Would this work?

[The Iron Mark]

Good one. I never bothered to see if it would really work. I just said someone had proposed that design. I assume you all are familiar with the Laser Sphere correct?

 

[hong]

On a thread in House Rules we came up with a weapon quite like this. Instead, you have abox. You teleport all the air out of it. Then a Permanent Teleportation Circle is made to teleport any objsct to a little below the top of the box. Put stone brick in. Wait a while. Contingency to teleport yourself to safety when you cast Dispel Magic. Cast Dispel magic on the box. The guy who made this claimed it caused temperatures hot enough to cause oxygen fusion. I nicknamed it the Oxynuke, after Oxyclean .

The dispel magic would dispel the teleportation circle. Other than that, is anything fancy supposed to happen?

 

[Umbran]

And on second thought, isn't there a law of conservation or somesuch that dicates that energy cannot be created or destroyed, so that if the speed of the object gets greater, due to the equation E=mC^2, wouldn't the mass be getting smaller and smaller as the object neareed the speed of light?

The idea that matter/energy cannot be created or destroyed only holds for closed systems. This is not a closed system. The object takes energy from the (magically generated) gravity fields.

However, this does suggest something...

There is a limit on what a spell of a given level can do - DMG, pg 95. 1st level spells cap out at 5 dice of damage to any particular target. They simply don't provide enough energy to do more. 9th Level spells cap out at 25 dice. And that's in normal damage dice - d4s, d6s, or d8s!

So, what happens? That Reverse Gravity, permanent or not, simply cannot accelerate the ball forever. It can only provide so much gravitational energy. After it gives up enough energy so that the creature struck by the ball takes 25 dice of damage, the ball cannot be accelerated further. Beyond that, the spell is simply tapped out.

So, you have created an expensive bazooka, but not a planet buster

 

[Umbran]

The dispel magic would dispel the teleportation circle. Other than that, is anything fancy supposed to happen?

The idea was that you put the rick in, it falls, hits the circle, gets teleported to the top, falls again, etc. Each fall speeds up the brick. One supposes that if allowed to run, the speed of teh brick will approach the speed of light, and it will be very destructive when it hits the ground.... As I noted, though, it won't work with a brick.

 

[hong]

The idea was that you put the rick in, it falls, hits the circle, gets teleported to the top, falls again, etc. Each fall speeds up the brick. One supposes that if allowed to run, the speed of teh brick will approach the speed of light, and it will be very destructive when it hits the ground.... As I noted, though, it won't work with a brick.

It's an open question whether momentum is conserved during a teleport; regardless, the guy who came up with this idea was certainly guilty of violating Hong's Third Law....

 

[Broken Fang]

I don't have my PHB handy so someone might be able to look this up...do you retain your current velocity when you teleport/gate? If not than the brick would just keep falling at the same rate until the gate was broken...no increasing speed near the speed of light.

 

[CRGreathouse]

I don't have my PHB handy so someone might be able to look this up...do you retain your current velocity when you teleport/gate?

It doesn't say. The rationalization that it does not has been used many times to defeat this "trick".

 

[Umbran]

It doesn't say. The rationalization that it does not has been used many times to defeat this "trick".

Interesting. Ring Gates, in the DMG, specificaly allow for conserved momentum - you can make physical attacks through the gates. However, the Ring Gate has a weight allowance - no using them for relativistic masses. Probably coincidence, but not a bad one, in this case.

 

[Rune]

You're missing the obvious problem. It's not physically possible for the steel ball to go through a gate that goes from "here" to "here". This is because the ball will be pushing against itself the moment it tries to go through the gate--that is to say, if the ball could go through the gate, part of it would be coming out while the rest is going in, but, because the part coming out is in the same place as the part going in, it simply isn't happening in the first place. Any solid object that tries to go through the gate will appear to reflect off of the gate instead. Actually, it will be reflecting off of itself.

 

[MythandLore]

Would this work?
No.

You are aware of the Gate spell, are you not?
Yes.

You are aware that Gate allows you to travel from Here to There, right?
Yes.

Some mages created a reasonable (and apparently useless) variant of the Gate spell that
causes you to go from Here to ... Here.
Okay.

A Gate can be made permanent.
No.

There is no point in going further.

A 'Gate' is an 'Instantaneous' spell, it cannot be effected by 'permanency' or duration extending 'meta-magic' feats.

A 'Cubic Gate' item comes close to what you are trying to do but still can't.
It has a 10% chance of something passing thru every round it is open, you couldn't leave it open for 3 days an average of 4,320 creatures would pass thru in that time.

The amount of times the object could pass thru a 'Ring Gate' is very limited by weight per day, so would not really work ether.

Even thee 'Portals' from the FRCS book (which act like perminent gates) would not work.
It has many rules which could be interprted to work with the spell 'Gate' inculding unattended objects (like throwing a rock) can't go thru on there own.

If you have the FRCS book I sugjest you look over the section on 'Portals' p59 and see what you think.
I myself would never allow what you are proposing.
Also if you take into account 'real science' after it gets too fast it will start to burn up do to friction of air etc.
If you were to fire a one pound ball of steel from space regardless of the speed, it will burn up before it gets to the ground.
Bottom line, don't waste anymore of your time on this sillyness.