Wikipedia:Reference desk/Archives/Science/2019 April 8

Science desk
< April 7	<< Mar | April | May >>	April 9 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

April 8

Why do asteroids avoid Earth's inclination?

And why are there horizontal bands here? Were so many asteroids discovered by so few surveys that their inclination cutoffs are this visible? Sagittarian Milky Way (talk) 02:25, 8 April 2019 (UTC)

Anything floating around in the ecliptic probably got eaten by Jupiter (or else the inner planets) eons ago. 173.228.123.166 (talk) 08:36, 8 April 2019 (UTC)

But Pluto, Eris, all c. 30 biggest non-transneptunian asteroids and all major planets besides Earth (by definition) and maybe Uranus have higher orbital inclinations than the gap, Jupiter is 1.31 degrees. Shouldn't the gap be wider and softer edged if that's the reason? And wouldn't the high eccentricities be most affected? But it's the eccentricities that are less likely to get near any of the 8 planets that show this effect more. Sagittarian Milky Way (talk) 14:37, 8 April 2019 (UTC)

These bands are called asteroid families. Ruslik_Zero 19:02, 8 April 2019 (UTC)

So the lower left family just fuzzes up a little weird? With more above and below the proper inclination than near it for some reason. Why don't proper inclinations need to be relative to Jupiter to keep the families sharp edged? It's probably easily shown with a celestial sphere globe but I'm not picturing it in my head. Sagittarian Milky Way (talk) 00:45, 9 April 2019 (UTC)

Is there theoretically a way to somehow permanently modify one's body so that one could eat however much one wanted without ever gaining weight?

Despite the word "theoretically", this question seems to be asking for speculation. That's not what we do here.
The following discussion has been closed. Please do not modify it.
This article talks about the idea of a weight pill which tricks the body into thinking that it is full: https://www.msn.com/en-gb/health/diet/fat-pill-which-tricks-the-brain-into-thinking-it-is-full-is-going-to-be-tested-on-humans-and-it-could-be-available-to-take-within-five-years/ar-BBSUbj7 However, I was wondering if, theoretically speaking, there is a way to permanently alter one's body in such a way that one could eat however much one wanted of whatever foods one wanted without ever gaining any weight. If so, what exactly would such a way look like? Futurist110 (talk) 06:14, 8 April 2019 (UTC) See here. Count Iblis (talk) 07:48, 8 April 2019 (UTC) Being vegan doesn't fit the OP's premise. He wants to be able to eat anything he wants. I can think of two possibilities. One was from an old Superman comic in which somebody somehow had taken a pill which caused him to be perpetually hungry yet he doesn't gain weight. A more practical way would be something like a colostomy bag attached to the stomach. Hence, nothing would get digested. (This is at least a welcome change from the OP's usual line of questions.) ←Baseball Bugs What's up, Doc? carrots→ 11:51, 8 April 2019 (UTC) While Neal Barnard promotes veganism, what makes this work is not per se not eating meat but not eating fat in the quantities most of us do. We eat lots of refined fats which is an extremely concentrated source of energy. He mentions that carbs contain less than half of the calories in fat per gram, but even then we're comparing pure fat to pure sugar. If you instead consider energy rich foods that are readily available from Nature, then you'll have to do with whole grains and starches. You may be able to find nuts and seeds which are more concentrated sources of energy, but they do also contain lots of fiber. One kg of potatoes only contains 770 Kcal, that's less energy than in 9 spoons of olive oil. And if the OP wants a solution for eating as much of the artificial foods he can put in his stomach, note that you can in principle drink liters of olive oil per day, getting 40,000 Kcal a day could well be feasible. Count Iblis (talk) 21:21, 8 April 2019 (UTC) Reducing the size of or bypassing the stomach completely is one not-only-theoretical possibility, see Bariatric surgery. It is not exempt from dangers and it is used only on serious cases of obesity (but it is not indicated in cases of bulimia) 89.204.138.56 (talk) 16:03, 8 April 2019 (UTC) Marco Pagliero Berlin Yeah, I'm well-aware of this option, but the problem with this option is that it actually limits how much food you can eat. I was looking for a solution that does not limit how much food one can eat. Futurist110 (talk) 17:02, 8 April 2019 (UTC) Nothing like what the OP is asking about exists at all. You can't have your cake and eat it too. --Jayron32 17:32, 8 April 2019 (UTC)

mechanical car

Would it be technologically or economically unfeasible nowadays to make a mechanical car like they used to make until say the 1970s? I.e. electric starter motor and stuff like headlamps, but no electronics in the moving bits, carbeurators instead of fuel injection, etc. Or since EFI really does seem to have been a big improvement over carbs, it could be a 1990's-ish car with EFI but without the supposedly 100 million lines of computer code supposedly found in a modern car. Does all that computerization really help safety, fuel economy, performance, or whatever? My friend bought a new car recently and has had to get multiple software updates for it, which seems completely insane. Teslas even keep self-installing updates over the air! So I wonder what the obstacles would be to current car manufacturer re-creating a 1996 Toyota Corolla or something like that. Thanks. 173.228.123.166 (talk) 08:52, 8 April 2019 (UTC)

Added: similar question if they wanted to make an electric car with a Tesla-like power system. I take for granted that they'd need computerized battery charging and motor control, but would want a normal dashboard with knobs instead of a computer screen, no autopilot, etc.` Again basically 1990s technology except for the batteries, I think. Thanks. 173.228.123.166 (talk) 08:57, 8 April 2019 (UTC)

Are you looking for a book that evaluates engineering trade-offs in modern car design?

Nimur (talk) 11:05, 8 April 2019 (UTC)

• Does all that computerization really help safety, fuel economy, performance, or whatever?

Yes. No. Maybe.

OK, maybe not "all" of it. Engine control systems do help, and do benefit from being heavily computerised. They allow more sensors (within a finite budget for components and connections), they're more reliable, they allow much better fault tolerance, they allow better diagnostics with simple local-garage tools (rather than needing a per-brand dealer). Anti-lock braking benefits massively too. Pollution is reduced as much pollution (especially diesels) isn't from new cars, it's from cars with wear and faults. Engine computerisation helps hugely with that.

The rest of it? Not so much. There's a diminishing return, once the major benefits have been achieved, then the next benefits are more minor, yet take more complexity to achieve them. Also the pace of change can be a problem – is increasing sophistication (i.e. complexity) overtaking quality (i.e. reliability). A number of cars now just can't be locked reliably, because basic engineering mistakes in cryptographic security are being made. Keyless entry systems (you just need the key in your pocket, not to press anything or put it in the lock) are mostly wide-open at present, even on some very high-end cars.

Features like overall integration, a single data bus around the whole car, internet connectivity and the integration of data services (such as giving Wi-Fi access to passengers) with the architecture of the "car" itself has been handled very badly. Some cars (mostly US) are now susceptible to hacking attacks whilst driving, because systems that a competent engineer would isolate completely have instead been integrated (they share hardware) to save money in the car factory. The car industry is very bad at this and it's now getting to a point where it can become damaging. In car production, cost-saving is everything.

Is assisted braking a good thing? Should cars start to brake on their own, if they detect an obstacle in front? Well, what's the worst that could happen? They might stop on a motorway. It's not a terribly difficult sensor issue (radar or optical sensors detecting an object in front) and the effect of this system (applying the brakes or not) is relatively simple. Even if the system fails suddenly and completely, it's not worse than any other recent car.

If we start to see more systems like intensive driver assistance, then things are likely to get much worse, before they get better. That's a far harder problem. The car has to go round a curve by choosing a line and a speed that's appropriate, from a restricted vision system. If I drive nearby to my house, I go round a perfect "Tesla trap", which is made safer for humans by a large hand-written sign saying "Cows!" (Teslas, as yet, cannot read). What the Tesla doesn't get any warning of is that the coefficient of friction on that steep, blind, tight curve past the farm entrance is only half what it ought to be (thankyou, cows). If you drive a car into that corner at a legal speed, you are quite likely to skid and crash. Locals in fast cars might drift 'interestingly' round that corner in a four-wheel slide (depending on skill). But an "average" robo-car of a decade from now is going to have enough smarts to drive badly (but legally) for the conditions, yet not have the Tesla's rally-car performance to corner it like a hooligan.

Computerisation of cars, especially engines, has so far been a great benefit. Analogue electronic fuel injection in the 1970s was much less so (good performance, but terrible for maintenance). I'm concerned though that we're now getting to a point where the push to integrate everything (do I really need Bluetooth? Why?) is exceeding the car industry's ability to deliver it competently and safely. Andy Dingley (talk) 11:38, 8 April 2019 (UTC)

Just one minor quibble, though most of your analysis is good, is that the Tesla may not be able to predict the cow shit on the road before it gets there, but what it CAN do much better than you is react to the cow shit once it hits it. Machines are much better than humans at reaction times, which is why assisted braking is a thing. If (and this is the biggest if) it can properly detect a problem, it can react and correct before you are even aware of the problem. Humans drivers kill more people with there cars than is really acceptable. I suspect that even with current technology levels, self-driving cars would kill far less people than humans do with their own cars purely because humans are stupid and slow. And yet, we freak the fuck out when a Tesla kills someone, the thousands of humans we kill every year with our cars gets a slight shrug. The expectation that self-driving cars need to have zero accidents and zero fatalities belies the problem that the human drivers they are replacing already have an unacceptable number of fatal accidents in their cars. Perfect is the enemy of good. --Jayron32 13:29, 9 April 2019 (UTC)

I suspect one reason the public gets hysterical about self-driving cars involved in accidents is the same reason that plane crashes get so much press: It's because when we drive a car, we have the illusion that we are in total control, whereas if someone (or something) else is driving, then we are dependent on them to make the right decisions. However, if you've seen many accidents over the years, you may have seen a pattern: That many accidents are due to one or more drivers not paying attention. Theoretically, self-driving cars should be better able to react to dangers and do something about them. That doesn't mean the driver should just lay back and take a nap. A combination of the two is ideal. Of course, even in a conventional car, the technology can betray us. But overall, as you indicate, the number of fatalities need not be so horrendously high as it is now. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:17, 9 April 2019 (UTC)

That's why I specifically avoided mentioning Teslas as the problem. A Tesla is a high-end, high-performance car, with the ability to drive as a 'drift car' quite effectively in conditions of four-wheel slip. But basic Newtonian physics means that granny's shopping trolley in a few years will have nothing like the same performance, or reaction time (limited by the forces and accelerations available). The current trick of fast reactions and a vast excess of instant power won't be available to those designers. Andy Dingley (talk) 15:05, 9 April 2019 (UTC)

Of course, if the self-steering vehicle is only moving slowly, then nothing could go wrong.

Could it? https://www.youtube.com/watch?v=mDsL4CwBEL4 Andy Dingley (talk) 19:55, 9 April 2019 (UTC)

My first car, a 1960s Hillman Hunter, was prone to inexplicable ignition failures. Usually, you had to remove the points from the distributor, rub the contacts with a bit of emery paper, put it back together and then check the gap with a feeler gauge. I once stripped down a reluctant carburettor on the dining room table (mother was not amused). Every so often, the timing would have to be re-synchronised so that the distributor was sparking at the right moment. You could pay a garage to do it, or try it yourself with the aid of a Haynes Manual, often with unpredictable results. There used to be a firm in London called "Home Tune" who would come to your house in a van and do it for you. On cold mornings, there was an art to manipulating the manual choke; not enough wouldn't start it and too much would flood the engine; it had to be fed in gradually over the first few miles to avoid a spluttering halt. Nowadays, you only have to lift the bonnet every now and again to check the oil and water. God bless electronics say I. Alansplodge (talk) 17:25, 8 April 2019 (UTC)

If you want a vehicle with little or no electronics, a good choice would be a first generation (1995–2006) Mercedes-Benz Sprinter with a Mercedes-Benz OM601 engine. That engine had mechanical fuel injection and of course diesels don't have electronic ignition (or any other kind). If you can find one, a Mercedes-Benz TN with the same engine would be an even better choice. The sprinter doesn't get "improved" as often as most vehicles. Your next step would be to work with a good mechanic/vehicle customizer to ferret out the few bits of electronics left and replace them with simpler systems. Basically you would want to end up with a 2006 Sprinter with the electrical system modified to look like a 1977 TN. --Guy Macon (talk) 18:55, 8 April 2019 (UTC)

If you want a car with virtually no electronics at all, you might be able to find a Model A Ford someplace. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:18, 9 April 2019 (UTC)

It might be interesting to design a car that could withstand an EMP. Some systems really do need to be electrical, like headlights and signal lights, but I suppose you could have backup kerosene lanterns to affix to the front as headlights, following an EMP, and use hand signals. And you would also lose the radio, etc. But with any luck you would still have basic transportation. Shielding the wires is another option, but whether that's enough depends on the strength and proximity of the EMP. SinisterLefty (talk) 16:59, 9 April 2019 (UTC)

If people with longevity genes are going to reproduce much more than the general population, are we going to see a massive increase in the number of 120+ year olds?

If people with longevity genes are going to reproduce much more than the rest of the population will for a sufficiently long time period, and assuming that there are not going to be any developments in the negative (such as a massive spread of some kind of new infections or new diseases), are we gradually going to see a massive increase in the number of 120+ year olds? Futurist110 (talk) 17:04, 8 April 2019 (UTC)

Probably not, because your premise "people with longevity genes are going to reproduce much more than the general population" is mistaken.

Barring extreme medical interventions, women do and will become infertile at the same age that they always have done, around 50, regardless of them subsequently living to, say, 110 rather than 70. Increased longevity therefore does not result in increased reproduction.

I meant reproduce more while they are still fertile. Futurist110 (talk) 17:49, 8 April 2019 (UTC)

See below. In countries where people live longer, they reproduce less while they are fertile. This is a well documented trend. --Jayron32 18:01, 8 April 2019 (UTC)

Moreover, longevity genes are not greatly favoured by Natural selection because their effects only become manifest after reproduction has ceased, so they don't get selected for very much. (There may be a minor effect because children with more living elderly relatives may have a slight advantage.) {The poster formerly known as 87.81.230.195} 90.200.138.194 (talk) 17:20, 8 April 2019 (UTC)

What if, purely hypothetically, they would have been favored more by natural selection, though? For instance, what if the government will subsidize people from long-lived families to reproduce much more? Futurist110 (talk) 17:49, 8 April 2019 (UTC)

Purely, hypothetically, we can't answer that question because there's no data on it. It would be pure speculation and we don't do that in this venue. --Jayron32 18:02, 8 April 2019 (UTC)

(edit conflict) In general, as a country's economic and health care situation improves, it's population growth rate declines. This is sometimes called the economic-demographic paradox. It is generally believed that in countries with advanced, post-industrial economies, having children is an economic liability, so the birthrate often drops to below replacement rate. This is confirmed in most of the post-industrial world, where population growth rates have plateaued or are declining, the exception is places like Canada and the U.S., where the declining population growth is offset by immigration. Without immigration, the U.S. and Canada would have demographics that looked like Japan, where the population is rapidly aging. So, in countries with the highest life expectancy, the birth rate is low, often for the same reason that the life expectancy is high. Highly educated, economically well-off populations have much less children, so even if they live longer they tend to still have declining populations. --Jayron32 17:29, 8 April 2019 (UTC)

Yes, I get that. However, this increase in lifespan was not caused by genes but rather due to environmental improvements (such as better medicine and healthcare) that allow people to live longer. Meanwhile, I was talking about humans evolving in such a way that causes them to live longer (as in, due to longevity genes becoming more widespread among the population due to higher fertility among people with these genes in this scenario). Futurist110 (talk) 17:49, 8 April 2019 (UTC)

Yes, but as I explain above, in countries where people live longer, it is well documented that they have much less children when they are fertile. This is a known, demonstrated, and repeatable bit of data. It's fairly settled science in population studies. --Jayron32 18:01, 8 April 2019 (UTC)

What about the people within developed countries? Do people in the U.S. who live longer also have less children than Americans who live less longer? Futurist110 (talk) 21:28, 8 April 2019 (UTC)

Well, there's two different questions to ask there, and it's important to note that a community of people is not the same as a bunch of individual people treated as a group. For example, if we selectively cull all Americans who lived to over the age of 100, and then looked at their fecundity, that is NOT the same thing as finding the U.S. state with the highest life expectancy, and then looking at THEIR fecundity. Those are different things, and should lead to different conclusions. --Jayron32 16:09, 9 April 2019 (UTC)

You can read Methuselah's Children to understand what can happen in such a case :). Ruslik_Zero 18:56, 8 April 2019 (UTC)

Futurist110, when you ask a question in the form "Since X is true, are we going to see Y" and you get multiple responses saying that X is false, please don't dig in your heels and keep asking. --Guy Macon (talk) 18:58, 8 April 2019 (UTC)

I didn't say since X is true, though. Rather, I said if X is true. In other words, it's a hypothetical question. Futurist110 (talk) 23:53, 8 April 2019 (UTC)

If the World were different than it is in way x, all sorts of other differences y₁, y₂, . . . y_n might result, but generally we can't tell what they would be because the World – and particularly peoples' reactions to it – is and are irreducibly complex. A lot of Science Fiction, for both entertainment and philosophical purposes, imagines various x's and proposes various y's, but the y's described are generally a deliberately restricted sub-set of what the writers are particularly interested in examining, and few really think their y's would be anywhere near the full story. Futurology is hard, Psychohistory has not yet been realised and may never be, and unforseen unintended consequences will likely always bedevil us. {The poster formerly known as 87.81.230.195} 90.200.138.194 (talk) 12:10, 9 April 2019 (UTC)

Pursuing what amounts to a question about selective breeding of humans as the OP is doing, whether couched as an "interesting theoretical idea of what might happen" or as a plan for government intervention, displays the reasoning of a naive eugenicist. The history of attempts to improve on millions of years of evolution should give reason to refrain from meddling with a quick fix that can have unintended consequences such as loss of Genetic diversity. DroneB (talk) 14:27, 9 April 2019 (UTC)

Are you opposed to all forms of eugenics (even positive eugenics)? For instance, do you oppose allowing pregnant women to find out if their fetus has Down's syndrome so that they could then proceed to abort it if it indeed has this syndrome? Likewise, do you oppose allowing people who use sperm donors or egg donors to find out various information about their donors--such as their IQ, education level, criminal history, et cetera? After all, whether you like it or not, choosing whom to reproduce with is also a form of eugenics. If you're going to reproduce with a genius, the odds of you having smart, successful children are going to be more than if you will reproduce with a low-IQ person--though this difference might not be too great in one generation due to regression toward the mean.

For what it's worth, I certainly consider negative eugenics to be abhorrent. However, I don't have a problem with positive eugenics. What would be really nice would be if everyone who did IVF could select for the embryo(s) with the best genes and implant those embryos--or, alternatively, edit the genes of embryos in order to improve their genes. Unless you also have a problem with, say, selective abortions of Down's syndrome fetuses, it would be rather hard to complain about this. As for the loss of genetic diversity, one would think that, for instance, a society where everyone has an IQ in the 160 to 190 range (before adjustment to make the average IQ 100 again, of course) would be much better off than a society where everyone has an IQ of 10 to 190. Sure, the latter is going to have much more genetic diversity, but it is also going to have much more underperformers and much less overperformers--which in turn will very likely mean a society that is going to be much poorer per capita (given the relationship between national wealth and average national IQ, as Garett Jones concluded in his book Hive Mind). Also, as much as you might object to this, the people who are going to select the smartest embryos/edit the genes of their embryos for traits such as intelligence are the ones whose descendants are going to get ahead in life--just like Ashkenazi Jews currently have an advantage in terms of wealth, IQ, achievement, et cetera as a very possible result of centuries of eugenic fertility patterns among them. Futurist110 (talk) 00:17, 10 April 2019 (UTC)

No comment. My citation of the article Eugenics about the history of human breeding control was not an invitation to debate. WP:NOTOPINION. DroneB (talk) 14:14, 10 April 2019 (UTC)

But who determines what the "best genes" are and what constitutes "improvement"? And selecting for IQ would require us to be able to truly determine what it actually is and what gene (or, more likely, genes) control it. --Khajidha (talk) 11:09, 10 April 2019 (UTC)

Also, you are highly oversimplifying (or misunderstanding) the distinction between negative eugenics and positive eugenics. Negative eugenics includes many things that are commonly accepted: sex education, access to birth control, etc. Conversely, I find some of the things considered "positive eugenics" to be morally repugnant (taxation of the childless, for example). --Khajidha (talk) 11:14, 10 April 2019 (UTC)

Life expectancy may rise a bit but by far less than what you might expect. Lifestyle factors account for the vast majority of all diseases in Western civilization. Our bodies have evolved not to get cardiovascular disease, cancer at rates that are quite a bit lower than the current rate, and Alzheimer's disease would not occur either. However, our civilization has evolved too, our lifestyle habits have been adapted over the centuries to what our bodies can tolerate on relatively short time scales and what we find convenient. It's then logical that whatever physiological system can be burdened the most before that leads to problem, would end up burdened the most by such a process. So, you would expect that the 120+ generation will quickly adopt a lifestyle that will undo most of the be benefit they get from their superior genes. If they have genes that make them far less prone to lung cancer, they may end up becoming chain smokers and get lung cancer at rates similar to what people get in our society. Count Iblis (talk) 21:41, 8 April 2019 (UTC)

As for 120-year-olds, we haven't had any such people, not even Jeanne Calment. She actually died in 1934; when she died her family pretended it was her daughter Yvonne's death to avoid tax problems, and this was done by having Yvonne (born in 1898) adopt Jeanne's name and birthdate. It might not seem a big deal that Yvonne lied about her age, but a lie is still a lie even if it doesn't hurt. Gerontologists are not admitting this because they are selfishly trying to prove it's not true and that JC's 122-year-life is genuine. Georgia guy (talk) 22:01, 8 April 2019 (UTC)

How does a 36 year old woman impersonate her 59 year old mother without anyone noticing? Sagittarian Milky Way (talk) 22:38, 8 April 2019 (UTC)

Please do research on articles that talk about this theory. Are you asking this question for real or are you asking it simply because you're trying to prove it is wrong?? Georgia guy (talk) 23:02, 8 April 2019 (UTC)

I've read a bit about this theory. Frankly, I wonder if any supercentenarian with a child of the same sex who died as a young adult could be accused of actually being this child--specifically being this child and impersonating his or her mother or father. Futurist110 (talk) 23:52, 8 April 2019 (UTC)

As the Spartans would say: If. In general terms, if individuals with a particular gene reproduce more than those without, then that gene will become more common in the population, and so whatever traits that gene causes will also become more common. That's pretty much the definition of evolution. However, your scenario makes a lot of assumptions. Others have explained why extreme longetivity generally doesn't offer any reproductive advantages. But on top of that, there are many causes of death other than "old age". Even if the entire population somehow evolved to be capable of living to >120, actually getting a "massive increase in 120+ year olds" would (depending on what counts as "massive") also require a massive reduction in other causes of death. Iapetus (talk) 09:28, 9 April 2019 (UTC)

Makes sense. Futurist110 (talk) 00:17, 10 April 2019 (UTC)

As an aside, actually your first sentence is a definition of natural selection, not of evolution. Scientists do not doubt that evolution is heavily influenced by natural selection, but other processes also influence it, such as genetic drift, mutation, introgression, etc. In general it is valuable to distinguish outcome (evolution) from a process (natural selection) generating, and thus explaining, the outcome. Jmchutchinson (talk) 17:44, 9 April 2019 (UTC)

Evolution is not forward looking. A benefit in the future is irrelevant to evolutionary pressures now. There would seem to be no more pressure to increase longevity alleles than there currently is to remove such "anti-longevity" alleles as Huntington's disease. In both cases, all or most of the individual's reproduction will be over before the alleles really come into play. --Khajidha (talk) 14:22, 9 April 2019 (UTC)