How does water respond to increased density?


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Shifty wrote:
johnlocke90 wrote:
The bubble only extends out 1 inch past the casters skin.
Actually... "You surround the touched creatures with a constant and moveable 1-inch shell of tolerable living conditions". Doesn't specify 'from the skin', therefore, like invisibility, it obviously covers the held objects too.

It specifies creature. The decanter isn't a creature.

Invisibility specifically states that it applies to gear. this spell makes no such statement.


It's worth pointing out too that the same thing which makes the scheme work - the thermodynamic isolation of the demiplane - also prevents its use as an actual weapon: the explosion will occur in the demiplane.

Unless your enemies are in there when it happens, it won't affect them (and they'd die before the explosion anyway because they'd be instantly crushed by the devastating pressures!)


The problem with this plan, like the problem with many physics + magic based plans, is that what kind of a Pathfinder character are you playing that would understand these concepts?

I think a DM in their right mind would just say no.


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johnlocke90 wrote:
David Haller wrote:
...
Thanks for the information. I still have to wonder what kind of effect charging this up for a year then unleashing it on an enemy base would have. It seems like the water would have a ton of energy in it simply because water takes a ton of energy to compress.

Certainly if you had a planeful of metastable ice II or III or something, and suddenly introduced it to normal terrestrial conditions, it might explode.

There are probably easier ways to kill enemies with water, of course!


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Whale_Cancer wrote:
The problem with this plan, like the problem with many physics + magic based plans, is that what kind of a Pathfinder character are you playing that would understand these concepts?

A Numerian, of course!


David Haller wrote:
Whale_Cancer wrote:
The problem with this plan, like the problem with many physics + magic based plans, is that what kind of a Pathfinder character are you playing that would understand these concepts?
A Numerian, of course!

That, I suppose, is an entirely fair answer.


David Haller wrote:

It's worth pointing out too that the same thing which makes the scheme work - the thermodynamic isolation of the demiplane - also prevents its use as an actual weapon: the explosion will occur in the demiplane.

Unless your enemies are in there when it happens, it won't affect them (and they'd die before the explosion anyway because they'd be instantly crushed by the devastating pressures!)

Talking about this in terms of an explosion is meaningless. Because the plane is thermodynamically isolated the energy has nowhere to go. It will just remain in the plane until an outlet appears(For instance, a portal to another dimension).


David Haller wrote:
johnlocke90 wrote:
David Haller wrote:
...
Thanks for the information. I still have to wonder what kind of effect charging this up for a year then unleashing it on an enemy base would have. It seems like the water would have a ton of energy in it simply because water takes a ton of energy to compress.

Certainly if you had a planeful of metastable ice II or III or something, and suddenly introduced it to normal terrestrial conditions, it might explode.

There are probably easier ways to kill enemies with water, of course!

Well it depends on the size of the explosion.


Imagine an arcane event which accidentally pierces the demiplane somehow:

"Hey guys, gimme a sec, I'm casting Mage's Magnificent Mansion... ahhh!"


Whale_Cancer wrote:

The problem with this plan, like the problem with many physics + magic based plans, is that what kind of a Pathfinder character are you playing that would understand these concepts?

I think a DM in their right mind would just say no.

Really? The problem isn't that it would take several times the age of the universe and you can only get a 2:1 time ratio on a demiplane? Because I can see someone wanting to use one or more decanters of endless water, a small permanent demiplane, and a modified gate spell to get a high pressure water jet, and then dieing and leaving their demiplane to build up pressure until some poor schmuck accidentally discovers it with a badly botched plane shift.


Atarlost wrote:
Whale_Cancer wrote:

The problem with this plan, like the problem with many physics + magic based plans, is that what kind of a Pathfinder character are you playing that would understand these concepts?

I think a DM in their right mind would just say no.

Really? The problem isn't that it would take several times the age of the universe and you can only get a 2:1 time ratio on a demiplane? Because I can see someone wanting to use one or more decanters of endless water, a small permanent demiplane, and a modified gate spell to get a high pressure water jet, and then dieing and leaving their demiplane to build up pressure until some poor schmuck accidentally discovers it with a badly botched plane shift.

Yes. Since my objection kicks in before you even need to start worrying about the physics.


johnlocke90 wrote:
David Haller wrote:

It's worth pointing out too that the same thing which makes the scheme work - the thermodynamic isolation of the demiplane - also prevents its use as an actual weapon: the explosion will occur in the demiplane.

Unless your enemies are in there when it happens, it won't affect them (and they'd die before the explosion anyway because they'd be instantly crushed by the devastating pressures!)

Talking about this in terms of an explosion is meaningless. Because the plane is thermodynamically isolated the energy has nowhere to go. It will just remain in the plane until an outlet appears(For instance, a portal to another dimension).

I feel like this is a big assumption on your part. In fact I would think the whole premiss relies on the fact that this isn't true. Every time you add water you add energy, that energy was not on the demi-plane until you added the water. It also assumes the physics of the real world apply to Pathfinder let alone Planes outside the material plane, which they obviously do not.


I would say once the demiplane is filled with water, it will stop coming out, because i don't think the decanter forces the water out with infinite pressure.


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If this is a thread aboout idiotic abuse of magic to exploit physics, why not use an evacuated (easy to with magic) container with a portal in the bottom linked to the top. Drop a stone in it, wait a year, cast a portal into it with exit above the city you dislike. Maybe make a few careful test, to adjust time and rock size, will work some way to destroy the city without destroying the planet.


My rough calculation for 1 year and 1 kg stone and earth gravity yields roughly 10^16 joule, which as far as i googled is about 2.5 megatons, so good chance to take care of a normal city. Unless of course the stop distance of near light speed stone is such that the energy mostly has effects miles beneath the city, though the resulting earthquake might be sufficient anyway.

Make it a 100 kg stone and we talk about knocking out small continents.

edit: Ok, 100 kg would be just 5 times tsar bomb, so not enough for a small continent. But well above anything lev 9 spells normally produce.


Furthermore, it doesnt require obscure knowledge, any caster capable of creating portals might ponder the questions, what would happen if some object just continous to fall forever. The first experiment will show him, that air ffriction would limit speed and then the mentally unstable ones will proceed trying it with air removed.


I can see the makings of a very nice 'side quest' from this though - say level 11/12 ish - agents from the plane of water contact you because the water level is draining and after years of research they discover some wizard did this...

Track down the wizard (or their notes/research) and shut it down - perhaps even reverse the process if possible...

Could even be a full adventure with cracking a wizards tower - perhaps the wizard either a) died and the experiment was left going, or b) is a lich and doesn't care about the timeframe.

Either way this is a neat situation and I think a nifty planar experience that could get your group some allies on the plane of water ;)


Real doomsday this way a bit complicated, to replicate the impact that might have led to the extinction of the dinosaurs it would take a 100 ton body falling for 100 years, probably multiplying that by 100 both to have a chance at destroying all life on a planet for good.


carn wrote:

My rough calculation for 1 year and 1 kg stone and earth gravity yields roughly 10^16 joule, which as far as i googled is about 2.5 megatons, so good chance to take care of a normal city. Unless of course the stop distance of near light speed stone is such that the energy mostly has effects miles beneath the city, though the resulting earthquake might be sufficient anyway.

Make it a 100 kg stone and we talk about knocking out small continents.

edit: Ok, 100 kg would be just 5 times tsar bomb, so not enough for a small continent. But well above anything lev 9 spells normally produce.

Did you account for relativity? Keep in mind classical physics breaks down at this point.


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johnlocke90 wrote:
carn wrote:

My rough calculation for 1 year and 1 kg stone and earth gravity yields roughly 10^16 joule, which as far as i googled is about 2.5 megatons, so good chance to take care of a normal city. Unless of course the stop distance of near light speed stone is such that the energy mostly has effects miles beneath the city, though the resulting earthquake might be sufficient anyway.

Make it a 100 kg stone and we talk about knocking out small continents.

edit: Ok, 100 kg would be just 5 times tsar bomb, so not enough for a small continent. But well above anything lev 9 spells normally produce.

Did you account for relativity? Keep in mind classical physics breaks down at this point.

I don't think relativity applies to Pathfinder.

First, there are planes of existence, so that invalidates general relativity (which depends on geometric curvature of spacetime); second, the presence of instantaneous travel (teleportation) kind of trumps special relativity (which is dependent on the speed of light as a speed limit).

In the case of my model, for example, I basically ignored gravity in favor of pressure (or more precisely, I assumed a constant terrestrial gravitational field).

As for dropping a stone, anything above colossal size is subject to GM handwaving anyway :)


David Haller wrote:
johnlocke90 wrote:
carn wrote:

My rough calculation for 1 year and 1 kg stone and earth gravity yields roughly 10^16 joule, which as far as i googled is about 2.5 megatons, so good chance to take care of a normal city. Unless of course the stop distance of near light speed stone is such that the energy mostly has effects miles beneath the city, though the resulting earthquake might be sufficient anyway.

Make it a 100 kg stone and we talk about knocking out small continents.

edit: Ok, 100 kg would be just 5 times tsar bomb, so not enough for a small continent. But well above anything lev 9 spells normally produce.

Did you account for relativity? Keep in mind classical physics breaks down at this point.

I don't think relativity applies to Pathfinder.

First, there are planes of existence, so that invalidates general relativity (which depends on geometric curvature of spacetime); second, the presence of instantaneous travel (teleportation) kind of trumps special relativity (which is dependent on the speed of light as a speed limit).

In the case of my model, for example, I basically ignored gravity in favor of pressure (or more precisely, I assumed a constant terrestrial gravitational field).

As for dropping a stone, anything above colossal size is subject to GM handwaving anyway :)

WIth some tweaking(heavy gravity, slow time), i got a 100kg stone up to 4 ^10 megatons. More than enough to take out an enemy base.


johnlocke90 wrote:


Did you account for relativity? Keep in mind classical physics breaks down at this point.

Upps, i assumed a constant mass in my laziness. But that doesnt matter, it will only increase the energy, so the actual energy will be higher.

But the change in mass might threaten the stability of the container, best thing to go to some plane with vacuum and gravity and put the thing up there and gate in to target from there.

Grand Lodge

Pathfinder Adventure Path, Starfinder Roleplaying Game Subscriber
johnlocke90 wrote:
The Terrible Zodin wrote:
Also keep in mind that gases are easily compressible but in order for hydrogen (for example) to achieve fusion you need an amount the size of a small star.
No you don't. Nuclear fusion is achieved with very small amounts of matter all the time in a laboratory. All you need is a lot of energy(stars obtain this through large amounts of matter creating gravity).

To be a bit more clarify. Yes you can achieve nuclear fusion, but these are short lived events which consume far more power than the result generates.

There's never been a problem in achieving nuclear fusion. The sticky wicket is creating a sustainable reaction which generates a net return of energy, or in other words, generates more power than what is required to set it up.


Heh. Physics and magic.

If I am understanding the exercise here, carn is supposing that you could put a rock into a separate airless demiplane with a portal connecting the bottom to the top such that the stone would "fall" endlessly until the caster decided to create another portal which would allow the stone to leave the demiplane and enter the prime material plane above a city with a resulting release of the accumulated energy.

The collection of assumptions involved here is rather extensive, but for the sake of argument, let's say this could work. Let's also assume that the demiplane and the prime material plane follow relativistic laws so that our math works.

Accelerating something at earth gravity for a full year would result in that object moving at roughly 3/4 the speed of light. That means the kinetic energy would be 1/2m(3/4*c)^2.

With a mass of 100kg that means E = .5*100kg*(2.25e6m)^2 or 2.25e6 which equals roughly 250 trillion Kgm^2/s^2 or roughly 250 trillion Joules.

Which sounds like a whole lot, doesn't it?

It's about .6 megatons, or roughly 600 kilotons. That's about 30 times as powerful as the bombs dropped on Hiroshima or Nagasaki, but less than half of a typical hydrogen bomb.

However, there are other things to take into account, depending on where the caster released the object.

At .75c the atmosphere would look and act like a solid object. Virtually all of the energy is going to be released within a few hundred feet of the object entering the air, essentially creating a spherical ball of expanding energy (it would look very much like an atomic explosion). To do the most damage to the city below, the detonation would have to occur at the optimal distance above the city for the shock wave to concentrate the maximum impact on the city structure itself. So to know where to detonate the "bomb" you would need to know the radius of the blast effect you want and then use geometry to calculate what height to release the projectile.

In general though, half a mile would not be a bad choice...

Update... I neglected to use the Lorentz factor on the mass. Doing so increases the mass to 151 kg, so increase everything above by 51%, coming out to about .9 megatons, still a bit below your typical hydrogen bomb.


Your 0.7 c seems to be roughly correct:
http://www.convertalot.com/relativistic_star_ship_calculator.html
This calculator gives the travel time for 0.8 light years as 1.94 earth years with 1 g accelaration, that means, as accelaration goes on half time (rest of time deecelration with that calculator), accelration for about 1 year with top speed about 0.7 c.

This calc confirms this:
http://ftlfactor.com/srcalc/

But the first calc gives
37100613778.25584 megajoules per kg or about 4*10^10 megajoule= 4*10^16 joule.

http://www.calctool.org/CALC/phys/newtonian/k_energy
This gives for 0.7 c 2.2*10^16 joule for 1 kg.

So my estimate of 1 kg for 1 year earth accelartion having 10^16 joule seems to be close, while yours is only 2.5 *10^12.

I just do not remeber how i did my estimate (too drunk), but i think its correct to say that 1 kg for 1 year earth surface acceleration gives something in the range of hydrogen bomb.

What we have to worry about is corriolis, the stone will drift slightly as it falls past earths center. I do not know how far this will be in 1 year. And anyone doing this might note it too late and then it will go off prematururally. Can be solved with a cube of connected gates.

@rest
This is just about numbers. Safely assume that an undead lich with gates and a decent hate for all living could wreak havoc by just preparing for a few thousand years in his hermitically closed underground lab.


Once you start breaking Newton's Laws to start doing your physics experiments (which happens pretty much right away when you use magic)I am not sure how much physics you can use to justify making fusion bombs. You are also assuming that the Pathfinder Universe is made up of atoms, which I am not sure it is.


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Timothy Hanson wrote:
Once you start breaking Newton's Laws to start doing your physics experiments (which happens pretty much right away when you use magic)I am not sure how much physics you can use to justify making fusion bombs. You are also assuming that the Pathfinder Universe is made up of atoms, which I am not sure it is.

Which is why I said in my analysis that "The collection of assumptions involved here is rather extensive."

I just thought it was an interesting exercise in applied special relativity. :)

As someone who actually has an entire cosmology and multiple worlds which exist in a rather familiar space-time continuum that I set all my games in, and considering I have a degree in physics, I am sort of surprised that I have never actually addressed quantum level physics or relativity in my own universe.

Now I am intrigued... I suppose I could make up an entirely unique set of physical laws, so long as they approximate Newtonian physics in the daily interactions of people and things.

Hmmm.... Do I want my own universe to have relativistic effects?

Yeah, I needed to add this to my world building analyses...


carn wrote:

Your 0.7 c seems to be roughly correct:

http://www.convertalot.com/relativistic_star_ship_calculator.html
This calculator gives the travel time for 0.8 light years as 1.94 earth years with 1 g accelaration, that means, as accelaration goes on half time (rest of time deecelration with that calculator), accelration for about 1 year with top speed about 0.7 c.

This calc confirms this:
http://ftlfactor.com/srcalc/

But the first calc gives
37100613778.25584 megajoules per kg or about 4*10^10 megajoule= 4*10^16 joule.

http://www.calctool.org/CALC/phys/newtonian/k_energy
This gives for 0.7 c 2.2*10^16 joule for 1 kg.

So my estimate of 1 kg for 1 year earth accelartion having 10^16 joule seems to be close, while yours is only 2.5 *10^12.

I just do not remeber how i did my estimate (too drunk), but i think its correct to say that 1 kg for 1 year earth surface acceleration gives something in the range of hydrogen bomb.

What we have to worry about is corriolis, the stone will drift slightly as it falls past earths center. I do not know how far this will be in 1 year. And anyone doing this might note it too late and then it will go off prematururally. Can be solved with a cube of connected gates.

@rest
This is just about numbers. Safely assume that an undead lich with gates and a decent hate for all living could wreak havoc by just preparing for a few thousand years in his hermitically closed underground lab.

Hmph... Geez, my calculations had a typo. I entered 3e^6 instead of 3e^8... So redoing those calculations, this time doing the Lorentz Factor from the start... The mass would still be the equivalent of 151 kg (starting with a 100kg object) but now the joules would be 3.82e18 joules, which is quite a bit more than my original figure. That now comes out to 913 megatons. Ouch. That's 9 times as much energy as the largest hydrogen bomb ever exploded. Still, not a continent destroying event. (Starting with a 1kg object, as you did, moves the decimal point two to the left, leaving a 1kg object delivering 3.82e16 joules or 9 megatons, also my analysis doesn't require falling through the earth, it only requires a demiplane with a portal connecting the bottom to the top, it can really be any size).

The link you provided does not include the Lorentz Factor, which is probably why my number is different than theirs.


Adamantine Dragon wrote:


Hmph... Geez, my calculations had a typo. I entered 3e^6 instead of 3e^8... So redoing those calculations, this time doing the Lorentz Factor from the start... The mass would still be the equivalent of 151 kg (starting with a 100kg object) but now the joules would be 3.82e18 joules, which is quite a bit more than my original figure. That now comes out to 913 megatons. Ouch. That's 9 times as much energy as the largest hydrogen bomb ever exploded. Still, not a continent destroying event.

Then our estimates agree, 1 kg would be just 1/100 of 100kg. So the 1 kg (9 megatons with your estimate) does a nice city destroyer with 1 year and the 100 kg at least can do away small islands. With 0.7c there is no problem of aiming the explosion as it will be stopped inside a few meters in air and/ ground.

For anything decent non-local effect, spell sizes and time would be a problem, 10000 kg for 100 years would be world changing (10^23 joule, 1000000 megatons), but hard to set up using the spells in spellbook and needs patience.


Adamantine Dragon wrote:


Which is why I said in my analysis that "The collection of assumptions involved here is rather extensive."

Changing the physic laws slightly (e.g. relativistic -> newton) wont change this method, as it is based on violation energy conservation (the rock is teleported upwards a few m, meaning its potential energy is increased with no energy decreased) and the moment one has controlled violation of energy conservation blowing up the universe is always only a matter of time and patience.


carn wrote:
Adamantine Dragon wrote:


Hmph... Geez, my calculations had a typo. I entered 3e^6 instead of 3e^8... So redoing those calculations, this time doing the Lorentz Factor from the start... The mass would still be the equivalent of 151 kg (starting with a 100kg object) but now the joules would be 3.82e18 joules, which is quite a bit more than my original figure. That now comes out to 913 megatons. Ouch. That's 9 times as much energy as the largest hydrogen bomb ever exploded. Still, not a continent destroying event.

Then our estimates agree, 1 kg would be just 1/100 of 100kg. So the 1 kg (9 megatons with your estimate) does a nice city destroyer with 1 year and the 100 kg at least can do away small islands. With 0.7c there is no problem of aiming the explosion as it will be stopped inside a few meters in air and/ ground.

For anything decent non-local effect, spell sizes and time would be a problem, 10000 kg for 100 years would be world changing (10^23 joule, 1000000 megatons), but hard to set up using the spells in spellbook and needs patience.

There is some debate amongst high energy physicists about what would happen if a solid object traveling at, say, .9999c, were to hit a planet. Some say it would convert to energy at quark distances, others say it would be so massive it would essentially be like a miniature black hole and would just punch through the planetary matter like an armor-piercing bullet going through cotton candy.

I think once you get into those energy ranges nobody really has a clue... The universe gets very weird at relativistic speeds, and something traveling that fast would be time-dilated to such an extent that the time it spends traveling through the planet would be viewed in femtoseconds or faster from its internal clock, which might not give enough time to begin fusion effects until after it's already through the whole planet...

Weird stuff that relativity...


carn wrote:

Your 0.7 c seems to be roughly correct:

http://www.convertalot.com/relativistic_star_ship_calculator.html
This calculator gives the travel time for 0.8 light years as 1.94 earth years with 1 g accelaration, that means, as accelaration goes on half time (rest of time deecelration with that calculator), accelration for about 1 year with top speed about 0.7 c.

This calc confirms this:
http://ftlfactor.com/srcalc/

But the first calc gives
37100613778.25584 megajoules per kg or about 4*10^10 megajoule= 4*10^16 joule.

http://www.calctool.org/CALC/phys/newtonian/k_energy
This gives for 0.7 c 2.2*10^16 joule for 1 kg.

So my estimate of 1 kg for 1 year earth accelartion having 10^16 joule seems to be close, while yours is only 2.5 *10^12.

I just do not remeber how i did my estimate (too drunk), but i think its correct to say that 1 kg for 1 year earth surface acceleration gives something in the range of hydrogen bomb.

What we have to worry about is corriolis, the stone will drift slightly as it falls past earths center. I do not know how far this will be in 1 year. And anyone doing this might note it too late and then it will go off prematururally. Can be solved with a cube of connected gates.

@rest
This is just about numbers. Safely assume that an undead lich with gates and a decent hate for all living could wreak havoc by just preparing for a few thousand years in his hermitically closed underground lab.

Corriolis effect is handled by using a demiplane instead of a rotating planet.

The Exchange

johnlocke90 wrote:
Thomas Long 175 wrote:

water is for all intents and purposes considered incompressible in liquid phase. Seeing as how the decanter of endless water lists a flow rate it must have an applied pressure to reach this rate.

AKA the decanter of endless water will not have enough pressure to significantly compress the water and when the pressure of the flow and the pressure of the water equalize the flow will stabalize and nothing should happen.

Basically you can calculate pressure from the endless decanter based on flow rate, density of water, and the size of the nozzle and you'll know where the pressure in the liquid should equalize.

This is a pretty big assumption. Nowhere does it state that the flow rate of water is dependent on the environment. It simply lists a flow rate for the water out of the decanter. What you are suggesting is that I change the flow rate from the listed value. Ultimately it doesn't matter though. Even if I accept your houserules, the water could be shot out of an air bubble or life shell and obtain the same results.

Also, water is considered incompressible for most intents and purposes. Not all. There is research into how water compresses at high and low pressures.

Yeah, but irrelevent.

Way before your decanter of water does anything interesting to the planar walls, or causes water to go solid or anything else like that:

the decanter is crushed as the pressure exceeds its structural strength.
And it doesn't matter if its in an air bubble or not: the air bubble will compress in size and the pressure within the air bubble is the same as the pressure in the water.

So, if you won't take the word of a mechanical engineer - take the word of a chemical engineer, a discipline that specializes in liquid reactions and flows.


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johnlocke90 wrote:

This is a pretty big assumption. Nowhere does it state that the flow rate of water is dependent on the environment. It simply lists a flow rate for the water out of the decanter. What you are suggesting is that I change the flow rate from the listed value. Ultimately it doesn't matter though. Even if I accept your houserules, the water could be shot out of an air bubble or life shell and obtain the same results.

Also, water is considered incompressible for most intents and purposes. Not all. There is research into how water compresses at high and low pressures.

Nowhere do the rules state that the water can be compressed. It outputs 1 gallon of water and that is by RAW 1 gallon of water. To be able to change the volume of that water you need to house rule.

Come on, it's just ridiculous to start a thread like this and then use the sentence "even if I accept your houserules".


Pathfinder Adventure Path, Lost Omens, Rulebook, Starfinder Roleplaying Game Subscriber

I had a similar thought to this one, though it involved resilient spheres and quite a few doses of dust of dryness.


johnlocke90 wrote:

Corriolis effect is handled by using a demiplane instead of a rotating planet.

The problem is not handling it, its knowing about it. The evil guy realizes "He, if i destroy the air in an enclosed adamantium container, put a gate at the bottom, connected it to the top and teleport a stone in it and then a few months later teleport it out, the world will understand how mean i am." So he sets his up in his basement, throws the stone in, but after a few (days?,weeks?, months?) the stone moving at hundreds of kilometers per second will contact the wall, damage it, air is sucked in and small explosion happens, evil guy dead.


Adamantine Dragon wrote:


There is some debate amongst high energy physicists about what would happen if a solid object traveling at, say, .9999c, were to hit a planet. Some say it would convert to energy at quark distances, others say it would be so massive it would essentially be like a miniature black hole and would just punch through the planetary matter like an armor-piercing bullet going through cotton candy.

Why shouldnt it be stopped?

The high energy particles with 10^20 MeV lose most their energy in the upper atmosphere.

10^20 MeV = 10^26 eV~10^7 joules. An object made up of protons with 1 kg has 10^23 protons, so a 1 kg stone with atoms having kinetic energys similar of cosmic high energys would have an energy of 10^30 joules. And at least the atoms individually would be stopped quickly.

For 0.9999c the "mass" of the 100 kg seems to be just 7000 kg, which is no problem. The 100 kg at 0.9999c would give 10^21 joule, which is in the range of 10000 megatons.


Some XKCD what ifs may be relevant.

crazy meteor impacts
the second to last entry briefly covers airflow through portals at different altitudes
more extremely destructive things to do with insane quantities of water


man, this almost makes me want to stay in school for an extra couple semesters and move up into quantum physics.


Pathfinder Adventure Path, Rulebook, Starfinder Roleplaying Game Subscriber

So far this has been pretty much a classical physics discussion - quantum mechanics has barely been mentioned, let alone actually used. Still, it's fun. The long and short of it is that kinetic energy weapons are pretty damned dangerous. The hard part is achieving a reasonable fraction of the speed of light in the object.


Classical Newtonian physics breaks down as you approach areas of high gravity and the speed of light. I hope you're compensating correctly :P


Thomas Long 175 wrote:
Classical Newtonian physics breaks down as you approach areas of high gravity and the speed of light. I hope you're compensating correctly :P

Classical Newtonian Physics breaks down as soon as you start using magic.


David Haller, Adamantine Dragon, I salute you!

Liberty's Edge

Timothy Hanson wrote:
Thomas Long 175 wrote:
Classical Newtonian physics breaks down as you approach areas of high gravity and the speed of light. I hope you're compensating correctly :P
Classical Newtonian Physics breaks down as soon as you start using magic.

Quantum Physics doesn't - if quantum entanglement isn't magic I don't know what is?!


Thomas Long 175 wrote:
Classical Newtonian physics breaks down as you approach areas of high gravity and the speed of light. I hope you're compensating correctly :P

With the 1 year stone we are just at 0.7c, no real problem there.


carn wrote:
johnlocke90 wrote:

Corriolis effect is handled by using a demiplane instead of a rotating planet.

The problem is not handling it, its knowing about it. The evil guy realizes "He, if i destroy the air in an enclosed adamantium container, put a gate at the bottom, connected it to the top and teleport a stone in it and then a few months later teleport it out, the world will understand how mean i am." So he sets his up in his basement, throws the stone in, but after a few (days?,weeks?, months?) the stone moving at hundreds of kilometers per second will contact the wall, damage it, air is sucked in and small explosion happens, evil guy dead.

Well I assume the bad guy would use a demiplane anyway in order to have controlled conditions. You wouldn't wanted someone to be able to stumble upon your experiment before its finished.


Ilja wrote:
johnlocke90 wrote:

This is a pretty big assumption. Nowhere does it state that the flow rate of water is dependent on the environment. It simply lists a flow rate for the water out of the decanter. What you are suggesting is that I change the flow rate from the listed value. Ultimately it doesn't matter though. Even if I accept your houserules, the water could be shot out of an air bubble or life shell and obtain the same results.

Also, water is considered incompressible for most intents and purposes. Not all. There is research into how water compresses at high and low pressures.

Nowhere do the rules state that the water can be compressed. It outputs 1 gallon of water and that is by RAW 1 gallon of water. To be able to change the volume of that water you need to house rule.

Come on, it's just ridiculous to start a thread like this and then use the sentence "even if I accept your houserules".

The decanter would output a gallon of water. After the water is out of the decanter it would compress.

No houserule needed.


cp wrote:
johnlocke90 wrote:
Thomas Long 175 wrote:

water is for all intents and purposes considered incompressible in liquid phase. Seeing as how the decanter of endless water lists a flow rate it must have an applied pressure to reach this rate.

AKA the decanter of endless water will not have enough pressure to significantly compress the water and when the pressure of the flow and the pressure of the water equalize the flow will stabalize and nothing should happen.

Basically you can calculate pressure from the endless decanter based on flow rate, density of water, and the size of the nozzle and you'll know where the pressure in the liquid should equalize.

This is a pretty big assumption. Nowhere does it state that the flow rate of water is dependent on the environment. It simply lists a flow rate for the water out of the decanter. What you are suggesting is that I change the flow rate from the listed value. Ultimately it doesn't matter though. Even if I accept your houserules, the water could be shot out of an air bubble or life shell and obtain the same results.

Also, water is considered incompressible for most intents and purposes. Not all. There is research into how water compresses at high and low pressures.

Yeah, but irrelevent.

Way before your decanter of water does anything interesting to the planar walls, or causes water to go solid or anything else like that:

the decanter is crushed as the pressure exceeds its structural strength.
And it doesn't matter if its in an air bubble or not: the air bubble will compress in size and the pressure within the air bubble is the same as the pressure in the water.

So, if you won't take the word of a mechanical engineer - take the word of a chemical engineer, a discipline that specializes in liquid reactions and flows.

Actually Life Shell will protect the person holding the container from the affects of pressure. And as long as the decanter is being held, it won't be affected by crushing damage(see rules for damaging objects and rules for damaging magic items for more information).


Pathfinder Adventure Path, Rulebook, Starfinder Roleplaying Game Subscriber
Thomas Long 175 wrote:
Classical Newtonian physics breaks down as you approach areas of high gravity and the speed of light. I hope you're compensating correctly :P

I feel it worth noting that relativity is defined as classical physics - I wasn't talking about Newtonian mechanics.


johnlock90, There are no rules regarding compression of water. Thus, there is no RAW. It is not RAW that water compresses. Strictly speaking, there is no RAW that dead people cannot act either. In order for something to be RAW it must be written. I challenge you to find a rule anywhere in the game that states water compresses.

This entire thread is outside of RAW. It does not even belong in the rules forum.

- Gauss

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