This reminds me of the classic industrial accident involving a large, pressurised storage tank. There is a man-sized door to allow access for maintenance and a pressure gauge. The maintenance man is supposed to wait for the pressure to fall to zero before he undoes the heavy steel latches. It is a big tank and he gets bored with waiting for the pressure to vent. The gauge says one pound per square inch. One pound doesn’t sound like much so the man undoes the latches. Since the force is per square inch it is several hundred times larger than expected. The heavy door flies open irresistibly and kills the man.
I’m not seeing how the parable helps one be less wrong in real life. In the parable the victim has seen a dog taken by the dragon. If the maintenance man had seen an apprentice crushed in an earlier similar accident the experience would scar him mentally and he would always be wary of pressure vessels. I’m worrying that the parable is cruder than the problems we face in real life.
I don’t know more than I’ve already said about pressure vessel accidents. Is there an underlying problem of crying wolf; too many warning messages obscure the ones that are really matters of life and death? Is it a matter of incentives; the manager gets a bonus if he encourages the maintenance team to work quickly, but doesn’t go to jail when cutting corners leads to a fatal accident? Is it a matter of education; the maintenance man just didn’t get pressure? Is it a matter of labeling; why not label the gauge by the door with the force per door area? Is it matter of class; the safety officer is middle class, the maintenance man is working class, the working class distrust the middle class and don’t much believe what they say?
I don’t know either, but I do know that an internalised, correct understanding of pressure and one of its measures ‘pounds per square inch’ would be a sufficient condition to save his life. The parable of the pressure vessel seems to be a case of an incorrect belief (one pound isn’t much), whereas the parable of the invisible dragon seems to be a case of a correct belief (invisible dragon in my garage) that hasn’t been internalised, and so has not produced beliefs it ought to (invisible DRAGON IN MY GARAGE!)
I don’t know either, but I do know that an internalised, correct understanding of pressure and one of its measures ‘pounds per square inch’ would be a sufficient condition to save his life.
I think this is a good opportunity to point out that many people haven’t internalized what it means to say “the atmosphere’s pressure is about 15 psi”. It implies that, if you were to lie face down and someone like me stood on your back, eliciting excruciating, “GET OFF ME!” pain on your end, they’ve only increased the pressure on your back by maybe 30% of what was on it your entire life, even as it may seem like much more than that.
Indeed, when I visited the Boston LW meetup, a few people there initially refused to believe the implications of 15 psi atmospheric pressure, apparently never having connected that figure to everyday experience.
Fortunately, there are easy experiments to impress people with. As a kid, my favorite one was laying a ruler on a table so half of it was sticking out perpendicularly, put a few layers of newspaper over the other half, and then quickly hit the exposed half downwards—and fail to knock it off the table because atmospheric pressure helped hold it down.
(At least, I think this is how it went. It was a long time ago. I’m sure there are other nifty experiments.)
I suppose that in doing it in the form of a parable (or this parable, anyway,) I erred on the side of being memorable over clear, but that was what I had in mind when I wrote it. A dragon in one’s garage is something where it’s intuitively obvious that you don’t want to go near, once you internalize the fact that it’s really there. That’s the kind of mistake that we’ve had millions of years of evolution to prepare us against making. Opening up the garage door to investigate is the sort of behavior that only makes sense when you haven’t internalized the idea that there’s really something in there that’s liable to eat you.
Realistically, the man would probably be terrified if he had seen it eat other animals already, but I threw that in to make the parable flow better. The invisibility and inaudibility probably wouldn’t be sufficient in real life given that, but they’re stand in qualities for the sort of remove that might prevent one from internalizing a belief.
I upvoted because I immediately understood what you meant; I am humble enough to believe that is a fact about the post and not about my skill at understanding.
Is there an underlying problem of crying wolf; too many warning messages obscure the ones that are really matters of life and death?
This is certainly an enormous problem for interface design in general for many systems where there is some element of danger. The classic “needle tipping into the red” is an old and brilliant solution for some kinds of gauges—an analogue meter where you can see the reading tipping toward a brightly marked “danger zone”, usually with a ‘safe’ zone and an intermediate zone also marked, has surely prevented many accidents. If the pressure gauge on the door had such a meter where green meant “safe to open hatches” and red meant “terribly dangerous”, that might have been a better design than just raw numbers.
I haven’t worked with pressure doors but I have worked with large vacuum systems, cryogenic systems, labs with lasers that could blind you or x-ray machines that can be dangerously intense, and so on. I can attest that the designers of physics lab equipment do indeed put a good deal of thought and effort into various displays that indicate when the equipment is in a dangerous state.
However, when there are /many/ things that can go dangerously wrong, it becomes very difficult to avoid cluttering the sensorium of the operator with various warnings. The classic example are the control panels for vehicles like airplanes or space ships; you can see a beautiful illustration of the ‘indicator clutter problem’ in the movie “Airplane!”:
The gauge says one pound per square inch. One pound doesn’t sound like much so the man undoes the latches. [...] I’m not seeing how the parable helps one be less wrong in real life.
This reminds me of the classic industrial accident involving a large, pressurised storage tank. There is a man-sized door to allow access for maintenance and a pressure gauge. The maintenance man is supposed to wait for the pressure to fall to zero before he undoes the heavy steel latches. It is a big tank and he gets bored with waiting for the pressure to vent. The gauge says one pound per square inch. One pound doesn’t sound like much so the man undoes the latches. Since the force is per square inch it is several hundred times larger than expected. The heavy door flies open irresistibly and kills the man.
I’m not seeing how the parable helps one be less wrong in real life. In the parable the victim has seen a dog taken by the dragon. If the maintenance man had seen an apprentice crushed in an earlier similar accident the experience would scar him mentally and he would always be wary of pressure vessels. I’m worrying that the parable is cruder than the problems we face in real life.
I don’t know more than I’ve already said about pressure vessel accidents. Is there an underlying problem of crying wolf; too many warning messages obscure the ones that are really matters of life and death? Is it a matter of incentives; the manager gets a bonus if he encourages the maintenance team to work quickly, but doesn’t go to jail when cutting corners leads to a fatal accident? Is it a matter of education; the maintenance man just didn’t get pressure? Is it a matter of labeling; why not label the gauge by the door with the force per door area? Is it matter of class; the safety officer is middle class, the maintenance man is working class, the working class distrust the middle class and don’t much believe what they say?
I don’t know either, but I do know that an internalised, correct understanding of pressure and one of its measures ‘pounds per square inch’ would be a sufficient condition to save his life. The parable of the pressure vessel seems to be a case of an incorrect belief (one pound isn’t much), whereas the parable of the invisible dragon seems to be a case of a correct belief (invisible dragon in my garage) that hasn’t been internalised, and so has not produced beliefs it ought to (invisible DRAGON IN MY GARAGE!)
I think this is a good opportunity to point out that many people haven’t internalized what it means to say “the atmosphere’s pressure is about 15 psi”. It implies that, if you were to lie face down and someone like me stood on your back, eliciting excruciating, “GET OFF ME!” pain on your end, they’ve only increased the pressure on your back by maybe 30% of what was on it your entire life, even as it may seem like much more than that.
Indeed, when I visited the Boston LW meetup, a few people there initially refused to believe the implications of 15 psi atmospheric pressure, apparently never having connected that figure to everyday experience.
Fortunately, there are easy experiments to impress people with. As a kid, my favorite one was laying a ruler on a table so half of it was sticking out perpendicularly, put a few layers of newspaper over the other half, and then quickly hit the exposed half downwards—and fail to knock it off the table because atmospheric pressure helped hold it down.
(At least, I think this is how it went. It was a long time ago. I’m sure there are other nifty experiments.)
I suppose that in doing it in the form of a parable (or this parable, anyway,) I erred on the side of being memorable over clear, but that was what I had in mind when I wrote it. A dragon in one’s garage is something where it’s intuitively obvious that you don’t want to go near, once you internalize the fact that it’s really there. That’s the kind of mistake that we’ve had millions of years of evolution to prepare us against making. Opening up the garage door to investigate is the sort of behavior that only makes sense when you haven’t internalized the idea that there’s really something in there that’s liable to eat you.
Realistically, the man would probably be terrified if he had seen it eat other animals already, but I threw that in to make the parable flow better. The invisibility and inaudibility probably wouldn’t be sufficient in real life given that, but they’re stand in qualities for the sort of remove that might prevent one from internalizing a belief.
I upvoted because I immediately understood what you meant; I am humble enough to believe that is a fact about the post and not about my skill at understanding.
This is certainly an enormous problem for interface design in general for many systems where there is some element of danger. The classic “needle tipping into the red” is an old and brilliant solution for some kinds of gauges—an analogue meter where you can see the reading tipping toward a brightly marked “danger zone”, usually with a ‘safe’ zone and an intermediate zone also marked, has surely prevented many accidents. If the pressure gauge on the door had such a meter where green meant “safe to open hatches” and red meant “terribly dangerous”, that might have been a better design than just raw numbers.
I haven’t worked with pressure doors but I have worked with large vacuum systems, cryogenic systems, labs with lasers that could blind you or x-ray machines that can be dangerously intense, and so on. I can attest that the designers of physics lab equipment do indeed put a good deal of thought and effort into various displays that indicate when the equipment is in a dangerous state.
However, when there are /many/ things that can go dangerously wrong, it becomes very difficult to avoid cluttering the sensorium of the operator with various warnings. The classic example are the control panels for vehicles like airplanes or space ships; you can see a beautiful illustration of the ‘indicator clutter problem’ in the movie “Airplane!”:
I must admit I up-voted the post mostly because I thought the parable was funny.
Easy—not using metric system will kill you.
Seventy grams per square centimeter sounds like even less, though.