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November 25

Planet axis configuration and seasons

I can't remember if I have asked this before or not, but I was curious anyway.

We all know the change of seasons on the Earth happens because the axis is tilted in relation to the orbit. So I thought of three alternate configurations for a planet:

Axis is exactly perpendicular to the orbit, pointing "up" and "down" on the orbit plane: No annual change in seasons. Temperature depends only on latitude and time of day.
Axis is parallel to the orbit: No seasons. Temperature depends only on time of day.
Axis points towards and away from the sun: No seasons. One side experiences permanent sunlight and the other experiences permanent darkness.

I know there might be local weather changes that might affect the temperature and sunlight but I'm ignoring these here for the sake of simplicity.

Have I understood these scenarios correctly, and is it possible they might actually occur (not on our Earth but on some other planet)? JIP | Talk 10:54, 25 November 2019 (UTC)[reply]

2 and 3 do not work like that due to conservation of angular momentum: The axis of rotation is fixed in space and therefore changes its direction with respect to the sun as the planet orbits around it. In the solar system, Uranus has its axis closely within the orbital plane and it does experience seasons much more extreme than ours. Scenario 1 works; if you want to remove diurnal variation, too, you need tidal locking. --Wrongfilter (talk) 11:29, 25 November 2019 (UTC)[reply]

Some seasonal effects also result from orbits being not exactly circular, but rather elliptical as is nearly always the case. The degree of effect is proportional to the degree of ellipticality, or eccentricity, of the orbit in question.

Earth's orbit is only modestly eccentric (with aphelion (furthest distance from the Sun) being in July and perihelion in January), so the resultant effects are mostly swamped by the greater ones of its axial inclination (they tend to ameliorate the Northern and intensify the Southern hemisphere's seasons, but only slightly). They are however readily observable on rocky planets like Mars and Pluto which have greater orbital eccentricities. Similar effects are detectable, though less obvious, on the gas and ice giant planets of our Solar system.

For an entertaining (and extremely well written) fictional examination of the effects on an Earth-like planet with a very eccentric orbit, see the Helliconia trilogy by my old acquaintence Brian Aldiss. {The poster formerly known as 87.81.230.195} 2.217.209.178 (talk) 13:38, 25 November 2019 (UTC)[reply]

So, "seasons" are a higher-order climate phenomenon and it's really hard to extrapolate from our Earthly experience... they obviously involve the planet's orbit and its axial tilt, but they also involve its atmospheric dynamics and its average temperature and so on.

The first-order item to consider, if we're speaking of a generic planet in a generic orbit - is the insolation - incoming solar radiation - and the equation of time that describes how insolation changes over a long period of time - let's call that a "year" cycle or a single orbit. If the planet is earth-like, its day-night cycle occurs hundreds of times per orbital-revolution; its axial tilt precesses very slowly (thousands ir millions of years go by with no meaningful precession); the orbit is nearly perfectly circular; and so on; the dominant "seasonal" change is caused by axial-tilt only.

If the planet is Venus-like - meaning that its day-night cycle is more like its orbital period - everything "seasonal" that we infer about its axial tilt gets dwarfed by other factors. If the planet is Jupiter-like, its nine-hour atmospheric rotation is so hard to describe that the variability in gas circulation probably affects local long-term temperatures and weather more than the orbit. Uranus, as we now know it, rotates prograde and nearly perpendicular to the rest of our solar system; and its temperature profile against latitude indicates that solar radiation does not directly dominate the seasons: the hottest parts of the planet get the least sunlight. Gas convection is really complicated when the gas blob is the size of an entire world and self-gravitates! And if the planet is as eccentric as Pluto, or Halley's Comet, the variable insolation due to orbital radius change - direct distance from the Sun - has a bigger impact than axial tilt. On certain moons of the big gas-giants, like the moon Io, the most severe long-term climate cycles are caused by tidal heating, and not by the variable Solar radiation itself.

The summary, then, is that every world is very unique; it happens that on Earth our dominant seasonal variation is caused by our orbit's weirdest peculiarity; but other worlds have their own weird peculiarities. The task of the planetary scientist is to rigorously and open-mindedly study which parameters, out of all the zillions of parameters into all the equations of physics, predominantly define the nature of any particular celestial body.

Nimur (talk) 15:52, 25 November 2019 (UTC)[reply]

The other thing with the potential on the seasons for the outer planets is that the seasons are caused by the variance in solar radiation due to axial tilt, and that variance is a function of the amount of solar radiation to begin with. The less overall solar radiation a planet receives, the less axial tilt "matters" to variances in solar radiation. If the earth were located out by Jupiter's orbit, with the same axial tilt, it would get less variation in its seasons. --Jayron 32 19:22, 25 November 2019 (UTC)[reply]

I once read somewhere or other that on a planet with tilt more than 54° the poles get more total insolation than the equator. I don't quite know how to confirm that! If that's the case, we can imagine a planet at exactly 54° where the average temperature is the same at every latitude, but the severity of seasons increases with latitude. —Tamfang (talk) 02:08, 1 December 2019 (UTC)[reply]

November 26

What kind of innervation does human heart have?

Does heart has innervation to the SA node only for influence on the rhythm only (sometimes) and not for pain sensation, or it has innervation inside it for pain sensation too? Theoretically, if a physician cut an heart of his patient without any anesthesia. Should the physician expect for pain from the heart? (assuming the the patient doesn't have any other pain, for example because it section were done by catheter or by local anesthetic for the opening of the chest). If it doesn't have innervation, so why people with MI feel so strong chest pain as if it the most innervated? 93.126.116.89 (talk) 06:19, 26 November 2019 (UTC)[reply]

Angina may explain. ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:08, 26 November 2019 (UTC)[reply]

The electrical conduction system of the heart (which includes the SA node) only makes the heart beat, by producing the action potentials that make the heart contract. In general throughout the body, there are separate afferent and efferent nerve fibers; afferent fibers transmit stimuli from the body to the central nervous system, while efferent fibers transmit from the CNS to the rest of the body. The heart does have efferent innervation, but this only serves to regulate the heart rate up or down. The heart itself generates its own action potentials. The heart has afferent innervation as well, and this is what transmits pain sensations to the brain. These nerves are separate from the heart's conduction system. Note that heart attacks don't always produce the "traditional" symptom of chest pain, and also, because the sensations are poorly "mapped" in the brain, pain from the heart can be referred to other parts of the body. --47.146.63.87 (talk) 08:18, 26 November 2019 (UTC)[reply]

Immune system and antimicrobial resistance

Why pathogens (fortunately) do not develop resistance to human immune system as quickly and intensely as to antibiotics? It seems that as they encounter immune system more often than antibiotics, the evolutionary pressure would be even greater. Also, since antimicrobial resistance states that it "threatens the world as we know it, and can lead to epidemics of enormous proportions", would immune system effectively offset the threat? 212.180.235.46 (talk) 22:09, 26 November 2019 (UTC)[reply]

Because any chemical that kills pathogens without killing the person taking them is necessarily less effective than the person's own defenses, which are alive and which adapt to new pathogens. See Immune system. --Guy Macon (talk) 00:02, 27 November 2019 (UTC)[reply]

I would say that is wishful thinking. The real reason pathogens don't develop resistance to immune systems is that a pathogen that kills its hosts before the hosts can spread the pathogen is selected against. Consider these counterexamples: Anthrax is quite lethal but avoids this problem by being non-contagious. Instead, it forms spores in the carcasses of its dead hosts and hopes to spread that way. Rabies is 100% fatal, and avoids the problem by getting its hosts to salivate, and bite new hosts. Abductive (reasoning) 09:40, 27 November 2019 (UTC)[reply]

You should tell this to the people who died of AIDS. HIV is known to quickly develop resistance to any immune responses eventually exhausting the immune system and killing its host. Ruslik_Zero 11:00, 27 November 2019 (UTC)[reply]

We're getting off track with the HIV and Rabies, since they are viruses. But note that HIV does not kill its hosts quickly. Abductive (reasoning) 11:57, 27 November 2019 (UTC)[reply]

Whether we're getting off track depends somewhat on the OP I guess. They asked about antimicrobial resistance but then seemed to talk about antibiotic resistance. As per the article, antimicrobial resistance is a broader category than antibiotic resistance. The article indeed talks about antiviral resistance including HIV Antimicrobial resistance#Viruses. I admit I found this a bit weird at first since of course in a strict biological sense viruses are often not considered microbes nowadays as they are not generally considered living. But it seems to be the same as the WHO [1] and the NZ MOH [2]. Possibly they consider it doesn't make sense to put viruses in a special category for monitoring etc and microbes is the best fit. (And indeed as our article mentions, viruses are normally studied as part of microbiology.) True the US CDC seems to use the term interchangeably with antibiotic resistance [3] like the OP. But then again they do track both fungal and bacterial resistance under this and specifically mention they don't include viruses or parasites in their report suggesting they don't think it's obvious [4]. And they do include viruses in the papers they list [5]. (And elsewhere they call viruses microbes [6].) It's true of course that antiviral resistance is not any where as much as a threat as antibiotic resistance or even antifungal resistance, but that's a different point. And on that point, while I didn't read the WHO report where the OP's quote came from, I strongly suspect they probably were at least concerned about anti-fungal resistance and probably anti-parasite resistance and not just antibiotic resistance. Nil Einne (talk) 13:29, 27 November 2019 (UTC)[reply]

This is a good question! The immune system has a diverse arsenal to attack pathogens: from antibodies to the complement system to the respiratory burst and more. It's harder for a pathogen to develop resistance to a bunch of things than to one. For instance, some bacteria develop resistance to penicillin by acquiring a modified penicillin binding protein that isn't inhibited by penicillin. For this reason, there is increased use of multi-drug regimens, such as co-amoxiclav, trimethoprim/sulfamethoxazole, and the regimens for tuberculosis and malaria. With that said, some pathogens do have a good ability to resist the immune system; examples include some Salmonella, Helicobacter pylori, and the aforementioned tuberculosis and malaria pathogens. Logically, if no pathogens could withstand the human immune system, no one with a healthy immune system would die of infectious disease or develop a chronic infection. There's a constant evolutionary arms race between disease-causing organisms and the organisms they infect. --47.146.63.87 (talk) 09:36, 27 November 2019 (UTC)[reply]

First, resistance to many classes of anti-microbials have existed in the nature for millions years. Bacteria only need to acquire necessary genes, which can be easily done by multiple routes. So, nothing to develop in the first place. Second, bacteria do develop or acquire resistance to immune responses. One notable example is acquisition of toxin genes (or other virulence factors), which are used as chemical weapons against cells of the immune system. Bacteria can also avoid expressing some proteins, which serve as targets for the immune system. One example is appearance of strains of Bordetella pertussis that lack pertactin protein, which is used in acellular vaccines. Ruslik_Zero 11:18, 27 November 2019 (UTC)[reply]

The immune system is more like a weapon factory than a weapon, and it takes no prisoners, even attacking the body cells. For instance, it can produce an infinite range of antibodies, and if a pathogen develops resistance to one though changing antigen, it creates a new pattern for which the immune system could very well be already ready. This is obviously harder to fight back that a single specific molecule. Gem fr (talk) 04:29, 29 November 2019 (UTC)[reply]

November 27

Helicopters spending more fuel hovering

Helicopters spend more fuel (much more actually) while hovering (per unit of time) than while flying. Is that something that happens due to helicopters being the way that they are or can we generalize this to any self-propelled flying vehicle due to physical laws? That is, is hovering always less efficient than flying, in the same way that going uphill is less efficient than going downhill? Or, is this per design, in the same way that, say, that an engine can have maximum torque at 2,000 RPM and others at 5,000 RPM? --C est moi anton (talk) 17:12, 27 November 2019 (UTC)[reply]

Who told you that Helicopters use much more fuel hovering than flying? Do you have a source for this claim? --Guy Macon (talk) 18:00, 27 November 2019 (UTC)[reply]

The graph of fuel consumption versus the velocity and altitude of the helicopter flight?C est moi anton (talk) 18:08, 27 November 2019 (UTC)[reply]

Any vehicle is likely to have an optimal fuel consumption range. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:59, 27 November 2019 (UTC)[reply]

And how many vehicles spend less fuel while moving than while quiet?--C est moi anton (talk) 19:43, 27 November 2019 (UTC)[reply]

Note that this isn't a sudden increase when in the hover itself, it's more of a gradual shift from when below moderate airspeeds.

It's the asymmetry of the rotor moving in a moving airstream, vs. a still airstream. This depends on the airspeed of the rotor, which of course stays constant around the rotor disc (proportional to radius), during a hover in still air. If there is some forward airspeed, then the rotor airspeed (and drag) when the blade is moving sideways (forwards or rearwards position) is just the same. But at the same time, the airspeed on the advancing rotor blade is increased (rotational speed + airspeed) and the airspeed on the retreating blade reduces (rotational speed - airspeed). Near the centre of the rotor, on the retreating side, where the blade's linear speed is least, this can reduce to zero and even becomes negative. That reduces the drag on the blade, but also reduces lift. To avoid the helicopter rolling, the incidence of the blades has to be adjusted as they rotate, so as to compensate. Overall, there's a non-linear effect. Efficiency gains more from the increased airspeed on the advancing side than it loses on the retreating side, so overall there's a gain with airspeed.

There's also a smaller effect from the tail rotor. In the hover, this is needed to counteract torque reaction and avoid yaw, entirely by itself. However when the helicopter is moving forwards, the static tail surface also assists.

Other effects may apply, depending on the shape of the helicopter. Streamlining is optimised for performance in the cruise, less so below this. That's important for helos because not only is the airflow faster, but it changes direction from the pure vertical of a hover to something more astern. There may even be a dynamic lift effect for some (if there's any sort of stub wing shaping) and they can give lift from airspeed rather than the rotor disc, which tends to be a more efficient way to do it. Andy Dingley (talk) 19:25, 27 November 2019 (UTC)[reply]

I think the helicopter is designed to work best when moving, and that include

The cabin intercept and hinder the downward flow of air when hovering, more than it does moving (the airflow is then somewhat rearward

aerodynamics of the craft is designed for a forward movement

it may incluse some feature of a fixed wing, delivering better lift that the rotor (as evidenced by the better performance of planes Vs helicopters)

Now, you could design it otherwise, with best aerodynamics when hovering. It just isn't very useful

Gem fr (talk) 21:46, 27 November 2019 (UTC)[reply]

I agree with the answers above, but there is another factor which can play part in this. Many helicopters use a turbine engine. These are usually optimized to work best at a cruise speed and may work much less efficient at low inlet speeds, see Propulsive_efficiency#Jet_engines. Rmvandijk (talk) 10:51, 28 November 2019 (UTC)[reply]

You right, I forgot this obvious one: the engine produce some forward thrust, and you have to fight it back to hover Gem fr (talk) 04:40, 29 November 2019 (UTC)[reply]

That wasn't the effect I meant, I suppose that one happens too. I meant that, if we assume a fairly constant outlet speed, the efficiency of the engine goes to zero (at zero inlet speed). That would mean no suction, which is wrong and violates the conservation of mass, but the idea works for low airspeeds relative to the exhaust speed. Rmvandijk (talk) 09:23, 29 November 2019 (UTC)[reply]

The above explanation sounds expert is probably right, but I'm not surprised more fuel is used when a helicopter is still. I'd have though the air would circulate down through the rotor then up outside to the top again. If the rotor was stopped there would be a wind pushing the helicopter down until the circulatio stopped compared to what would happen if going through still air. Dmcq (talk) 12:31, 29 November 2019 (UTC)[reply]

More power is required by the rotor to hover (airspeed zero) than to fly forwards with non-zero airspeed. There are complicating effects due to proximity to the ground, so I will say more power is required to hover out-of-ground-effect (OGE) than to fly forwards slowly at the same height above the ground. Fuel efficiency is usually unaffected by a helicopter’s airspeed so I can say rate of fuel consumption is greater in the hover OGE than flying forwards slowly at the same height. The short explanation for this phenomenon is lift-induced drag.

When we investigate the power required by a helicopter rotor there are two competing processes. Firstly, as the speed of the helicopter increases up to its maximum forward speed, the parasite drag on the rotor blades and the fuselage increases, necessitating progressively increasing power. This is the same process that necessitates progressively increasing power from the engine of any road vehicle or ship.

Secondly, there is an opposing process that requires increasing power as the forward speed of the helicopter decreases! This is counterintuitive and has no counterpart in road vehicles or ships. It is due to the phenomenon of lift-induced drag. Fortunately, it can be illustrated by some simple arithmetic. Imagine a helicopter hovering out of ground effect. Let’s examine the rotor blade elements 75% of the distance out to the tip of the blade. Let’s imagine these blade elements have a speed of 300 knots due to the speed of the rotor. The angle of attack on the rotor blade is controlled by the pilot so that the lift on the rotor exactly matches the weight of the helicopter and causes the height above the ground to remain constant.

Now let’s imagine that the helicopter has accelerated to a forward speed of 30 knots. On the advancing blade our blade element at 75% is experiencing an airspeed of 330 knots; but on the retreating blade it is experiencing only 270 knots. The mean of these two speeds remains unchanged at 300 knots so it is tempting to imagine that the rotor will produce the same lift at the same angle of attack, but that is incorrect.

The lift on every blade element is directly proportional to the square of the airspeed. Assuming no change in angle of attack, the lift on our blade element on the advancing blade is proportional to 330/300 squared, or 1.21 of its original value, an increase of 21%; the lift on our blade element on the retreating blade is proportional to 270/300 squared, or 0.81 of its original value, a decrease of 19%. An increase of 21% and a decrease of 19% means a net increase of 2%. This increase in lift would cause the helicopter to accelerate upwards. The pilot wishes to maintain a constant height so she lowers the collective lever to reduce the angle of attack on the rotor blades and eliminate that 2% net increase.

Reducing the angle of attack is associated with a reducing lift coefficient; and a reducing lift coefficient causes the component of the drag coefficient associated with lift-induced drag on the rotor blades to also reduce. As lift-induced drag reduces, the power required to turn the rotor at constant RPM also reduces, and so too does the rate of fuel consumption.

As the helicopter leaves the hover and begins to accelerate forwards, the reduction in lift-induced drag is more pronounced than the increase in parasite drag. These two effects become equal in magnitude and cancel each other at the speed for minimum power. As forward speed increases even further, the increase in parasite drag on the rotor is more pronounced than the reduction in lift-induced drag. Dolphin (t) 13:12, 30 November 2019 (UTC)[reply]

How much alcohol?

The other day I was going down the production line filling up the little water bottles we use to wet sponges for cleaning soldering iron tips. Because of past experience with the water turning green I put a glug of alcohol in the water. We have Isopropyl, Methanol and Ethanol available; I usually use Isopropyl.

This got me to thinking: what is the minimum percentage of each kind of alcohol needed so that nothing - no germs, algae, mold, yeast, tribbles, politicians, etc. -- grows in the water?

I am guessing that for Ethanol the percentage will be about that of the strongest available wine. I believe that windshield wiper fluid is 50% Methanol but I suspect that is for the antifreeze effect. --Guy Macon (talk) 18:11, 27 November 2019 (UTC)[reply]

Who told you tribbles grow in water? --C est moi anton (talk) 18:44, 27 November 2019 (UTC)[reply]

You forgot about the politicians. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:59, 27 November 2019 (UTC)[reply]

Politicians grow everywhere like weeds.C est moi anton (talk) 19:32, 27 November 2019 (UTC)[reply]

I recall reading about Nicolae Ceaușescu who, because of pathological fear of poisoning or infection later in life, asked his hands to be sanitized with 90% alcohol, presumably ethanol. Perhaps the real minimum percentage needed to kill all germs is somewhat lower. Brandmeister^talk 21:43, 27 November 2019 (UTC)[reply]

Antiseptic concentration vs. killing power is not a linear or direct relationship. For example, 60-70% isopropyl alcohol is a more effective disinfectant than 90-95%. And nothing will kill everything. - Nunh-huh 00:27, 28 November 2019 (UTC)[reply]

You don't see a lot of things growing in whiskey bottles do you? (smile.) Bottles of isopropyl alcohol also tend to be notably lacking in thing growing in them. --Guy Macon (talk) 05:26, 29 November 2019 (UTC)[reply]

If things didn't grow in whiskey, there wouldn't be any alcohol in it. And bourbon makers need to be aware of which bacteria are contaminating their product. Pediococcus, lactobacillus and other bacteria change the flavor of the end product in different ways. And it's best not to read about the alcohol tolerant features of E. faecium before drinking... - Nunh-huh 23:08, 29 November 2019 (UTC)[reply]

I linked that microbe in your post, to help others not-read about a meaning of "shitty beer" other than what I drank when I was a poor college student. DMacks (talk) 23:12, 29 November 2019 (UTC)[reply]

You poor dear! Pabst? -Nunh-huh 04:41, 2 December 2019 (UTC)[reply]

Re: "If things didn't grow in whiskey, there wouldn't be any alcohol in it". see Distillation.

Re: E. faecium and alcohol "In preliminary experiments, various concentrations of alcohol and E. faecium inoculum sizes were assessed. At 'full strength' isopropanol [70% (v/v)], killing was complete and resulted in greater than 8 log10 reductions in broth culture and an inability to detect differences between isolates. However, by lowering the alcohol concentration in a stepwise fashion, we were able to identify a dynamic range in which we observed marked differences in the time-kill curves between isolates." Source:[7] (the study goes on to conclusively show that 23% doesn't reliably kill and that the tolerance is getting higher from year to year.) That's a frighteningly high alcohol tolerance for an organism that causes lots of trouble in hospitals and it's getting worse. We haven't quite gotten to the point where something can grow in a bottle of 70% isopropyl alcohol though. --Guy Macon (talk) 06:38, 2 December 2019 (UTC)[reply]

Here, when you have a strong drink outdoors in summer, especially in a cafe (where there's always a healthy supply of alcohol drinkers), don't be surprised when tiny flies arrive to feast on what you didn't drink (or if you're drinking too slowly). 60% brandy doesn't seem to faze them at all... 93.136.178.2 (talk) 21:30, 29 November 2019 (UTC)[reply]

You're talking about beverages created, or at least bottled, under sterile conditions as sterile products. You don't generally see much growing in bottled water if bottled under the same conditions, and that's 0% alcohol. What you are observing is more the fact that spontaneous generation doesn't exist, so a bottle sealed under sterile conditions with sterile contents won't grow anything. 70% ethanol (or isopropanol) is what is used in biosafety laboratories as a disinfectant. That and 10% bleach. --OuroborosCobra (talk) 22:43, 29 November 2019 (UTC)[reply]

I don't know the OP is necessarily talking about sealed bottles. I think it's true that even if you open a bottle of whiskey, let alone propan-2-ol even if you're careless and allow contaminants you're not going to get that much growing, although it's not likely to be nothing either. I wouldn't try this with UHT milk. Of course even with water you're probably not going to get that much in a lot of cases, in part because while it may not kill stuff, plain water is not a great growth medium either. Whiskey would actually be far better in that regard. There are obviously lots of factors at play here, like what can grow in the medium, how fast, how easy it is for the those to be picked up from the environment, etc/ 19:00, 1 December 2019 (UTC)

I have a lot of experience with containers of water with a small "squirt" opening on top. Dozens and dozens of them, used to wet soldering sponges on a production line. Use tap water and the water turns green in days. Use distilled water and it takes weeks. A little alcohol (maybe 5% to 10%) added to either and the water stay clear indefinitely. I figure that the algae can't live on nothing but 100% pure water but that it doesn't take much exposure to the environment for a little dust to fall in and add needed minerals. --Guy Macon (talk) 06:38, 2 December 2019 (UTC)[reply]

Why does this peripheral drift illusion stop working when rotated 45°?

When viewed fullscreen, moving waves appear on this checkerboard. Yet when I rotate it 45 degrees, such as on a mobile phone, the illusion stops working for me. It works again when rotated 90 degrees. Is there a reason for this?

Thanks,
cmɢʟee⎆τaʟκ 20:05, 27 November 2019 (UTC)[reply]

For me, it even stops if I turn the head about 45 degrees. Very interesting. I second this question ;-). --Stephan Schulz (talk) 20:40, 27 November 2019 (UTC)[reply]

Chirality is conditioning most everything we experience (test yourself on the picture with shells at the bottom of the article) --Askedonty (talk) 21:04, 27 November 2019 (UTC)[reply]

Try doing this closing one eye. Gem fr (talk) 21:25, 27 November 2019 (UTC)[reply]

Rather reading Popeye. It's Screen reading and Vision span (which could be improved). we are highly trained to exercise viewing along recurring patterns. --Askedonty (talk) 21:30, 27 November 2019 (UTC)[reply]

Works just as well for me when I rotate 45 degrees. Dmcq (talk) 11:59, 29 November 2019 (UTC)[reply]

It seems to work best on me when the picture is moving, like if I'm zooming in with my head or scanning around with the eyes. When I'm simply staring at the center of the picture it only seems to ripple when my stare wanders a little involuntarily. At 45 degrees only the connections between perpendicular lines ripple. 93.136.178.2 (talk) 21:34, 29 November 2019 (UTC)[reply]

Thanks so much, everyone. I think movement causes attempts to match left and right eye views to vary between correct and wrong matches, causing the waving. When rotated 45°, it always matches correctly, so I stop seeing the illusion. cmɢʟee⎆τaʟκ 22:06, 30 November 2019 (UTC)[reply]

What the hack, after reading this and tilting my head, trying with one eye closed then the other, now it's not rippling no matter how I look at it! אילן שמעוני (talk) 04:08, 2 December 2019 (UTC)[reply]

after 3 minutes it's back to normal. Interesting. אילן שמעוני (talk) 04:13, 2 December 2019 (UTC)[reply]

What are these creatures?

I saw these little animals in a mangrove forest in Shenzhen. They're maybe 2-3 cm long and look something like fish, but I didn't see them swimming, just sitting on the rocks, using their short fins to crawl, and skipping across the surface of the water. I couldn't get a picture from up close, because they jumped away when I approached. Any idea what they are? —Granger (talk · contribs) 23:49, 27 November 2019 (UTC)[reply]

To my untrained eye they look to be in the family that includes Mudskippers. Other editors may have a more accurate link for you Granger. MarnetteD|Talk 23:53, 27 November 2019 (UTC)[reply]

That looks right—thank you! If anyone can identify a genus or species that would be great, but I'm also satisfied with the general identification. —Granger (talk · contribs) 00:10, 28 November 2019 (UTC)[reply]

Hard to be sure, but barred mudskipper looks likely. Mikenorton (talk) 08:37, 28 November 2019 (UTC)[reply]

November 28

Nostrils

Why do human nostrils have their opening pointing down compared with chimps, and other mammals who have them sticking out normal to the plane of their face.,? Ie forward. 86.8.202.181 (talk) 00:29, 28 November 2019 (UTC)[reply]

This article[8] discusses the question. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:12, 28 November 2019 (UTC)[reply]

As does the following:

Cimons, Marlene (March 16, 2017). "Climate may have shaped the evolution of the human nose". Popular Science.

...which references the following journal article:

Thomson, Arthur; Buxton, L. H. Dudley (1923). "Man's Nasal Index in Relation to Certain Climatic Conditions". The Journal of the Royal Anthropological Institute of Great Britain and Ireland. 53: 92–122. doi:10.2307/2843753. ISSN 0307-3114.

—2606:A000:1126:28D:9417:2118:29F3:6E25 (talk) 01:31, 28 November 2019 (UTC)[reply]

I must admit I find the explanations rather unsatisfactory. If it is so much less efficient evolution would have acted against it, after all they're saying evolution has changed it going from warmer to colder climates. It would ha eto be somethng reasonably important like aiding swimming or persistence hunting or countering disease. Something a bit better than what thy say I'd have thought. Dmcq (talk) 12:19, 29 November 2019 (UTC)[reply]

The swimming nose idea is used as evidence by supporters of the discredited aquatic ape hypothesis (but it still sounds reasonable to me!). Alansplodge (talk) 22:07, 1 December 2019 (UTC)[reply]

Who is a climate scientist?

where I can find definition? — Preceding unsigned comment added by 61.68.141.189 (talk) 02:46, 28 November 2019 (UTC)[reply]

You could start by reviewing List of climate scientists. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:19, 28 November 2019 (UTC)[reply]

See also: Climatology (a scientist who studies climate is a climatologist; also related: paleoclimatology) —2606:A000:1126:28D:9417:2118:29F3:6E25 (talk) 03:57, 28 November 2019 (UTC)[reply]

Since underwater military (Submarines) became a very important focus in the last century and science was very surprised by the huge impact of earthe's Oceanography on it's atmosphere, very specialized sciences like Bathymetry have become a thing you can actually study and make your profession. --Kharon (talk) 03:52, 29 November 2019 (UTC)[reply]

Cybertron is the size of Saturn

In the Transformers comics, Cybertron is said to be the size of Saturn. Cybertron is obviously a solid planet, consisting almost entirely of rock and metal, not a gas planet like Saturn. Now ignoring the fiction that it's all populated by sentient living robots, could a rocky planet of such a size exist in the first place? JIP | Talk 11:07, 28 November 2019 (UTC)[reply]

This is all very hypothetical. What's the biggest planet which could form? Would it be rocky? What happens if it's bigger?

Kevin C. Schlaufman has written on this https://iopscience.iop.org/article/10.3847/1538-4357/aa961c

His work is mostly based on observation (we see evidence for things up to the mass of 10 Jupiters, but not bigger). We do see bigger things, but they mostly become luminous as stars.

In our limited Solar experience, larger planets have been formed as gas giants: once they had a large rocky core, they then accreted lighter elements and so their main volume remains gaseous. But could a large rock have accreted, if the materials were there?

Schlaufman's paper takes the accepted view that large bodies form either by core accretion (as planets do), or by gravitational instability (as stars do). But these both form objects in a range of masses, and those mass ranges don't overlap. So "planets" aren't found with more than 10 Jupiter masses (which would be a problem for something as dense as a rocky planet that diameter). Andy Dingley (talk) 12:56, 28 November 2019 (UTC)[reply]

List of transiting exoplanets has several planets with estimated densities that are larger than Earth's, including planets of several Jupiter masses. This high density is presumably not sufficient to characterise them as rocky planets, though. --Wrongfilter (talk) 13:29, 28 November 2019 (UTC)[reply]

We can set an upper limit by assuming that somebody would have noticed it if Cybertron was a Neutron star or a Black hole... --Guy Macon (talk) 17:03, 28 November 2019 (UTC)[reply]

According to our article Hot Jupiter the biggest planetary mass cannot be greater than approximately 13.6 Jupiter masses, because then the planet would start burning deuterium and become a brown dwarf aka a star. However the search for exoplanets is still a very young science field and we know there are "gazillion popillion" of stellar objects out there waiting to be found. --Kharon (talk) 03:19, 29 November 2019 (UTC)[reply]

Though if it was made of rock, deuterium would be low level, and thus it may not be a brown dwarf. The problem may be to get a lot of rock together without getting too much gas, otherwise you would get something like Neptune. Graeme Bartlett (talk) 03:32, 29 November 2019 (UTC)[reply]

If you're big enough, you become a vacuum cleaner for the light elements too, and thus you not only accrete rock, but you acquire the gaseous layers of Jupiter or Saturn. Do it on a big enough scale, and you also get the deuterium and tend towards starhood. It's not simply that "you might or might not acquire fusible materials", it's that if you're big enough, you will. Schlaufman also ties this to the mechanism by which the body forms. Andy Dingley (talk) 16:28, 29 November 2019 (UTC)[reply]

Let's go back to the beginning assumption. The question at the top of this thread says

"Cybertron is obviously a solid planet, consisting almost entirely of rock and metal"

but our article on Cybertron says

"Cybertron is described in the first issue of the Marvel comic book as being the size of Saturn, which would logically mean it possessed incredibly dense gravity, and yet it did not, possibly as a result of its hollow structure, honeycombed as it is by tunnels. However, in later depictions the art suggests Cybertron is much smaller..."

So that answers the question for Cybertron. But the more general question of very large planets is still interesting. Assuming a large planet made of the same stuff as a Stony-iron meteorite, and assuming that it is far enough way from the star to not be torn apart by tidal forces, is there an upper limit to size other than the neutron star and black hole limits? --Guy Macon (talk) 05:39, 29 November 2019 (UTC)[reply]

November 29

Pluto

The description of this image of Pluto (right, top) on Wikimedia Commons says:

This is the clearest view yet of the distant planet Pluto and its moon, Charon, as revealed by NASA's Hubble Space Telescope (HST). The image was taken by the European Space Agency's Faint Object Camera on February 21, 1994 when the planet was 2.6 billion miles (4.4 billion kilometers) from Earth; or nearly 30 times the separation between Earth and the sun.

If it's the clearest view yet, then where did the second image (right, bottom) come from? Or is it because the description is apparently from 1998 and hasn't been updated since then? JIP | Talk 14:09, 29 November 2019 (UTC)[reply]

New Horizons. "New Horizons" Pluto.—eric 14:51, 29 November 2019 (UTC)[reply]

Thanks. So why does the description of the first image say "This is the clearest view yet of the distant planet Pluto" when the New Horizons image is clearly clearer (pun intended)? JIP | Talk 14:55, 29 November 2019 (UTC)[reply]

It also goes on to say"...and its moon, Charon" May I suggest that the first image is that of Charon. Though the top image resembles neither, and the appropriate moon article has a better picture. Another option is that the first image is mislabelled. Anton 81.131.40.58 (talk) 15:02, 29 November 2019 (UTC)[reply]

copied from JPL's description. It's pluto.—eric 15:07, 29 November 2019 (UTC)[reply]

Also the description needs to be updated as Pluto is no longer considered a planet. It is a dwarf planet. Dja1979 (talk) 15:37, 29 November 2019 (UTC)[reply]

(ec) Check the description on commons (eric's first link): The image was created in 1998, uploaded to en.wikipedia in 2008, transferred to commons last week, obviously without changing the text, which was accurate in 1998 and 2008, but not any more. --Wrongfilter (talk) 15:38, 29 November 2019 (UTC)[reply]

I have made some updates to the 1994 picture's description. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:15, 29 November 2019 (UTC)[reply]

Apparently someone copied the caption from the NASA page, but only part of the image. The one in question does not show Charon at all, so the caption is nonsense as applied to it. Maybe the complete image is somewhere on Commons as well; I haven't searched. --76.69.116.4 (talk) 06:43, 30 November 2019 (UTC)[reply]

@JIP: Please feel invited to correct/update or mark such entries yourself right away on its own page. Worst thing that can happen is that it will be re corrected instead of drawing 20-30 people into a missplaced discussions. Please read WP:MAINT. --Kharon (talk) 08:21, 30 November 2019 (UTC)[reply]

If it was on Wikipedia rather than Commons I might, but I don't know how to call attention to such things over there. Feel free to do so yourself. --76.69.116.4 (talk) 12:06, 30 November 2019 (UTC)[reply]

So read WP:MAINT to learn how to make YOUR account on commons! We answer scientific Questions - not offer general or specific maintenance here. — Preceding unsigned comment added by Kharon (talk • contribs) 21:57, 1 December 2019 (UTC) (and the signature added by CiaPan (talk) 20:31, 2 December 2019 (UTC))[reply]

@JIP: The description at the image page File:Pluto1.JPG clearly says:

At the time this picture was taken, it was the clearest view...

and later it specifies the image was taken in 1994, whilst the other one was taken in 2018. --CiaPan (talk) 20:26, 2 December 2019 (UTC)[reply]

Fix: the second image was taken in 2015, not 2018. --CiaPan (talk) 21:05, 2 December 2019 (UTC)[reply]

The description was changed to include "At the time this picture was taken" after I posted my question. It originally just read "This is the clearest view yet". JIP | Talk 20:43, 2 December 2019 (UTC)[reply]

ANS receptors

Why do Beta 2 receptors of the Sympathetic ANS relax blood vessels of the skeletal muscles but Alpha receptors also part of the Sympathetic ANS constrict the same blood vessels of the skeletal muscles? --217.97.100.184 (talk) 18:16, 29 November 2019 (UTC)[reply]

Links: adrenergic receptor, alpha-1 adrenergic receptor, alpha-2 adrenergic receptor, beta-1 adrenergic receptor, beta-2 adrenergic receptor. It looks to me from those articles that under physiological stimulus (as opposed to synthetic agonists), the effect of beta adrenergic receptors is stronger than that of alpha receptors, and so adrenergic stimulus overall causes vasodilation of blood vessels supplying skeletal muscle. Additionally, alpha-1 receptors are downregulated in muscles under stress. This causes increased vasodilation in muscles being heavily used, which shunts more blood to those muscles as opposed to inactive ones. This is likely the primary evolutionary purpose. --47.146.63.87 (talk) 07:34, 30 November 2019 (UTC)[reply]

Thank you very much! --217.97.100.184 (talk) 22:17, 30 November 2019 (UTC)[reply]

Microwaving food

Heated discussion closed.

The following discussion has been closed. Please do not modify it.

I've noticed that some foods, such as rice, heat up faster in a microwave than other foods, such as meat, and end up taking all the heat while the latter remain lukewarm. Why is that so and why is cooked meat in particular so hard to rewarm? 93.136.178.2 (talk) 21:00, 29 November 2019 (UTC)[reply]

Meat is likely to be a lot more dense than rice. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:25, 29 November 2019 (UTC)[reply]

The microwave wavelength is chosen so that it's absorbed effectively by water. Dry food isn't heated so effectively by it, nor is ice. IMHE, rice isn't heated well by a microwave. When reheating it, I always sprinkle it with some extra water.

There used to be a problem of poor energy distribution within the oven cavity, hence the turntables. But modern microwaves are much better for this.

If you make some cup-shaped icecubes specially, you can do the experiment of boiling water in an ice cube. Andy Dingley (talk) 21:30, 29 November 2019 (UTC) Edited with poster's permission. DroneB (talk) 23:47, 2 December 2019 (UTC)[reply]

Interesting, for me rice heats up the fastest, while watery food such as a soup or a stew needs the extra hard setting. Maybe my microwave has the wrong wavelength? 93.136.178.2 (talk) 21:43, 29 November 2019 (UTC)[reply]

Your soup may be gaining a lot of heat, but still staying at a low temperature. It's coupling the microwave energy in pretty well, but water also has a remarkably high specific heat capacity, thus takes a lot of energy to warm up. Andy Dingley (talk) 22:12, 29 November 2019 (UTC)[reply]

And soup is mostly water, whereas rice is mostly not (and also has lots of air pockets, so the "cup of rice" has even less heat capacity than "a grain of rice". It also depends what other ingredients are present on the rice, meat, soup. Added salt or certain other chemicals can increase microwave absorption. DMacks (talk) 22:23, 29 November 2019 (UTC)[reply]

"Added salt or certain other chemicals can increase microwave absorption. "^{[citation needed]}

pmid:17249886. And "Microwave heating of alkaline or salt solutions in open or closed vessels will concentrate these solutions, causing precipitation of salts and formation of crystal deposits on vessel walls. These crystal deposits will absorb microwave energy, causing localized heating which may char and damage vessel components, leading to possible failure." from [9] to get started. [10] is too technical for me to grasp the implications at a casual read. DMacks (talk) 22:45, 29 November 2019 (UTC)[reply]

"microwaves of 2.5-20 GHz frequencies,"

Mine's 2.45GHz. So's yours. So's everyones. To get those frequencies, I have to go in the workshop and get the radar bits out. Salted water might improve absorbtion at 2.45GHz, but not crystals. Andy Dingley (talk) 22:52, 29 November 2019 (UTC)[reply]

The cem.com URL is 2.45 GHz. Sorry, I wasn't clear that the quote is from the subsequent link, not the PMID link. I don't have access to doi:10.1080/00207217908938675, but it seems like it might have useful info. I won't have time to run those sorts of controlled experiments (for example, T-vs-t plot for constant power at various [NaCl]) for a week or two. DMacks (talk) 23:00, 29 November 2019 (UTC)[reply]

More general answer: microwave ovens work primarily by heating water. Heat is transferred to the rest of the food by thermal conduction. This means foods with a higher water content get heated more quickly and evenly. This is also why microwave cooking directions often advise you to let food sit after microwaving, and sometimes to stir it between cooking stages, or to use lower power settings. This allows the heat to diffuse from the water. --47.146.63.87 (talk) 07:39, 30 November 2019 (UTC)[reply]

Good microwave ovens offer multiple automatic heating programs that use predefined heating and heat dispatching phases to warm and/or melt up food. Of course thous are more expensive than the cheapest ones and they need more time and a little more energy to achieve the task. --Kharon (talk) 08:06, 30 November 2019 (UTC)[reply]

Please don't pass on the misinformation that microwaves only heat water or that they don't heat ice. From Microwave oven#Principles:

"Water, fat, and other substances in the food absorb energy from the microwaves... It is a common misconception that microwave ovens heat food by operating at a special resonance of water molecules in the food... Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted... Compared to liquid water, microwave heating is less efficient on fats and sugars (which have a smaller molecular dipole moment)... However, due to the lower specific heat capacity of fats and oils and their higher vaporization temperature, they often attain much higher temperatures inside microwave ovens." --Guy Macon (talk) 08:13, 30 November 2019 (UTC)[reply]

Go boil some water in an ice cup, then come back and say that. Andy Dingley (talk) 14:11, 30 November 2019 (UTC)[reply]

Careful: "things that start off at a higher temperature wind up getting to a higher temperature" doesn't really prove a whole lot, and "liquid water gets hotter faster than ice" is actually completely consistent with what Guy just said. We are obviously not operating at equilibrium conditions. DMacks (talk) 14:43, 30 November 2019 (UTC)[reply]

I generally refrain from responding to Andy Dingley, because I have never seen him change his opinion when faced with evidence against it. For those who doubt what our Microwave oven article says ("Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted") it is a simple matter to confirm at home that microwaves do indeed heat ice. Simply place an ice cube in a microwave, heat it on high, and see how long it takes to melt. Now repeat the experiment without turning the microwave on. It is also interesting to try dry sugar and pure cooking oil, but be careful; it is easy to make a hard-to-clean mess. And if anyone still thinks that microwaves only heat water, buy one of these [ https://www.amazon.com/dp/B01D9V8Z9O/ ], [ https://www.amazon.com/dp/B07BDK7BZY/ ] (or just read the customer reviews for them). --Guy Macon (talk) 16:58, 30 November 2019 (UTC)[reply]

Actually Guy, what you usually do is post insulting and personally targetted cartoons.[11] And a bit of pontification has always been your way. BTW - WP articles are not reliable sources. Andy Dingley (talk) 18:48, 30 November 2019 (UTC)[reply]

No but their sources should be. Nil Einne (talk) 18:42, 1 December 2019 (UTC)[reply]

Andy Dingley, explain how the dipole moment of ice differs from the dipole moment of water to make it a non-absorber of microwave radiation. Indeed, we actually find the opposite, that the dipole moment of ice is somewhat higher than the dipole moment of liquid water, but other factors reduce the thermal heating effects. Reduce, but not get rid of completely. Ice is absolutely a microwave absorber, and thus absolutely will heat in a microwave oven. --OuroborosCobra (talk) 23:26, 1 December 2019 (UTC)[reply]

Don't bother responding to Andy Dingley. I never do. Once he says that ice isn't heated by microwaves, he will never back off and admit that he was wrong. Talking to him about it is a waste of time. He is completely ineducable. The good news is that he doesn't attempt to "correct" our Microwave oven article, so the only harm is him posting false information on the reference desks.

All he has to do is put an ice cube in the microwave and heat it, then do the same with another ice cube but without turning the microwave on. Or read the sources in our article that are used for citations for the claim "Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted" ^[1]

References

^ Chaplin, Martin (28 May 2012). "Water and Microwaves". Water Structure and Science. London South Bank University.

I await the rather boring insult that typically follows showing Andy Dingley that he is wrong. --Guy Macon (talk) 07:07, 2 December 2019 (UTC)[reply]

Try it for yourself, do the experiment. The OP in this thread opened with "faster", not "is not heated by". Of course ice is heated in a microwave, same as rice is, but not as effectively as liquid water is. Thus it's enough to do the (pretty common, high school science) of the "boiling water in an ice cup" demo. Much the same as boy scouts years ago used to boil water over a campfire in a cup made from folded paper. It's not a black and white, all or nothing distinction, but there is a difference. Andy Dingley (talk) 13:41, 2 December 2019 (UTC)[reply]

"The microwave wavelength is chosen so that it's absorbed effectively by water. Dry food isn't heated by it, nor is ice." --posted by Andy Dingley on 21:30, 29 November 2019 [12], emphasis added.

--Guy Macon (talk) 15:11, 2 December 2019 (UTC)[reply]

As a first approximation, I would still stand by that. Yes, it would be nice to cite precise numbers for everything, but that's both a lot of legwork, and also obscures what's still the basic point. Andy Dingley (talk) 15:19, 2 December 2019 (UTC)[reply]

Which are you standing by? ice is not heated, or ice is heated, but not as effectively as water? It can't be both. Shall I quote your reply when I pointed out that Microwave oven says (with a citation) that "Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted"? On second thought, don't bother. I see that I have been sucked into responding to you, breaking my own rule. I will now go back to letting you post false information without responding. Nothing good will come from attempting to correct your error. --Guy Macon (talk) 15:36, 2 December 2019 (UTC)[reply]

It depends on the context, of course. People with basic conversational skills can appreciate that. It's common knowledge that a massively popular use of microwave ovens is to heat up frozen bachelor chow, straight from the freezer. So clearly "ice is heated in microwaves". And yet, that microwave oven will probably have a defrost setting on it, which runs the oven at a duty cycle of only 1/6 or so, because it is so poor at heating a frozen meal. Considerable additional time is needed to microwave cook from frozen. In fact, much of that initial heating of the ice (to defrost it, if not to make it hot) is from conduction of water around the package which has already begun to melt. This is why microwaveable meals are so much more easily cooked (and more evenly cooked) if defrosted first, before microwaving. This is why such rapid meals often include a susceptor, microwave-absorbing packaging so that they can get an "early start" on this otherwise difficult defrosting.

So yes, "ice absorbs microwaves" and yet at the same time, "You can't cook an ice cube, same way you can cook the water sat next to it". It's a subtlety and a distinction, not a contradiction. Andy Dingley (talk) 15:56, 2 December 2019 (UTC)[reply]

I recently had a disagreement with somebody who firmly believed that cast-iron was a poor conductor of heat. (It is a good conductor of heat.) That fundamental mistake is the same one AD is making. The difference is in the rate of heating of water, due to microwaves, in its liquid form, and water in its solid form. It heats faster in liquid form, but still heats up in solid form. Guy is correct. -Roxy, the PROD. . wooF 18:18, 2 December 2019 (UTC)[reply]

what an amount if useless flame. Of course Guy is right. and so is AD. The silly dispute is much of the "the glass is half full! No it is half empty!" kind, with very marginal focus on OP question Gem fr (talk) 21:13, 2 December 2019 (UTC)[reply]

Ah yes Roxy, the one where Guy stripped out all the changes and sources, just because I'd written them and he can't abide that. Andy Dingley (talk) 22:54, 2 December 2019 (UTC)[reply]

December 1

Why is isospin separated in Gell-Mann–Nishijima?

In the Gell-Mann–Nishijima formula, isospin is separated out: $Q=I_{3}+{\frac {1}{2}}(B+S+C+B^{\prime }+T)$ .

Wouldn't it be simpler to write it as: $Q={\frac {1}{2}}(B+U+D+S+C+B^{\prime }+T)$ (where U is Upness and D is Downness).

In fact, why does isospin exist at all? Shouldn't we just talk about Up/Down same as the other quark flavors?

Ariel. (talk) 18:43, 1 December 2019 (UTC)[reply]

You're looking back at some of the history that led to the quark model. At the time, there was just a "particle zoo" with some observed patterns but no unifying model. The Gell-Mann–Nishijima formula is one of the stepping-stones that got us to the quark model and to electroweak unification. The term inside the parentheses gets labeled "hypercharge", and these two terms later lead to weak isospin and weak hypercharge, which have a more fundamental role in the standard model. The original up-down isospin can still be practically useful because there's an approximate symmetry between up and down quarks, which have very similar mass. --Amble (talk) 20:21, 2 December 2019 (UTC)[reply]

December 2

[Martin-1] Chaplin, Martin (28 May 2012). "Water and Microwaves". Water Structure and Science. London South Bank University.

[1]

@@ Line 248: / Line 248: @@
 == Microwaving food ==
+{{hat|Heated discussion closed.}}
 I've noticed that some foods, such as rice, heat up faster in a microwave than other foods, such as meat, and end up taking all the heat while the latter remain lukewarm. Why is that so and why is cooked meat in particular so hard to rewarm? [[Special:Contributions/93.136.178.2|93.136.178.2]] ([[User talk:93.136.178.2|talk]]) 21:00, 29 November 2019 (UTC)
 :Meat is likely to be a lot more dense than rice. ←[[User:Baseball Bugs|Baseball Bugs]] <sup>''[[User talk:Baseball Bugs|What's up, Doc?]]''</sup> [[Special:Contributions/Baseball_Bugs|carrots]]→ 21:25, 29 November 2019 (UTC)
@@ Line 266: / Line 266: @@
 ::Good microwave ovens offer multiple automatic heating programs that use predefined heating and heat dispatching phases to warm and/or melt up food. Of course thous are more expensive than the cheapest ones and they need more time and a little more energy to achieve the task. --[[User:Kharon|Kharon]] ([[User talk:Kharon|talk]]) 08:06, 30 November 2019 (UTC)
-{{hat|Heated discussion closed.}}
 * Please don't pass on the misinformation that microwaves only heat water or that they don't heat ice. From [[Microwave oven#Principles]]:
 :"Water, fat, and other substances in the food absorb energy from the microwaves... It is a common misconception that microwave ovens heat food by operating at a special resonance of water molecules in the food... Microwave heating is more efficient on liquid water than on frozen water, where the movement of molecules is more restricted... Compared to liquid water, microwave heating is less efficient on fats and sugars (which have a smaller molecular dipole moment)... However, due to the lower specific heat capacity of fats and oils and their higher vaporization temperature, they often attain much higher temperatures inside microwave ovens." --[[User:Guy Macon|Guy Macon]] ([[User talk:Guy Macon|talk]]) 08:13, 30 November 2019 (UTC)