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October 31

Genetic testing on plants.

Don't anyone do genetic testing on plants? Would it be easy to genetically change the color of leaves? Say, leaves can already be red yellow and dark purple, can trees be genetically altered to produce those colors year-round? But then, let's say there are no naturally colored blue leaves. Can blue genes say, from the fur of a blue-colored animal, or blue colored flower petal, be used to make the leaves of a tree be blue? The only genetic testing I have heard of, was some plants have been genetically altered to produce fluorescence. This happened when I asked a plant professor can any plants produce light, he said the ones that can naturally fluoresce, are not bright enough for the human eye to see, so some plants have genetically modified to produce brighter. So, I imagine genetic testing on plants are more legal than on animals, anyone have any feedback for vegetables/fruits? 67.165.185.178 (talk) 02:14, 31 October 2022 (UTC).[reply]

Genetically engineering plants is a major field of human endeavor, but aside from making a blue rose I have not heard of much effort being expended on purely aesthetic modifications. Abductive (reasoning) 03:29, 31 October 2022 (UTC)[reply]

And also, can random probabilities be distributed? For example, a tree with 4 gene colored leaves, red blue green purple, but each leaf has a 1/4th relatively random probability of each color. That would be dope! 67.165.185.178 (talk) 04:07, 31 October 2022 (UTC).[reply]

Epigenetic variations may determine phenotypical aspects such as leaf colour. In fact, the cell differentiation in higher organism, in which some cells become neurons and others muscle cells, is an example of local epigenetic variation. The discovery of a genetic switch controlling Streptococcus pneumoniae that allows the bacterium to randomly change its characteristics would appear to imply that random leaf colours or similar random local phenotypical variations are theoretically possible. Human fingerprint patterns may be a somewhat unspectacular example, but the situation is unclear. Perhaps some Turing patterns and variegated animal coloration are also be due to local random epigenetic variations. --Lambiam 09:07, 31 October 2022 (UTC)[reply]

A relevant research paper: "Integument pattern formation involves genetic and epigenetic controls: feather arrays simulated by digital hormone models". --Lambiam 09:19, 31 October 2022 (UTC)[reply]

Genetic modification has been done for millenia on both plants and animals. Cross-breeding, inbreeding, etc. are all artificial selection using the genetics the organisms already have. If the OP is talking about lab-based genetic modification, that's where the law might come into the picture. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:06, 31 October 2022 (UTC)[reply]

As noted above, artificial selection (aka "breeding") is unregulated, and has been done by humans since before recorded history (see Neolithic Revolution). In terms of laboratory-modified organisms, what is usually called "GMO"s or genetically modified organisms, many countries have a type of ethics committee which must review all GMO-based research, in the U.S. this is called an Institutional Biosafety Committee, which reviews all prospective genetic modification experiments. There is required, by US law, to be an IBC at any institution carrying out such research, whether academic, governmental, or private. Genetic modification of plants is an active area of research, but it is carefully regulated. --Jayron 32 15:02, 31 October 2022 (UTC)[reply]

The green color of most plant's leaves derives from chlorophyll, which is an essential part of the plant's metabolism. I don't think it would be as easy to change leaf color as it is to change, for example, flower color, without impacting the viability of the plant. Green leaves change color in the autumn because they're dying. CodeTalker (talk) 16:05, 31 October 2022 (UTC)[reply]

One year I planted some beans, and 2 or 3 of them came up out of the ground, completely white. Obviously they didn't survive very long, once they exhausted the nutrients inside the original beans. There is a simple explanation for that. A green leaf reflects green and absorbs red and blue light, converting it into energy the plant can use. So a white plant reflecting everything cannot sustain itself. But a plant that is a darker color, for instance purple like some coleuses or red cabbage are, will absorb more green and less blue and red, and will sustain itself. Dhrm77 (talk) 16:56, 31 October 2022 (UTC)[reply]

Lots of plants have leaves of colors other than green. Tradescantia pallida, Tinantia pringlei, some cultivars of Japanese maple and of Begonia and of ti plants, for examples. Many of these plants still have chlorophyll, but there are additional compounds in the leaves that lead to the other colors. --Jayron 32 18:14, 31 October 2022 (UTC)[reply]

Most of those are due to the red/blue/purple colors of anthocyanins. Note that these chemicals change from reddish to bluish based on pH.--User:Khajidha (talk) (contributions) 19:16, 31 October 2022 (UTC)[reply]

And for a really blue plant see Eryngium ovinum.[1] Graeme Bartlett (talk) 21:09, 31 October 2022 (UTC)[reply]

What about changing the color of say, strawberries or raspberries, to something else? I don't think the red is necessary for survival? And ss this something that an undergraduate biology lab can do? Or are these all done by PhD people? — Preceding unsigned comment added by 67.165.185.178 (talk) 01:32, 1 November 2022 (UTC)[reply]

There are the first stirrings of a GMO biohacker movement, with people doing it in their garages, ala Steve Jobs/Steve Wozniak. Abductive (reasoning) 03:42, 1 November 2022 (UTC)[reply]

So when we add new genes or DNA say to a plant, and I just adding new genes/DNA or am I replacing (like substituting)? Take that blue rose for example. Adding a blue-colored gene/DNA when it already might have that for the red color, I would have to remove it, right? And that would require looking for the particular gene or DNA to replace? 67.165.185.178 (talk) 10:26, 2 November 2022 (UTC).[reply]

In the case of the not-remotely-actually-blue rose, as it states in article, they spliced in a gene for the naturally occurring delphinidin into a white rose, then, when the color was not satisfactory, used "RNA interference (RNAi) technology to depress all other color production by endogenous genes by blocking a crucial protein in color production, called dihydroflavonol 4-reductase (DFR)", which could hardly be called successful. This shows to go you that genetic engineering is not remotely simple, that living things are difficult to work with, and that such intricacies are not easily taught on a forum such as this. One would have to take university courses the equivalent of a Master's degree in order to fully understand this material and the limitations of genetic manipulation. Abductive (reasoning) 00:34, 3 November 2022 (UTC)[reply]

Would any bio major know, what is the easier part, extracting DNA, or insertion? For example, suppose someone gave the "here's the blue DNA you're looking for" then was that the harder part or easier part. And how about the fact that we have so many cells in our body, does adding/replacing DNA in a few cells actually change anything? 67.165.185.178 (talk) 01:28, 3 November 2022 (UTC).[reply]

Finding genes is not easy, but it preceded our ability to genetically engineer by many years. Back in the day they used to use an air pistol to shoot DNA into plant cells. Also they use viral machinery to deliver the DNA, see CRISPR gene editing. Generally one can tranform only a few cells or low percentage of cells, so one usually thinks along the lines of the offspring being the ones that one is genetically engineering. Gene therapy aims to help individuals now, rather than cure their future offspring, and is fraught with difficulties. Abductive (reasoning) 02:25, 3 November 2022 (UTC)[reply]

Abductive, I'm looking at the blue rose article and it took 13 years of collaborative work between an Australian company and Japanese company. So that GMO work-at-home garage lab, I would think would not be able to do as something as sophisticated as a blue rose? Btw, the process for how the 2 companies did it, adding 2 genes and altering a 3rd, that would strike me as proprietary company secret. Was it a secret at the time, and they decided to make it known years later? I note that the article says nothing about the current blue roses they sell, only their 1st 1s, which were not blue, so maybe their current blue roses are proprietary information. 67.165.185.178 (talk) 18:43, 3 November 2022 (UTC).[reply]

Perhaps there is more to the editing than the article states, but there are Plant Patents, and it's likely that they were doing it to advance the field rather than for profit. And those guys didn't have CRISPR. The garage analogy stands: The technology is getting cheaper every day, the machines less finicky, and the methods more widely disseminated due to undergrads and grad students getting trained on how to do it all the time. Abductive (reasoning) 08:40, 4 November 2022 (UTC)[reply]

November 1

Of Frogs and Men

I've always held this notion that humans are somehow descended from frogs. Even apes and monkeys appear to have certain frog-like features. Unfortunately I can't find much of anything in the way of direct genetic evidence to support such a claim. (Most people seem to believe that we are rather highly-evolved mice, but I just don't see it.) Earl of Arundel (talk) 04:47, 1 November 2022 (UTC)[reply]

What you're looking for is the Most Recent Common Ancestor in each case (see also Phylogenetic tree), that is, if you go back in time, you will find an organism that evolved into frogs and humans, another for mice and humans and yet another for apes and humans. For the first you would need to go back hundreds of millions of years (see Tetrapods), for the second several tens of millions (see Euarchontoglires) and for the last (taking the Chimpanzee as an example) about 10 million years (see Chimpanzee–human last common ancestor). Mikenorton (talk) 09:58, 1 November 2022 (UTC)[reply]

(edit conflict) Are you serious? Both humans and mice are tetrapods, but the split in the evolutionary tree between the Lissamphibia, to which frogs belong, and all other tetrapods, including the Amniota to which all mammals belong (not considering shape-shifting reptilians, which presumably, if not alien, are Sauria – also not Lissamphibia) took place more than 300 million years ago. It is hardly surprising you cannot find genetic evidence for the extraordinary claim. As there is an unsurmountable mountain of evidence against it, you'd need extraordinarily extraordinary evidence. --Lambiam 10:07, 1 November 2022 (UTC)[reply]

So, you're making a common misconception; that humans (or any other species) descended from some species that still exists. That's not really how it works. Instead, it's helpful to think that somewhere in the past there is a most recent common ancestor (MRCA) to both humans and to frogs. That species may (or may not) be convenient to categorize as a "frog", but that's really irrelevant; by definition both modern humans and modern frogs are equally as related to that species. The most recent common ancestor of humans and frogs would have been among the earliest tetrapods, before the development of amniotes; the oldest amniote fossils date to 313-316 million years ago, which would be the latest possible most recent common ancestor of both frogs and humans. It likely looked nothing like either a frog (or a human). Being from the carboniferous period, it would look like one of the animals listed at List of Carboniferous tetrapods. --Jayron 32 12:20, 1 November 2022 (UTC)[reply]

Pederpes finneyae

Maybe it looked like this whatcheeriid, which doesn't resemble a frog except for the smile. I must say, though, she reminds me of one of my great aunts. --Lambiam 17:25, 1 November 2022 (UTC)[reply]

You may be interested in Frogs and humans are kissing cousins from Nature and Frogs Surprisingly Like Humans, Genetically Speaking, both referencing research by Richard Harland (biologist). Alansplodge (talk) 13:43, 1 November 2022 (UTC)[reply]

It is both surprising and unsurprising; unsurprising when you realize that the other organism noted in the study, the zebrafish, is much more distantly related to the other three, something we know that since the MRCA of zebrafish to tetrapods would be much older than that, which would be the divergence of ray-finned fish and lobe-finned fish, which would have happened in the Silurian, about 418 mya. The commonality of the genetics of all tetrapods is unsurprising; most of our major structures and components are quite similar. We have the same skeletal structure, the same major organ groups in the same places, the same kinds of metabolism, etc. etc. Most of the genes would be the same or very similar. Even humans and bananas have 60% of their DNA in common. --Jayron 32 14:30, 1 November 2022 (UTC)[reply]

Wow, much thanks to everyone for the informative comments. This is a such a complex field of study. Also interesting how parallel evolution can produce somewhat similar traits/features. So I guess this extends to our relationship with modern apes; not necessarily directly per-se from chimpanzees, although we do share a common recent ancestor. Fascinating. Well, humans ARE at more or less highly-evolved worms anyway. I wonder if that direct ancestor still exists (eg. C. elegens)? Earl of Arundel (talk) 23:22, 3 November 2022 (UTC)[reply]

The MRCA of C. elegans and H. sapiens was a nephrozoon, a worm-like aquatic animal. The split into Protostomia (to which nematodes belong) and Deuterostomia (to which mammals belong) is estimated to have occurred some 620 million years ago. Obviously, the earliest protostomes were also worm-like, but there is no reason to think they closely resembled nematodes, Because of their soft bodies, nematodes leave not much of an imprint on the fossil record, but the oldest putative nematoid fossils appear to date to 470 million years ago.^[2] --Lambiam 12:50, 4 November 2022 (UTC)[reply]

I often wonder if we will ever see a technology emerge that will allow us to see much further back in the fossil record. Now obviously if the fossil has been exposed to magma or what have you, in those kinds of cases the remains will likely be destroyed for all practical purposes. But otherwise, special imaging techniques or what have you might be able to look even deeper into the past. Who knows, we may find that C. elegans for example dating back even a billion years or more, I imagine. (Just being an "arm-chair scientist" here, of course. Surely there are many other important considerations.) Earl of Arundel (talk) 02:44, 5 November 2022 (UTC)[reply]

BTW, C. elegans is as "highly evolved" as H. sapiens. It is exquisitely adapted to its ecological niche. --Lambiam 12:54, 4 November 2022 (UTC)[reply]

Just to clarify and elaborate on Lambiam's very salient point, every living being alive today is equally as "highly evolved" as every other one. The entire system of life started out in the murky past, but that nematode is part of a chain of evolution which is equally as long as the chain of evolution that produced you. In terms of "time we've spent evolving", all of life has been evolving since life began, so we're all equally as highly evolved. If you really want to get pedantic, since nematodes have a shorter life cycle than mammals (which is to say, they get in more generations in less time), if you want to get down to it, the nematode is actually more evolved than a human is. --Jayron 32 16:30, 4 November 2022 (UTC)[reply]

I see. So the assumption that "less complexity" necessarily means "lower on the chain of evolution" is clearly flawed. Modern organisms are highly-evolved in their own, unique ways, adapting to changing environmental pressures for aeons. Fair enough. Kind of sad to think that not a single extant ancestor of ours can be found on Earth today in its original form though. Like, the DNA sequences of our ancestors have literally been forever erased by the sands of time! How utterly depressing.... Earl of Arundel (talk) 02:27, 5 November 2022 (UTC)[reply]

Watt and erg relation

Can we write that: 1 Watt/cm^2 = (10^7 ergs/cm^2) * sec Why or Why not ? — Preceding unsigned comment added by Malypaet (talk • contribs) 18:16, 1 November 2022 (UTC)[reply]

Because that's not right. A Watt is a J/sec, so a Watt/cm^2 is a J/(sec * cm^2), and since a J = 10^7 ergs, then a Watt/cm^2 = 10^7 ergs/(sec * cm^2). You need to divide by sec, not multiply. --Jayron 32 18:56, 1 November 2022 (UTC)[reply]

Creating calcium carbonate blocks

Is it possible to cast calcium carbonate in large format solids, or create via some chemical reaction? I was watching some folks laser etch eggshells and wanted to get my hands on some large pieces of solid caco3 but cant find any suppliers, or if its even possible. thanks ^Thanks,L3X1 ◊distænt write◊ 22:25, 1 November 2022 (UTC)[reply]

sounds to me you're trying to reinvent limestone :) Dr Dima (talk) 22:56, 1 November 2022 (UTC)[reply]

"We are one of the noted manufacturers and suppliers of High Quality Calcium Carbonate Blocks. These blocks are made under the supervision of our trained professionals so that the final output fulfill with the international quality standards. As per the variegated requirements of clients, these blocks are made available in different sizes and specifications. With the help of our wide distribution network, we make sure safe transportation of these blocks within the specified period of time. High Quality Calcium Carbonate Blocks are known for high strength, wear & tear resistance and excellent electricity conductivity". [3] Alansplodge (talk) 23:11, 1 November 2022 (UTC)[reply]

Thanks! ^Thanks,L3X1 ◊distænt write◊ 00:35, 2 November 2022 (UTC)[reply]

Depending on what you want to use it for, perhaps optical purposes, see Iceland spar. Graeme Bartlett (talk) 00:10, 2 November 2022 (UTC)[reply]

Calcium carbonate is what is the difference between hot tap water and cold tap water. How would 1 extract it from water though? Or ice. 67.165.185.178 (talk) 00:47, 2 November 2022 (UTC).[reply]

Reportedly, the temperature also makes a difference between hot tap water and cold tap water. Allow the water to evaporate, and you'll be left with limescale. --Lambiam 03:29, 2 November 2022 (UTC)[reply]

Calcium carbonate is a very common mineral, and exists in MANY different forms and in many different contexts in the world. It is a major component of hard water, often in places where the water supply is in contact with soil or rocks that contains high quantities of calcium carbonate. Various forms of calcium carbonate, or rocks that include calcium carbonate, include calcite, chalk, limestone, and marble. When used as a soil additive, it is commonly called lime, though that term also refers to a number of other calcium compounds, such as calcium oxide and calcium hydroxide, among others. --Jayron 32 11:17, 2 November 2022 (UTC)[reply]

Can Alansplodge speaking for SS Industries of Rajasthan, India please clarify what "excellent" electricity conductivity calcium carbonate is known for? When anhydrous (dry) it is an insulator. Philvoids (talk) 22:38, 2 November 2022 (UTC)[reply]

Sadly my expertise lies in interrogating Google rather than physics or chemistry. Please don't shoot the messenger. Alansplodge (talk) 13:54, 3 November 2022 (UTC)[reply]

Perhaps they consider an electrical conductivity of < 10⁻¹¹ S·m⁻¹ to be excellent. Curiously, they do not mention the material's high thermal conductivity, ~4 W·m⁻¹·K⁻¹, higher than glass. --Lambiam 08:13, 3 November 2022 (UTC)[reply]

November 3

Empty calories

I read a statement by a Dr. Rosen in an article on yahoo!life[4]. She states that diet sodas "are loaded with empty calories". Is that true? Thank you. Hevesli (talk) 10:22, 3 November 2022 (UTC)[reply]

According to Coca-cola, their diet coke has only one calorie per 330 ml can, so more just empty I would have thought, apart from E numbers. Mikenorton (talk) 10:42, 3 November 2022 (UTC)[reply]

I wonder if that particular quote was taken out of context by the article writer. It would seem to apply better to non-diet drinks. Alansplodge (talk) 13:51, 3 November 2022 (UTC)[reply]

Yes, the usual meaning of "empty calories" is calories consumed without benefit of any other nutrients such as vitamins or protein. Abductive (reasoning) 03:50, 4 November 2022 (UTC)[reply]

Cooling hot oven racks

Situation: I start heating up my oven, and at one point take two oven racks out when they are quite hot. I hold one with my one hand steadily (in a mitten), and another with another hand (in mitten), shaking it vigorously so that the individual rods vibrate. Will there be an appreciable difference in cooling rate between the two? --Ouro (blah blah) 18:09, 3 November 2022 (UTC)[reply]

The "standard equations" for such scenarios tend to be large and painful to solve. I pulled up my go-to reference - Incropera et al., Fundamentals of Heat and Mass Transfer, (my copy is a 7th edition). As you would expect, arrays of long-cylindrical-metal-rods are solved around Page 618. Rather than quote a complicated equation out of context, it's worth saying that the math is complicated. It would take six hundred and seventeen pages of preparatory explanation to do it justice (... that's why this equation is on Page 618). "Will there be an appreciable difference in cooling rate?" Yes. "Exactly how appreciable?" ... So, let's break this down: what is the metal made of? What is the air made of? How hot is the metal? How hot is the air? How precisely can you measure temperature? How many places (throughout your scenario) are you using a simplifying assumption? (Did you extract the rail from the oven in zero seconds, or in finite time? Is air viscous, or not viscous? When a steel rod vibrates, to what extent do you assume the displacement to be infinitesimal? Exactly how round are the metal rods that constitute your oven-rack?) We can literally (literally) spend hundreds of pages - hundreds of thousands of complicated mathematical words to talk about all the details. Golly, even I had to actually look up Nusselt number to refresh my memory - and I'm some kind of scientist - not just anyone, either - I happen to be the original author of the Official Wikipedia Science Reference Desk Mathematical Model And Numerical Simulator For How Much My Coffee Has Gone Cold As I Expend Time Answering Thermal Physics Questions On The Science Reference Desk!

The more pertinent questions revolve around a more general question: which of these complicated details of engineering and physics are relevant to your scenario?

Are you simply baking cookies? Few of these details materially affect the quality of your cookies.

Nimur (talk) 18:34, 3 November 2022 (UTC)[reply]

And don't forget that by shaking one hand, you are likely causing minor vibrations in the rest of your body so that the other hand is not "steady". AND the waving of the one rack will produce air currents that will blow past the other rack..... --User:Khajidha (talk) (contributions) 18:55, 3 November 2022 (UTC)[reply]

Nimur... I do not need to be baking anything, that's just something I thought of... I just wondered... I can appreciate the diversity of variables that need to be taken into account and am thankful for Your answer - doing justice to the complexity of the problem. Appreciable would mean in excess of a few percent I'd say. Thanks.

Khajidha... of course. Then again, it's just a thought exercise (a WP:RD exercise if you will).

Thanks friends --Ouro (blah blah) 19:13, 3 November 2022 (UTC)[reply]

Right-o - it's just that it's hard to say confidently whether we're looking at differences in - let's just pick one quantifiable parameter, cooling rate - of a few parts per hundred, or a few parts per million. It's hard to know - confidently - whether we can safely ignore some effects!

The beauty, and the curse, of the mathematics that model convective heat transfer is that they are highly sensitive (in the mathematical sense of that word). Small changes can be amplified by physical processes that are governed by nonlinear equations.

It is no coincidence that heat transfer is studied as a part of statistical physics. It is also no coincidence that convective heat transfer relates strongly to turbulent flow.

Your thought-experiment is a great one - but to really do it justice, we do need to start with much simpler thought-experiments. By this, I mean that we have to spend a pretty significant amount of study before we can come to any conclusion, if we care about a scientifically valid answer - let alone one that is accurate and precise enough to say "yeah, that's an effect whose size is, say, 3% to 5%."

Otherwise, we're kind of just not doing science - we're just guessing.

There is a lot of stuff in our universe - basically, the entire set of topics that we call experimental physics - where we can perform a controlled experiment more easily than we can answer from a theoretical perspective. But, a true experimental physicist cares about controlling the experiment so that they can draw some kind of generalizable conclusion. This is exactly how we end up with thousand-page textbooks where we can say, "hm, for a rack made out of an array of rods, use Equation 9.34 from the chapter on Free Convection." I mean, a correct answer does exist - a correct answer can exist - and that's what separates real physicists from postmodernist nihilists. We (physicists) subscribe to a world-view in which we believe we can find out truth and assign a number to it. They (post-modernist nihilists) tell us that truth defies understanding, let alone quantification.

"Neither of these world-views is more correct," say the post-modernist nihilists.

"Post-modern nihilists are in no position to tell us about correctness," retort the physicists.

Only... the experimental physicist has the fortitude of moral character, nay, the intellectual resolve, to spend thousands of hours slogging through the work to prove the philosophers are wrong.

So, uhm, ... let's get crackin' on that!

Nimur (talk) 21:11, 3 November 2022 (UTC)[reply]

Yes, waving them around will increase the rate of cooling. That's because as well as radiative and convective heat loss you also get conductive heat loss into cooler gas. That's why car radiators have fans. Greglocock (talk) 21:45, 3 November 2022 (UTC)[reply]

Car radiators use the simplifying assumption that the gas outside the engine cowling will be cooler, so they use a fan to impel cool gas across the radiator. Ambient air outside can be approximated as an infinite cold reservoir. So, it is thermodynamically efficient for the engine to spend a few extra joules (... which needs energy, which means burning more fuel, which adds extra heat), and then convert this surplus heat energy into kinetic energy in the fan, and we assert that the fan shall impel cold air toward the radiator, improving net efficiency during normal operation in normal, specified conditions.

Fans, like all non-perpetual motion machines, need energy to spin - and in this case, the energy comes from the engine, and so ... amazingly, adding the fan to the automobile engine causes heat to be added to the universe. It only so happens that the automobile engine is designed to put this heat "somewhere else". Somebody, (an engineer, perhaps) had to study those horrible airflow and convection equations to make sure this actually has a net cooling effect on the portion of the machine we care about! Does the fan actually cool the engine if... the outside air temperature is in Flagstaff, Arizona, in the summer, while driving 400 kilograms of astrophysicists up a steep hill, or is this contrived situation a case of inversion in parameters, in which the existence of this cooling-fan actually adds heat to the radiator?

What about other scenarios - where the normal operation of the system does not necessarily rely on forced air cooling? What if we designed for maximum efficiency with passive cooling - a fan would move us away from maximum efficiency!

Would a cooling fan be of any assistance in, say, an airplane engine? ...Or a coal-fired powerplant turbine? Would it cool the metal any faster if the "oven" were an iron smelter? How about a blast furnace (where cold air is added to increase the net temperature)? How about a sports car with a turbocharger, where cold air is blown at the engine intake by a fan? It really, really matters where the fan is and where the air goes - turbocharging an engine usually makes it get hotter, because cold air does more than convect - it can combust!

How about if the "cylindrical metal tube" is radiating into a cooling fluid that radiates into the vacuum of space (... or is exposed to direct sunlight in the vacuum of space), fluctuating between 4 and 280 kelvins, depending on the time of the month? How many billions of dollars does it cost if a simplified assumption flips the sign of the cooling rate, and what is the impact to weather forecasting for half a planet for the next two decades?

The scenarios are diverse, and in this diversity, the magnitude of the rate of cooling changes dramatically. In fact, even the sign of the value changes. So, it's never so simple unless we know what the scenario is doing!

Nimur (talk) 16:10, 4 November 2022 (UTC)[reply]

"What if we designed for maximum efficiency with passive cooling" For interest, this is exactly the case for Formula One (and other) racing car engines, which is why, when they return to their pits, team personnel have to direct externally driven cooling fans into their air intake ducts. {The poster formerly known as 87.81.230.195} 5.64.163.219 (talk) 08:15, 5 November 2022 (UTC)[reply]

In the case of practical engines, and particularly turbines, cooling is not just part of the Carnot cycle, but is also for engineering purposes. Differential expansion and contraction modified the clearances and if the oil gets too hot it looses its lubricating properties. Martin of Sheffield (talk) 08:24, 5 November 2022 (UTC)[reply]

A steadily held hot rod mainly cools by transferring heat to the surrounding air. Since the rate of heat flow is proportional to the difference in temperature between the rod and the air, the heat flow will thereby decrease and the cooling slows down more than necessary. This can be avoided by replacing the warm air continually by fresh cold air. One way of accomplishing this is by aiming a ventilator at the rod. Another way is swinging the rod through the air. Shaking it will mainly have an effect if the absolute displacement is considerable. --Lambiam 21:43, 3 November 2022 (UTC)[reply]

Just to add another important perspective here, and add on a bit to the excellent (though a bit TLDR) responses by Nimur above; when you wave the rack through the air, you're basically trying to take advantage of convection to the heat transfer situation. We can confidently say yes to the notion that it will cool off faster. The devil is in the details, however; if it cools an extra 0.01 kelvin per hour, that's hardly worth the effort spent doing it. The problem is that fluid dynamics is a famously impenetrable science to work in theoretically. You would need something akin to Newton's laws of motion and the work equation and the law of conservation of energy and the like for fluids (rather than objects). For objects, these are simple three-variable equations that any middle schooler can solve. For fluids, we've got the equations, its just that no one can solve them. No really, the fluid equivalent of all of the dynamics and kinematics equations you learned in high school physics are called the Navier–Stokes equations; actually solving them in three dimensions represents one of the Millennium Prize Problems, which tells you they are still unsolved. The issue is that Navier-Stokes doesn't play well with turbulence, and that's why we have the Navier–Stokes existence and smoothness problem. Since solving "how much energy is carried away by convection" requires us to accurately model fluid dynamics around your waving oven grid, and that flow will be turbulent, not only do we not have solutions for such a model; we don't even know whether or not they exist. --Jayron 32 12:30, 4 November 2022 (UTC)[reply]
I'll work on brevity, (but not today)! Nimur (talk) 16:11, 4 November 2022 (UTC)[reply]

I got my brevity down pat, Nimur, but you forget it if you do such excellent work. I am reading through your answers, friends, and thanks. Of course we could have (should have) started off much simpler, with say - one rod (one wire) that is shaken or not and then to measure the heat transfer away from the object... and then somehow transpose that (with all the details like material, make-up, design details, etc.) and work upwards towards the oven rack. And Jayron you're absolutely spot on about fluid dynamics being difficult - I know. Thanks anyway, you got me a lot to think about. --Ouro (blah blah) 18:18, 4 November 2022 (UTC)[reply]

One thing that is still true; you can work this stuff out empirically. You can shake rods of different thicknesses at different speeds in different environments, you can plot the results on graphs and interpolate and extrapolate the data to develop models of cooling that don't depend on knowing anything about fluid dynamics. Newton himself developed Newton's law of cooling using carefully controlled experiments. However, the problem is that you can't work from first principles to develop a theory of cooling that would work here, in the same way that we have good theories explaining things like balls rolling down hills and hockey pucks colliding on ice. Even though the same principles apply to describe colliding hockey pucks and cooling off waving chunks of metal in the air, the math is just too intractable using the tools we have today to do so. --Jayron 32 18:37, 4 November 2022 (UTC)[reply]

Kem Kem Leptocleidid.

When is the new leptocleidid plesiosaur from the Kem Kem going to be given a name? CuddleKing1993 (talk) 21:27, 3 November 2022 (UTC)[reply]

If you mean a binomial name, it is not so simple as naming a new-born baby. The first issue is the assignment of a genus. Do all fossils from this group belong to the same genus? And if so, is it one of the known genera, or a new one? Such questions require careful study. If this can be resolved, the questions repeat at the species level. --Lambiam 22:12, 3 November 2022 (UTC)[reply]

The ICZN, International Commission on Zoological Nomenclature, maintains the process for assigning binomial names; they don't name the organisms themselves but they do set the standards for how things are supposed to be named, and they do adjudicate disputes. The process is described in a document called the International Code of Zoological Nomenclature (also abbreviated ICZN). The process of granting the name does take time, so it's hard to predict "when" such a name will be published. It depends a bit both on the discoverer of the species (who has the right to name it) and to the publisher of the work in which it is named. As Lambiam notes above, what needs to be done first is to figure out what the taxonomy/cladistics of the species is; such as to which genus it should belong, or does it represent a new genus; should it be a species on its own, or a subspecies, to which family should it belong, and so on up the line. That kind of determination takes real labor and work on the part of scientists who need to look at the fossils, analyze them, and come to conclusions. --Jayron 32 12:16, 4 November 2022 (UTC)[reply]

In the past discoverers would name specimens without taking such careful precautions. But this led to many cases of multiple names being given to what turned out to be the same thing. Which meant standards had to be set up for which name was to be used going forward. Usually strict priority is the determining factor, but there have been exceptions that were explicitly made for good reasons (if the oldest name was never used after its initial publication and a later name was used in numerous publications, it would be counterproductive to insist on strict priority). --User:Khajidha (talk) (contributions) 13:41, 4 November 2022 (UTC)[reply]

November 4

fungal infections from ancient tombs

I've been seeing stories[5][6] that after 12 research scientists entered the 500 year old tomb of Casimir IV Jagiellon, 4 of them died days later, and another 6 died months later. It is speculated that the deaths may have been due to a fungal infection caused by exposure to Aspergillus while in the tomb. My question is about the specific incident involving the King of Poland's tomb in the 1970s. I've had a difficult time finding contemporary accounts or any reliable sources to confirm these deaths. Any additional info would be greatly appreciated. mikeu ^talk 23:28, 4 November 2022 (UTC)[reply]

This is already mentioned in the article you link, in the section Tomb, with a reference cited to a reliable source. {The poster formerly known as 87.81.230.195} 5.64.163.219 (talk) 08:19, 5 November 2022 (UTC)[reply]

Specifically; this. Alansplodge (talk) 12:32, 5 November 2022 (UTC)[reply]

Yes, I saw that. If ten out of twelve researchers died after entering the tomb it would be an extraordinary occurrence. I would expect it to have been covered in the news, yet the ProQuest historic news database does not return any results. It would be of great scientific interest, but Scholar lacks any hits. One source that I linked to mentions a "Dr. B. Symk" who survived. Scholar shows one paper by the author about microbiology but nothing about this dramatic incident. All of the sources that I've found repeat the same vague claim without details or reference to a primary source. --mikeu ^talk 14:31, 5 November 2022 (UTC)[reply]

What I understand from an article in the English edition of the printed magazine Poland (volume 351, no. 3, 1987) with the title "Anathemas, Microbes and Scholars", is that the role of prof. Bolesław Szyk, a microbiologist from the Kraków Agricultural Academy, was that he examined the microbes in the tomb.^[7][8] One may assume that as a microbiologist he understood the risks and took proper precautions, unlike the hapless archaeologists. The snippet view makes it hard to see the full story. The author of the article is science journalist Zbigniew Święch,^[9] who has an article on the Polish Wikipedia. He wrote a book with the title Klątwy, mikroby i uczeni,^[10] which in English means Anathemas, Microbes and Scholars, the same as the title of the magazine article. --Lambiam 02:44, 6 November 2022 (UTC)[reply]

The Polish Wikipedia also has an article on Klątwy, mikroby i uczeni, which turns out to be a series of three books. The first book in the series is devoted to "the curse of Casimir Jagiellon". --Lambiam 02:54, 6 November 2022 (UTC)[reply]

November 5

Nature versus nurture

It is often said that the heritability of IQ increases with age and was/is greatest in school. This worries me a bit, it looks very much like an artifact. Where the children receive by force a same way of life, the way of life changes nevertheless depending upon family etc.. Have the intelligence researchers considered this? 2A02:908:424:9D60:0:0:0:F38B (talk) 00:02, 5 November 2022 (UTC)[reply]

What do you mean by "receive by force a same way of life"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:23, 5 November 2022 (UTC)[reply]

The evidence is increasingly pointing to intelligence being all nurture, no genetics. Abductive (reasoning) 01:02, 5 November 2022 (UTC)[reply]

What evidence? ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:37, 5 November 2022 (UTC)[reply]

I'm not sure that is correct; see e.g. this article. See also Heritability of IQ. The present scientific consensus in the "nature versus nurture" debate appears to be that when it comes to intelligence as measured by IQ tests, both are an important factor. --Lambiam 08:20, 5 November 2022 (UTC)[reply]

They are forced to go to school, to learn and so on. They hang out in classes, they have the same environment. 2A02:908:424:9D60:0:0:0:F38B (talk) 08:14, 5 November 2022 (UTC)[reply]

And they all make the same grades? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:26, 5 November 2022 (UTC)[reply]

Some monozygotic twins get separated at birth and are raised in different environments; see e.g. this article, "Personality traits, mental abilities and other individual differences: Monozygotic female twins raised apart in South Korea and the United States".^[11] --Lambiam 08:24, 5 November 2022 (UTC)[reply]

Here is a popular articel about that study from one of the autores. 2A02:908:424:9D60:0:0:0:F38B (talk) 00:04, 6 November 2022 (UTC)[reply]

Heritability is the proportion of the total variation that is explained by the genetic variation. If the environment is more variable in a way that causes an increase in total variation, the heritability will be lower even though the mechanisms underlying the genetic effects are unchanged. Geneticists are very well aware of this. Heritability of IQ in adults is surprisingly high, about 0.75. The figure is smaller in children, probably because children of the same age vary in how developed they are. Jmchutchinson (talk) 16:03, 5 November 2022 (UTC)[reply]

Concerns about page for Thermal Medicine

Hey all, Straight to the topic: I'm concerned about this page: https://en.wikipedia.org/wiki/Society_for_Thermal_Medicine

Basically, we don't have a thermal medicine page, and googling thermal medicine leads you to it.

The page is at best subpar for what Wikipedia would consider an acceptable medicine article, and I'm concerned that it presents a health risk. Even though the page is referenced, the references are from a time when p-hacking and using "researcher degrees of freedom" was rampant, and I'm not sure they represent the scientific consensus on the subject.

Any suggestions? Thanks!

Best regards, Victor ~victorsouza (talk) 22:06, 5 November 2022 (UTC)[reply]

I'm not convinced that the Society for Thermal Medicine meets WP:NORG; with a quick web search I can't find any significant, independent coverage on it (except maybe this), and none of the sources currently in the article appear to help establish its notability. Also, I'm pretty sure there is an article about thermal medicine: Hyperthermia therapy. Shells-shells (talk) 00:11, 6 November 2022 (UTC)[reply]

Considerable swaths of text are verbatim or almost verbatim copies of passages on the history page of the Society for Thermal Medicine. --Lambiam 01:44, 6 November 2022 (UTC)[reply]

November 6

entropy

How might the universe look if the second law of thermodynamics worked in reverse? Instead of the universe's entropy increasing over time, entropy would generally decrease over time in this alternate universe. Might life have still come into existence, and if so how might it be different? I heard about an MIT study about how the universe's increasing entropy might make the development of life inevitable, which got me interested in this question. How might stars, galaxies, planets etc might look if they even exist at all? 2600:4040:1014:7300:594B:5953:EE8F:274C (talk) 00:49, 6 November 2022 (UTC)[reply]

Take a film of the universe and play it in reverse. --Lambiam 01:18, 6 November 2022 (UTC)[reply]

See "Entropic Time (Backwards Billy Joel Parody)" (A Capella Science) on YouTube DMacks (talk) 22:17, 6 November 2022 (UTC)[reply]

Your question doesn't make sense in physics, because this event didn't happen. In France we say "with if we put Paris in a bottle".

But in mathematics you can define this kind of postulate and pose a problem in this new theoretical set. Malypaet (talk) 18:07, 6 November 2022 (UTC)[reply]

This would make the universe unstable. Ruslik_Zero 18:43, 6 November 2022 (UTC)[reply]

first law

Along a similar note, how might the universe look if it was possible to create energy out of nothing or destroy energy? 2600:4040:1014:7300:594B:5953:EE8F:274C (talk) 01:14, 6 November 2022 (UTC)[reply]

This question is unanswerable. If the law of conservation of energy is broken, all physical laws as we know them are broken, since this implies that the laws of physics are not constant but change with time (see Conservation of energy § Noether's theorem). --Lambiam 01:29, 6 November 2022 (UTC)[reply]

So anything might be possible in that case (and its impossible to predict) because the laws of physics can change over time. — Preceding unsigned comment added by 2600:4040:1014:7300:594B:5953:EE8F:274C (talk) 02:05, 6 November 2022 (UTC)[reply]

You're waaay over in the region of speculative science fiction or magic rather than anything that can be answere in the science reference desk. NadVolum (talk) 11:54, 6 November 2022 (UTC)[reply]

Unit in physics and multiplication by time

In several definitions of physical quantities, we find a multiplication by a second (J.s, A.s) when we refer to a quantity dependent on the time which flows towards the future and therefore expressed by the division of a second. Mathematically, I understand the operation, because it ultimately consists in removing any reference of this magnitude to time. In physics, the division of time on a quantity relates to associating a time interval which flows towards the future with this one (J/s, C/s, m/s), this is regularly experienced. On the other hand in physics, the multiplication of time on a quantity would consist in associating a time interval which flows towards the past, except that has never been experienced (except by reversing the progress of a video!). How can we allow ourselves to use this kind of notion in physics when it only comes under the domain of mathematics or science fiction? Malypaet (talk) 02:49, 6 November 2022 (UTC)[reply]

I don't know where you get this idea of an association of multiplication or division with time flowing or the past or future. In the case of corn in a field on can have corn per hectare or total corn in the field. Both figures are useful for different purposes but there is no flow involved. In the same way for fuel in a car one can have the total number of litres and kilometres per litre which together give an idea of how far it can go between refills. Speed can be measured in kilometres per hour and together with a distance that can give how long it'll take to arrive. The multiplication or divisions involved imply nothing about the future or the past. NadVolum (talk) 11:46, 6 November 2022 (UTC)[reply]

You write "Speed can be measured in kilometres per hour" : km/h, this is not a division ? You write "how long it'll take to arrive", this has no thing to do with the futur ? If you don't have the base of language or in physics, don't loose your time here and mine too ! Malypaet (talk) 17:58, 6 November 2022 (UTC)[reply]

You can also ask how long it took to arrive. Past tense. --Wrongfilter (talk) 19:23, 6 November 2022 (UTC)[reply]

Being rude towards those who can (or at least try) help you may turn out counterproductive... --CiaPan (talk) 21:12, 6 November 2022 (UTC)[reply]

Sorry, you are right Malypaet (talk) 08:12, 7 November 2022 (UTC)[reply]

Cats' eyes

I have two cats; each cat has eyes that reflect in a different color. One reflects red, the other green. I had assumed eye reflection color would be species dependent, but evidently it is not. What determines the color of eye reflection? 136.56.52.157 (talk) 03:09, 6 November 2022 (UTC)[reply]

Humans can have red/pink, green, blue, black etc eyes. Even purple I think.

. Sagittarian Milky Way (talk) 03:14, 6 November 2022 (UTC)[reply]

Humans have only red, because we lack the tapetum lucidum. Foxes eyes reflect green; supposedly a murder case hinged on this fact, as the shooter claimed he was aiming at a fox at night and accidentally shot a person. Your cat may be explained further down in the tapetum lucidum article, or s/he might have a damaged or missing tapetum lucidum in one eye. Abductive (reasoning) 03:34, 6 November 2022 (UTC)[reply]

Interesting article, thanks for the link. Accordingly, green reflection ("eyeshine") is normal for cats, and blue-eyed cats are an exception, glowing red. In my case, the cat with red eyeshine does indeed have blue eyes. The article doesn't explain why a blue iris would affect eyeshine color; presumably it is coincidentally caused by genetics. 136.56.52.157 (talk) 04:31, 6 November 2022 (UTC) ... Edit: I should clarify that each cat has same color in both eyes; but one cat reflects green in both, the other (blue-eyed cat) reflects red in both -- sorry for the confusion.[reply]

I wonder if blue-eyed cats don't see as well in the dark (?). 136.56.52.157 (talk) 04:51, 6 November 2022 (UTC)[reply]

If the cat's eyes really don't reflect green from any angle then I would say, yes, their night vision is impaired. Supposedly cats can detect a single photon under the right circumstances, while our detection level is something like 4 photons. Cat vision says their night vision is about seven times more sensitive than ours. Abductive (reasoning) 08:56, 6 November 2022 (UTC)[reply]

Dubious animal with only one layer of cells

I remember reading about an animal that may or may not actually exist. It was microscopic and had only a single layer of cells in its body. It was like a sausage in shape, with a pore and extra cillia on each endd Quick Trundleteacher (Talk) (Inputs) 18:52, 6 November 2022 (UTC)[reply]

Jiufotang Dinosaurs

Why is there such a lack of variety of non avian dinosaurs in the Jiufotang formation compared to the Yixian formation which has iguanodonts, compsognathids, therizinosaurs, sauropods, ornithomimosaurs and troodontids, while the Jiufotang only has microraptorines, ceratopsians, ankylosaurs, and proceratosaurs which the Yixian also has? CuddleKing1993 (talk) 19:44, 6 November 2022 (UTC)[reply]

I can't answer myself, but Jehol Biota may contain some clues. {The poster formerly known as 87.81.230.195} 5.64.163.219 (talk) 08:12, 7 November 2022 (UTC)[reply]

November 7