More from John Salvatier
I. My dad emigrated from Colombia to North America when he was 18 looking looking for a better life. For my brother and I that meant a lot of standing outside in the cold. My dad’s preferred method of improving his lot was improving lots, and my brother and I were “voluntarily” recruited to help working on the buildings we owned. That’s how I came to spend a substantial part of my teenage years replacing fences, digging trenches, and building flooring and sheds. And if there’s one thing I’ve learned from all this building, it’s that reality has a surprising amount of detail. This turns out to explain why its so easy for people to end up intellectually stuck. Even when they’re literally the best in the world in their field. Consider building some basement stairs for a moment. Stairs seem pretty simple at first, and at a high level they are simple, just two long, wide parallel boards (2” x 12” x 16’), some boards for the stairs and an angle bracket on each side to hold up each stair. But as you actually start building you’ll find there’s a surprising amount of nuance. The first thing you’ll notice is that there are actually quite a few subtasks. Even at a high level, you have to cut both ends of the 2x12s at the correct angles; then screw in some u-brackets to the main floor to hold the stairs in place; then screw in the 2x12s into the u-brackets; then attach the angle brackets for the stairs; then screw in the stairs. Those goddamn stairs. Next you’ll notice that each of those steps above decomposes into several steps, some of which have some tricky details to them due to the properties of the materials and task and the limitations of yourself and your tools. The first problem you’ll encounter is that cutting your 2x12s to the right angle is a bit complicated because there’s no obvious way to trace the correct angles. You can either get creative (there is a way to trace it), or you can bust out your trig book and figure out how to calculate the angle and position of the cuts. You’ll probably also want to look up what are reasonable angles for stairs. What looks reasonable when you’re cutting and what feels safe can be different. Also, you’re probably going to want to attach a guide for your circular saw when cutting the angle on the 2x12s because the cut has to be pretty straight. When you’re ready to you will quickly find that getting the stair boards at all the same angle is non-trivial. You’re going to need something that can give you an angle to the main board very consistently. Once you have that, and you’ve drawn your lines, you may be dismayed to discover that your straight looking board is not that straight. Lumber warps after it’s made because it was cut when it was new and wet and now it’s dryer, so no lumber is perfectly straight. Once you’ve gone back to the lumber store and gotten some straighter 2x12s and redrawn your lines, you can start screwing in your brackets. Now you’ll learn that despite starting aligned with the lines you drew, after screwing them in, your angle brackets are no longer quite straight because the screws didn’t go in quite straight and now they tightly secure the bracket at the wrong angle. You can fix that by drilling guide holes first. Also you’ll have to move them an inch or so because it’s more or less impossible to get a screw to go in differently than it did the first time in the same hole. Now you’re finally ready to screw in the stair boards. If your screws are longer than 2”, you’ll need different ones, otherwise they will poke out the top of the board and stab you in the foot. At every step and every level there’s an abundance of detail with material consequences. It’s tempting to think ‘So what?’ and dismiss these details as incidental or specific to stair carpentry. And they are specific to stair carpentry; that’s what makes them details. But the existence of a surprising number of meaningful details is not specific to stairs. Surprising detail is a near universal property of getting up close and personal with reality. You can see this everywhere if you look. For example, you’ve probably had the experience of doing something for the first time, maybe growing vegetables or using a Haskell package for the first time, and being frustrated by how many annoying snags there were. Then you got more practice and then you told yourself ‘man, it was so simple all along, I don’t know why I had so much trouble’. We run into a fundamental property of the universe and mistake it for a personal failing. If you’re a programmer, you might think that the fiddliness of programming is a special feature of programming, but really it’s that everything is fiddly, but you only notice the fiddliness when you’re new, and in programming you do new things more often. You might think the fiddly detailiness of things is limited to human centric domains, and that physics itself is simple and elegant. That’s true in some sense – the physical laws themselves tend to be quite simple – but the manifestation of those laws is often complex and counterintuitive. II. Boiling A Watched Pot Consider the boiling of water. That’s straightforward, water boils at 100 °C, right? Well the stairs seemed simple too, so let’s double check. Put yourself in the shoes of someone at the start of the 1800’s, with only a crude, unmarked mercury thermometer, trying to figure the physics of temperature. Go to your stove, put some water in a pot, start heating some water, and pay attention as it heats. (I suggest actually doing this) The first thing you’ll probably notice is a lot of small bubbles gathering on the surface of the pot. Is that boiling? The water’s not that hot yet; you can still even stick your finger in. Then the bubbles will appear faster and start rising, but they somehow seem ‘unboiling’. Then you’ll start to see little bubble storms in patches, and you start to hear a hissing noise. Is that Boiling? Sort of? It doesn’t really look like boiling. The bubble storms grow larger and start releasing bigger bubbles. Eventually the bubbles get big and the surface of the water grows turbulent as the bubbles begin to make it to the surface. Finally we seem to have reached real boiling. I guess this is the boiling point? That seems kind of weird, what were the things that happened earlier if not boiling. To make matters worse, if you’d used a glass pot instead of a metal one, the water would boil at a higher temperature. If you cleaned the glass vessel with sulfuric acid, to remove any residue, you’d find that you can heat water substantially more before it boils and when it does boil it boils in little explosions of boiling and the temperature fluctuates unstably. Worse still, if you trap a drop of water between two other liquids and heat it, you can raise the temperature to at least 300 °C with nothing happening. That kind of makes a mockery of the statement ‘water boils at 100 °C’. It turns out that ‘boiling’ is a lot more complicated than you thought. This surprising amount of detail is is not limited to “human” or “complicated” domains, it is a near universal property of everything from space travel to sewing, to your internal experience of your own mind. III. Invisible vs. Transparent Detail And Getting Intellectually Stuck Again, you might think ‘So what? I guess things are complicated but I can just notice the details as I run into them; no need to think specifically about this’. And if you are doing things that are relatively simple, things that humanity has been doing for a long time, this is often true. But if you’re trying to do difficult things, things which are not known to be possible, it is not true. The more difficult your mission, the more details there will be that are critical to understand for success. You might hope that these surprising details are irrelevant to your mission, but not so. Some of them will end up being key. Wood’s tendency to warp means it’s more accurate to trace a cut than to calculate its length and angle. The possibility of superheating liquids means it’s important to use a packed bed when boiling liquids in industrial processes lest your process be highly inefficient and unpredictable. The massive difference in weight between a rocket full of fuel and an empty one means that a reusable rocket can’t hover if it can’t throttle down to a very small fraction of its original thrust, which in turn means it must plan its trajectory very precisely to achieve 0 velocity at exactly the moment it reaches the ground. Some important details for colonizing the universe. You might also hope that the important details will be obvious when you run into them, but not so. Such details aren’t automatically visible, even when you’re directly running up against them. Things can just seem messy and noisy instead. ‘Spirit’ thermometers, made using brandy and other liquors, were in common use in the early days of thermometry. They were even considered as a potential standard fluid for thermometers. It wasn’t until the careful work of Swiss physicist Jean-André De Luc in the 18th century that physicists realized that alcohol thermometers are highly nonlinear and highly variable depending on concentration, which is in turn hard to measure. You’ve probably also had experiences where you were trying to do something and growing increasingly frustrated because it wasn’t working, and then finally, after some time you realize that your solution method can’t possibly work. Another way to see that noticing the right details is hard, is that different people end up noticing different details. My brother and I once built a set of stairs for the garage with my dad, and we ran into the problem of determining where to cut the long boards so they lie at the correct angle. After struggling with the problem for a while (and I do mean struggling, a 16’ long board is heavy), we got to arguing. I remembered from trig that we could figure out angle so I wanted to go dig up my textbook and think about it. My dad said, ‘no, no, no, let’s just trace it’, insisting that we could figure out how to do it. I kept arguing because I thought I was right. I felt really annoyed with him and he was annoyed with me. In retrospect, I think I saw the fundamental difficulty in what we were doing and I don’t think he appreciated it (look at the stairs picture and see if you can figure it out), he just heard ‘let’s draw some diagrams and compute the angle’ and didn’t think that was the solution, and if he had appreciated the thing that I saw I think he would have been more open to drawing some diagrams. But at the same time, he also understood that diagrams and math don’t account for the shape of the wood, which I did not appreciate. If we had been able to get these points across, we could have come to consensus. Drawing a diagram was probably a good idea, but computing the angle was probably not. Instead we stayed annoyed at each other for the next 3 hours. Before you’ve noticed important details they are, of course, basically invisible. It’s hard to put your attention on them because you don’t even know what you’re looking for. But after you see them they quickly become so integrated into your intuitive models of the world that they become essentially transparent. Do you remember the insights that were crucial in learning to ride a bike or drive? How about the details and insights you have that led you to be good at the things you’re good at? This means it’s really easy to get stuck. Stuck in your current way of seeing and thinking about things. Frames are made out of the details that seem important to you. The important details you haven’t noticed are invisible to you, and the details you have noticed seem completely obvious and you see right through them. This all makes makes it difficult to imagine how you could be missing something important. That’s why if you ask an anti-climate change person (or a climate scientist) “what could convince you you were wrong?” you’ll likely get back an answer like “if it turned out all the data on my side was faked” or some other extremely strong requirement for evidence rather than “I would start doubting if I noticed numerous important mistakes in the details my side’s data and my colleagues didn’t want to talk about it”. The second case is much more likely than the first, but you’ll never see it if you’re not paying close attention. If you’re trying to do impossible things, this effect should chill you to your bones. It means you could be intellectually stuck right at this very moment, with the evidence right in front of your face and you just can’t see it. This problem is not easy to fix, but it’s not impossible either. I’ve mostly fixed it for myself. The direction for improvement is clear: seek detail you would not normally notice about the world. When you go for a walk, notice the unexpected detail in a flower or what the seams in the road imply about how the road was built. When you talk to someone who is smart but just seems so wrong, figure out what details seem important to them and why. In your work, notice how that meeting actually wouldn’t have accomplished much if Sarah hadn’t pointed out that one thing. As you learn, notice which details actually change how you think. If you wish to not get stuck, seek to perceive what you have not yet perceived.
Followup to: Words as Mental Paintbrush Handles, Guessing The Teacher’s Password Jessica Taylor recently wrote a description of Paul Christiano’s and MIRI’s differing driving intuitions for thinking about the AI alignment problem. Jacob Steinhardt observes that the “do cognitive reductions” intuition seems to be at the heart of MIRI’s thought and the “search for solutions and fundamental obstructions” intuition at the heart of Paul’s thought. As I read his comment, I noticed myself make an error I’ve made before: thinking I get the intuitions by mere virtue of not thinking they’re crazy. I call this The “I Already Get It” Slide, and I suspect this error happens to people all the time but passes unnoticed. This is unfortunate because the error prevents you from actually absorbing other’s intutions, and absorbing other’s intuitions is important for doing anything hard. Jessica describes Search For Solutions And Fundamental Obstructions like this: Almost all technical problems are either tractable to solve or are intractable/impossible for a good reason. […] If the previous intuition is true, we should Search For Solutions And Fundamental Obstructions. If there is either a solution or a fundamental obstruction to a problem, then an obvious way to make progress on the problem is to alternate between generating obvious solutions and finding good reasons why a class of solutions (or all solutions) won’t work. In the case of AI alignment, we should try getting a very good solution (e.g. one that allows the aligned AI to be competitive with unprincipled AI systems such as ones based on deep learning by exploiting the same techniques) until we have a fundamental obstruction to this. Such a fundamental obstruction would tell us which relaxations to the “full problem” we should consider, and be useful for convincing others that coordination is required to ensure that aligned AI can prevail even if it is not competitive with unaligned AI. As I thought about Paul’s Search For Solutions And Fundamental Obstructions intuition, a justification easily came to mind — a non-verbal feeling that it looked like other well-accepted problem solving strategies. This justification was easy, familiar and wrong. There is no way that “it looks like other accepted strategies” is actually the reason Paul thinks finding fundamental obstructions is central. And yet it was very easy for me to mentally slide from getting the conclusion and not immediately thinking it’s crazy, into thinking I also got the intuitive argument that generated it. If I had to guess at Paul’s actual intuitive reasons, I would guess something like this In Computer Science Theory, whenever there have been these kind of hard and confusing problems and people have tried to solve them, they’ve always turned out to either be possible or have some very revealing fundamental problem. For example, here are 4 clear examples. Furthermore, this makes intuitive sense because X. Also, this is also the case in these 3 other fields. And AI alignment looks a lot like these fields because it has Y and Z in common.“ But I also bet that not only will Paul have a more detailed argument, but also he will use a different ontology in a way that makes the argument meaningfully different. The argument is not yet compelling to me. Now, perhaps his arguments sound weak or just boring to you. How could a useful intuition be consistent with weak sounding arguments? To answer, put yourself in Paul’s shoes, and ask yourself what could explain weak or boring sounding arguments? Maybe you have a strong but difficult to articulate intution – maybe a mental picture of how different parts of the research process move against each other. Or maybe you can articulate your intuition, but when you do people quickly offer counterarguments that are — sigh — totally off topic. They nod along as if understanding, but then go right back to what they were doing before. You can probably imagine your conclusion being wrong, but not your insight being irrelevant. If Paul is at least as sensible as you are and his arguments sound weak or boring, you probably haven’t grokked his real internal reasons. Your intuitive mental picture of how parts of the research process moves is shaped differently than his. Maybe you’re even using different piece. If so, then it is not surprising that you come to different conclusions. You don’t even have the machinery to come to his conclusion. Maybe instead you think that getting his intuitive reasons from him doesn’t matter. After all, now that I know what Search For Solutions And Fundamental Obstructions means, I can just check that it should be a central strategy myself. But without an intuitive model of why it should be a central strategy, to check I would probably have to do computer science theory for at least a few months. Without my own intuitive model pulled from Paul’s intuitive model, there’s little to distinguish Search For Solutions And Fundamental Obstructions from a near-infinite variety of nearby strategies like “search for solutions and obstructions on complexity problems” or “search directly for fundamental obstructions”. Intuitive models let us cut down our uncertainty in great swaths by concentrating our probability on simple hypotheses. With my own intuitive model, checking often just requires seeing a few well chosen examples, or even just thinking back on past problems. All this is to say that Paul almost certainly has a valuable intuitive reason for his position. If I don’t catch my slide from understanding the conclusion to thinking I understand the argument, I’ll never notice that there’s something more to absorb. There’s a world of difference between understanding what Search For Solutions And Fundamental Obstructions means, and understanding the intuition that generates it. A difference, in other words, between understanding the conclusion and understanding the argument for it. If you mistake the conclusion for the argument, you will never get the argument. This reasoning doesn’t just apply to Paul and his intuitions, it applies to anyone who you think is about as reasonable as you. If they avoid errors about as well as you, then it would be silly to think that their intutions don’t point to real insight about the world. This also applies nicely to MIRI’s intuition that doing Cognitive Reductions is the main thing that can push AI alignment research ahead. Jessica describes Do Cognitive Reductions like this: Cognitive Reductions are great. When we feel confused about something, there is often a way out of this confusion, by figuring out which algorithm would have generated that confusion. Often, this works even when the original problem seemed “messy” or “subjective”; something that looks messy can have simple principles behind it that haven’t been discovered yet. Again, it is tempting to gloss over the fact that cognitive reductions are useful but not central, since we do already agree to some extent. But consider: if I were in their position, what kind of intuitions would actually lead me to think that Cognitive Reduction is so central? It couldn’t be just a stronger version of the belief that I already have, that would just make me think its somewhat more useful, rather than something to base my whole strategy around. Only a new argument could make sense of that. If I go argue with MIRI without noticing that there’s an argument I’m missing, we’ll just go around in circles. I suspect that The “I Already Get It” Slide happens all the time and passes unnoticed. That people mistake a person’s conclusions with their intuitive reasons and don’t end up absorbing their real arguments, even when they have insight. That would explain why peoples opinions converge so slowly.
More in science
the economics are especially interesting
[Note that this article is a transcript of the video embedded above.] If you have a fluid-filled system of pipes in your life, whether liquid or gas, (and who among us doesn’t?) there’s a very good chance that it passes through a simple device at some point on its journey to you. This device is almost unbelievably reliable for a purely mechanical system, and it has changed very little since the mid 1800s. So reliable that there’s a good chance you’ve probably never serviced or replaced one and maybe never even noticed one, despite them controlling so many aspects of our everyday lives. Of course, I’m talking about pressure regulators. But don’t let the jargon bore you, because these things are fascinating. They’re basically Victorian-era mechanical computers, and I cut one in half so we can see how it works. I’m Grady and this is Practical Engineering. “Control theory” is the branch of engineering that we use to describe managing dynamic systems, including the flow of fluids in pipes. I have a bunch of videos and demonstrations of just how dynamic those systems can get. A fundamental idea in this field is that, to garner any amount of control, you need some kind of feedback. And this is not a complicated idea. Say I want to control the pressure in my garden hose. I can put a pressure gauge on it, look at that gauge, and adjust the valve until I hit my setpoint. If something changes, like someone flushing all the toilets in the house simultaneously, I’m the feedback loop. I look at the gauge and make the change to get the pressure back to where it’s supposed to be. In fact, this exact situation (more or less) contributed to the pressure regulation equipment that we know and love today. The legend goes that in 1876, a massive fire broke out in Marshalltown, Iowa. William Fisher, a city engineer, spent all day and all night adjusting the throttle on steam-driven pumps by hand to manage the water pressure in the system to help the firefighters. Exhausted by the effort, he went on to develop the constant pressure pump governor, a precursor to the modern pressure regulators that are absolutely ubiquitous today. And I really mean that. Let’s take a little tour. One of the easiest regulators to find is on an air compressor. You generally want the reservoir as full as possible, which means pressurizing it to a level higher than what you would actually want out of the hose. Every air tool has its own maximum pressure, so you have a knob like this so that, no matter how much higher the pressure in the tank is, you get a consistent and controllable pressure out. If you use pressurized tanks of gas like oxygen, argon, or propane - exact same thing. You’re almost always going to see a regulator on top to control the pressure leaving the tank. Maybe you have a natural gas connection to your house. In most cases, residential plumbing and appliances are designed for very low pressures, like a half a psi or about 30 millibar. That’s great for getting gas from your basement up to your kitchen, but it’s hard to get gas to flow long distances at those pressures, so the lines feeding houses are usually at pressures quite a bit higher. You don’t want high pressure explosive gas in the walls of your house, so it has to be regulated down at the meter. That’s the pancake shaped device you often see outside. Even a standard pressure cooker has a regulator on top. A weight on top of a small pipe balances the steam pressure inside, providing only enough release to maintain a constant pressure inside. It’s not just gases either. The pressure in your water main can be too high for residential plumbing, so you might have a pressure reducing valve on your water service line. Most internal combustion vehicles have regulators that manage fuel pressure between the pump and injectors. And, of course, there are countless industrial applications of pressure regulators used in factories, power plants, and more. If you can find a pipe anywhere in the world, there’s a good chance that, no matter what’s in it, somewhere along it is a pressure regulating device. By the way, the stakes associated with pressure regulation are extremely high, particularly when it comes to natural gas. In 2018, the Merrimack Valley in Massachusetts saw over a hundred structures damaged by fire and explosions, 22 people injured, and 1 dead all as part of a single incident. It all came down to a mistake made during a pipe replacement project that kept the regulators from working correctly. This was a system where pressure was regulated down at a district level instead of each individual meter. The mistake sent natural gas into homes and businesses at pressures way above what the plumbing was designed to handle, ultimately resulting in one of the worst natural gas disasters in American history. I covered the whole story in a video a while back if you want to learn more after this. Here’s the thing: it’s not that complicated to reduce the pressure in a stream of fluid. Basically any kind of obstruction to the flow will do it. A simple way to do it is to put a flat plate with a hole inside the pipe. But a graph will show you why it’s not quite that easy. Let’s assume you have a constant pressure on the inlet side. If you graph the outlet pressure as a function of flow rate through the pipe, you don’t get a flat line, but a curve. And, critically, when there’s no flow, the pressure on the outlet side is the same as the inlet. There’s no reduction at all. If you let the pressure on the inlet vary, things get even more complicated. It’s easy to see why a static device, like an orifice plate, is not a very good regulator. There’s no feedback and no control. You definitely get a lower pressure in some situations, but if you need a consistent pressure that doesn’t exceed some maximum level, this is not going to work. Early gas regulators were bulky contraptions, but actually pretty simple. You could suspend an iron bell in a tank of water. A cast iron cone was attached to the top of the bell, sliding inside the inlet pipe. If the pressure inside the bell rose, it would float upward, pulling the cone too. The higher the cone is, the more restriction you get on the inlet pipe, decreasing the flow to maintain a consistent pressure leaving the device. It’s a pretty clever invention, but not entirely practical. The water level had to be maintained; it could freeze or get gross; the metal corrodes. And importantly, when it failed, it didn’t fail safely. If the bell sprung a leak or the counterweight cable broke, the cone would fall downward, fully opening the inlet. Modern regulators have a few features that improve on the original idea, and I happen to have a natural gas regulator so we can take a look inside. This is a used regulator that probably came from a large commercial building or a light industrial setting. And it’s actually built by Fisher Controls, the company William Fisher started after his firefighting pump throttling experience. Not a sponsor, but I like to think he would appreciate us cutting it up to learn more about it. I tried to be strategic about this to allow a look inside without it completely falling apart. From the outside, it kind of looks like gas would make a straight shot through, but when you cut it open, you can see that there's a separation here where the regulator connects to the line. I have it set where the discharge is pointed down. Gas has to pass through this valve to make it to the discharge side, and you can see that, past the valve, the discharge side is connected to this chamber in the main body of the regulator. Inside the chamber is this flexible membrane called the diaphragm sandwiched between the two sides of the housing. It’s a little floppier than usual, since I cut the whole thing in half, but hopefully you can still see how this works. This regulator has a stiffening plate attached to the diaphragm that acts against a spring at the top. The spring is a little too stiff for me to show you the full range of motion, so I’m going to take the seat off just to demonstrate. Let’s say there’s no demand for gas downstream. In that case, the pressure in the discharge line will build up, pushing the diaphragm upward. The diaphragm is connected to this lever, which is connected to a poppet, which pushes up against an orifice to close the valve, preventing gas from flowing. Let’s say someone opens a valve downstream, like a stove or a heater. As the gas flows out of the system, the pressure in the discharge line will fall, reducing the pressure on the diaphragm. The spring at the top will push the diaphragm down, lowering the lever, and opening the poppet so that gas can start flowing. If the demand increases, the pressure will drop further, lowering the diaphragm and opening the valve even more. And this system will constantly adjust to the downstream pressure, throttling the valve to keep it consistent - a completely mechanical control loop maintaining equilibrium. Any difference in the setpoint and actual downstream pressure creates a proportional movement of the diaphragm and poppet valve. And it’s adjustable too: The compression of the spring at the top can be increased or decreased, which allows you to dial in the exact pressure the regulator will supply. This is just so impressive to me. It’s a dead simple idea, but it does such an important job. But one of the difficulties, especially with natural gas, is that, like all mechanical devices, there’s some friction in the system. I mentioned that the downstream pressure of natural gas is pretty low. This regulator has an outlet range of about 1.5 to 3 psi above ambient air pressure, or about 100 to 200 millibar. Force is pressure times area. If the area of the diaphragm was small, the total force from the gas pressure acting against the spring would be practically indistinguishable within that range, especially when you consider the friction of the lever and valve. That’s why the diaphragm in natural gas regulators is so big. Even small changes in pressure create large difference in force, so you get more sensitivity, and the valve positions are more closely tied to the actual changes in pressure. You might see an issue with this design though: For the valve to open wider to allow more flow, the diaphragm must move down. For the diaphragm to move down, the pressure holding it up (the downstream pressure) must drop. Engineers call this droop, which I love. But there is still some variability in the downstream pressure. Pressure is tied to the valve position, so it’s necessary that it be allowed to fluctuate some. It will never be rock solid in this model. If you need that, the solution is usually a pilot-operated regulator. In this design, the downstream pressure is connected to a tiny, ultra-sensitive pilot regulator, and that regulator basically uses the higher-pressure inlet gas to move the main valve. In this way, you can go from 0 percent to 100 percent flow with almost no change in downstream pressure. Regulators can also be sensitive to inlet pressure. You can see on my model that the inlet pressure acts against the spring to open the valve. Of course the valve is a lot smaller than the diaphragm, so the effect isn’t as big, but there’s still a relationship between inlet pressure and outlet pressure, which isn’t always ideal. A lot of regulators work the opposite way, where the inlet pressure acts to close the valve. If you use a regulator on a tank, this can cause the counterintuitive issue of discharge pressure spiking as the tank empties, since the inlet to the regulator isn’t pushing as hard to close the valve. If you want to reduce this sensitivity, you can use a two stage regulator where you drop the pressure in steps. Let the first stage handle the coarse reduction, providing a more consistent inlet pressure to the second stage which can then keep the discharge pressure rock steady. One thing this regulator doesn’t do is fail closed. If this diaphragm rips, the outlet pressure won’t be able to push it upward to close the valve. So we have to account for that potential in other ways. Lots of gas systems will use a secondary, redundant regulator set to a slightly higher pressure that will take over if the primary fails. There is also a circuit breaker equivalent for gas systems called an overpressure shut-off or slam-shut. This model uses another option: an internal relief valve. Say the pressure on the discharge end somehow got too high. Maybe something got stuck in the valve, keeping it from fully closing. Or maybe the discharge line was exposed to sunlight, expanding the gas inside. In this case, the diaphragm can bottom out and act against this secondary spring, lifting off this plate. Gas is allowed to escape through a hole in the center of the diaphragm into the top half of the casing and out of this vent hole. And here we have another valve called a flapper. It can open inward to balance the pressure inside the regulator. And it can open outward if the relief valve activates, letting the excess pressure escape. The regulator would normally be mounted like this so the vent points downward, keeping rain out. And it has a screen so bugs don’t make a home inside. Obviously, this has some tradeoffs. This regulator has to be mounted outside or be attached to a ventilation pipe running outdoors to make sure it’s not releasing gas into a closed space. Even so, you don’t necessarily want to vent a bunch of natural gas outside. But because of the odorant that’s added to it, the idea is that someone would notice pretty quickly that some part of the system is malfunctioning and shut the line down for repairs. Like every part of engineering, it’s a game of tradeoffs: pressure versus flow, capacity versus cost, accuracy versus redundancy, and safety here versus safety there. I just love that there’s stuff like this out there, pretty much anywhere you’re willing to look, doing an essential job that few people even consider, and that their basic function really hasn’t changed in centuries. Samuel Clegg, one of the early engineers in natural gas systems had this to say about the pressure regulator: “Its use is nowhere sufficiently appreciated. Had it been a complicated piece of machinery, or expensive in its first cost and after application, objections to its adoption would not have been surprising; but it is perfectly simple: its action is certain and unvarying, and its first cost inconsiderable.” Nearly 200 years later, I couldn’t have put it any better myself.
TLDR: yes, models are getting funnier over time I love laughing. Well, who doesn’t? Good jokes have a certain notion of cleverness to them and I do believe that great comedians display high intelligence. Cracking a good joke requires astute observations about odd situations, and linking them to something we find familiar. Jokes are hard!… Read More The post How funny are the frontier AI models? appeared first on Inverted Passion.
The biggest empire the world has ever seen was run by a small elite who partied all night, drank liters of port, and stayed in bed until the afternoon.
Turbulence is all around us: bumping our planes, roiling our rivers, swirling milk into our coffee. These systems quickly become extremely chaotic and complex. On this episode of The Quanta Podcast, host Samir Patel speaks with contributing writer Stephen Ornes about a recent study that used sea monkeys to complicate one of turbulence’s many mysteries. This topic was covered in a recent story for Quanta Magazine. Each week on The Quanta Podcast, hear the people behind the award-winning publication navigate through some of the most important and mind-expanding questions in science and math.