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Yeah; you notice pressure changes easily when you skin dive, but you notice them mostly because of the compressive load on your lungs and the various air spaces in your head, which are full of air at surface pressure. If you go scuba diving instead, you won't notice the load on your lungs anymore -- the regulator delivers air at ambient pressure, not at surface pressure. You do need to equalize the pressure in your ears and facemask frequently as you go up and down the water column, since they're set to ambient pressure every time you do so and that changes as your depth does, but breathing itself doesn't get much harder as you go deeper.

(There are various other pressure-related problems that can crop up, though -- nitrogen narcosis is the most important one at recreational diving depths.)

ikrase12y00

One also needs a lower amount of oxygen in the breathable air.

See in context

58 Minor, perspective changing facts

by Stuart_Armstrong

22nd Apr 2013

1 min read

158

58

There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.

Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.

Think terrorist attack on Israel - did the phrase "suicide bombing" spring to mind? If so, you're so out of fashion: the last suicide bombing in Israel was in 2008 - a year where dedicated suicide bombers managed the feat of killing a grand total of 1 victim. Suicide bombings haven't happened in Israel for over half a decade.
Large scale plane crashes seem to happen all the time, all over the world. They must happen at least a few times a year, in every major country, right? Well, if I'm reading this page right, the last time there was an airline crash in the USA that killed more that 50 people was... in 2001 (2 months after 9/11). Nothing on that scale since then. And though there has been crashes on route to/from Spain and France since then, it seems that major air crashes in western countries is something that essentially never happens.
The major cost of a rocket isn't the fuel, as I'd always thought. It seems that the Falcon 9 rocket costs $54 million per launch, of which fuel is only $0.2 million (or, as I prefer to think of it - I could sell my house to get enough fuel to fly to space). In the difference between those two prices, lies the potential for private spaceflight to low-Earth orbit.

World Modeling

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[-]Stabilizer12y420

Things that have made me sit up:

Japan has a population of 130 million. It is the largest (by population) non-western developed nation. Edit: It is also the second-largest developed nation in the world.
Areas of countries, especially African nations. For example, Mali is larger than France, Germany and Italy combined.
My idea of real-world violence changed dramatically after reading Randall Collins. In short, it is far rarer than you think, everybody involved is extremely fearful of it, nobody is very good at it and it really is nothing like the movies. For example, they are usually very short: O.K. Corral was 30 seconds long.
Chile is in the same time zone as the East Coast of the US.

[-]Dahlen12y120

Japan has a population of 130 million. It is the largest (by population) non-western developed nation. Edit: It is also the second-largest developed nation in the world.

In a similar vein, Canada has a population of barely 35 million -- that's 9 times smaller than the US population -- while being the second largest country (by territory) in the world. It is almost as big as the whole continent of Europe, and yet there are 8 European countries (or 7 if you don't count Russia) with higher population counts. Most Canadians live within 100 km from the border with the US. The rest of the country is basically empty.

2A1987dM12y

Huh. I thought Canada would be a lot bigger than Europe, probably because I know that Western Europe is not that big and tend to forget how big Eastern Europe, especially the European parts of the former USSR, is.

7NancyLebovitz12y

Another possible factor is that Mercator maps increase the size of areas that are farther from the equator.

3A1987dM12y

Yes. I somewhat compensate for that (e.g. I don't expect Greenland to be ginormous), but apparently I don't do that enough.

1taelor12y

Speaking of European countries and size/distance, according to google maps it takes almost an hour less time to drive between London and Paris as it does to drive between San Francisco and LA.

0A1987dM12y

If anything, I expected the difference to be larger: London is in the far south of Britain and Paris is in the far north of France, so they are quite close together, whereas SF and LA are pretty much at opposite ends of California. (OTOH, I had no clear idea how long it'd take to take the train in the tunnel below the Channel -- according to Google Maps it takes one hour and a half to drive from Dover to Calais.) (Exercise for the reader: guess how long it takes to drive from Milan to Rome and how that compares to those two.)

4taelor12y

The California-Oregon Border hits the coast at the 42 parallel, and the California Mexico Border starts at 32.5. SF's latitude is 37.8, making it only 55% of the way up the coast. Far from being on opposite sides of California, San Francisco is only a bit past the midpoint. The misconception that SF is at the opposite end of California is likely due to the fact that past San Francisco, Northern California is pretty sparcely populated (an Oregonian friend of mine once describe Northern California past the Bay as "not inhabited by humans").

[-][anonymous]12y100

Chile is in the same time zone as the East Coast of the US.

I think more people get caught off-guard by the fact that Chile is in the opposite season of the US.

[-]Alicorn12y180

Those people must not like pomegranates nearly as much as I do. I spend several months of each year appreciating that Chile is in the opposite season.

[-]NancyLebovitz12y110

Gene Wolfe's Book of the New Sun was full of many exotic things, but the fact that temperatures were hotter when the characters went north was still reliably weird for me.

4prase12y

Just out of curiosity, what population did you expect Japan to have?

[-]Username12y130

Not OP, but I expected Japan to have about 40-50 million, about on par with California and South Korea. 130 million is huge.

[-]Desrtopa12y110

The Tokyo metropolitan area alone has approximately the population of California. The population of Japan has pretty intense urban concentration.

5Stabilizer12y

Likewise. I was thinking that it'd be about a rich European nation. I was very surprised because Japan is tiny in area; it's smaller than Montana. Another fun population fact: there are about 250 million people in Indonesia.

[-]Roxolan12y150

Making it the largest Muslim country in the world.

(Before learning this fact, Indonesia wasn't even on my radar when discussing Islam. It's quite moderate, so it rarely makes the news.)

9JackV12y

And the fourth largest country of any sort :)

3Larks12y

India is the second biggest

3FiftyTwo12y

I assumed around 60/70 based on ananlogy with the UK.

1DaFranker12y

China is not considered a developed nation? Dang. The things you learn. (sure, if you look at average well-being including all the people not living in urban areas and average per-capita economic statistics and other similar things, it doesn't look like a major developed power at all... but China has launched manned space missions, has massive high-tech cities, has some pretty darn good scientific projects, and the parts that aren't backwater farms look pretty damn first-world apart from all that oppression-from-the-state business) At any rate, going by all that's happening over there and all they're doing, I would've expected them to be one by now.

7Stabilizer12y

I was thinking more in terms of human development. Nations with large populations and high HDI are important because they support a very large number of people with a very high standard of life. China has a HDI-rank of 101. Japan has a HDI-rank of 10.

4DaFranker12y

Yeah, that and China's low per-capita everything. I also doubt China has a bigger service sector than its industry and farming. I was correcting my erroneous assumption based on other correlates of developed nations (space missions, nuclear power, high-tech, lots of science, etc.).

2A1987dM12y

Yes, China included developed and not-yet-developed areas. An interesting question would be how many people live in the developed parts of China -- I'd guess that's in the same ballpark as Japan.

8Stabilizer12y

China seems to have an urban population of about 690 million. So much more than Japan. But this doesn't tell us much, as you can live in a city but not necessarily enjoy high standard of living. The real interesting question is: how many people in China have the same standard of living as the average person in Japan. So Japan has a HDI of 0.912. Based on this list the only regions of China with a comparable HDI are Hong Kong (0.944), Macau (0.944), Shanghai (0.908) and Beijing (0.891). The populations of these cities combined is about 51 million. So, about 40% the population of Japan. Excluding Hong Kong and Macau doesn't change it much: get's it down to about 43 million, about 30% of Japan. But easily comparable to the population European nations. So yes, China definitely has a developed nation 'embedded' in it.

0Shmi12y

Must be the archaic designation of it as a "second world" country, whereas the developed and developing countries roughly match "first world" and "third world".

0DaFranker12y

Well, the wikipedia articles on human development and developed nations seem to indicate that to be considered a "developed nation" you have to have good per-capita rates, widespread infrastructure (admittedly, while China has first-rate infrastructure, it is only present in urban centers, to hell with rural areas!), and probably the most critical point re China is that you are into a Post-Industrial economy, with a larger service sector than industrial sector. As far as my readings and knowledge can tell, the above are indeed points where China fails.

[-]NancyLebovitz12y250

Here's one, though of a different sort. Five or ten years ago, I heard about an African film festival held in Africa. I immediately realized I'd been assuming things were much worse in Africa than they really were.

Since then, I've heard various pushbacks against the idea that Africa is a continent of disaster.

[-]A1987dM12y230

I immediately realized I'd been assuming things were much worse in Africa than they really were.

Presumably, things are different in different parts of Africa.

[-]NancyLebovitz12y220

Yes, thinking that Africa is just one thing is part of the problem.

0ikrase12y

It does seem to have more bigger messes than the other continents, but the awful seems to be pretty restricted in area.

[-]moridinamael12y230

This is less a discrete fact and more a body of experience that influenced my view here, but I think it still falls under the topic. Part of me feels like this should be obvious to the average LWer, but on the other hand it seems to be a very common malfunction among adults.

When I was a kid, probably until sometime in High School, I thought that if I saw someone wearing, e.g.

a backwards hat, an overlarge basketball jersey, and sagging jeans, or
Spanish-language tattoos, thick gold necklace and stud ear piercings, or
a black leather jacket, spiked dyed black hair, facial piercings, or
... some other stereotype which is barred from American public school dress code ...

... I would believe that this individual was probably actually dangerous. I would be frightened by the sight of them, and believe that there was a good chance that they would mug me.

Eventually I realized that these are merely the uniforms of various subcultures loosely enveloped by ethnic lines, and that seeing somebody wearing "thuggish" attire is very very weak Bayesian evidence that they are actually a thug, especially if you encounter them in a shopping mall or walking their dog at a park.

The most in... (read more)

[-]Prismattic12y180

For some (not all) of these cultural patterns, what happened was that the attire in question really was initially associated with thugs. In a rough neighborhood, you are either predator or prey. Even if you are not actually a thug yourself, it is safer to look like one, so that the actual predators mistake you for another predator rather than prey. It's like viceroy butterflies imitating monarchs, but without the actual evolution.

6DanielLC12y

I thought areas like that are where poorer people live, which leads to a higher crime rate.

6Desrtopa12y

In some cases this is true, but the associate between income and crime rate is not hard and fast, and people often overestimate it. Plus, people will often mistake "concentration of racial minorities" for "unsafe." The book I just finished discusses a particular community where the geographical divide of a particular street also has functioned for decades as a racial divide, and people on the white side continue to believe that the black side is "the bad part of town," and avoid it as dangerous, with businesses even refusing to deliver there, when crime statistics fail to bear out that it's any more dangerous. In fact, there is a dangerous part of town, where crime rates are particularly elevated, but it's only a small part of the alleged dangerous part of town.

9NancyLebovitz12y

Is there a term for the way biases persist because the cost of updating them seems high compared to the cost of maintaining the bias?

5syllogism12y

http://en.wikipedia.org/wiki/Rational_ignorance

3NancyLebovitz12y

Red Holsteins are the result of a recessive gene in the more usual black and white Holsteins(1). Considerable and expensive efforts were made to eliminate the trait until is was discovered that they're at least as productive as Holsteins with black spots. This should be remembered when you think tradition means people are doing something reasonable. Tradition, like evolution, probably means that disastrously bad traits are eliminated, not that exists is anywhere near excellence. (1)]In the US, a white cow with black spots is the default image for a milk cow, and for those of us less educated about cattle, for cows in general.

1fubarobfusco12y

Sounds like a sort of double-counting. "If I stopped believing the bad side of town is the bad side, then I might go over there and get mugged!"

8NancyLebovitz12y

I don't think that's necessarily it, I think it's more like "avoiding that section of town costs me so little that I don't want to bother to think about whether avoiding it makes sense".

4Jayson_Virissimo12y

Or higher crime leads to poorer people, or some other factor causes both (this is my bet).

2fubarobfusco12y

Just because there's a higher crime rate there doesn't mean that each individual there is looking to mug you, though. (Football fans may be more prone to fistfights than baseball fans, but that doesn't mean that every football fan is going to beat you up — or that no baseball fan will do so.)

1DanielLC12y

No, but I'd also expect that lower income areas would be more likely to mug someone in particular. You have to be pretty poor to be willing to attack someone for pocket change.

0fubarobfusco12y

I was not disagreeing with you; I was clarifying a difference between the claim that you made and that which moridinamael made.

1ikrase12y

Also people who are dangerous, may not be dangerous to you specifically.

0Sabiola12y

Or the other way around.

2moridinamael12y

I suppose the point is that "higher crime rate" is a deceptive piece of language. When people use that phrase there tends to be an implicit assumption that "higher crime rate" = "exactly correspondingly higher danger to you, the average visitor." This is rarely true. You may be subject to more risk in a high crime rate area than you would be in a nearby lower crime rate area, but that leads to the next point - the issue of unqualified relativity. The word "higher" in "higher crime rate" is relative and allows you to attach whatever meaning you want. "Higher" relative to what? To adjacent neighborhoods? To neighborhoods in similar cities with similar demographics and/or socioeconomic profiles? How much risk do you subject yourself to by taking a stroll down the streets of that area? Is it more or less risk than you take by riding your bicycle a short distance without a helmet, or walking around outside in a rainstorm? I'm sure someone's job is to quantify this information, but when the average citizen tells you "don't go west of 43rd, it's a high crime rate area," you really have no idea what they're trying to tell you and they probably have no concrete idea what they mean. edit: Lest I confuse my own point, people tend to very often be flat-out wrong about the crime statistics in their own cities. Local consensus about which areas are dangerous follows an availability cascade, where you tell people that an area is dangerous because that's what people told you when you moved there, and nobody ever goes online and notices that the crime rate in that area is actually no higher. I encourage everyone to Google the crime rates in their own cities, for you may be surprised.

[-]CronoDAS12y100

Also, the difference in crime rate might amount to something like "if you walk through the areas once a day, you'll be mugged on average once every ten years or once every thirty years."

[-]Desrtopa12y120

There may be a difference between the rate at which a resident (who's probably at similar income to other residents in the area, and perceived as an insider) would be mugged, and the rate at which a visitor (seen as likely to be carrying more money, and perceived as a outsider, and the residents won't have to come face to face with them or their families again) would be mugged.

That said, as I noted in a previous comment, there are definitely cases where people are prone to designate a place as "dangerous" when it's not actually statistically more dangerous than where they already live. The fact that visiting these neighborhoods may be more dangerous per time spent than living in them doesn't make it likely that people who refuse to visit them are assessing risk realistically.

2Baughn12y

Either of those would be really high, though!

6taelor12y

Getting mugged once every thirty years means that there's a 3.3% chance that you will get mugged in any given year. According to this data, the Robbery rate in Metropolitan Areas in 2009 was 133 per 100,000, meaning that each individaul stood about .133% chance of getting robbed that year. Note that this data likely includes instances of robbery that we wouldn't think of as mugging, so the actual chance of getting mugged is probably lower. Edit: apparently Metropolitan Areas include suburbs; To get a better picture of what crime rates are in urban areas, he's the robbery rates for selected big cities (all per 100,000 people): New York 221; LA 317; Chicago 557; Houston 500; Dallas 426; Detroit 661; San Francisco 423; Boston 365. So, somwhat higher than the .133% number I gave earlier, but still well below the numbes that the Grandparent Post implied.

5Viliam_Bur12y

It would be nice if someone compiled a statistic with photos of various dangerous people, and how many micromorts each type of person represents for you. Also micromort maps of different towns and parts of town. Even better, compare it with risk levels of other activities. For example "it is better to jump from an airplane with a parachute to avoid this person, but not to avoid that one".

[-]FiftyTwo12y220

Looking at the relative calorie values of different foods radically changed my eating habits. Especially realising how high calorie 'boring' things like rice and bread were, vs. 'fun' things like bacon. Good example chart here.

6Xachariah12y

Woah. Instead of potato chips, I could be eating an equal amount of bacon. I'm never going to eat another potato chip again.

2Desrtopa12y

Well, the fact that they have about the same calories per gram doesn't mean that they're equally healthy. The fat in bacon is almost all saturated. Bacon is probably more filling per calorie though, so you'd be less likely to gain weight snacking on bacon than potato chips.

5RomeoStevens12y

The evidence that saturated fat is bad for you is dubious. However there is good evidence that processed meats are bad for you, even though every test of possible causal pathways has failed so far.

1Richard_Kennaway12y

Really? I heard something on the radio a few days ago about a study to that effect, and then I came across a blog posting by someone apparently reputable finding little substance in the original paper, so what am I to make of that? For that matter, what is unprocessed meat? Raw? ETA: This is the study (open access), and "processed" means "having had its shelf life extended". From a brief glance at the paper, I don't think they did any sort of causal analysis beyond controlling for possible confounders such as the tendency of high consumers of red meat to smoke more. I don't care enough about this to study it in any more detail.

2RomeoStevens12y

Unprocessed means untreated with preservatives. Smoked, salted, dried, potassium benzoate, etc. The evidence I'm referencing is a meta-review of epidemiological studies. The lack of a causal pathway refers to the failure to find anything when doing intervention studies on particular substances. So it could very well be that the epidemiological studies are all failing to properly control for confounding factors. Nutritional self reporting is notoriously terrible. Epidemiological studies often rely on spaced surveys, sometimes asking questions about food habits over an entire year. That people are unable to provide accurate info is unsurprising. Still, it is not zero evidence. My own hypothesis is that the animal's diet has a lot more to do with the potential harm to you than currently realized. Animals with crappy diets are sickly. We likely have a natural aversion to eating sickly animals for a reason.

3TitaniumDragon12y

Uh, yeah. The reason for that is that sickly animals carry parasites. It is logical that we wouldn't want to eat parasite-ridden or diseased animals, because then WE get the parasites. If the animal is not parasite-ridden, there's no good reason to believe it would be unhealthy to eat. My personal suspicion for the cause is underlying SES factors (wealthy people tend to eat better, fresher food than the poor) as well as the simple issue of dietary selection - people who watch what they eat are also more likely to exercise and generally have healthier habits than those who are willing to eat anything.

2Desrtopa12y

There might be some factors which the study is failing to control for, but from the link in the grandparent The study seems to control for the more obvious associated factors. Also, the full text states that the consumption of red meat is associated with an increase in mortality when controlling for the confounders assessed in their study, with processed meat being associated with a greater increase, but poultry not being associated with an increase in mortality.

2TitaniumDragon12y

The problem is that the choice to eat differently itself is potentially a confounding factor (people who pick particular diets may not be like people who do not do so in very important ways), and any time you have to deal with, say, 10 factors, and try to smooth them out, you have to question whether any signal you find is even meaningful at all, especially when it is relatively small. The study in particular notes: [quote]Men and women in the top categories of red or processed meat intake in general consumed fewer fruits and vegetables than those with low intake. They were more likely to be current smokers and less likely to have a university degree [/quote] At this point, you have to ask yourself whether you can even do any sort of reasonable meta analysis on the population. You're seeing clear differences between the populations and you can't just "compensate for them". If you take a sub-population which has numerous factors which increase their risk of some disease, and then "compensate" for those factors and still see an elevated level of the disease, it isn't actually suggestive of anything at all, because you have no way of knowing whether your "compensation" actually compensated for it or not. Statistics is not magic; it cannot magically remove bias from data. This is the problem with virtually all analysis like this, and is why you should never, ever believe studies like this. Worse still, there's a good chance you're looking at the blue M&M problem - if you do enough meta analysis of a large population you will find significant trends which are not really there, and different studies (noted in the paper) indicate different results - that study showed no increase in mortality and morbidity from red meat consumption, an American study showed an increase, and several vegetarian studies showed no difference at all. Because of publication bias (positive results are more likely to be reported than negative results), potential researcher bias (belief that a v

2Desrtopa12y

Well, if you already know how much each of the associated factors contributes alone via other tests where you were able to isolate those variables, you can make an educated guess that their combined effect is no greater than the sum of their individual effects. The presence of other studies that didn't show the same significant results weighs against it, but on the other hand such cases are certainly not unheard of with respect to associations that turn out to be real. The Cochrane Collaboration's logo comes from a forest plot of results for whether an injection of corticosteroids reduce the chance of early death in premature birth. Five out of seven studies failed to achieve statistical significance, but when their evidence was taken together, it achieved very high signficance, and further research since suggests a reduction of mortality rate between 30-50%. While a study of the sort linked above certainly doesn't establish the truth of its findings with the confidence of its statistical significance, "never believe studies like this" doesn't leave you safe from a treatment-of-evidence standpoint, because even in the case of a real association, the data are frequently going to be messy enough that you'd be hard pressed to locate it statistically. You don't want to set your bar for evidence so high that, in the event that the association were real, you couldn't be persuaded to believe in it.

-1TitaniumDragon12y

You can't make an educated guess that a combination of multiple factors is no greater than the sum of their individual effects, and indeed, when you're talking about disease states, this is the OPPOSITE of what you should assume. The harm done to your body taxes its ability to deal with harm; the more harm you apply to it, whatever the source, the worse things get. Your body only has so much ability to fight off bad things happening to it, so if you add two bad things on top of each other, you're actually likely to see harm which is worse than the sum of their effects because part of each of the effects is naturally masked by your body's own repair mechanisms. On the other hand, you could have something where the negative effects of each of the things counteracts each other. Moreover (and worse), you're assuming you have any independent data to begin with. Given that there is a correlation between smoking and red meat consumption, your smoking numbers are already suspect, because we've established that the two are not independent variables. In any event, guessing is not science, it is nonsense. I could guess that the impact of the factors was greater than the sum of the parts, and get a different result, and as you can see, it is perfectly reasonable to make that guess as well. That's why it is called a guess. When we're doing analysis, guessing is bad. You guess BEFORE you do the analysis, not afterwards. All you're doing when you "guess" how large the impact is, is manipulating the data. That's why control groups are so important. Regarding glucocorticosteroid use in pregnancy, there actually is quite a bit of debate over whether or not their use is actually a good thing due to the fact that cortiocosteroids are tetratogens. And yes, actually, it is generally better not to believe in true correlations than it is to believe in false ones. Look at all the people who are raising malnourished children on vegan and vegetarian diets.

0Desrtopa12y

Well, there's certainly no shortage of evidence that it's unhealthy for children to be malnourished, so that amounts to defying one true correlation in favor of the possibility of another. Supposing that there were a causative relation between red meat consumption and mortality, with a low effect size, under what circumstances would you be persuaded to believe in it?

[-]RomeoStevens12y180

It's worthwhile to pay people to do mundane things for you more often than you'd think. Most people underestimate the cognitive load these mundane tasks place on them in that they are surprised how happy they are with not doing them once they try it.

[-]sixes_and_sevens12y200

Do you have any specific examples? :-)

2Error12y

And do you know a good source for finding trustworthy people to pay to do mundane things?

3Tenoke12y

Amazon turk works for at least some mundane things.

5Error12y

I was more thinking of things like housekeeping, grocery shopping, taking the car to the shop, and the like...things that are routine, time consuming, and can't be automated, so that over a lifetime they take up a truly infuriating number of hours. Unfortunately they also require a good deal of trust for anyone hired to do them.

[-]gwern12y200

You can automate aspects of them. I have heard that people have had success using Amazon's 'subscriptions' where you set up a recurring order every X months for a particular foodstuff or household good, which certainly could help reduce time on grocery shopping.

7Jayson_Virissimo12y

Am setting this up now.

2Error12y

That wouldn't work for groceries for us, because Reasons, but I was unaware that feature existed and can think of other things for which it may be helpful. Thanks. [ETA: Some places have companies that do grocery delivery, which I would totally pay for, but none of them deliver here. Too far out from the city, seems like. :-( ]

4sixes_and_sevens12y

Do you have any specific examples? (I've been looking into the literature on ego depletion recently, so I actually have a lot of sympathy for the OP's position, but I can't think of any tasks in my life so cognitively exhausting relative to their mundanity that it would make sense to outsource them to India.) EDIT: I should think for five minutes before I say things like that. A few are coming to mind, but I think I'll mull them over for a while before saying what they are.

5Tenoke12y

I am not currently using this or anything like this but proofreading, compiling lists, searching for scattered information on someone across the internet and inputting some data in a certain format can be outsourced in this manner.

0Daniel_Burfoot12y

I think part of OP's point is that you don't realize how much relief you will feel about outsourcing the task until you actually do the outsourcing.

0sixes_and_sevens12y

I don't think that is the OP's point (though OP is welcome to correct me on this). If it is, it's highly implicit in the original comment. It is a worthwhile point to mention, though. The difficulty with these tasks seems to be identifying them, rather than solving or managing them.

0RomeoStevens12y

laundry, food, dishes, cleaning, organizing, recurring household purchases (toiletries etc.) Most can be automated with varying degrees of capital commitment. My point was that yes, even if you shut up and multiply you are likely underestimating the benefits column of your cost-benefit analysis.

[-]Eneasz12y170

This is already known to readers of XKCD, but I was blown away when it was pointed out that The Little Mermaid was released closer to the first moon landing than to the present day. It made me realize how much time has already passed in my life.

3A1987dM12y

I sometimes think about the fact that my children (assuming they will be born when I'm in my thirties) will be as far removed chronologically from the Beatles, Pink Floyd, Led Zeppelin, the Doors, etc. (i.e. the music I listen to most often) as I am from music of the 1930s, of which I hardly know any.

2NancyLebovitz12y

The first time I heard that the 60s were forty years ago, I literally counted the decades off on my fingers because I couldn't believe it. Yes, I know it's more like fifty years now, but I'm used to it.

2[anonymous]10y

I don't know if some periods of pop-cultural history are simply more remarkable than others and thus leave more vivid memories, or it just comes from aging. I am 37 and everything post-2000 is a blur. I don't think I could name more than one popular song esp. one I liked that was released after 2000. To me the difference between 1992 and 1996 was huge, such as techno-house went from underground to mainstream and transformed the whole musical landscape, 2000 to 2010 is like, meh, some hipster bands got more popular than some other hipster bands?...

[-]SilasBarta12y150

Atmospheric pressure, how strong it is (in absolute terms, ~15 psi/100 kN/sq m), and how little we notice. A rough demonstration:

You know those 15-lb (~7 kg) dumbbells? Ever lifted one? They're heavy. (No bragging, please.)

Now, place your hand on a table, palm up, and rest the dumbbell on your palm. "Ow!", right? That hurts! It feels like your hand is getting crushed! Get that thing off!

Well, you've only increased the pressure that's normally on your hand by about 5%, plus or minus.

[-]Caerbannog12y310

This is very misleading. Most of the discomfort would be from the hard table against the back of your hand, and this would be because of local pressure on specific points.

Pressure causes problems when there's a big change in a relatively short time. Ears, for example, have a hard time with this, but you can equalize them by closing your nose and mouth and trying to blow out. Before I knew about this trick, I could never dive to the bottom of the pool. Now, no problem.

A more realistic example would be to bury your hand in a foot or two of fine sand. Does that sound uncomfortable?

In the sand example, it's also important that the pressure is acting from all sides (top, bottom, left, right) so there's no force acting to deform your hand.

We can handle a relatively large range of pressures, and there are other problems before you start causing mechanical damage from the actual pressure (lack of oxygen at low pressure, dissolved gas at high pressure).

edit: grammar

0SilasBarta12y

Good point, but it feels about as uncomfortable if you use a padding over the table that eliminates the stress concentrations at your bones and knuckles. Especially if you double the dumbbell weight and recognize that it's only a pressure increase of 10%.

[-]Caerbannog12y110

I don't agree with this.

Your thought experiment with the dumbbell is an incorrect way of thinking about ambient pressure. Ambient pressure pushes against an object from every direction. It does not work to deform or break, only compress from all sides.

Picture this: You have a hand-sized water balloon on a table. You place the two dumbbells on it; it breaks. You have another water balloon. You take this one, tie it to a dumbbell, and drop it into deep water. Do you expect it to break when descends to 3 feet (i.e. 10% increase in pressure)?

I would not expect it to break at all. When water and other non-gases are put under pressure, the bonds and repulsive forces within push back.

Don't quote me on this part, but I would guess that to break a bone with just ambient pressure, you'd have to raise the pressure to about the compressive strength of the bone, around 100 megapascals. For reference, standard atmospheric pressure is around 100 kilopascals.

edit: changed 3 meters to 3 feet, per prase's comment.

9prase12y

3 meters underwater is about 30% of atmospheric pressure added, not mere 10%.

2Caerbannog12y

Sorry, I forgot feet != meters. Ha.

8sketerpot12y

Alternately, go swimming. The water adds roughly another atmosphere of pressure every ten meters. You will notice this.

2ikrase12y

Atmospheric pressure is HUGE. It's enough that a variety of pneumatic systems use vacuum instead of high-pressure air.

0NancyLebovitz12y

What did you deduce from finding out about atmospheric pressure?

0John_Maxwell12y

So colonizing a planet that has even a slightly thicker atmosphere than ours could be problematic?

9Stabilizer12y

I think colonizing any planet has way too many problems before you confront this one.

5kilobug12y

Not so sure about that, just dive a few meters under water, and the pressure gets up very quickly, roughly, every 10m you dive, you get an additional atmosphere of pressure, and people are known to be able to dive below 100m with training but without special apparatus. The problems arise mostly when the pressure changes quickly (or when it gets very high), but a pressure of 10 atmosphere, with sufficient preparation and adjusting time, doesn't kill a human being.

7Nornagest12y

0ikrase12y

One also needs a lower amount of oxygen in the breathable air.

4Nornagest12y

Depends on the gas mix and the application. The gas mixes used at depth in technical diving are usually hypoxic, since oxygen toxicity becomes an issue with ordinary air at an ambient pressure of about six and a half bar or depths of around fifty meters; heliox, for example, is usually around ten percent oxygen. On the other hand, it's fairly common for the gas mixes used during the decompression phase of a technical dive to be richer in oxygen than air is, since that helps flush nitrogen out of your tissues. This isn't usually an issue for recreational divers, though, who generally don't dive below forty meters and use pressurized air or, more rarely, enriched nitrox mixtures. At those shallower depths, you compensate for the richer breathing gas by breathing in a slower, more controlled fashion than you would on the surface, though this has more to do with conserving gas and controlling buoyancy than it does with oxygen issues.

3John_Maxwell12y

I don't see how this squares with Silas' claim that a 15-lb dumbbell hurts your hand when you rest it on it. OK, I just tested this by balancing the end of a ~21 pound dumbbell on my palm while my palm rested on a counter (surface area of dumbbell end looks to be about 0.60 square inches, making the pressure around 35 psi, or about 2.3 atmospheres?) It was a little painful, but I didn't cry out or feel the need to get the thing off immediately. So in conclusion, I think Silas might have been exaggerating. Resting my palm on a pillow instead of a counter, I don't really experience pain anymore, just discomfort. Maybe that has something to do with the fact that deep diving doesn't cause pain?

2NancyLebovitz12y

People's pain tolerances vary a lot.

0[anonymous]10y

But shouldn't you rather take into account the tolerances of pregnant women and people younger than the age when one can be trained? If they can't live on the planet, it can't be colonized.

0kilobug10y

I'm not an expert in diving (I only dived once about 10m deep during holidays), but AFAIK the training (and the trouble) is mostly to handle the change in pressure, much more than the high pressure itself. Going from 1Am to 10Am is dangerous if done without respecting many safety measures, but once you're adjusted at 10Am, it's not so much a problem. So a child born on higher pressure wouldn't have too much troubles. Maybe 10Am is too much, but I don't think 1.5Am or 2Am would cause any serious trouble, if the composition of the atmosphere is good enough.

0[anonymous]10y

That is quite interesting. I'll ask my friends in human physiology department what they think about it and get back to you.

[-]Jiro12y130

The suicide bombings in Israel drastically decreased after the construction of the wall to keep Palestinians out.

Also, it's dangerous to use Wikipedia articles that are "lists of X" to find the prevalence of X. You don't know how well the article is maintained; it could be that for some reason (perhaps as simple as what year the majority of the editing was done) one year's incidents are just represented in the list more.

[-]MrMind12y120

The suicide bombings in Israel drastically decreased after the construction of the wall to keep Palestinians out.

That's one of those "uncomfortable but true" things that sometimes surfaces here (and threads get dedicated to explore): segregating walls do work.

3Stuart_Armstrong12y

It's at least, some evidence in that direction.

9Stuart_Armstrong12y

I didn't say anything about the reasons for that shift - just that it was there, and surprised me. And Wikipedia may be unreliable, but it's the best I can do without a very slow and thourough search that would take days... The point is that we need to be able to change our minds on minor points without huge amounts of effort.

[-]Qiaochu_Yuan12y80

Before looking up all of these facts, it would've been interesting to attempt to Fermi estimate them; that could've helped you uncover more stuff that's mistaken in your model of reality.

[-]gwern12y200

Isn't that like trying to estimate unknown unknowns? If one has already reached the point of thinking, 'wait how many major plane crashes have there been in the USA in the past decade, exactly? Why... I can't seem to think of any!'', one has already done most of the perspective changing.

2CoffeeStain12y

What's interesting about the Fermi Estimate post is that its examples encourage you look for predictors that are unexpectedly reliable, rather than those that first jump to mind. That I haven't heard of many plane crashes in the past decade, this sounds like something I might hear on a post arguing an opposite point. "Sure, you've haven't heard of plane crashes in a decade, but why suspect that reliable predictors are in the neighborhood of your daily activities rather than your knowledge about the world? And now I will eye you knowingly until you learn something of your cognitive biases!" Although, perhaps there aren't any estimated-statistics approaches that would be any good here, that wouldn't rely on other more incidental bits of information you happen to possess. Sure, you could try to list the top causes of flight disasters (human error and mechanical malfunction?) and estimate the likelihood these things occur, and also estimate how many of these flights result in large scale deaths. But there may be too many variables; either that, or I have ways to go in making Fermi estimates. In any case, it would be hard to incorporate the time variation of flight disaster outcomes. For all I know, flight safety has skyrocketed in the past decade due to widespread process improvement resulting from studying past disasters. And how could I ever predict that effectiveness, or predict how long it would take to come about?

0gwern12y

Please see my sibling comment on why the availability heuristic delivers in spades about jumbo jet crashes.

2DanielLC12y

I can't think of many car crashes either. That just means that I don't hear about them.

[-]gwern12y100

If every car crash received headline coverage due to hundreds of people dying simultaneously horribly, followed by sporadic articles as the investigation of that car crash went on and profiles of people who died in the crash, then not being able to think of any recent car crashes probably means that there weren't any, not that the entire media industry collectively decided to stop covering them.

4Randy_M12y

So, you don't commute much? I can think of a few specific ones I've driven past in the last few months, and I know that I'm not even remembering them all. Plus hearing traffic reports, etc.

2DanielLC12y

Sometimes they're easier to look up, and it's almost always more reliable.

[-]Qiaochu_Yuan12y100

Of course it's more reliable to look them up, but the point of doing a Fermi estimate here is to figure out what else you might be mistaken about. For example, if you do a Fermi estimate about how much a rocket costs and it turns out to be really inaccurate, you might learn that that's because you have a really inaccurate picture of how much engineers get paid, or how many engineers it takes to build a rocket, or how much the materials for something like a rocket cost, or...

1Stuart_Armstrong12y

I don't see how I could have Fermi-estimated the relative costs of the rocket and the fuel...

[-]CarlShulman12y260

Anna and I actually did a Fermi estimate of the fuel for the Apollo 11 mission over dinner last week, and we were off by a factor of two. Some of the available inputs:

A crude estimate of the potential energy of mass lifted from Earth's surface to a distance of many times its radius
The heights reached by jet aircraft using fuel amounting to only a very small portion of their mass
A crude estimate of the energy content of gasoline (one approximation is to energy content of food, and/or the energy output of humans), with adjustment for the need to carry oxygen into space
Images of rockets launching, which show that the fuel tanks are much bigger than payload, but not thousands or millions of times bigger
Knowledge of the price of consumer gasoline, or the price of oil
The existence of science fiction writers with physics backgrounds, SpaceX, the L-5 societies, and other groups seriously pushing for advancements to slash cost-to-orbit
Rough knowledge of NASA's budget, either directly or by bounding it relative to known US budget items
Knowledge of the enormous cost of producing military aircraft and naval vessels, which can be in the hundreds of millions to billions of dollars
The existence of an ecology of NASA contractors condemned for their enormous costs (these would be trivial if fuel was the major cost)

0Qiaochu_Yuan12y

Estimate how many people you would have needed to employ and what their salaries might be, estimate the cost of materials...

2Stuart_Armstrong12y

But those aren't the main reasons for the costs. The main reasons are that rockets have not benefited from reduced costs through mass production - something that would be very hard to estimate if you didn't know or guess that.

6Qiaochu_Yuan12y

Right, and attempting to do a Fermi estimate and then checking it would help you see that that was something you didn't know. (Maybe I'm not getting my point across well here. My point wasn't that such a Fermi estimate would have been in any way accurate. My point is that identifying what made it inaccurate would have helped you update more.)

2Stuart_Armstrong12y

Ah, I see. I'll try and bear that in mind next time I go looking for info like that!

[-]bramflakes12y70

What is the fastest-growing Asian economy? China? India?

Mongolia.

[-]gwern12y240

That's more a fact about the massive volatility of resource-extraction economies than anything else, really. That's how you get things like a projected GDP growth rate of +60% this year and -50% last year in Southern Sudan (those are not typos).

[-]Jiro12y110

Besides, it's much easier to be "fast growing" when you start from a low base. That's why "fastest growing" almost always indicates hype when used to try to sell you something.

[-]Nornagest12y40

Declines in air passenger volume lead to substantial excess deaths from auto accidents, as consumers substitute driving for less dangerous air travel. The variables are pretty hard to isolate and the linked paper examines only one unusually dramatic case, but this effect could have far-reaching implications; for example, if the paper's accurate in citing a 5-8% decline in American air travel linked to stricter and less convenient passenger security screening, then these screening procedures may be actively counterproductive.

[-]JoshuaFox12y40

Think terrorist attack on Israel - did the phrase "suicide bombing" spring to mind?

Stuart, does "rocket" spring to mind? I wonder to what extent the rain of rockets on the southwest since 2006 (on and off, but with long periods of "on") registers on one's consciousness out there in the UK.

7Stuart_Armstrong12y

Rocket does spring to mind - but I still think that "suicide bombing" is more likely to spring to people's minds, here in the UK. It's the iconic example of terrorist attacks on Israel, and the fact that it hasn't been used recently hasn't really registered.

[-]Larks12y40

Rating agencies have historically actually been very good at predicting corporate defaults.

I have data on this but it is not public. However, I suspect there is public data available as well.

4RomeoStevens12y

Please tell me that this is currently poorly priced into the market for mysterious reasons. I would like some free money.

0[anonymous]12y

Unfortunately I cannot epistemically responsibly do that.

0Metus12y

I saw a list at wikipedia somewhere. I wonder if it is already priced in.

[-]MileyCyrus12y20

I can think of a few examples but they're all political.

[-]FiftyTwo12y120

Not sure if this is political, but I understood why people in America were so obsessed with gay marriage much more when I realised that spouses get health care automatically. So people weren't really (or not exclusively) getting upset over a symbolic distinction but a practical one.

[-]Larks12y140

There's been a similarly large fuss over gay marriage in the UK, where 1) the NHS provides healthcare to everyone and 2) existing civil partnership legislation gave gay couples all the benefits of straight couples. So I don't think that practical issue is very important.

(Also, there are many far easier ways of getting health insurance than by upsetting arguably the most important institution in the history of the world!)

[-]sixes_and_sevens12y100

Your observation on this subject disagrees with mine. I'd say there was significantly less fuss about gay marriage in the UK. I suggest this is selection effect on one or both of our parts.

1John_Maxwell12y

Interesting paper on monogamous marriage: http://www.gwern.net/docs/2012-heinrich.pdf

3Randy_M12y

I don't know exactly what you mean by that, but my (optional) employer-provided health insurance had a premium increase when I opted to include my family vs just insuring myself. Of course, the increase wasn't the same as doubling the price, but the coverage was contingent on my having a full-time job that chose to offer it and my paying more for it.

1private_messaging12y

Thing is, they don't know about that either, and/or don't care.

8Shmi12y

Like that under the US criminal definition of a Weapon of Mass Destruction almost anything that can disrupt a mass qualifies?

[-]knb12y160

I guess there really were WMDs in Iraq.

-6Thomas12y

8Stabilizer12y

Holy shit. You're not even kidding! Check out the definition here. Under the definition, it says that it includes (among other things) anything that is a 'destructive device' as defined here which in turn includes, This is so funny, it's not even funny. Note: the above links say it's a U.S. Code prelim (i.e. some revisions might happen). But I found similar things here.

8IlyaShpitser12y

The Boston marathon bomber was charged with using WMDs...

4Stabilizer12y

I actually did not know that. Thanks.

3wedrifid12y

That would totally make sense if the marathon bomber had managed to blow up an entire 42.2km course with one device. It's less credible for the actual Boston [finishing line of a] marathon bomber.

3Kindly12y

It's not that bad. At the very least, a destructive device must be "designed for use as a weapon" or else it doesn't count. I'm still not sure why these things (the definition seems to include most guns, although I'm not sure what the bore measurements imply) are called "weapons of mass destruction", though...

2Nornagest10y

The bore measurement requirement excludes any guns of .50 caliber or under (or around 12.7 mm in metric) from the "destructive device" category for legal purposes, which covers most modern small arms. Aside from a handful of experimental or exotic weapons, the only real exceptions are a few Eastern Bloc heavy machine guns and anti-materiel rifles, which you'd have a hard time getting ahold of in the States anyway. It's common for black powder weapons to have larger bores -- .5 to .8 inches were typical calibers for colonial-era muskets -- but they're excluded from the "destructive device" category by a separate provision.

1BlazeOrangeDeer12y

Like a cannon from a civil war reenactment?

3Kindly12y

That is one of the deliberately excluded cases.

2Zaine12y

I want to believe this is a pun. That definition includes swords.

1Viliam_Bur12y

I thought that swords of mass destruction exist only in anime.

0Zaine12y

Cut a piece off a body of mass, and its mass has been disrupted.

[-][anonymous]10y00

I used to think that wild flowers were a cute and unassuming gift and generally not a big deal until I had an occasion to participate in a confiscation operation at a train station. We chose to seize a load of snowdrops from Crimea on St. Valentine's day and have the press make the event into propaganda of nature conservation. Even then I still hadn't entirely abandoned the stereotypes I got from pop culture. What we were going to do was just another drop into the ocean, and not a necessary one at that.

But when the middleman whose plants we confiscated dem... (read more)

2gjm10y

I'm feeling a bit dim. What point did it drive home? What specifically is wrong with movies' portrayal of "harmony with nature"?

2[anonymous]10y

...that we can bring it to our homes in discrete little pieces, since we are part of it, and by doing so benefit nature, too. (Interestingly, I have heard people tell me that it was we who 'murdered the flowers'.)

0gjm10y

Oh, OK. (I don't think I've ever before encountered the idea that we benefit nature by having cut flowers in our homes.) I'd always just assumed that flowers one buys are grown especially for that purpose and wouldn't have been grown otherwise. If that's so, it doesn't seem like having flowers around your house does much harm.

2[anonymous]10y

I have encountered it many times:) usually after I ask people why they do ..., they often ramble to the point.

[-]aelephant12y00

I always thought that Insulin resistance was bad, always & forever, & that anything that increased Insulin sensitivity was good. But now I've realized this isn't necessarily true. When fasting, the peripheral tissues (fat & muscle) SHOULD become Insulin resistant so that Glucose is spared for the brain. Further, high insulin sensitivity in the morning could be BAD because Insulin is either going to help calories get stored in Fat or Muscle, & 1st thing in the morning, who has produced the proper stimulus to preferentially target those calories to the Muscle? What we really want is a selective Insulin sensitizer and/or timed Insulin sensitivity (eg, after a heavy workout).

0hyporational12y

While you're technically right, I don't see the point. Insulin secretion is minimal in the fasting state, so why would you need to dabble with insulin resistance?

1aelephant12y

Many Diabetes drugs, like PPAR agonists, stimulate Insulin sensitivity, but where do they do it? The body has PPAR receptors pretty much everywhere EXCEPT in the Muscles, so patients taking these drugs & continuing to consume excessive amounts of Carbohydrates are basically switching on every mechanism they can to make sure all of their calories are being stored as Fat. These drugs were approved by the FDA based on surrogate endpoints (they reduce Insulin resistance!) but they increase the risk of having a Heart attack by something like 28%, so I think we really need to question whether decreasing Insulin resistance without any finer specification (ie, in Muscle vs. Fat, Fasting vs. Post-prandial) is the goal we want to have in mind. Maybe it is just solving 1 part of a bigger problem & exacerbating other parts of that problem.

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