, is explicitly a spherical world that orbits a sun, as is Oerth (http://en.wikipedia.org/wiki/Oerth), while Hollow World is just that.

Liga orbits Oerth, not the other way around. Plus, Liga is not an actual star, it's just a huge ball of molten material that is much, much smaller than any real star.

erikun
2010-03-04, 06:18 PM
That's why the proposed plan of action is to teleport into deep space first, so that the WoF is immovable with respect to that point in space, rather than the Earth.
Relativity would like to have a word with you, good sir. You are abusing it horribly.

lsfreak
2010-03-04, 06:18 PM
... what is this 'outer space' of which you speak? And why would you assume that the world moves? Any fool can see that the sun and stars move about the world.

My standard response to 'I teleport X into the SUN!' would be to have the pissed-off Sun God come down in his chariot and smite the idiot who just popped a villain into the back seat of his ride. And the response to outer space shenanigans along these lines is for the caster to find himself adrift in the Astral plane, where he can sit until he gets a chance to prepare Plane Shift and get back to the completely-stationary Material Plane where he belongs. :smallwink:

D&D default rules assume that the world corresponds to Earth in terms of such things an environment and basic physics.

Your plan has a problem: what happens to walls of force that are actually on the planet? Since they are immovable, consider the following: the Earth rotates at over 1600km/hr, spins about the sun at a speed of 108.000km/hr, and and spins around the galactic core at roughly 800.000km/hr. Simply throwing up a wall of force in a dungeon and you've got major problems, once you start doing silly things like this.

Haven
2010-03-04, 06:22 PM
You see, the thing about Walls of Force is--

WHAM

What the f*** was that?!

Volkov
2010-03-04, 06:23 PM
That's why the proposed plan of action is to teleport into deep space first, so that the WoF is immovable with respect to that point in space, rather than the Earth.

Einstein is rolling in his grave with this comment.

Haven
2010-03-04, 06:28 PM
Anyway, that said:


D&D default rules assume that the world corresponds to Earth in terms of such things an environment and basic physics.


True, but "basic physics" doesn't extend to astrophysics, where the closest--and, moreover, awesomest--canonical precedent is Spelljammer.

absolmorph
2010-03-04, 06:38 PM
D&D default rules assume that the world corresponds to Earth in terms of such things an environment and basic physics.

Your plan has a problem: what happens to walls of force that are actually on the planet? Since they are immovable, consider the following: the Earth rotates at over 1600km/hr, spins about the sun at a speed of 108.000km/hr, and and spins around the galactic core at roughly 800.000km/hr. Simply throwing up a wall of force in a dungeon and you've got major problems, once you start doing silly things like this.
Only if you're trying to make the WoF immovable in respect to the galactic core.
I'd say the wall is immovable in respect to the original position of the caster at the time of casting.

Also: Violet veil, wall-shaped warding and a Green veil, wall-shaped warding.
Level 16 character (Wizard 9/Initiate of the Sevenfold Veil 7) destroying the world.
Consider the effect of removing a 70 ft by 35 ft rectangle from the earth. All the way through. Of course, it would be curved, and probably would miss the core, but it still would do a lot of damage. Add in the ability to throw up a few Walls of Force, and the world is pretty much done.
NOTE: The given character could throw up 12 WoFs. Each one would consist of up to 16 10-foot squares.
This gives 12 80 by 80 squares of force, unaffected by most things and immovable, and 1 70 ft by 35 ft rectangle that disintegrates all objects and kills anything that can't make a Fort DC of 22 (or higher, but I'm going for the minimum). I'd consider that a pretty major effect (especially if the walls are separated by about 30 ft. Twelve shockwaves running into each other are gonna cause more damage than one really big one.

Volkov
2010-03-04, 06:39 PM
Only if you're trying to make the WoF immovable in respect to the galactic core.
I'd say the wall is immovable in respect to the original position of the caster at the time of casting.

Also: Violet veil, wall-shaped warding and a Green veil, wall-shaped warding.
Level 16 character (Wizard 9/Initiate of the Sevenfold Veil 7) destroying the world.
Consider the effect of removing a 70 ft by 35 ft rectangle from the earth. All the way through. Of course, it would be curved, and probably would miss the core, but it still would do a lot of damage. Add in the ability to throw up a few Walls of Force, and the world is pretty much done.
NOTE: The given character could throw up 12 WoFs. Each one would consist of up to 16 10-foot squares.
This gives 12 80 by 80 squares of force, unaffected by most things and immovable, and 1 70 ft by 35 ft rectangle that disintegrates all objects and kills anything that can't make a Fort DC of 22 (or higher, but I'm going for the minimum). I'd consider that a pretty major effect (especially if the walls are separated by about 30 ft. Twelve shockwaves running into each other are gonna cause more damage than one really big one.
Gravity will simply reform the planet around the walls.

absolmorph
2010-03-04, 06:42 PM
Gravity will simply reform the planet around the walls.
The main damage will be caused by the shock waves.
Cities would be torn to pieces. People would burn. Many things would die.
All in all, a pretty good use of his spells for the day.

Volkov
2010-03-04, 06:43 PM
The main damage will be caused by the shock waves.
Cities would be torn to pieces. People would burn. Many things would die.
All in all, a pretty good use of his spells for the day.

Yes, but it's still a planet that is still around, thus meaning you failed your objective of DESTROYING the planet, wiping out all life or civilization is a trivial task compared to utterly destroying one.

absolmorph
2010-03-04, 06:47 PM
Yes, but it's still a planet that is still around, thus meaning you failed your objective of DESTROYING the planet, wiping out all life or civilization is a trivial task compared to utterly destroying one.
That's just the first day, and you forgot that the planet reforming to fill the space would also cause massive earthquakes.
I mean, really, if you want to destroy the world, just create a coil gun using pure force for the projectile. Make it about a mile long. That should destroy the world. And create a ton of asteroids.

erikun
2010-03-04, 06:50 PM
That probably wouldn't do it, but creating a portal to the Plane of Vacuum would be trivally easy to do if you wanted to get rid of all matter on the planet. Or you could animate the planet, then create a portal to the Positive Energy Plane. Yay, spontaneously exploding temporary HP!

Brendan
2010-03-04, 06:50 PM
remember, the earth is moving thousands of miles an hour as is, but the WoF keeps in movement with the planet. I think it just would also continue moving around the sun at a high velocity.

Superglucose
2010-03-04, 06:51 PM
Gravity will simply reform the planet around the walls.
Specifically, number 9. In short: not if you do it hard enough!

Volkov
2010-03-04, 06:51 PM
That's just the first day, and you forgot that the planet reforming to fill the space would also cause massive earthquakes.
I mean, really, if you want to destroy the world, just create a coil gun using pure force for the projectile. Make it about a mile long. That should destroy the world. And create a ton of asteroids.

Nope, that won't be anywhere near enough energy unless the projectile was solid anti-neutron star matter being accelerated to a significant portion of the speed of light. And even that's not a guarantee, as it may not be enough energy to do it in. Not only must you break the planet apart, you must do it so violently that none of the bits can ever come back together and reform the planet.

Volkov
2010-03-04, 06:52 PM
That probably wouldn't do it, but creating a portal to the Plane of Vacuum would be trivally easy to do if you wanted to get rid of all matter on the planet. Or you could animate the planet, then create a portal to the Positive Energy Plane. Yay, spontaneously exploding temporary HP!

Animate object makes constructs, which aren't affected by the positive energy plane in the slightest.

absolmorph
2010-03-04, 06:52 PM
That probably wouldn't do it, but creating a portal to the Plane of Vacuum would be trivally easy to do if you wanted to get rid of all matter on the planet. Or you could animate the planet, then create a portal to the Positive Energy Plane. Yay, spontaneously exploding temporary HP!
I lol'd at the idea of healing the planet.
I think I'll have an insane villain whose goal is to do just that.
Let's see, how could he get a CL of 32....

Volkov
2010-03-04, 06:53 PM
I lol'd at the idea of healing the planet.
I think I'll have an insane villain whose goal is to do just that.
Let's see, how could he get a CL of 32....

Animating the planet gives you a construct, which cannot be affected by the positive energy plane.

AstralFire
2010-03-04, 06:54 PM
Animating the planet gives you a construct, which cannot be affected by the positive energy plane.

All of that plant and animal life blowing up at once won't end well.

Volkov
2010-03-04, 06:56 PM
All of that plant and animal life blowing up at once won't end well.

It won't do jack diddly squat to the planet. Even if you replaced all the world's biomass with it's worth of C4 or U235, the planet will not be significantly damaged.

erikun
2010-03-04, 06:56 PM
Polymorph Any Object? Construct > Animal, then heal it to oblivion!

[EDIT]
Actually, that would make a really interesting antagonist group. An order of Druids, thinking the planet is sick and dying, is performing a ritual to turn the planet "alive" for a short while so they can heal it with the Positive Energy Plane. Needless to say, if they succeed, then the planet will only remain "alive" for a few rounds afterwards.

Thufir
2010-03-04, 06:59 PM
Einstein is rolling in his grave with this comment.

Only in some frames of reference. :smallwink:

Volkov
2010-03-04, 07:00 PM
Polymorph Any Object? Construct > Animal, then heal it to oblivion!

Assuming the planet doesn't just kill you with it's first action.

ericgrau
2010-03-04, 07:01 PM
WoF is immune to fire, and presumably won't heat up as it goes through the atmosphere, so unless it breaks on its initial contact with the upper atmosphere (which, arguably, could happen), it probably won't break until it hits the ground.

I'm just saying my interpretation of the situation, after all :p

It's not specifically immune to fire. It's immune to all damage. That's why I added the caveat "if any object can destroy a wall of force". But for that matter entering the atmosphere does not merely heat up that object. It's the enormous force of air pounding past it that causes friction and then heat. This is what would tear the wall apart before the ground does. Either that or nothing breaks it and it goes all the way through the earth. But both of these forces are far stronger than, say, a dreadnaught and he can break a wall of force as a non-magical extraordinary ability.

Reynard
2010-03-04, 07:02 PM
It has no arms, legs, mouth, eyes, nose, etc.

It can't do anything.

Volkov
2010-03-04, 07:02 PM
It has no arms, legs, mouth, eyes, nose, etc.

It can't do anything.

Animate object still gives it an attack.

erikun
2010-03-04, 07:04 PM
Animate object still gives it an attack.
DM: "The planet rolls over you."
Player: "I don't think gravity works that way..."

Flickerdart
2010-03-04, 07:07 PM
Awakened/animated creatures are automatically friendly to you, no? You could Animate it, Permanency it, then apply the Awakened Construct template, making it a Giant and vulnerable to hijinks.

Volkov
2010-03-04, 07:11 PM
DM: "The planet rolls over you."
Player: "I don't think gravity works that way..."

Maybe it could do a gravity whiplash, or make a mountain rise really fast to launch you into space with such great speed that you are instantly killed by friction with the atmosphere.

absolmorph
2010-03-04, 07:20 PM
Nope, that won't be anywhere near enough energy unless the projectile was solid anti-neutron star matter being accelerated to a significant portion of the speed of light. And even that's not a guarantee, as it may not be enough energy to do it in. Not only must you break the planet apart, you must do it so violently that none of the bits can ever come back together and reform the planet.
At a mile long? (http://www.giantitp.com/forums/showthread.php?t=135812&highlight=coil&page=2)
Please.
If you want, you could even extend it further. For the sake of overkill, I'll go with 5 miles, and the cannon is moved and fired by constructs.
That should get our force projectile (enchanted with the properties of a conductor stone) up to a high enough speed to tear the planet apart.

Volkov
2010-03-04, 07:21 PM
At a mile long? (http://www.giantitp.com/forums/showthread.php?t=135812&highlight=coil&page=2)
Please.
If you want, you could even extend it further. For the sake of overkill, I'll go with 5 miles, and the cannon is moved and fired by constructs.
That should get our force projectile (enchanted with the properties of a conductor stone) up to a high enough speed to tear the planet apart.

I did the calculations (thank goodness for asteroid impact calculators), that's still not enough energy.

absolmorph
2010-03-04, 07:25 PM
It's not specifically immune to fire. It's immune to all damage. That's why I added the caveat "if any object can destroy a wall of force". But for that matter entering the atmosphere does not merely heat up that object. It's the enormous force of air pounding past it that causes friction and then heat. This is what would tear the wall apart before the ground does. Either that or nothing breaks it and it goes all the way through the earth. But both of these forces are far stronger than, say, a dreadnaught and he can break a wall of force as a non-magical extraordinary ability.
You're comparing an epic-level prestige class to physics?
That dreadnaught stopped caring about physics around when he became able to survive a fall from the highest cliffs in the world and then kill a dragon. With a spoon.


I did the calculations, that's still not enough energy.
How much energy is needed?

erikun
2010-03-04, 07:29 PM
http://qntm.org/destroy <- This should get you started. It indicates you'd need around 25,000,000,000,000 tonnes of antimatter to blast the earth to pieces. I'm not sure what that would be converted to energy, though.

Volkov
2010-03-04, 07:29 PM
You're comparing an epic-level prestige class to physics?
That dreadnaught stopped caring about physics around when he became able to survive a fall from the highest cliffs in the world and then kill a dragon. With a spoon.


How much energy is needed?

As much as the sun produces in a week at bare minimum. Not the amount that the earth recieves, every last watt of energy that the sun radiates in all directions is needed to destroy a planet of the earth's size and composition. And at this bare minimum, you would need to detonate it at the core of the earth to make it work, and you won't get a spectacular destruction of the earth, it'd slowly expand outwards, and would take 10 minutes just to double in volume. To do it the way the death star did, you'd need all the energy the sun produced since the time of moses.

magic9mushroom
2010-03-04, 07:37 PM
My interpretation: Planets impose their own reference frames on nearby objects. WoF stops.

I mean, this is really bad physics, but so is something that's "immovable".

absolmorph
2010-03-04, 07:40 PM
As much as the sun produces in a week at bare minimum. Not the amount that the earth recieves, every last watt of energy that the sun radiates in all directions is needed to destroy a planet of the earth's size and composition. And at this bare minimum, you would need to detonate it at the core of the earth to make it work, and you won't get a spectacular destruction of the earth, it'd slowly expand outwards, and would take 10 minutes just to double in volume. To do it the way the death star did, you'd need all the energy the sun produced since the time of moses.
Taken from the thread:

XD Thanks. You learn something new every day. Or so it's said.

About Conductor Stones:
They have a repulsion force so high that even a coach weighing 100 tons can't force it closer than a few feet (but less than 5)

That's... a pretty high force.
assuming it's 100 short tons = 200 000 lbs = 90 718 kg. That's a supporting force of 889 948 N. (!!)

Assuming you start from 3 feet, and the force decreases linearly to 0 at 5 feet...
Each conductor stone puts out 542 512 J of energy.

If each ring has 4 stones, and there are 100 rings plus 1 initiating stone... Projectile has final energy of 217 547 489 J.
217 MJ. Assuming the conductor stone you're firing weighs 1kg, it has a speed of 20 859 m s-1. (newtonian 0.5 m v^2 calculation)

Around 60 times the speed of sound. That's going to do some major damage.

Too bad you got to fire a conductor stone each shot. =/

************************************************** ***

EDIT: Calculation error. Energy output is half that.

Speed is actually 14 749 m s-1. Around 43 times the speed of sound.

Assuming each ring takes up a 5 ft square, the calculations are done with a 125 ft long gun. A 5 mile gun is 211.2 times as long.
A rough estimate of the final out put: 45946029676.8 J.
You can fire this multiple times. It may not destroy the earth on the first shot, but given a minute or two, it should do the job.

Volkov
2010-03-04, 07:42 PM
Taken from the thread:

XD Thanks. You learn something new every day. Or so it's said.

About Conductor Stones:
They have a repulsion force so high that even a coach weighing 100 tons can't force it closer than a few feet (but less than 5)

That's... a pretty high force.
assuming it's 100 short tons = 200 000 lbs = 90 718 kg. That's a supporting force of 889 948 N. (!!)

Assuming you start from 3 feet, and the force decreases linearly to 0 at 5 feet...
Each conductor stone puts out 542 512 J of energy.

If each ring has 4 stones, and there are 100 rings plus 1 initiating stone... Projectile has final energy of 217 547 489 J.
217 MJ. Assuming the conductor stone you're firing weighs 1kg, it has a speed of 20 859 m s-1. (newtonian 0.5 m v^2 calculation)

Around 60 times the speed of sound. That's going to do some major damage.

Too bad you got to fire a conductor stone each shot. =/

************************************************** ***

EDIT: Calculation error. Energy output is half that.

Speed is actually 14 749 m s-1. Around 43 times the speed of sound.

Assuming each ring takes up a 5 ft square, the calculations are done with a 125 ft long gun. A 5 mile gun is 211.2 times as long.
A rough estimate of the final out put: 45946029676.8 J.
You can fire this multiple times. It may not destroy the earth on the first shot, but given a minute or two, it should do the job.
I'm sorry, but the energy all has to be dumped at once, doing it over a period of time is useless because instead of breaking apart the planet, you are merely heating it up. And the instant the vapor starts to cool, the planet will be right where it used to be.

DaedalusMkV
2010-03-04, 07:45 PM
How much energy is needed?
10^32 Joules. For reference, the Sun's entire yearly output is roughly 10^34 Joules. It would take the entire energy output of the sun for about 4 days to build up enough energy to destroy a planet in a situation of perfect conversion, which is impossible. A railgun powerful enough to destroy a planet would need to be hooked up to multiple Dyson Spheres to work, barring a capacitor the size of a large sun.

Killing all human life on a planet? Easy. Destroying a planet? Really, really hard.

Edit: Ninja'd. Oh, so ninjad.

absolmorph
2010-03-04, 07:47 PM
Oh, hell with it. I'll just raise a kobold.

Volkov
2010-03-04, 07:59 PM
Oh, hell with it. I'll just raise a kobold.

That won't work either, Pun-pun's attack will pour all of it's energy in too small a spot to destroy the earth.

taltamir
2010-03-04, 08:02 PM
you don't need to teleport into space to do that... anyone with even a basic understanding of physics would tell you that it should happen every time a wall of force is cast anywhere...

as for "tunneling into earth and not really destroying"... actually it will make a massive explosion/crater and continue to do so, literally tearing the planet apart. it is immoveable and indestructible... the planet has a LOT of inertia.

WOTC fails phyiscs forever. thats ok though, we just handwave it.

Karoht
2010-03-04, 08:13 PM
2 step process to killing practically anything made of normal matter.
1-Find or create the plane of anti-matter.
2-Teleport the being/object in question to said plane.

Boom. Big Bada Boom.

Ironically, I was involved in a campaign where this actually came up. It was to defeat some beast that devoured whole planes of existance at a time.

You know those immovable rods? In this one campaign, one member of the player party decided he wanted to build a flying castle/city. A few members of the player party purchased some of the immovable rods, and formed stone around them. They then snuck these into his stockpile of construction materials, which he then used as the keystones to archways and the like. They bartered the trigger switch for free houses in the city. It was win win.

Volkov
2010-03-04, 08:13 PM
you don't need to teleport into space to do that... anyone with even a basic understanding of physics would tell you that it should happen every time a wall of force is cast anywhere...

as for "tunneling into earth and not really destroying"... actually it will make a massive explosion/crater and continue to do so, literally tearing the planet apart. it is immoveable and indestructible... the planet has a LOT of inertia.

WOTC fails phyiscs forever. thats ok though, we just handwave it.

Gravity would reform the planet around the wall.

taltamir
2010-03-04, 08:16 PM
Gravity would reform the planet around the wall.

it might, but I think the amount of energy released will literally blow it apart too far to reform.
the initial impact will cause a massive explosion, greater then any nuclear weapon produced by man, but the thing is, the wall of force will remain, the planet will keep on going forward due to inertia and as it presses on it keeps on "impacting" the wall of force, creating more ridiculous releases of energy...

someone should do the math.

Volkov
2010-03-04, 08:18 PM
it might, but I think the amount of energy released will literally blow it apart too far to reform.
the initial impact will cause a massive explosion, greater then any nuclear weapon produced by man, but the thing is, the wall of force will remain, the planet will keep on going forward due to inertia and as it presses on it keeps on "impacting" the wall of force, creating more ridiculous releases of energy...

someone should do the math.

It wouldn't. Given that most of a planet is fluid, you wouldn't do crap to anything but the crust. Which would absorb the entire impact, and instantly break the wall with a strength check. (Every DM I know, including myself would rule that the planet would get a strength check in this situation)

ericgrau
2010-03-04, 08:23 PM
People who keep thinking impact from fluids is harmless need to try cliff diving. Or at least jumping into a pool from a high diving board. Do a belly flop and it can hurt, almost like hitting a solid object. Not only would pushing the wall through the earth's mantle still cause enormous resistance, even pushing it through the earth's atmosphere at thousands of miles per hour would be an extreme impact. This is why I keep saying that if it gets destroyed at all, it won't even make it to the earth's surface.

EDIT: Btw, the math depends on a few unknowns, but I can say that we're talking about atomic bomb levels of energy here.

taltamir
2010-03-04, 08:27 PM
People who keep thinking impact from fluids is harmless need to try cliff diving. Or at least jumping into a pool from a high diving board. Do a belly flop and it can hurt, almost like hitting a solid object. Not only would pushing the wall through the earth's mantle still cause enormous resistance, even pushing it through the earth's atmosphere at thousands of miles per hour would be an extreme impact. This is why I keep saying that if it gets destroyed at all, it won't even make it to the earth's surface.

absolutely true...
volkov... fluids just don't work the way you THINK they do. the impact with the fluid converts the same amount of energy into thermal energy. The reason planets don't crack open like rotten eggs is because in the REAL world we do not have "immovable" and we do not have "indestructible"..
and who cares what a DM would rule? this was a question of REAL LIFE SCIENCE not DM ruling.

As a DM I would say "the moment the wall touches the surface it magically accelerates to match its spell and now appears "immovable" compared to the planet.


EDIT: Btw, the math depends on a few unknowns, but I can say that we're talking about atomic bomb levels of energy here.
Atomic bombs don't even come CLOSE to the amount of energy we are talking about here.

Volkov
2010-03-04, 08:27 PM
People who keep thinking impact from fluids is harmless need to try cliff diving. Or at least jumping into a pool from a high diving board. Do a belly flop and it can hurt, almost like hitting a solid object. Not only would pushing the wall through the earth's mantle still cause enormous resistance, even pushing it through the earth's atmosphere at thousands of miles per hour would be an extreme impact. This is why I keep saying that if it gets destroyed at all, it won't even make it to the earth's surface.

EDIT: Btw, the math depends on a few unknowns, but I can say that we're talking about atomic bomb levels of energy here.

The wall of force is too small to do much damage to the planet itself. We're talking 6 sextillion tons of ROCK and METAL. Three fourths of which is fluidic.

taltamir
2010-03-04, 08:30 PM
The wall of force is too small to do much damage to the planet itself. We're talking 6 sextillion tons of ROCK and METAL.

EXACTLY (in regards to the mass)! that much mass has a LOT of kinetic energy, and it impacts an IMMOVABLE and INDESTRUCTIBLE object... all of said energy gets converted into heat. If it was an asteroid it wouldn't do a lot of damage, the asteroid will VAPORIZE from the impact with the GAS around the planet (known as air)... then its superheated vapour hits the ground creating a massive explosion, the earth is slowed down by an inconsequential amount as the superheated gas from the asteroid is accelerated to match the earths velocity (and direction). the wall of force will never be destroyed, will never match speeds, it simply forces its way through.

well, actually not all the energy gets converted, because as it is converted into heat the surrounding rock gets vaporised and no longer transfers the impact fully, it will tunnel through releasing massive amount of energy as it tunnels... it will have an entery hole of a few hundred feet, and an exit hole the other side that is a huge chunk of the planet.

Parts of the planet will fly forward, part of it will bounce the OTHER way, part of it will fly normal (perpendicular) to the axis of impact... the thing will be torn to shreds which will fly off in different directions.

Volkov
2010-03-04, 08:34 PM
EXACTLY (in regards to the mass)! that much mass has a LOT of kinetic energy, and it impacts an IMMOVABLE and INDESTRUCTIBLE object... all of said energy gets converted into heat.

well, actually not all, because as it is converted into heat the surrounding rock gets vaporised and no longer transfers the impact fully, it will tunnel through releasing massive amount of energy as it tunnels... it will have an entery hole of a few hundred feet, and an exit hole the other side that is a huge chunk of the planet.

The planet would be slown down a lot as the fluid struggles against the wall, (which I would count as a strength check to break, and it would most certainly succeed instantly) So the planet will be moving at pitifully slow speeds as the comparatively tiny wall passes through.

erikun
2010-03-04, 08:35 PM
At sizes like we're talking about, the fluidity of the material means nothing. The sheer gravity from an object the size of earth will keep it together, regardless of how much damage you do to its crust, or how many holes you bore through it with fantasy immobile devices.

I am, however, curious what is supposed to happen if a planet runs into a planet-sized wall of force in its orbital path. Would momentium allow it to "flow" around (more accurately, fall around) after impact, or would simply stop? Or would it ricochet, like a clumsy cue ball?

taltamir
2010-03-04, 08:41 PM
The planet would be slown down a lot as the fluid struggles against the wall, (which I would count as a strength check to break, and it would most certainly succeed instantly) So the planet will be moving at pitifully slow speeds as the comparatively tiny wall passes through.

ok see, you are allowing the INDESTRUCTIBLE wall to BREAK.

if it can be broken it will never even impact the planet, it will break as soon as it hits the atmosphere and have NO noticeable effect on the planet whatsoever.


At sizes like we're talking about, the fluidity of the material means nothing.
correct, it might as well be solid.


The sheer gravity from an object the size of earth will keep it together, regardless of how much damage you do to its crust, or how many holes you bore through it with fantasy immobile devices.

that is just not how physics works. it will be torn asunder with chunks flying in every direction.

absolmorph
2010-03-04, 08:42 PM
That won't work either, Pun-pun's attack will pour all of it's energy in too small a spot to destroy the earth.
When I'm more powerful than most deities and can give myself an ability to do anything, not to mention have arbitrarily high ability scores, I probably CAN.

Superglucose
2010-03-04, 08:47 PM
At sizes like we're talking about, the fluidity of the material means nothing. The sheer gravity from an object the size of earth will keep it together, regardless of how much damage you do to its crust, or how many holes you bore through it with fantasy immobile devices.

That's not strictly true. If you hit something hard enough, it will break apart.

It's just a question of "how hard is hard enough?"

What I'm saying is: you're right, slowly boring holes into earth does nothing... but on the other hand sending it into a collision with a body that has the capability to reduce significant portions of the earth's crust from its current speed to 0? (keep in mind that Earth is moving at a pretty good clip)

Volkov
2010-03-04, 08:48 PM
When I'm more powerful than most deities and can give myself an ability to do anything, not to mention have arbitrarily high ability scores, I probably CAN.

Unless you are using a spear the size of mount everest, no you are not destroying the planet, and even if you were strong enough to lift the spear, your tiny little hands would only manage to push it around.

ericgrau
2010-03-04, 08:48 PM
At sizes like we're talking about, the fluidity of the material means nothing. The sheer gravity from an object the size of earth will keep it together, regardless of how much damage you do to its crust, or how many holes you bore through it with fantasy immobile devices.

I am, however, curious what is supposed to happen if a planet runs into a planet-sized wall of force in its orbital path. Would momentium allow it to "flow" around (more accurately, fall around) after impact, or would simply stop? Or would it ricochet, like a clumsy cue ball?

The planet would be unlikely to slow down noticeably against a 10'x10' wall of force. There'd only be an enormous explosion, whether the wall of force is destroyed in the atmosphere or bores all the way through and comes out the other side.

Against a planet sized wall of force OTOH the earth would splash like a drop of water, as the crust would not be nearly strong enough to hold it together. The backside would be relatively unaffected until it gets within a few hundred miles of the wall of force, at the same time that the front is already scattering into space. That's because the wall of force is moving faster than the vibrations travel through the earth. i.e., there would be ridiculous earthquakes on the far side of the earth, if it weren't for the fact that the wall of force reaches the other side before the quakes do.

Lysander
2010-03-04, 08:49 PM
The planet doesn't have official stats as far as I know. So technically, if it comes up, it has whatever special abilities the DM rules it should have. It's sort of like asking why the universe doesn't fall if it doesn't have a fly speed.

taltamir
2010-03-04, 08:57 PM
newtons three laws:

I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.

III. For every action there is an equal and opposite reaction.

Your planet hits an immovable and in destructive object the size of which is irrelevant (it really is irrelevant).
according to a quick google search:
the mass of earth is: 5.9742 × 10^24 kilograms
the speed of earth orbit around the sun is: 29658 m/s

to get the force which it exerts on the wall of force (use second law) you multiply the two.
F = 1.771828236x10^29 Newtons.
F = 177182823600000000000000000000 N.

the wall then applies an equal amount of force to the earth according to the third law.
the earth gets destroyed.

erikun
2010-03-04, 08:57 PM
that is just not how physics works. it will be torn asunder with chunks flying in every direction.
Now might be a good time for an example.

Let's start with a rather large-sized rock. Say, one 3 feet/1 metre across. Let's drop it out of an airplane at 1,000 feet, causing it to hit a thick metal table (our Wall of Force in this example). How far would the pieces of rock scatter after the impact? 20 feet? 40 feet?

By comparison, Mars would be rock 1 foot across, aproximately 5 miles away at its closest. Venus is another rock 3 feet across, also around 5 miles away. These are the two closest gravitational forces, besides the pieces of Earth itself. In order for the Earth to be blown apart (and not reform) you need to overcome the mutual attraction of the Earth-pieces, or else it will just pull itself back together. We need to be moving at a low higher velocity (or a lot more mass) to blast the planet into pieces.


Also note that I was using my example of a "planet-sized" Wall of Force. If you're not using one that's 4,000 miles on each size, the impact will be a lot less dramatic - more like dropping the rock on a needle. Needless to say, a lot less "boom".

Noble Savant
2010-03-04, 09:00 PM
Guys, why are we working hard to disprove this? Wall of Force has a range of close, teleporting is inaccurate, and space has no landmarks. The wizard teleports into space, tries to position himself correctly, and gets hit by a planet.

taltamir
2010-03-04, 09:00 PM
Now might be a good time for an example.

if you want an example, take a gun and shoot a cantelope.
All your conjectures have nothing to do with physics, needles and planes etc are not indestructible or immovable, nor are your examples even accurate with the things you have described, you have obviously never thrown a rock from an airplane unto a steel table.


Guys, why are we working hard to disprove this? Wall of Force has a range of close, teleporting is inaccurate, and space has no landmarks. The wizard teleports into space, tries to position himself correctly, and gets hit by a planet.

technically this should happen every time anyone casts a WOF on the planet surface itself, because it is immoveable and indestructible (except specific magic) by definition.

erikun
2010-03-04, 09:07 PM
if you want an example, take a gun and shoot a cantelope.
I highly doubt the second cantelope 5 miles away will keep the destroyed one from reforming.

Or are we talking about simply breaking up the crust on the planet? Because conventional expolsives could do that. So could any decent sized meteor, which would probably be easier to steer than trying to plot out the orbital path of the object you are standing on.

Heck, for that matter, the moon is nearby. You're pretty much guaranteed to shatter the crust if you could pull the moon into the earth.

absolmorph
2010-03-04, 09:13 PM
Unless you are using a spear the size of mount everest, no you are not destroying the planet, and even if you were strong enough to lift the spear, your tiny little hands would only manage to push it around.
"A sarrukh may also grant the target an extraordinary, supernatural, or spell-like ability or remove one from it."
You don't have to grant yourself a published ability.

taltamir
2010-03-04, 09:22 PM
http://img96.imageshack.us/img96/3997/wofvsplanet.png

ZeroNumerous
2010-03-04, 09:33 PM
That won't work either, Pun-pun's attack will pour all of it's energy in too small a spot to destroy the earth.

You don't know anything about Pun-Pun, do you? Instead of attacking the planet he gives himself the ability called "Explode Planet(Ex)" using Alter Reality. It, naturally, explodes planets. He then uses this ability targeting any planet he chooses.

DaedalusMkV
2010-03-04, 09:34 PM
"A sarrukh may also grant the target an extraordinary, supernatural, or spell-like ability or remove one from it."
You don't have to grant yourself a published ability.
Indeed. The whole point of Pun-Pun is that he can do anything, ever. He wants to blow up a planet, he gives himself "Destroy Planet (Ex): Target planet within 5 LY explodes, doing 1000000d6 damage to everyone on it. Reflex half.". There are absolutely no limitations on the abilities he can give himself, which means saying "Pun-Pun couldn't do that" is always a false statement.

Note that the wall of force would deflect the planet long before it went right through unless it struck at an absolutely perfect angle directly at a point in which it would not be effected by its curvature. Similarly, it wouldn't hit with anywhere near the equivalent of the planet's kinetic energy; it's not big enough unless it's very close to the size of the planet. Besides, we're taking a situation which is impossible by the standards of modern physics and applying modern physics to it. I'm tempted to go with the "everything on the Prime is entirely stationary except the suns, which are overseen by the Gods and immune to magic" approach, since it makes so much more sense in this case.

Project_Mayhem
2010-03-04, 09:47 PM
Indeed. The whole point of Pun-Pun is that he can do anything, ever. He wants to blow up a planet, he gives himself "Destroy Planet (Ex): Target planet within 5 LY explodes, doing 1000000d6 damage to everyone on it. Reflex half

Heh. The reflex half made me chuckle. Good time to have evasion.

And taltamir ... oh Science, your ms paint diagram caused me physical pain

Megaduck
2010-03-04, 10:00 PM
10^32 Joules. For reference, the Sun's entire yearly output is roughly 10^34 Joules. It would take the entire energy output of the sun for about 4 days to build up enough energy to destroy a planet in a situation of perfect conversion, which is impossible. A railgun powerful enough to destroy a planet would need to be hooked up to multiple Dyson Spheres to work, barring a capacitor the size of a large sun.

Killing all human life on a planet? Easy. Destroying a planet? Really, really hard.

Edit: Ninja'd. Oh, so ninjad.

Ah, I see someone else knows where to find The Boom Table.

Mikeavelli
2010-03-04, 10:09 PM
*Ahem*

Physics is a dame of culture and sophistication. She'll take you in, keep you warm at night, provide all kinds of insight into yourself and the world you never find on your own.

RAW is the wild, kinky sort of girl you'd never bring home to mother. She'll let you try new things, anything you can imagine, and more! She's flexible like a gymnist, and never has a headache.

that said, both of these ladies have one thing in common. they are possessive, jealous *****es! When you're going at it, you have to choose one or the other. Mixing the two does not lead to a clever or interesting theoretical situation, it leads to heavy, breakable objects getting thrown at your face from both sides.

Dilb
2010-03-04, 10:09 PM
Your planet hits an immovable and in destructive object the size of which is irrelevant (it really is irrelevant).

The size is not at all irrelevant. If the WOF is motionless compared to the earth's orbital speed, and the WOF is completely unmovable, the impact will be like a fluid hitting a solid. Every realistic thing behaves like a fluid at that speed. As a fluid, it will tend to deform around the wall.

Bear in mind that a solid can't react to things faster than the speed of sound. For the earth, this means the edges of the earth can't move until the earthquake from the collision reaches them. It would take the WOF about three minutes to travel through the earth, while it takes earthquakes several hours to travel from the impact site to the sides. A standard size WOF is going to auger a small hole through the planet, not bring the entire thing to a halt. The earth will shake and cave in on the hole, and you'll be left with an earth with a crater at the entrance and exit points.


according to a quick google search:
the mass of earth is: 5.9742 × 10^24 kilograms
the speed of earth orbit around the sun is: 29658 m/s

to get the force which it exerts on the wall of force (use second law) you multiply the two.
F = 1.771828236x10^29 Newtons.
F = 177182823600000000000000000000 N.

the wall then applies an equal amount of force to the earth according to the third law.
the earth gets destroyed.

To get a force you multiply mass by acceleration, not speed. Multiplying the earth's mass by it's velocity gives you the earth's momentum. Momentum doesn't mean anything if you have a WOF, because a WOF ignores conservation of momentum: you can push off without an equal amount of momentum being created going in the opposite direction.

Even if that was a force, it wouldn't mean anything: destroying the earth requires energy. Any force is survivable as long as it's done over a short enough distance, or a brief enough period of time.

You can look up high speed videos of fruit getting shot (http://www.youtube.com/watch?v=xEIvPD6zpL0): the fruit isn't dragged along with the bullet. The shockwave causes the fruit to explode in all directions, but the bullet is roughly continent sized, rather than smaller than a pin, like a regular WOF would be compared to a realistically sized planet. This apple (http://www.youtube.com/watch?v=XIayrDbVdJ0&feature=related) isn't blown apart, for example, even though apples aren't held together by their own gravity, like planets are.

RandomNPC
2010-03-04, 10:13 PM
Needs more Awaken Construct. Now it can take class levels, and call itself Ego.

I was thinking Mogo

absolmorph
2010-03-04, 10:38 PM
*Ahem*

Physics is a dame of culture and sophistication. She'll take you in, keep you warm at night, provide all kinds of insight into yourself and the world you never find on your own.

RAW is the wild, kinky sort of girl you'd never bring home to mother. She'll let you try new things, anything you can imagine, and more! She's flexible like a gymnist, and never has a headache.

that said, both of these ladies have one thing in common. they are possessive, jealous *****es! When you're going at it, you have to choose one or the other. Mixing the two does not lead to a clever or interesting theoretical situation, it leads to heavy, breakable objects getting thrown at your face from both sides.
I'm sigging the part on RAW.

JoshuaZ
2010-03-04, 10:38 PM
This isn't well-defined. Objects can't be immovable with respect to space. You have to be not moving with respect to something. Presumably when there's a big object like a planet nearby the magic somehow makes that the object chosen. But it isn't at all clear what this means. However, saying that the wall of force would stay in that point in space isn't well-defined unless you have a privileged coordinate system like in Aristotelian physics in which case the planet presumably won't be moving at all.


it might, but I think the amount of energy released will literally blow it apart too far to reform.
the initial impact will cause a massive explosion, greater then any nuclear weapon produced by man, but the thing is, the wall of force will remain, the planet will keep on going forward due to inertia and as it presses on it keeps on "impacting" the wall of force, creating more ridiculous releases of energy...

someone should do the math.

There's nowhere near enough energy to prevent the planet from reforming. This will be orders of magnitude more. Rough back of the envelope calculation: Earth has a mass of around 6 * 10^24 kilograms. In order to blow up the earth in a meaningful sense so it can't reform we need to accelerate a substantial portion of that to escape velocity (around 40,000 km/hour or about 10,000 m/s). Let's say we're trying to blow up about a third of the planet or around 2*10^24 kg. So the total energy to raise that to escape velocity is around (1/2)(10,000 m/s)^2(2*10^24 kg)=10^32 joules. That's how much energy we need.

Now how much energy will we get from this procedure? For simplicity assume a 20th level caster, so the wall has an area of 200 square feet or about 20 square meters. Now, assuming the wall stops everything it has going through it so it is reducing to 0 relative velocity a cylinder carved out of the earth with velocity around 50 km/s or 5*10^4 m/s (I'm assuming that the wall of force is stationary with respect to the sun because otherwise this isn't well-defined. I saw different estimates from googling but this is around the upper limit). The cylinder has length radius of the earth (6000 km) and base about 20 square meters so total volume is 6*10^6 * 20= about 10^8 cubic meters. The average density of the earth is around 5000 kg/m^3, but let's be generous and assume you get lucky and hit a core of about twice that density so around 10,000 kg /m^3 for a total mass of about 10^12 kg. So we need to know how much energy is in 10^12 kg going 5*10^4 m/s. So (1/2) * 10^12 kg * (5 *10^4 m/s)^2 = 5 * 10^20 joules. That's nowhere near enough energy. Since we need 10^32 joules, we are off by a factor of around 500 million. Since I rounded a fair bit this calculation could be off by as much as a factor of about a 100 either way, but that's still nowhere near the energy necessary.

If you redo this calculation with the wall of force being stationary with respect to the center of the galaxy you get around 400 times as much energy, so you would still be way off.

Edit: Also to be clear this is probably a wild overestimate since most of the mass in the cylinder won't actually get stopped but will move a bit to the sides and keep going only slightly slowed.

Edit: Just saw above uses radius of the earth when it should be the diameter. So the energy you get out is about twice as much as calculated above. Still much too small.

Knaight
2010-03-04, 10:44 PM
EXACTLY (in regards to the mass)! that much mass has a LOT of kinetic energy, and it impacts an IMMOVABLE and INDESTRUCTIBLE object... all of said energy gets converted into heat. If it was an asteroid it wouldn't do a lot of damage, the asteroid will VAPORIZE from the impact with the GAS around the planet (known as air)... then its superheated vapour hits the ground creating a massive explosion, the earth is slowed down by an inconsequential amount as the superheated gas from the asteroid is accelerated to match the earths velocity (and direction). the wall of force will never be destroyed, will never match speeds, it simply forces its way through.\

No, nowhere near all of said energy gets converted into heat. The earth itself is not one object, and the rocks that compose the crust could distort to some extent, could be compressed to some extent due to being porous, and all sorts of other things that dramatically reduces the amount of energy converted to heat. Sure, rock is melted away in addition, but the wall would punch through the crust, as the planet wouldn't stop, and a tiny, tiny fraction of the kinetic energy from orbit is involved, as it breaks. Then it goes through the earth with a negligible change in speed. Now, life on the surface anywhere near the point of entrance or exit? Gone. Further away, probably gone. But the earth itself isn't affected much.

Let me put it this way. It makes an arc through the earth, of varying length, if optimized cutting around the surface (circular orbit guys, circular orbit. Circularish anyways.) So, lets give it the most volume possible. Its a 400 square foot wall, that goes for 1/2 the earth's circumfrence, about 13700 miles. Now lets look at that compared to the earths total volume, just for an understanding of how tiny this really is.

Forever Curious
2010-03-04, 10:50 PM
*Ahem*

Physics is a dame of culture and sophistication. She'll take you in, keep you warm at night, provide all kinds of insight into yourself and the world you never find on your own.

RAW is the wild, kinky sort of girl you'd never bring home to mother. She'll let you try new things, anything you can imagine, and more! She's flexible like a gymnist, and never has a headache.

that said, both of these ladies have one thing in common. they are possessive, jealous *****es! When you're going at it, you have to choose one or the other. Mixing the two does not lead to a clever or interesting theoretical situation, it leads to heavy, breakable objects getting thrown at your face from both sides.

I declare this thread won. You, sir, win several internets.

taltamir
2010-03-04, 10:54 PM
The size is not at all irrelevant. If the WOF is motionless compared to the earth's orbital speed, and the WOF is completely unmovable, the impact will be like a fluid hitting a solid. Every realistic thing behaves like a fluid at that speed. As a fluid, it will tend to deform around the wall.

Bear in mind that a solid can't react to things faster than the speed of sound. For the earth, this means the edges of the earth can't move until the earthquake from the collision reaches them. It would take the WOF about three minutes to travel through the earth, while it takes earthquakes several hours to travel from the impact site to the sides. A standard size WOF is going to auger a small hole through the planet, not bring the entire thing to a halt. The earth will shake and cave in on the hole, and you'll be left with an earth with a crater at the entrance and exit points.



To get a force you multiply mass by acceleration, not speed.

*facepalm* I can't believe I did that. oops :P
point still stands but that bit of math was wrong.

multilis
2010-03-04, 10:56 PM
if you want an example, take a gun and shoot a cantelope.
All your conjectures have nothing to do with physics, needles and planes etc are not indestructible or immovable, nor are your examples even accurate with the things you have described, you have obviously never thrown a rock from an airplane unto a steel table.



technically this should happen every time anyone casts a WOF on the planet surface itself, because it is immoveable and indestructible (except specific magic) by definition.
Unmovable in relation to *planet*. If you take wall of force position as *always* being relative to world (including rotation), then will never have a problem, wall will orbit planet always over same spot, rotating at planets speed.

If you take "planet" as centre of gravity of all objects in space, things get very complicated, mage would likely have to bring an asteroid along to doctor the centre of gravity.

IMO force applied by entry into planet is so much beyond conventional forces ever encountered that should be treated as equivalent to disintegrate spell. I would consider " immune to damage of all kinds" to apply to conventional sorts of damage possible, not to damage similar to being next to nuclear bomb.

taltamir
2010-03-04, 10:58 PM
Unmovable in relation to *planet*. If you take wall of force position as *always* being relative to world (including rotation), then will never have a problem, wall will orbit planet always over same spot, rotating at planets speed.

which is why I said I would rule that as soon is it moves from space to "the planet" it will "affix" to the planet and start moving with it with no ill effects whatsoever.
but then we went on a tangent on what would happen if it was truly immovable and went right through the planet.

CarpeGuitarrem
2010-03-04, 11:05 PM
*Ahem*

Physics is a dame of culture and sophistication. She'll take you in, keep you warm at night, provide all kinds of insight into yourself and the world you never find on your own.

RAW is the wild, kinky sort of girl you'd never bring home to mother. She'll let you try new things, anything you can imagine, and more! She's flexible like a gymnist, and never has a headache.

that said, both of these ladies have one thing in common. they are possessive, jealous *****es! When you're going at it, you have to choose one or the other. Mixing the two does not lead to a clever or interesting theoretical situation, it leads to heavy, breakable objects getting thrown at your face from both sides.
Indeed. This man speaks truth!

Admiral Squish
2010-03-05, 12:19 AM
If it's ALWAYS relative to the planet and it's rotation, why not take out the moon with a wall of force suspended at the right height? Perhaps even b****-slap the sun?

LibraryOgre
2010-03-05, 12:29 AM
No, he needs to use wish to turn it into a giant transformer.

I have summmoned you here for a purpose.

JoshuaZ
2010-03-05, 12:33 AM
If it's ALWAYS relative to the planet and it's rotation, why not take out the moon with a wall of force suspended at the right height? Perhaps even b****-slap the sun?

Neither of those will have much of an effect. The moon would leave a noticeable entry and exit but that's about it. The sun would barely notice. I'm not inclined to go through all the calculations since I just ran through a similar set on the previous page for plowing the wall through the earth but they should be roughly the same results. The moon will likely get more decent damage but still survive (there are three scaling factors at work since the moon's velocity is slow compared to Earth's orbital velocity, but the moon is a smaller body, and total mass scales with the cube of the radius while maximum mass stopped scales linearly) The sun will barely notice because of the mass going as a cubic matter. Although the drag created by such an object if it kept going through the sun might be enough to slow the earth down. I haven't thought about that possibility in any detail.

2xMachina
2010-03-05, 12:47 AM
But the image of the earth roundhouse kicking the sun every few hours is too awesome. More awesome when the sun just shrugs it off.

a_humble_lich
2010-03-05, 02:18 AM
Interesting thread.

I agree, doing some quick calculations the Wall of Force would be destructive but it would be nowhere near close enough to destroy the earth. As a very rough estimation of the energy involved, you could treat the wall as traveling though the Earth at orbital velocity and calculate the drag on the wall. The total energy released will be that force of drag times the distance the wall travels. If the drag is F=C*density*area*velocity^2 I get a force of 4.5e13 N (assuming the density is a constant 5500 kg/m^3 and the drag coefficient is one) for a 10 ft by 10ft wall. If it travels though the Earth it will then release a total of 6e20 J of energy, equivalent to 140,000 megatons of TNT. That this is the same order of magnitude as JoshuaZ calculated gives me more faith that it is at least close to the right order of magnitude.

As JoshuaZ pointed out his is much much less than the energy needed to "destroy the earth." in fact looking at Wikipedia, http://en.wikipedia.org/wiki/Richter_magnitude_scale, that energy is comparable to the energy release in the 1960 earthquake in Chile. The asteroid that hit the Yucatan and killed the dinosaurs had about 600 times more energy. The above estimate would have to be off by a *lot* before you started to get to the destroy the world level.

Relatedly, if you calculate the momentum the Earth will loose you get a momentum loss of 2e16 Ns, compared to a total momentum of about 1.8e29. This means the Earth's speed would slow from a initial speed 29.8 km/s to a final speed of 29.799999999997 km/s. Not quite grinding to a halt.

Basically while the Wall of Force would be devastating the Earth as a planet would hardly notice. The fragile things on the surface on the other hand....

FishAreWet
2010-03-05, 02:23 AM
Are those energy equations assuming that the Wall of Force breaks? Sure it's only a big Earthquake when it hits, but the Wall is still there. Either the Earth moves around it, throwing it out of orbit, or a hole is drilled through the Earth. Right?

a_humble_lich
2010-03-05, 03:47 AM
No that is the energy from the drag caused by moving a 10 ft square of indestructible stuff into the Earth and out the other side at 29.8 km/s. At those sorts of speeds the Earth (and most anything really) acts like a fluid. Now there are some big assumptions I made (like I don't actually know what the drag coefficient of a flat disk at those speeds is), but it should be accurate to a couple orders of magnitude. The wall would move right though, and then the immense pressure from literally the weight of the world pushing from above would cause the hole to be nearly immediately filled with magma.
It would be like the hole drilled in a lake when you fire a bullet in it.

And as for pushing the Earth out of orbit, to do that you'd have to somehow take momentum away from the Earth. The wall of force only takes away about .00000000001 % of the Earth's momentum

absolmorph
2010-03-05, 04:26 AM
No that is the energy from the drag caused by moving a 10 ft square of indestructible stuff into the Earth and out the other side at 29.8 km/s. At those sorts of speeds the Earth (and most anything really) acts like a fluid. Now there are some big assumptions I made (like I don't actually know what the drag coefficient of a flat disk at those speeds is), but it should be accurate to a couple orders of magnitude. The wall would move right though, and then the immense pressure from literally the weight of the world pushing from above would cause the hole to be nearly immediately filled with magma.
It would be like the hole drilled in a lake when you fire a bullet in it.

And as for pushing the Earth out of orbit, to do that you'd have to somehow take momentum away from the Earth. The wall of force only takes away about .00000000001 % of the Earth's momentum
90 ft rectangle. 10 ft square/caster level. Level 5 spell.
You low-balled it.

Dervag
2010-03-05, 05:00 AM
*Ahem*

Physics is a dame of culture and sophistication. She'll take you in, keep you warm at night, provide all kinds of insight into yourself and the world you never find on your own.

I'm sigging the part on RAW.I'm sigging the part on Physics.

a_humble_lich
2010-03-05, 06:17 AM
90 ft rectangle. 10 ft square/caster level. Level 5 spell.
You low-balled it.

It doesn't matter. If you assume the rest of the estimate was correct, it would take a level 600 mage to have energy equal to the meteor which killed the dinosaurs. And that not only did not destroy the Earth, it didn't even kill all the life on the surface--the dinos may have died, but lots of other stuff survived just fine.

absolmorph
2010-03-05, 06:43 AM
It doesn't matter. If you assume the rest of the estimate was correct, it would take a level 600 mage to have energy equal to the meteor which killed the dinosaurs. And that not only did not destroy the Earth, it didn't even kill all the life on the surface--the dinos may have died, but lots of other stuff survived just fine.
That's what cults are for.

Volkov
2010-03-05, 06:49 AM
That's what cults are for.

Said cult get's the circle of eight knocking on the doorstep and kicking it's @$$.

PhoenixRivers
2010-03-05, 07:19 AM
Said cult get's the circle of eight knocking on the doorstep and kicking it's @$$.

Said doorstep is shielded from scrying, of course. Psh, like any self respecting cult leaves a welcome mat, an unlocked door, and a tray of cookies in the foyer.

Volkov
2010-03-05, 07:22 AM
Said doorstep is shielded from scrying, of course. Psh, like any self respecting cult leaves a welcome mat, an unlocked door, and a tray of cookies in the foyer.

Every single member of the circle of eight is an epic level wizard. Every single one.

Cyclocone
2010-03-05, 07:27 AM
It has no arms, legs, mouth, eyes, nose, etc.

It can't do anything.

...And yet, it must scream.

Volkov
2010-03-05, 07:29 AM
...And yet, it must scream.

Slaps Cyclocone with his cybernetic hand for the awful joke, then gets his cybernetically enhanced dog chitzkoi to tear his throat out

absolmorph
2010-03-05, 08:08 AM
Said cult get's the circle of eight knocking on the doorstep and kicking it's @$$.
What door step?

Cyclocone
2010-03-05, 08:27 AM
Slaps Cyclocone with his cybernetic hand for the awful joke, then gets his cybernetically enhanced dog chitzkoi to tear his throat out

:smallbiggrin:

Lysander
2010-03-05, 12:04 PM
The thing to remember is how tiny a Wall of Force is compared to a planet as a whole. Fun fact: If the earth were the size of a basketball, you wouldn't even be able to feel Mount Everest by running your hand over it. A small obstacle like a wall of force would behave like an incredibly microscopic bullet flying through an elephant.

Where it gets weird is that the Wall of Force doesn't have momentum or mass. It's just arbitrarily stationary. An asteroid of any size will stop upon hitting the earth and its energy spreads outwards into a crater shape. The wall of force on the other hand can't be slowed, it's basically the same as numerous asteroids hitting the earth continuously at progressively deeper and deeper depths, then progressively shallower depths until it breaks through the surface on the other side.

Hatu
2010-03-05, 12:36 PM
*Ahem*

Physics is a dame of culture and sophistication. She'll take you in, keep you warm at night, provide all kinds of insight into yourself and the world you never find on your own.

RAW is the wild, kinky sort of girl you'd never bring home to mother. She'll let you try new things, anything you can imagine, and more! She's flexible like a gymnist, and never has a headache.

that said, both of these ladies have one thing in common. they are possessive, jealous *****es! When you're going at it, you have to choose one or the other. Mixing the two does not lead to a clever or interesting theoretical situation, it leads to heavy, breakable objects getting thrown at your face from both sides.

Finally someone has a sensible answer to this thread! :-) I heartily endorse this analysis!

-H

Eric Tolle
2010-03-05, 12:36 PM
it might, but I think the amount of energy released will literally blow it apart too far to reform.

That's not even close to the ballpark amount of energy needed. A Wall of Force will do quite a bit of localized damage at the entrance and exit points, but we're not even talking at the level of Chicxulub or Manicouagan; we're talking more at the level of Berringer or Tungaska. Remember, the WoF is simply a super-hard weightless object, without the mass and dimensions of an actual asteroid. Without any mass to be vaporized, it's basically just going to burrow itself downward at hypersonic speeds. It'll make a mess out of anything nearby, but unless it happens to hit a semi-dormant supervolcano, the damage will be trivial on a continental, much less planetary scale.

Also bear in mind, to destroy a planet, one has to overcome the gravitational binding energy of all the materials- in other words, you have to lift all the material of the planet to escape velocity. As an example of how much energy that requires, bear in mind that sometime in our past the Earth was hit at orbital velocity by an object the size of Mars, and the only thing that happened was a moon was formed. Compared to cosmic billiards events like that, a small force wall is nothing.

Thidrek
2010-03-05, 09:00 PM
There was this argument I saw a while back proposing that Wall of Force could be used to destroy a planet, or at least cause major damage. Here's what you do. Become immune to cold/heat/vacuum, teleport somewhere in deep space in the path of the planet, then start throw up Walls of Force. The walls are immovable and invulnerable so when the planet hits them they should dig tunnels right through the core of the planet at thousands of miles per hour. If not outright destruction we're talking major earthquakes and volcanic activity as a result.

But Walls of Force aren't completely invulnerable. The Legendary Dreadnought epic prestige class has the Unstoppable class ability which lets it make a DC32 Str check to break walls of force. So, should we assume that a freaking planet also has the ability to smash walls of force apart?
The main flaw in this logic is this (quoted from 3.5 errata):


Does an object with momentum maintain that
momentum if teleported?
Nothing in the rules suggests that the rules of physics
wouldn’t continue to apply, so it appears that momentum is
maintained. If you’re plummeting toward the ground when you
cast teleport to reach a safe spot, you’d still be “falling” and
would therefore take damage as appropriate to the distance you
actually fell before teleporting.

So it will create a WOF that travels space the same way the earth does.

Next question would be if it actually IS possible to teleport into space or if "space" is considered as another plane by RAW...

Also, take from the SRD:

The wall cannot move
So by RAW the wall can not move of its own but it isn't stated that it can't be moved at all :smallwink:

Emmerask
2010-03-05, 10:29 PM
Every single member of the circle of eight is an epic level wizard. Every single one.

Yep epic magic beats those puny arcane defenses a cult could set up pretty easily ie they will just be ignored by your epic scrying ^^:smallsmile:

Eric Tolle
2010-03-06, 06:13 AM
The main flaw in this logic is this (quoted from 3.5 errata):


Does an object with momentum maintain that
momentum if teleported?
Nothing in the rules suggests that the rules of physics
wouldn’t continue to apply, so it appears that momentum is
maintained.

So it will create a WOF that travels space the same way the earth does.

Man, we covered this about 25 years ago. :smallbiggrin:

On the other hand, the Teleport spell evidently doesn't conserve momentum in certain reference frames. That is, there's nothing in the rules to suggest that if you teleport to the opposite side of a planet, you arrive at a velocity of 2000 mph relative to the ground. In fact, if momentum was conserved in Teleport, than the spell would be useless after distances of a few tens of miles, due to the earth's curvature flinging the teleportee upwards in one direction, and downwards in the opposite direction. In fact, the only truly safe long-range teleports would be from a location in one hemisphere to the corresponding point in the other hemisphere at the same latitude. Likewise, teleports of more than a mile up or down would be lethal, due to the change in potential energy. (Thank you, Larry Niven for your essay on teleportation).

Since none of those complications are listed in the Teleport spell (and for a good reason, since it would make a very lethal weapon), it's safe to assume that Teleport transfers you to a location at rest relative to a nearby body.


...why do I get so geeky after my fourth glass of wine?

Thidrek
2010-03-06, 10:04 AM
Man, we covered this about 25 years ago. :smallbiggrin:

On the other hand, the Teleport spell evidently doesn't conserve momentum in certain reference frames. That is, there's nothing in the rules to suggest that if you teleport to the opposite side of a planet, you arrive at a velocity of 2000 mph relative to the ground. In fact, if momentum was conserved in Teleport, than the spell would be useless after distances of a few tens of miles, due to the earth's curvature flinging the teleportee upwards in one direction, and downwards in the opposite direction. In fact, the only truly safe long-range teleports would be from a location in one hemisphere to the corresponding point in the other hemisphere at the same latitude. Likewise, teleports of more than a mile up or down would be lethal, due to the change in potential energy. (Thank you, Larry Niven for your essay on teleportation).

Since none of those complications are listed in the Teleport spell (and for a good reason, since it would make a very lethal weapon), it's safe to assume that Teleport transfers you to a location at rest relative to a nearby body.


...why do I get so geeky after my fourth glass of wine?

Well I read most of the thread before posting but this particular piece of information I couldn't find, otherwise I wouldn't have bothered posting it :smallwink:

Regarding the conservation of momentum: You can do funny things with this rule. We did the math once and figured out that you would end up about 15 km/h too slow if teleporting from sea-level to a really high mountain because of earth's rotation :smallbiggrin:

Darklord Xavez
2010-03-06, 02:05 PM
There was this argument I saw a while back proposing that Wall of Force could be used to destroy a planet, or at least cause major damage. Here's what you do. Become immune to cold/heat/vacuum, teleport somewhere in deep space in the path of the planet, then start throw up Walls of Force. The walls are immovable and invulnerable so when the planet hits them they should dig tunnels right through the core of the planet at thousands of miles per hour. If not outright destruction we're talking major earthquakes and volcanic activity as a result.

But Walls of Force aren't completely invulnerable. The Legendary Dreadnought epic prestige class has the Unstoppable class ability which lets it make a DC32 Str check to break walls of force. So, should we assume that a freaking planet also has the ability to smash walls of force apart?
Actually, you can never use a wall of force to attack. All wall spells are of a totally defensive nature. So no, none of that could happen. Wall of force is a passive spell, not an active one.
-Xavez

Flickerdart
2010-03-06, 02:09 PM
Actually, you can never use a wall of force to attack. All wall spells are of a totally defensive nature. So no, none of that could happen. Wall of force is a passive spell, not an active one.
-Xavez
You're not attacking anything. In fact, the entire thing relies on the wall standing in place and not moving.

Also, you can drop a Wall of Iron on people, and a Wall of Fire hurts things, so that's not even true.