Item question regarding Bags of Holding

[Argyle King]

Thanks for correcting me on the space. My mistake.

If you're not interested in the "how" of how the object gets to the top, it's not clear to me what we're talking about any more. "It says so" isn't an answer that will advance the discussion, since that's not in dispute.
.

I think you have to sing the backpack song.

http://www.youtube.com/watch?v=9KqXFhRxybE

 

[N'raac]

Okay, let's talk about those things. Oh, wait, we already have.

Is there "physics" in the game world? Well, there's the physics of the game world, which is to say that there are some aspects that are acknowledged already in the rules.

So if I, as a DM, say, "You fell 30 feet, so you take...", and a players complains, "Wait, you're trying to bring physics into a magic oriented game world", I cast a huge, double-empowered Dispel BS on them before they finish the sentence. Things like falling damage, water pressure, air pressure etc. are already accounted for in the rules. (See Falling Damage, the section of Overland Travel relating to climbing high mountains, and spells like Cloak of the Manta.)

And yet the air pressure does not change the weight of the air in a bag of holding, does it?

So, is there water pressure? Already established. Will water flow into an open and unprotected container if you immerse it?

Sorry, but that last question was so stupid that I threw up in my mouth a little while typing it. We shouldn't have to even ask it, but some people don't like the answer and try to invent excuses to question the obvious. (In fact, I have a bet with myself that someone will try to argue it, even now. "What if it's upside down? Why would it work across dimensional boundaries. Are you sure there's air in the game world? What if it's a Tuesday and I have a Royal Fizbin?"", etc. )

"Is a Bag of Holding the same as a mundane container in this regard" is the real question, though. How permeable is the aperture between our dimension and the non-dimensional space within the bag?

Now, to more serious questions: Can you use the bag as an air supply? Yes. the rules say so.

Actually, the rules say a closed bag with a person in it can support that person for 10 minutes, regardless of the capacity, used or unused, regardless of the size of the creature/person, always 10 minutes of air. That seems inconsistent with physics. It's a close enough compromise for gameplay, but then again so is "something must either pass through the aperture or remain on one side so you can't stick your head in there indefinitely but liquids don't flow in".

Why do all bags have the same amount of air? I rationalized an explanation, but the real, according to RAW, unarguable reason is because the rules say so. Come up with the in-game explanation of your choice.

OK. How about "because all bags of holding hold air sufficient to sustain a creature for 10 minutes, replenishing same whenever the bag is opened". Now, that seems to fly in the face of "oh, it's all full of water now", doesn't it?

Will air pressure change the amount of air in the bag, and thus change the weight of the bag? Since the rules say that the bag doesn't change weight when you add things, I'd say it doesn't change weight when you add things. Even something as dense and massive as air. Of course, the air in your game world may be more massive than the air in my game world, so you'd better check with your DM.

I'm not discussing the weight of the bag with air in it, but the weight of the air in the bag. You're weighing it down with water, but air is not weightless, nor is its weight a constant. So why does the weight of the air not change, thereby altering the remaining weight the bag can hold? Perhaps because the air in the bag is a constant and it doesn't allow other media to flow in automatically. "The only answer?" No. But not an answer with no merit either. The fact is, we are dealing with magic, and magic by definition defies the laws of physics. It's bigger on the inside than it is on the outside. Its weight is a constant regardless of what is placed within it. A scruple over the limit and it is destroyed. None of that is consistent with real world physics, so real world physics is not the only reasonable basis for a ruling.

Will a bag sink? By the rules, a person with 15 pounds of gear will sink if they fail a swim check. The lightest/smallest bag weighs 15 pounds all the time, and can't make a swim check.

I submit that a person carrying 30 pounds of cordwood strapped to him will not sink based on the laws of physics. Does that mean, in your game, they will? What about 15 pounds of stout leather, sufficient to make a huge inflatable bladder, full of air? Does it sink or float? If I dive under a ship, then grab it, and next fail a swim check, does it sink because I am carrying far more than 15 pounds of gear and I failed my swim check? That sounds pretty stupid as well, but, as you said, "By the rules, a person with 15 pounds of gear will sink if they fail a swim check."

Will the amount of air inside make a difference? No more than the amount of gold or anything else. We could get into air displacement v fresh water v salt water, but since the bag changes neither size nor weight whether full or empty, it doesn't matter. The inside is a non-dimensional space (not actually a separate dimension, just a space that takes no space), so whether it's air or lead, it doesn't displace any water on the outside.

As I said, it's the weight inside that matters. But let's look to your SpandexBag again - why could that magical spandex not expand just enough to hold the weight the bag is capable of holding, requiring someone exert pressure to push it over the limit? Is that somehow illogical magic? More illogical than a bag that is bigger on the inside than the outside and whose weight outside never varies?

If we make the bag invisible, can you see out of it? That's actually a really good question. Since your head is still ijn the same dimension (bags are non-dimensional, not extra-dimensional), the answer should be yes. But because of the spacial distortion that comes from having your head take up no space, the answer is really anybody's guess. And by that I mean, it's the DM's call.

According to http://www.wizards.com/default.asp?x=dnd/rg/20051101a, those nondimensional spaces are also extradimensional.

Now, what happens if the portal to the non-dimemsional space closes while something is part way through. I'd say, see Gate. Whatever the rules say there is what I'd apply.

I don't believe there is any indication of what happens if a gate is closed when something is part way through. It says "anyone who chooses to step through the portal is transported" and that "You may hold the gate open only for a brief time (no more than 1 round per caster level), and you must concentrate on doing so, or else the interplanar connection is severed.", but doesn't speak to anything being part way through.

Now, one other interpretation would be that, just as we don't count your hands as you place things in, and remove things from, the bag, and we don't count the air within the bag, we do not count any medium which fills the bag, only things placed in the bag within that medium - so you can fill it with water without contributing to its capacity. Not my preferred ruling, but a potentially viable one - especially if we are playing an underwater campaign and decide to assume water, not air, is the default medium.

 

[Greenfield]

I'm sad to say that I just won a bet with myself. In fact I should have lost two of them I didn't think anyone would seriously argue the weight of the air in the bag. Air must be really heavy someplace in the world.

Tell me, how hard do you have to push, in your game, to force something through the opening of a Bag of Holding? How much resistance does that dimensional barrier offer? Figure that water, facing that same resistance, has to push just as hard. That seem fair?

With that comparison in mind, is there still an argument over whether water will enter an open container that's immersed? (Cringingly, I'm pretty sure I know the answer to that question.)

I do have to admit that I made a mistake in my answers, though. Since I presume a variable internal size, up to the maximum volume, holding a bag upside down under water and opening it wouldn't work. Water would still go inside. It doesn't need to displace the air if the bag can expand its internal volume to accommodate. (Try it: Take a piece of plastic pipe and rubber-band a deflated plastic bag around one end. Shove the other end into water. The bag will inflate with air from the tube, and water will come in just fine.)

Now, obviously not everyone uses my "Spandex" model. But since it is my model, I'll be consistent and admit my mistake.

By extension, the diving bell trick won't work either. The bag will fill with water and rupture when you try.

As for the idea that a bag will resist overfilling: On volume, that makes sense. Any bag would. Weight wise, I'm not seeing the mechanism of the resistance. I mean, I don't see the clerk at the grocery store having the slightest problem when he overloads my shopping bags.

 

[Vegepygmy]

With that comparison in mind, is there still an argument over whether water will enter an open container that's immersed?

A magic open container? Sure, of course there is.

And in the absence of an explicit rule, it's an unresolvable argument.

 

[N'raac]

I'm sad to say that I just won a bet with myself. In fact I should have lost two of them I didn't think anyone would seriously argue the weight of the air in the bag. Air must be really heavy someplace in the world.

The temperature impacts the density of air - see http://www.engineeringtoolbox.com/air-density-specific-weight-d_600.html. So even before considering whether we are at sea level (or lower) or high on a mountain peak, which also impacts air density, from the chart, the specific weight of air rises almost 30% if the temperature falls from 30 degrees Celsius to -4 Celsius (both temperatures we tend to see annually around this part of the country). Air has a weight, and it varies, so if the goal is to apply scientific principals to assess when the bag is overloaded, the weight of air is a scientific principal which can indicate a surprise overload of the bag.

Tell me, how hard do you have to push, in your game, to force something through the opening of a Bag of Holding? How much resistance does that dimensional barrier offer? Figure that water, facing that same resistance, has to push just as hard. That seem fair?

Once again, it seems like one possible interpretation.

With that comparison in mind, is there still an argument over whether water will enter an open container that's immersed? (Cringingly, I'm pretty sure I know the answer to that question.)

To me, the argument is whether the magic of a bag of holding makes it something other than "an open container". No official rule answers that question. We can try to apply science, but now we're applying physics to an item that, by its very definition, defies the laws of physics - that is what magic does.

I do have to admit that I made a mistake in my answers, though. Since I presume a variable internal size, up to the maximum volume, holding a bag upside down under water and opening it wouldn't work. Water would still go inside. It doesn't need to displace the air if the bag can expand its internal volume to accommodate. (Try it: Take a piece of plastic pipe and rubber-band a deflated plastic bag around one end. Shove the other end into water. The bag will inflate with air from the tube, and water will come in just fine.)

Now, obviously not everyone uses my "Spandex" model. But since it is my model, I'll be consistent and admit my mistake.

In other words, how we interpret the magic impacts how the question is answered, pretty much what I, and I think some others, have been saying all along. Can we inflate the spandex bag, or does it exert pressure internally to force the air back out? If it exerts pressure to force air back out, why can it not exert pressure to force water back out? What other substances or contents might the spandex seeking its original form exert pressure to remove from the bag?

BTW, the reason the bag in your example inflates is because the air pressure outside exceeds the air pressure inside - heavier air is moving into your bag. I presume, then, that we will hear no more claims that the weight of air is irrelevant.

As for the idea that a bag will resist overfilling: On volume, that makes sense. Any bag would. Weight wise, I'm not seeing the mechanism of the resistance. I mean, I don't see the clerk at the grocery store having the slightest problem when he overloads my shopping bags.

A nonmagical bag follows the rules of physics. As I have yet to see a grocery store which uses Shopping Bags of Holding, I cannot scientifically test the premise that a magical bag of holding behaves like an ordinary grocery bag (paper? plastic? one of those new lifetime bags?). Rather, I will have to set a ruling on how that magic works in this game, just as you had to set a ruling on spandex stretchy bag insides.

A magic open container? Sure, of course there is.

And in the absence of an explicit rule, it's an unresolvable argument.

Exactly, on both counts.

 

[Umbran]

Tell me, how hard do you have to push, in your game, to force something through the opening of a Bag of Holding? How much resistance does that dimensional barrier offer? Figure that water, facing that same resistance, has to push just as hard. That seem fair?

With that comparison in mind, is there still an argument over whether water will enter an open container that's immersed? (Cringingly, I'm pretty sure I know the answer to that question.)

Here's a bit of a physicsy answer for you - don't confuse weight with mass!

Take a normal bag, and put it on a scale. It will weigh some amount, X.

Take that bag, open it, and put it in a pool. Put a scale in the pool too, and weigh the bag while it is still submerged. It will *not* weigh X+somewater. It will weigh somewhat *less* than X! The water that flowed into the bag was already supported by other water - it doesn't add to the weight of the bag, only to the mass stored within.

So, you don't risk overloading the bag until you try to remove it from the pool without dumping out water.

(This is, of course, a form of handwaving to make you feel comfortable with the idea. Since the darned thing is *magic*, we can't really say how it works - this is just a way to not be a jerk to your players if you don't want to be.)

 

[Greenfield]

N'raac, how does the 10 minute supply of air in the bag refresh itself? Does fresh air enter when the bag is opened, as you suggested in an earlier post? If so, why wouldn't water enter exactly the same way?

As for the weight of air: Wasn't asking whether air gets more dense with temperature or humidity. Just wondering why you're arguing about it. (Of course, I've been wondering why you're arguing about any of this, but that point is of particular lack-of-interest.)

But since you can't let it go, air at sea level weighs about 0.08 lbs per cubic foot. A person goes through about one cubic foot of air every four minutes, so two and a half cubic feet will last ten minutes. So the answer is that the ten minute air supply the bag holds is about ten gold pieces in weight (GP being 1/50th, or 0.02 pounds.)

And, again, if you've calculated the weight in your Bag of Holding that precisely, and cut it so close that the weight of the air is the difference between being overloaded or not, you have way too much time on your hands.

Umbran, I agree that a normal bag can be loaded with all the weight you like without harm, until you try to lift it. In the water or out, that would be the rule.

But the bag, being larger on the inside than outside, doesn't displace water in the normal fashion. Neither does it carry weight in the normal fashion. So, just as air inside doesn't count for buoyancy in the water, neither will the weight/mass inside be affected/supported by the water outside, at least not in any differential manner. (Buoyancy is the same, empty, full, or overloaded.)

A normal bag, when overloaded, will tear when it has to actually support the weight. But a Bag of Holding is always supporting what's inside. The strain certainly isn't going to the straps, cords or handles.

But if the meta-physicsy answer doesn't work, consider another aspect: The rules as written say it bursts if you load too much weight in it.

Vegepygmy, there is no explicit rule on how much a Gelatinous Cube weighs. Does that mean that it's weightless? Air and goods pass in and out of the magic bag without resistance. (There's no Strength check needed to access the bag.) So why would there be a special exception for water?

 

[MarkB]

I'm still intrigued by the "logic" that says water pressure doesn't count. Could someone explain why, other than to say "Because there's nothing in the rules that says it does"?

Because it seems like a fundamental design flaw in an item designed for use in an unpredictable adventuring environment, and one which the demanding customer base would have wanted fixed, pronto.

At worst, I'd guess that a number of the first generation of Bags of Holding ever produced might have been ruptured in this fashion, and after that the wizards who created them would have built in some countermeasure - most likely some form of simple enchantment to prevent uncontained liquids from flowing into the bag.

Do the rules mention this? No - probably because the designers never spotted this potential problem, or had it pointed out to them.

Congratulations on having noticed the issue and figured out its implications, but that doesn't mean players in general are going to decide that bags of holding will rupture when used underwater from now on. Most will, like the respondents in this thread, handwave the matter in some fashion that does not deny players access to a very useful item while adventuring underwater.

 

[Greenfield]

I don't think it's a design flaw. It's just a caveat, a noted limit on what you can do with the bag, or where you can safely use it.

To me, the argument seems like, "You shouldn't be able to accidentally overload the bag because that would destroy it." That runs counter to the written rule, which implicitly says it can be overloaded, and explicitly says what happens when you do.

So let's look at some common sense rules.

You can't open it in an Anti-Magic field because it just won't open.
You shouldn't store your Portable Hole in there because that will destroy both.
You shouldn't try to keep your pet Porcupine (giant or otherwise) in one because he'll suffocate after ten minutes, and his quills may destroy the bag (and cost you your favorite pet purcupine).
You should be careful taking things like these into Rope Trick spells because putting one extra-dimensional space inside another is dangerous.
Don't try to use scrolls under water because the water may ruin them (waterproof ink is a relatively recent invention).
Don't overload your Bag or Haversack, and don't open them where they're likely to overload on their own.
Don't go swimming within half an hour of eating a sizable meal, and don't try to open your Bag when you do.
Don't test a bag you find by dropping daggers in, point first.
Don't stuff magic bags full of 10 foot lances, unless you cover or bate the points somehow.
Don't use a Bag of Holding as a belt pouch. There's a reason some thieves are called "Cut-purse".
Don't leave your Decanter of Endless Water running inside your Bag of Holding.

Any others to add to this list?

 

[N'raac]

N'raac, how does the 10 minute supply of air in the bag refresh itself? Does fresh air enter when the bag is opened, as you suggested in an earlier post? If so, why wouldn't water enter exactly the same way?

"Why wouldn't it" and "why would it" are very similar questions, though.

As for the weight of air: Wasn't asking whether air gets more dense with temperature or humidity. Just wondering why you're arguing about it. (Of course, I've been wondering why you're arguing about any of this, but that point is of particular lack-of-interest.)

But since you can't let it go, air at sea level weighs about 0.08 lbs per cubic foot. A person goes through about one cubic foot of air every four minutes, so two and a half cubic feet will last ten minutes. So the answer is that the ten minute air supply the bag holds is about ten gold pieces in weight (GP being 1/50th, or 0.02 pounds.)

And, again, if you've calculated the weight in your Bag of Holding that precisely, and cut it so close that the weight of the air is the difference between being overloaded or not, you have way too much time on your hands.

So why will the bag stop at 2.5 cubic feet of air, a twelfth of the capacity of the smallest bag and a mere 1% of the capacity of the largest, but keep taking on water until it bursts? That same 2.5 cubic feet weights 156 lb or so, not enough to burst even the smallest capacity bag. Did you not just ask why air and water would behave differently in regards to a Bag of Holding? Your premise seems to rely on it!

Umbran, I agree that a normal bag can be loaded with all the weight you like without harm, until you try to lift it. In the water or out, that would be the rule.

Kind of like how we agree normal bags interact with air and water, but not that this is definitive of how magical bags leading to extradimensional space interact with air and water?

But if the meta-physicsy answer doesn't work, consider another aspect: The rules as written say it bursts if you load too much weight in it.

But they do not address the bag flooding with water, hence the discussion. Your physicsy answer is one possible answer, no less legitimate than many others, but also no more so.

Vegepygmy, there is no explicit rule on how much a Gelatinous Cube weighs. Does that mean that it's weightless? Air and goods pass in and out of the magic bag without resistance. (There's no Strength check needed to access the bag.) So why would there be a special exception for water?

Air fills no more, and no less, than 2.5 cubic feet, by your own math above, regardless of the other contents of the bag. Why would that be different for water?

Because it seems like a fundamental design flaw in an item designed for use in an unpredictable adventuring environment, and one which the demanding customer base would have wanted fixed, pronto.

At worst, I'd guess that a number of the first generation of Bags of Holding ever produced might have been ruptured in this fashion, and after that the wizards who created them would have built in some countermeasure - most likely some form of simple enchantment to prevent uncontained liquids from flowing into the bag.

Do the rules mention this? No - probably because the designers never spotted this potential problem, or had it pointed out to them.

Congratulations on having noticed the issue and figured out its implications, but that doesn't mean players in general are going to decide that bags of holding will rupture when used underwater from now on. Most will, like the respondents in this thread, handwave the matter in some fashion that does not deny players access to a very useful item while adventuring underwater.

Some will, some won't. Greenfield would at least warn the players of his ruling, so the issue could be discussed, and his interpretation is valid, just not the sole valid interpretation, so I would have no issue accepting, at his table, that Bags of Holding flood if opened underwater. However, I also have no difficulty envisioning equally valid rulings that it will not flood and burst. The only approach I would consider truly "bad" would be the "hahaha it opens floods and bursts" approach, and I think Greenfield agrees that a "gotcha" would be poor GMing.

I don't think it's a design flaw. It's just a caveat, a noted limit on what you can do with the bag, or where you can safely use it.

Emphasis added. This limit is not noted - if it were, we should have a page reference by now, I would think. We know it will be destroyed if overloaded. We do not know that opening it underwater overloads it.

To me, the argument seems like, "You shouldn't be able to accidentally overload the bag because that would destroy it." That runs counter to the written rule, which implicitly says it can be overloaded, and explicitly says what happens when you do.

So let's look at some common sense rules.

You can't open it in an Anti-Magic field because it just won't open.
You shouldn't store your Portable Hole in there because that will destroy both.
You shouldn't try to keep your pet Porcupine (giant or otherwise) in one because he'll suffocate after ten minutes, and his quills may destroy the bag (and cost you your favorite pet purcupine).
You should be careful taking things like these into Rope Trick spells because putting one extra-dimensional space inside another is dangerous.
Don't try to use scrolls under water because the water may ruin them (waterproof ink is a relatively recent invention).
Don't overload your Bag or Haversack, and don't open them where they're likely to overload on their own.

This assumes an accepted standard of when, or even whether, they are likely to overload on their own.

Don't go swimming within half an hour of eating a sizable meal, and don't try to open your Bag when you do.

koff koff http://health.howstuffworks.com/mental-health/human-nature/health-myths/swimming-after-eating.htm koff koff

Not everything we think is "common sense" is correct - even without adding magic to the equation.

Don't test a bag you find by dropping daggers in, point first.
Don't stuff magic bags full of 10 foot lances, unless you cover or bate the points somehow.
Don't use a Bag of Holding as a belt pouch. There's a reason some thieves are called "Cut-purse".
Don't leave your Decanter of Endless Water running inside your Bag of Holding.

If its spandex volume shrinks down to the size of "contents + 2.5 cuFt, this will result in wet stuff, but will not necessarily overload the bag.

Do reasonable minds come to differing interpretations? I believe the 1e DMG sees EGG suggest a Bag of Holding in a second Bag of Holding leaves sufficient room for only a single extra coin or ring. The 3.5 rules say placing one ED space in another is hazardous. SKR felt there was no harm eliminating that hazard, and Pathfinder adopted that approach, with a ruling that an ED space becomes inaccessible while in a second ED space. Was one of them clearly right, and the others wholly wrong? I think different interpretations can be equally valid myself.