ScienceNostalgia101

In the United States, being "over"weight is associated with physical inactivity, and with the overeating of fast food, which happens to be high in saturated and trans fat. So this leaves a question; when the medical community tries to determine what is supposedly the medically optimum weight based on age, height, etc... do they go by correlation or not? If not, what is their alternative to mere correlation, and if so, then how do they distinguish whether it is the weight that is causing those problems and not, let's say, the inactivity, the saturated fat, and the trans fat? If someone was physically active, but binged on unsaturated fats like avocado, fish, lentils, tofu, etc... to the point of being overweight, would they be healthier than the average "healthy" weight person? Would the weight itself do more good or harm, and on what grounds would they presume to know? (Not speaking as someone with weight issues; though ironically I used to be underweight with high cholesterol, so that might have sparked my skepticism on this matter.)

One thing I notice is that many shapes in 2-space; squares, circles, etc... can all have the common word "surface" apply to them. Even non-2-space descriptions like "the Earth's surface" still refer to the kinds of things that could intersect with each other at a point, along a line, along a curve, etc... just like 2-D shapes can. It seems the word surface more generally refers to that which is either 2-dimensional or could theoretically be unfurled to FORM something 2-dimensional. (Granted, if you did that with the Earth's surface a lot of people would get hypothermia pretty quickly!) Alternatively, it seems to refer to anything which Stokes' Theorem may apply to. Are these two interpretations of the word logically equivalent? Which leaves a question; is there any specific descriptor for 3-space that doesn't apply to 2-space? If I said "region" I am not sure whether or not that's a 2-space or 3-space descriptor. For instance, if I said "this region of town" or "this region of the country" I'm not sure whether that refers to the exact ground/pavement surface in that part of the country/town, or to that surface PLUS all the air above it. I in the meantime say "region for lack of a better word. Is there any super-category of words that could apply to spheres, cubes, etc... that cannot apply to surfaces? While I'm at it, is there any common descriptor that a line, a path, a curve, etc... could have in common? (I don't mean function, I mean something broad enough to include curves or sequences of line segments that would fail the vertical line test, but still narrow enough to have only two directions on it; forward and backward; with no equivalent of right or left.)

I'm a little reluctant to butt in, but I'm slightly concerned that the OP seems somewhat new to chemistry (I don't have much hands-on experience but I've done a few chem courses in college and watched a lot of chem videos) so I figured just in case OP plans on doing this indoors I should ask whether or not rebar releases toxic fumes when dissolved in hydrochloric acid like silver does in nitric. Because if it does, it might be an idea to do this outdoors or in a fume hood.

Gah, forgot about this thread until now. Thank you for the info on salmon, Sensei. In the meantime, another question now, hopefully I'll remember to check the thread more frequently, and it is also on the topic of fluid dynamics. WARNING: Game portrays graphic violence: https://www.youtube.com/watch?v=JU9e_7QRF5A#t=1m27s In Ninja Gaiden Black, an airship is flying through a cloud during a thunderstorm. There appears to be no gap between the cloud and the windows. Assailants break open an exterior window attempting to attack the protagonist, and none of the mist from the cloud appears to wet the inside surfaces of the airship. I'll put aside whether or not it's at a high enough altitude for explosive decompression, but if, let's say, the motion of the cloud were either parallel or antiparallel to the motion of the airship (ie. no perpendicular components) would air and/or moisture be more likely to enter the airship or leave the airship? Would small enough liquid water droplets be in simple random motion analogous to the air molecules, or moving directly parallel to the outdoor airflow? Would the turbulence of the airflow ensure that some liquid water droplets made it inside if only by simple random chance?

Actually, I'm Canadian, although to be fair my association of religion with the right might have developed listening to a lot of American news. I still suspect it's not just Trump voters who'd condemn atheists for being left-wing, but to a lesser extent centrists and independents as well; you'll note that Joe Biden seems far more in favour of religion than, let's say, Bernie Sanders. (Glad as I am Biden won instead of Trump.)

I'm well aware that much of a teacher's time is spent marking; it is partly because of that, not in spite of that, that I proposed the one time slot, one course approach; 1/6 of the teaching burden translates to 1/6 of the marking burden, spreading it out amongst a greater fraction of the public, partly because many hands make light work and partly to prove to them just how much work is involved in the job. (How many voters say things like "teachers get paid to work 6 hours half the days of the year?") If there are many learning styles, why not give students the option of learning by video or book, rather than imposing the latter on them? Stuff that in theory is in the discretion of the individual teacher in practice might be bad for a teacher's career if popular opinion among voters who elect the school board officials doesn't favour it. I think drawing public attention to the benefits of these things will allow them to more effectively be done top-down.

Got it, thanks! The abstract looks very promising and I'll read the rest of it when I get a chance.

More precisely, the distinction is between "personally doesn't happen to believe in God" and "considers belief in God a bad thing." The former I wouldn't want to conflate with the latter; they shouldn't need to actively oppose it to be protected from being suspected of ill intent for having some foundation for morality other than some ancient internally contradictory scriptures; but at the same time I don't think it's a coincidence that "belief in God is a good thing" is just a milder version of the same beliefs that lead people to mistrust atheists and anti-theists alike. It's a damned if you do, damned if you don't. Throw leftism under the bus, people will say "this is how little people value honesty when they don't believe in God!" Refuse to and people say "this is how much people will fall for everything leftism is saying this week when they don't believe in God!"

They're not THE most pressing concerns, but every little bit helps. A youth centre could supervise their kids too, but for some reason taxpayer support doesn't seem to be as strong for that sort of thing. Even though they'd probably do better on a science quiz after binge-watching Magic School Bus in the lounge room than in an average science classroom.

On other sites, back when I didn't value honesty as much, I used to have a nasty habit of throwing various things associated with leftism (cannabis culture, criticism of capitalism, etc...) under the bus to see if people respect a non-liberal anti-theist more than a liberal one. It seems not to have worked. As if to drive the point home, religious-but-otherwise-leftist colleagues of mine IRL seem to get (relatively) more respect than centrist anti-theists. Over the years my disagreements with the rest of the left have increased for real anyway, yet I regret trying to throw it under the bus more than ever before. As if on cue, it's now down to a few weeks before Georgians decide whether to vote for a Democrat Reverend or a challenger who could tip the balance in favour of the Republican Party, with its recent track record of cowering before Trump. How public a show should those of us who regret attempting to throw the left under the bus make of this? I don't want to put my real name out there, as it could cost me my job, but would drawing attention (by whatever other means are available) to the fact that there were people like us out there harm the reputations of anti-theism and/or leftism, or could it help one and/or the other?

So I keep hearing about how using a plugged-in appliance, or taking a shower, or using a water faucet, during a thunderstorm, can be a safety hazard because of the indirect contact with charge carrying conductors. However, this leaves behind the question; if the insulation provided by the exterior surface of your appliance, or the presumably salt-content-limited shower water, is inadequate to prevent electrocution, why is the air between an electrical outlet and furniture placed near it considered adequate? When arranging furniture, I never saw my parents pay that much attention to how close the furniture was to the electrical outlets. Does furniture provide a plausible path from lightning hitting the wires to reaching the ground?

Not yet, but if it's "urgent just barely short of too late" now, it might've been simply "too late" if not for the hundreds of millions of potential polluters prevented from being born. That said, this whole notion might be re-evaluated based on the case CharonY's source has to make.

So I was recently thinking; hot air balloons, as a travel mechanism and leisure activity, use hot air for buoyancy on a large scale, and party balloons use helium on a small scale. Is there a way to form a middle ground between these traits? Not between helium and a large scale, but between hot air and a small scale. Is there any substance out of which a small-scale balloon can be made that can withstand steam (or at the very least warm, humid air) with which it is inflated and/or be well-insulated to retain its higher temperature for a non-trivial amount of its ascent through cold winter air? I ask this partly out of curiosity; partly because I'm considering trying it myself if I can carry out with proper safety precautions; and partly because I'm thinking, if this works, this will serve not only as a good demonstration of buoyancy (warmer than surroundings = ascent) but convection as well. (Once it cools, the liquid water weighs it down and it falls back to the ground.) This will also serve as a form of balloon that, even if let go into the air, could theoretically fall back down on its own before reaching an altitude at which it breaks, as opposed to a helium balloon which would just keep rising and rising. A re-usable balloon, in other words.

I would very much like that. I used to outright condone the one-child policy, (now I'm less sure what to think of it, other than considering the objections semi-hypocritical in light of the OP) but my contempt for the Chinese government has lately been growing for obvious reasons and I would love anything that could justify considering this criterion as valid a criticism of them as all the others.

So the pandemic has cast much about education in a whole new light. For all people's virtue-signaling about lofty ideals of education, it seems a lot of people were just using the education system as a de facto babysitting centre. Makes one wonder what else people have to say about it they might not really mean. While we're re-evaluating voters' reasons for supporting the education system, (or at least its continued existence) let's re-evaluate our ideas on what to do with it. 1. I think standardized testing should be lower-stakes, but more frequent. Disagreement among teachers about "how good is good" as far as student answers go, let alone which answers fit the bill compared to each other, should not be playing too crucial a role in entrance to university. A standardized test assessed exclusively by former teachers at that grade level, where each teacher assesses a different question, but assesses it for each student, should keep even the most unintended biases to a reasonable minimum. However, the present approach to high-stakes testing lends too much weight on too few tests, causing anyone who isn't at their A-game that day for a variety of legitimate reasons to have the deck stacked against them. 2. If we can't give students re-usable textbooks without getting parents' complaints about graffiti and students' complaints about how heavy their backpacks are; and we can't give students single-use worksheets without environmentalists complaining that we're wasting paper (never mind that, according to the education system's own statements about the carbon cycle, a tree being converted to paper and burned is better climate-wise than it dying and rotting in the forest) why not just print standardized re-usable elaminated worksheets, and have them show their workings in their exercise books so that they don't waste quite as much paper, and have less-heavy backpacks with less potential for graffiti? (Putting aside the risk of marking on them with sharpies, in which case, since it's only a few worksheets a week, it'd be easier to tell who was responsible than with an entire textbook?) 3. Bring coats into the classroom. Not to wear them, but to leave them on the chair in case of a fire in the middle of winter. You can't "stand by the fire" to keep warm; if you're downwind from the fire there's bound to be a distance at which you get smoke inhalation and frostbite at the same time. Have them bring in their coats. Putting them in their lockers reduces space for other items, and in practice at some middle schools some students leave their lockers unlocked anyway. 4. Speaking of which, why can't paper waste (to whatever extent it is inevitable and/or worse than the alternatives) be incinerated in the backyards of schools? I don't mean open-pit fires, but rather a closed, tightly-knit wire-mesh where all the paper waste from [x] past few weeks (however much is the right tradeoff between safety and efficiency to burn) is burned underneath a giant pot of water, whether to make enough coffee for everyone or turn a turbine, (or both, if it can be safely done) so as to demonstrate many principles of physics and chemistry, while demonstrating a good environmental alternative to throwing paper in the trash at the same time? 5. We're told students should be "involved" in the lesson, rather than just being talked to about the content. Something like mixing chemicals is something they can do for themselves while seeing the results, while changing electron energy levels... well, they can see the colours that result, but not the orbitals themselves. So why not make science cross-curricular with physical education, and have students role-play electrons in different orbitals? 6. So what's with the bias in favour of the written word? People are assessed on aspects of books that weren't in their movie adaptations, and some schools even do silent reading where it doesn't matter what you're reading, as long as it's a book. If the point of books like To Kill A Mockingbird was to tackle racism, doesn't the movie do so comparably effectively, if possibly more? If the point of books like Sarah Plain And Tall was to tackle the struggles of the old midwest, doesn't the movie do so comparably effectively, if possibly more? What business is it of the taxpayer the medium by which students choose to consume their fiction? 7. How do we tackle the topics about which the education system has cried wolf? Most famously the "marijuana is addictive" myth, but even things like claiming people used to believe the world was round, or that Edison invented the light bulb, tarnish the education system's credibility among those who know these things aren't true. How does the education system come clean about this without tarnishing its reputation even further? (Maintaining lies on the taxpayer's dime is not an acceptable option.) 8. Last but not least... why not have teaching be a secondary job instead of their only job? A teacher who teaches only one slot of one course will have plenty of time left over for a second part-time job, if not a full-time one, and students seem to have much more respect for teachers who are teaching from experience than from someone who teaches only from what other academics taught them. Even if the latter looks more like them.

Right, but perceived culpability for climate change; and whether or not the response is just; affects people's motivations to act on the issue, or they wouldn't bring it up. Even if the people bringing it up are being disingenuous, that still leaves voters they're pandering to whose willingness to act on climate change hinges on "who's pulling their weight" and who isn't, for real. So why CO2 per person isn't considered the relevant criteria; yet China preventing fewer potential future polluters from being born isn't either; is still a question worth considering.

For the record, I say this as someone who believes China needs to be called out more on its disproportionate role in foreign overfishing, in ozone depletion, etc... yet finds it odd that people deflect criticism of American greenhouse gas emissions by comparing them to total Chinese greenhouse gas emissions, instead of per-capita ones. Why is it that the total country's emissions matter more than the per capita emissions? Wouldn't it be more meaningful to compare the USA to, let's say, a randomly selected region of China containing a comparable number of people to the USA? For that matter, China's "one-child policy;" though implemented more for economic reasons than for environmental ones, is estimated to have prevented hundreds of millions of births. Why, then, are the same people who deflect criticism of American greenhouse gas emissions with references to Chinese greenhouse gas emissions therefore in turn crediting the one-child policy with cutting China's greenhouse gas emissions by double-digit percentages? If it's because they're climate change denialists, how come they aren't saying so outright? If not, why is it?

So with the rise of "E-sports," people who tout sports over video games have shifted their argument from their previous "but sports are more normal" to their current "but sports are healthier." But there's a tradeoff. Video games don't give you exercise, but they're also less likely to get you killed. As such, that leaves the question. Why have sports in particular become the go-to standard for encouraging fitness? Parents drive their kids to sports practice, which burns more fossil fuels and fewer calories than if they rode their bicycles there. But then if they rode their bicycles there, they might be too tired to give it their all when they get there. Individuals drive to the gym, which in cities might be a case of their car being cleaner than the outdoor air, but this sort of thing happens in clean-air small-towns as well. I keep hearing it's about teamwork, but aren't there other ways to encourage teamwork? Like, let's say, have students bicycle to and from school, and work as a team to figure out how to set up a tarp that will protect their bicycle paths from the rain and snow? What are the supposed benefits of sports, and the supposed alternatives to it? As nostalgic as I am for cartoons and video games, I'm thinking that can't necessarily be the most constructive way for kids to spend their spare time either. (Putting aside that one could always watch cartoons on the treadmill, lame as that may sound.)

So I noticed yesterday a speed indicator that plainly showed motorists in no uncertain terms how fast above the speed limit they were driving. Motorists ignored this. I assume there was a hidden camera nearby to catch these speeders so they could be ticketed later on. But that does nothing to prevent them from running over pedestrians in the meantime. So I was thinking... a car is a Faraday cage, right? As in, it spreads electrons out throughout its exterior, preventing those inside from getting shocked. So why not use an electron gun on cars caught speeding (with an exemption for emergency vehicles, of course) such that the attraction between the negatively charged car and neutral ground would increase surface friction and slow down the car?

I wasn't referring to the weight load, but to whether or not vertical oscillation hampers the way in which helicopters generate lift.

Sorry about that. Does it belong in biology instead? I brought up NGE because it drew my attention to the topic in the first place. I figure it'd be better than leaving everyone wondering what my intentions were in bringing up the topic at all. In any case, thanks for pointing out the lack of precise way to detect genetic relatives.

I originally was going to make it only about this NGE scene, but I think using TV as a jumping point for talking about real-life medical issues would be a worthwhile theme to repeatedly revisit, so I'd like to make this a megathread if moderators are okay with this. Without giving too much away, one of these characters is a clone of a member of the other character's immediate family, but neither of them knows it yet. One would think that genetics alone would prevent that kind of attraction that... seems to be what's being portrayed here. And yet, it occurs. It makes sense evolutionarily that something with risks of birth defects would generally be not sought after. But how much of this is down to ability to detect genetic similarities with someone and circumstances in life establishing their relationship as a strictly non-sexual one? Or is there something else I'm missing? (Incidentally, the same episode features the guy featured in that scene being averse to the sexual advances of the purple-haired woman shown in that scene, even though she's not related, but had been his legal guardian formonths by then. Yeah, it's that kind of show. But obviously the "circumstances, not genetics, lead to this aversion" claim seems to be a recurring theme here.)

So I'm trying to picture a scenario here. (Not a homework scenario, just a hypothetical I thought of years ago that came back to mind recently.) A bunch of people need to be rescued from a fire, but there isn't enough room in the helicopter, and the only thing attached to the helicopter they can grab onto is a spring. As they all leap onto the spring, the helicopter begins oscillating vertically; as in, they rise when the helicopter falls, the helicopter rises when they fall, etc. Presuming they didn't otherwise exceed the helicopter's weight load limit, would the vertical motion prevent the helicopter from achieving the kind of lift it would need to achieve in order to move forward without falling to the ground?

Got it, then. So is there some sort of optimum density? I assume it being TOO light means it won't stop you in time to prevent you from hitting the ground. Is there some function relating density to the rate at which it slows you down?

This is an occasional activity from my childhood. Whenever my backyard would be filled with an abundance of snow I'd dive off the patio into the snow. I am curious now how much of a risk I was assuming when I did that. I didn't jump from a very high height, but I am curious now how the ability to be safely slowed to a stop by the snow; without hitting the ground underneath and without accelerating fast enough to injure myself; relates to factors like the wetness of the snow, the snow pack, and the snow depth.