## Potion of Diminution (warning, physics content)

Before anyone hassles me about my geekiness, remember you are posting on a DnD forum - pot, kettle and all that ;)

And yes I realise "it's magic" often resolves any such arguments about realism, what with fireballs, flying dragons, etc. But still this amused me enough to do the maths.

Potion of Diminution "You shrink to 10 percent of your normal size and weight"

A regular human has a mass of 70kg, a density approximated to that of water of 1000kg/m^3, hence a volume of 0.07m^3.

If you shrink to 10% of your normal size, that reduces your volume to 0.1% of your normal volume (as you shrink in 3 dimensions). Hence your volume becomes 0.00007m^3. Meanwhile shrinking to 10% of your normal weight, your mass becomes 7kg. This implies a density of 100,000kg/m^3.

To put that into context, lead has a density of 11,340kg/m^3. So we're talking an order of magnitude more dense than lead. The core of the Sun is about the ballpark density we're talking.

en.wikipedia.org/wiki/Density
trebor_rjf
Joined Sep 2006
1355 Posts
I too watched mythbusters the other day.

Happy to be back on the best D&D forum on the internet!

Saelorn
Joined May 2012
5758 Posts
Maybe, by "size" they are referring to "volume"; then it would be consistent.

The metagame is not the game.

luke_twigger
Joined Apr 2011
14 Posts
Maybe, by "size" they are referring to "volume"; then it would be consistent.

Hmmm, good thinking. That would require height becoming 46% of normal. So a 2m human would become 92cm tall, about the size of a halfling.
CorrinAvatan
Joined Jan 2007
1246 Posts
Maybe, by "size" they are referring to "volume"; then it would be consistent.

Hmmm, good thinking. That would require height becoming 46% of normal. So a 2m human would become 92cm tall, about the size of a halfling.

I'm going to geekily point out that any "negative" effects (like being more dense than the sun, for example), would be pointed out.

If you are 6 feet tall and 200 pounds, after drinking the potion you would be 7.2 inches tall, and weigh 20 pounds.  Where does the extra density go?  Somewhere between dimensions if you want the hand-wave, but if you want the "rules" explanation, it's because people can figure out 10% easily.

I get where you're going at, but most people don't play D&D to play calculus.  *looks up at your first post*
Salla, on minions: I typically use them as encounter filler. 'I didn't quite fill out the XP budget, not enough room left for a decent near-level monster ... sprinkle in a few minions'. Kind of like monster styrofoam packing peanuts.
Qmark
Joined May 2002
18912 Posts
For reference: en.wikipedia.org/wiki/Square-cube_law

Of course, someone instantly losing 90% of his mass would create an explosion large enough to level a very large city and probably also the closest city in any direction.
CarlT
Joined Apr 2009
2977 Posts
For reference: en.wikipedia.org/wiki/Square-cube_law

Of course, someone instantly losing 90% of his mass would create an explosion large enough to level a very large city and probably also the closest city in any direction.

Only if by 'losing' you mean 'converting into energy'.  If by 'losing' you mean 'ceasing to exist
' - then you just get a loud bang and a big wind as the surrounding air moves into the void left by the disappearing mass.

There is no requirement for mass to be conserved in a magical universe.

---
And you know you made the density calculations much more complicated than you needed to (and, of course, the relative change is independant of the starting dimensions)

You should increase to 100 times your current density.

You drop to  1 / 103 of your current volume.  You drop to 1/10 your current weight.

1/ 10 current weight in 1 /  103 current volume result in a 100-fold increase in density or 100,000 kg/m 3 (with the 'we are equal in density to water' simplification).

Not 'star core' density by far (actually more like 1 one-thousandth of star core density) - but far more dense than any normal matter and more dense than the core of the Earth (by a factor of 10).

Carl
Orzel
Joined Aug 2007
5690 Posts
The magic is the the explosion is teleported to the Plane of Fire where it dissapates harmlessly.

Any idiot mage can make a potion that shrinks you.
Only the smart ones make one that solves the density problem.

Orzel, Halfelven son of Zel, Mystic Ranger, Bane to Dragons, Death to Undeath, Killer of Abyssals, King of the Wilds. Constitution Based Class for Next!

Qmark
Joined May 2002
18912 Posts
One tenth the size and one thousandth the weight is how it should be.
Our 200lb guy would drop to 7.2 inches and 0.2 pounds (a bit over 3 ounces).
fluxpoint
Joined Sep 2012
275 Posts
In a lot of other places (in various rule books here and there) they do "more proper" weight conversions. Increasing by double in height and raising weight by a factor of 8.

So you decrease in height to 10%, but weight to 0.1%

Maybe dimunition could use some numbers that 'do' make more sense. Of course being a 'hand' tall and weighing 0.2 lbs (or 0.01kgs) might have its own issues. Which you could fix in other ways if you like.  Bugs are prepared to deal with this issue in a variety of ways. But it also makes them relatively impervious to brutal falling damage and the like. How far do you want to take this? :P

Also, since the person isn't minature forever, I kinda assume the mass isn't just 'lost' but must be kept somewhere (magically?). However, a 20lb - 7 inch hero will certainly crush any dimunitive mount that may have existed outside the dimunitive pot itself.well I'm 7 inches so I hop on a salamander and kill it outright - squiiiiiish. Oops. We tend to try to overlook things like that in the spirit of the rules/fantasy in our group even if a few of us are physics/math/engineering nerds.

However, if your suspension of disbelief - wait what I'm 7 inches tall!? - is offended...fix it;)

Currently running a playtest, weekly, online D&D Next Session using a virtual table system called roll20.
Qmark
Joined May 2002
18912 Posts
Also, since the person isn't minature forever, I kinda assume the mass isn't just 'lost' but must be kept somewhere (magically?).

Hammerspace.

Orzel
Joined Aug 2007
5690 Posts

Also, since the person isn't minature forever, I kinda assume the mass isn't just 'lost' but must be kept somewhere (magically?).

Fighter: I can drink this potion of diminution and flying and fly through the hole.
Wizard: No. You will be under the effect of two potions. There could be a mishap.
Fighter: So? One fails, big whoop. I'm immune to poison as I am a dwarf so that's out. And I can take the damage. I did so last week with those delusion potions.
Wizard: But the diminution could become permanent.The spell is designed to wear off after 4 hours. The collasped mass will not remain in the magic containment for longer than 6 hours. If it isn't dispelled, you will regain you normal dens... where are the potions.
Fighter: Drank 'em. Only got small. Bummer.

6 hours later.

Wizard: Wait. Are you still...
DM: Everyone roll Dexerity saves

Orzel, Halfelven son of Zel, Mystic Ranger, Bane to Dragons, Death to Undeath, Killer of Abyssals, King of the Wilds. Constitution Based Class for Next!

fluxpoint
Joined Sep 2012
275 Posts
@Orzel I literally laughed reading this - thanks.
Currently running a playtest, weekly, online D&D Next Session using a virtual table system called roll20.
Mand12
Joined Jun 2010
17444 Posts
"If your diminution lasts more than 4 hours, seek immediate magical help."

?
D&D Next = D&D: Quantum Edition
mellored
Joined Jul 2008
29364 Posts
Better question.  Which way do you shrink?  (example)

A Party Without Music is Lame: A Bard

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Elven Critters Crit op with crit generation. 5 of these will end anything. Broken.

King Fisher Optimized net user.  Moderate.

Boominator Fun catch-22 booming blade build with either strong or completely broken damage depending on your reading.

Very Distracting Warlock Lot's of dazing and major penalties to hit. Overpowered.

Pocket Protector Pixie Stealth Knight. Maximizing the defender's aura by being in an ally's/enemy's square.

Yakuza NinjIntimiAdin: Perma-stealth Striker that offers a little protection for ally's, and can intimidate bloodied enemies. Very Strong.

Chargeburgler with cheese Ranged attacks at the end of a charge along with perma-stealth. Solid, could be overpowered if tweaked.

Void Defender Defends giving a penalty to hit anyone but him, then removing himself from play. Can get somewhat broken in epic.

Scry and Die Attacking from around corners, while staying hidden. Moderate to broken, depending on the situation.

Skimisher Fly in, attack, and fly away. Also prevents enemies from coming close. Moderate to Broken depending on the enemy, but shouldn't make the game un-fun, as the rest of your team is at risk, and you have enough weaknesses.

Indestructible Simply won't die, even if you sleep though combat.  One of THE most abusive character in 4e.

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Quidhala
Joined Sep 2008
292 Posts
@Mellored,

Thanks. You inspired me.

When Rick Moranis shrunk his kids, he explained that he was really only shrinking the empty space found in what we consider solid matter. The space between atoms and also the space within atoms (between the electron valence shells and the nucleus). The amount of matter remained unchanged. Their mass was the same even though they were reduced to the size of 1/10th inch. A few initial considerations:

1. Hopefully the shrinking process occurs at exactly the same rate all over their body or else; their cells would explode/implode, their eyes and hollow organs would rupture, and their bones would shatter.

2. Where does the effect of the shrink ray end? Does it shrink only the child (dense matter like solids and liquids) or the air/gasses in and around the child? If the air in the child's lungs and bowels is not shrunk they will also explode if the shrinking process is fast. If it shrinks the air around them, how much air will it shrink before the effect weakens? If this happens too quickly a vacuum will be created by the shrinking atoms and the room will implode, sending more matter into the shrink ray's area of effect but also probably disabling the shrink ray so it is unlikely that a singularity type situation would occur.

So let's assume that that stuff is accounted for. As they shrink the structure of their body becomes smaller but weighs the same. The atoms within them still have the same properties, ability to form and break bonds. The strength of such bonds are not diminished even though the size of all the structures in their bodies shrink. They reduce to 1/10th of an inch and are able to move just as freely as before even with their extreme density. If you put a 20 pound ball of lead on top of them they should be able to hold it aloft without being crushed, though it would be hard to balance. Unfortunately you wouldn't get the chance to try it because immediately after the shrinking process they would start suffocating because the oxygen in the air is too big to diffuse across the tissue of their alveoli and into their blood stream. They die from oxygen deprivation.

And that is why Disney movies suck!
Qmark
Joined May 2002
18912 Posts
And that is why Disney movies suck!

Quite a bit of all fiction falls completely apart when Conservation of Mass is considered.

Jenks
Joined Apr 2008
2906 Posts
And that is why Disney movies suck!

Quite a bit of all fiction falls completely apart when Conservation of Mass is considered.

So true. Teleportation has had this problem in pretty much every instance it's been in
My two copper.
fluxpoint
Joined Sep 2012
275 Posts
Or your original self as being stored extra-dimensionally while this new body is a magically averaged version of your old self created to conform to these new physical characteristics.

Magic is meant to break physics anyway. It is sorta the point.
Currently running a playtest, weekly, online D&D Next Session using a virtual table system called roll20.
Jenks
Joined Apr 2008
2906 Posts
I think you just have to admit to it not making physical sense. I mean cmon, 50% of sci fi can be torn apart by the theory of relativity and it's conclusion that matter can't travel faster than light.
My two copper.
fluxpoint
Joined Sep 2012
275 Posts

Can energy travel faster than light ?
Currently running a playtest, weekly, online D&D Next Session using a virtual table system called roll20.
Qmark
Joined May 2002
18912 Posts

Can energy travel faster than light ?

No.  Energy is what defines the speed of light.

Garthanos
Joined Jan 2009
22412 Posts

Can energy travel faster than light ?

No.  Energy is what defines the speed of light.

E=mc2/(1 - v2/c2 )

as the velocity v approaches c (the speed of light) the bottom of the equation approaches zero... somethings gotta give....
 Creative Character Build Collection and The Magic of King's and Heros  also Can Martial Characters Fly?  Improvisation in 4e: Fave 4E Improvisations - also Wrecans Guides to improvisation beyond page 42The Non-combatant Adventurer (aka Princess build Warlord or LazyLord) Reality is unrealistic - and even monkeys protest unfairnessReflavoring the Fighter : The Wizard : The Swordmage - Creative Character Collection: Bloodwright (Darksun Character)  At full hit points and still wounded to incapacitation? you are playing 1e. By virtue of being a player your characters are the protagonists in a heroic fantasy game even at level one "Wizards and Warriors need abilities with explicit effects for opposite reasons. With the wizard its because you need to create artificial limits on them, they have no natural ones and for the Warrior you need to grant permission to do awesome."
Qmark
Joined May 2002
18912 Posts
somethings gotta give....

And that's why photons are massless.

fluxpoint
Joined Sep 2012
275 Posts

Can energy travel faster than light ?

No.  Energy is what defines the speed of light.

E=mc2/(1 - v2/c2 )

as the velocity v approaches c (the speed of light) the bottom of the equation approaches zero... somethings gotta give....

And there's the other idea which is that it works only if you buy into the fact that the actual change in distance has to be a velocity. Moving to a higher dimension and then back (worm hole types of ideas), might give you a greater change in distance but at a lower velocity by folding through space itself. Perceived velocity would then be faster than light there as well.

Currently running a playtest, weekly, online D&D Next Session using a virtual table system called roll20.
warrl
Joined Apr 2009
5268 Posts
I think you just have to admit to it not making physical sense. I mean cmon, 50% of sci fi can be torn apart by the theory of relativity and it's conclusion that matter can't travel faster than light.

Actually, the theory of relativity does not make that conclusion.

It concludes that matter can't travel *at* the speed of light, because of mass.

Matter definitely can travel faster than the speed of light, according to relativity - the problem is how to get above the speed of light without ever, even instantaneously, traveling precisely at the speed of light.

(Interestingly, there's a currently-theoretical construct called "negative mass". If you could gather together a bunch of matter with negative mass - tricky because gravity is a repulsive force for that stuff - and confine it at one end of a beam, and put the appropriate amount of ordinary matter at the other end of the beam, you get a really interesting thing. The negative mass is repulsed by the gravity of the ordinary mass, and tries to move away from it. Meantime the ordinary mass is attracted by the gravity of the negative mass, and tries to move toward it. Both these attempted motions are in the same direction, and since the two masses are held at a fixed distance by the beam, neither can ever win. So they accelerate perpetually. And if you've balanced it exactly right, the whole system has zero net mass so is not subject to the speed-of-light limitation.)

"The world does not work the way you have been taught it does. We are not real as such; we exist within The Story. Unfortunately for you, you have inherited a condition from your mother known as Primary Protagonist Syndrome, which means The Story is interested in you. It will find you, and if you are not ready for the narrative strands it will throw at you..." - from Footloose
Qmark
Joined May 2002
18912 Posts
Negative Mass is a math trick, and you know it.
Garthanos
Joined Jan 2009
22412 Posts
somethings gotta give....

And that's why photons are massless.

And strangely seem to be affected by gravity (or perhaps space and distance is as the light is bent by massive bodies)
 Creative Character Build Collection and The Magic of King's and Heros  also Can Martial Characters Fly?  Improvisation in 4e: Fave 4E Improvisations - also Wrecans Guides to improvisation beyond page 42The Non-combatant Adventurer (aka Princess build Warlord or LazyLord) Reality is unrealistic - and even monkeys protest unfairnessReflavoring the Fighter : The Wizard : The Swordmage - Creative Character Collection: Bloodwright (Darksun Character)  At full hit points and still wounded to incapacitation? you are playing 1e. By virtue of being a player your characters are the protagonists in a heroic fantasy game even at level one "Wizards and Warriors need abilities with explicit effects for opposite reasons. With the wizard its because you need to create artificial limits on them, they have no natural ones and for the Warrior you need to grant permission to do awesome."