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January 29

baseball in space

If the inhabitants of a Stanford torus or something similar formed a baseball team, would the Coriolis effect have any sort of effect on the ball? For example, if I were standing on the habitable surface of my rotating space station, and threw the ball straight up (up meaning from my perspective experiencing the pseudo-gravity of the rotating space station) would it seem to me to curve away in an unusual manner?

Duomillia (talk) 01:19, 29 January 2021 (UTC)[reply]

It will rotate around the space station in the opposite direction, this is then the centripetal acceleration of the ball in the rotating frame, so you have a fictitious centripetal force in the direction of the rotation axis. This fictitious centripetal force is the sum of the fictitious centrifugal force, which is equal in magnitude as the centripetal force but it points away from the rotation axis, and the fictitious Coriolis force which has a magnitude of twice the centripetal force and points in the direction of the rotation axis. Count Iblis (talk) 02:12, 29 January 2021 (UTC)[reply]

So the short answer is "Yes". The effect is very asymmetric in one direction. Given a hollow spinning disk instead of a torus, a ball thrown vertically up in the air at just the right speed (there is actually an infinite number of speeds that will do), neglecting air forces (assume a vacuum), will make a loop and return to its point of departure. The initial deviation of the ball's curve from the vertical is in the direction the space station is rotating. To an outsider, the ball's trajectory is a straight line through the centre of rotation. For an inside observer, stationary in the rotating frame, the trajectory is part of a two-armed Archimedean spiral. --Lambiam 10:31, 29 January 2021 (UTC)[reply]

What are the lines in these satellite images?

I see a series of faint but visible neatly parallel lines in the sea in the following satellite images of the same area: false-color and natural color. What do those lines represent? StellarHalo (talk) 15:20, 29 January 2021 (UTC)[reply]

It could be the imaging error explained in the 'Landsat 7 Scan Line Corrector (SLC) Failure' section of this page, although i'm not sure. Zindor (talk) 17:10, 29 January 2021 (UTC)[reply]

According to the USGS Landsat 7 page, the SLC failed on May 31, 2003, and affects all subsequent data. But the image in question is from September 22, 2002, more than half a year before the failure happened. Therefore, I don't think we're seeing that particular artifact here. --Amble (talk) 17:43, 29 January 2021 (UTC)[reply]

The features I'm seeing look like ocean waves. --Amble (talk) 17:58, 29 January 2021 (UTC)[reply]

I'm not sure whether I'm seeing the same (artefact?) as the OP but both images have two versions on Commons. The first version of the false-colour image was lower resolution but doesn't seem to have the same striations, so I wonder if this is caused by the .jpg rather than the camera. where did you get the higher resolution version from, StellarHalo, as you were the one who uploaded it? Mike Turnbull (talk) 18:11, 29 January 2021 (UTC)[reply]

The higher resolution version I uploaded is from https://avax.news/pictures/44776 as stated in the source information. StellarHalo (talk) 18:19, 29 January 2021 (UTC)[reply]

Where exactly are the lines? I can only see what looks like natural patterns, that to me look like sediment plumes. PaleCloudedWhite (talk) 18:37, 29 January 2021 (UTC)[reply]

I am not talking about the sediment plume directly coming out just above the delta. The lines I am referring to a series of curved ones that are found all over the ocean area of the image. Admittedly they are not easy to see but they form a pattern. I am trying to get the false-color image featured on Wikimedia Commons and someone there asked me about it. StellarHalo (talk) 18:58, 29 January 2021 (UTC)[reply]

I can't see anything except sediment plumes and deposits, so either my eyes can't see what others see, or the person who commented at the FPC page is mistaken when they said that sediment plumes "wouldn't be so neatly parallel". PaleCloudedWhite (talk) 19:14, 29 January 2021 (UTC)[reply]

Both pictures have the pattern, though I find it a lot easier to see in the natural colour image. For example, in the extreme top-left corner, the false colour pic is pretty murky while the same area in the natural colour pic shows distinct banding of, well, blue-green and green-blue, I guess. I don't think they're waves; if they were, I think we'd see them affected by the land form and I don't think that's happening. Instead, they're all at about 40 degrees off of straight up and down (sorry, I don't have a protractor handy). To me it looks like a Moiré pattern. Matt Deres (talk) 19:53, 29 January 2021 (UTC)[reply]

In the true-color image, I see what seems to be the same pattern -- in the same direction -- over some parts of the river and lakes. Probably not ocean waves, then. --Amble (talk) 21:11, 29 January 2021 (UTC)[reply]

I don't want to speculate, but I would emphasize that the provenance of an image on the internet - and the chain of image-processing-operations that have been performed to transform scientific data into a viewable image file - is almost impossible to prove. The artifacts may be real (radiometric artifacts, physical terrain, ocean waves, sea surface variations); or they may be a processing artifact (algorithmic; compression; intentional or ununintentional; ... we just can't know. This is the science of photogrammetry and radiometry. Anyone who pretends to tell you a simple answer that explains why any individual pixel is brighter or darker in your "photograph" isn't thinking about the problem hard enough - and if they extend that answer to explain why you see a pattern of dark- or bright- ... well, they're basically just repeating one wrong/incomplete answer a million times.

If the answer matters - if you're using the image for a scientific data processing operation - the procedure you'd want to use is:

Find the exact source data that was used to produce this image - in this case, you're looking at an image composed from Landsat 7 data, on or around September 22, 2002. You can pull up the exact orbit. For what it's worth, the SLC device was on and operational at that time (you can verify using the metadata for any of the Level 1 or Level 2 products).
Learn everything about the way that source data is transformed - in this case, the Landsat Product Generation System software.
Run that software yourself - and verify the effect is visible in the pixels rendered on your screen. And then... conduct radiometric and algorithmic analysis to determine where that digital signal originates, and then conduct some earth science and optical physics to explain what physical process corresponds to the digital signal that is measured.

If satellite imaging was easy, satellite imaging scientists wouldn't need to ask rocket scientists for help getting their cameras in to position.

Nimur (talk) 20:49, 29 January 2021 (UTC)[reply]

It looks consistent with Landsat coherent noise: [1], [2]. From the abstract of the second link, which is a journal article: "A coherent pattern of system noise observable on all visible wavebands of Landsat Thematic Mapper images over homogeneous surfaces such as waterbodies is regarded as serious enough to impair visual interpretation and affect image analysis results." --Amble (talk) 21:24, 29 January 2021 (UTC)[reply]

(ec) Since none of the waviness is visible over land, I think we can exclude digital artifacts as explanations. The patterns I see are compatible with waves. The parallel strands do each extend lengthwise over only about four to six wavelengths; then the pattern is interrupted as if by interference. Think of an arrangement of frankfurters (wieners). The points of interruption, where complimentary waves appear to cancel each other, follow a pattern of roughly straight lines roughly orthogonal to the waves. These could be wave patterns in the sediment. --Lambiam 21:27, 29 January 2021 (UTC)[reply]

When I posted the above, I had not yet seen the refs to the USGS page and the article in the International Journal of Remote Sensing. So apparently the issue does not manifest over land, which invalidates the conclusion I drew in the first sentence. --Lambiam 21:34, 29 January 2021 (UTC)[reply]

Interesting. I work in hydrographic surveying, and know about and can recognise all sorts of artefacts in sonar imagery that others might e.g. misinterprate as the lost city of Atlantis. But I know next to nothing about Landsat images and the sort of artefacts you get in them, and would have misinterpreted those as "almost certainly waves on the sea surface, or possibly large-scale ripples on the seabed". Iapetus (talk) 17:45, 30 January 2021 (UTC)[reply]

January 30

Why blood won't come if tooth loose naturally?

Why blood won't come if tooth loose naturally? I remember blood clot won't happen fast after dental extraction. Rizosome (talk) 10:14, 30 January 2021 (UTC)[reply]

You mean when kids lose their baby teeth? Sometimes bleeds for a whole. --jpgordon^{𝄢𝄆 𝄐𝄇} 02:04, 31 January 2021 (UTC)[reply]

January 31

Which theory explains Earth rotation?

If Einstein's General relativity explains Earth revolution, then which theory explains Earth rotation? Rizosome (talk) 06:34, 31 January 2021 (UTC)[reply]

Are you asking why the earth spins? ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:03, 31 January 2021 (UTC)[reply]

Courtesy link: Earth's rotation, specifically Earth's rotation#Origin.

Please clarify the premise of your question. Are you highlighting some aspect of the Earth's revolution which is inadequately described by Newtonian physics?

Note: It is best to use internal wikilinks (double square brackets) when linking Wikipedia articles. If you wish text other than the article name to appear in a link, then use piped links (see WP:PIPE), such as "[[Earth's orbit|Earth revolution]]" which yields Earth revolution.

-- ToE 14:02, 31 January 2021 (UTC)[reply]

What makes Earth spin? Rizosome (talk) 14:14, 31 January 2021 (UTC)[reply]

Love Makes the World Go 'Round —2603:6081:1C00:1187:3439:5742:B1FB:BCCC (talk)~ — Preceding undated comment added 16:03, 31 January 2021 (UTC)[reply]

Spin is ubiquitous in the cosmos. Planets rotate, as do stars and galaxies. This comes about simply from conservation of angular momentum. When two ice skaters (or celestial bodies) approach each other and link arms (or are attracted due to gravity), they will start rotating.--Shantavira|^{feed me} 16:24, 31 January 2021 (UTC)[reply]

Unfortunately, the angular momentum Wikipedia article is rather technically dense, and by the second paragraph is already introducing terminology likely to confuse the average layperson. This video from the YouTube channel "Science Asylum" does a pretty good job explaining the role of angular momentum in the formation of the solar system. This video from Universe Today deals with the same issue as well. --Jayron 32 14:50, 1 February 2021 (UTC)[reply]

Into what does the human body convert acetic acid?

The human body normally converts ethanol to acetaldehyde which is more poisonous. Then acetaldehyde to acetic acid (vinegar) which is less poisonous than ethanol. But what does it convert the acetic acid into? JRSpriggs (talk) 22:20, 31 January 2021 (UTC)[reply]

WHAAOE. It's metabolised to acetyl-CoA: see Ethanol metabolism#Acetic acid to acetyl-CoA, which also explains what happens next. {The poster formerly known as 87.81.230.195} 90.200.40.9 (talk) 02:48, 1 February 2021 (UTC)[reply]

Yep, this is how it can be "burned" for energy as a macronutrient. Acetyl-CoA is the "entry point" into the citric acid cycle for nutrients. The all-ethanol diet is not recommended, however. --47.152.93.24 (talk) 17:31, 1 February 2021 (UTC)[reply]

February 1

Stabbing someone in the midst of a heart attack

Hello, Wikipedians I`m just posting this question because I`m curious what would happen if you stabbed someone in the heart while they were in the midst of a heart attack? Thank You — Preceding unsigned comment added by 98.113.197.52 (talk) 00:51, 1 February 2021 (UTC)[reply]

They would probably die. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:16, 1 February 2021 (UTC)[reply]

If you have reason to think they are a vampire, the recommendation is to use a wooden stake for best results. --Lambiam 11:48, 1 February 2021 (UTC)[reply]

There is a famous scene showing an emergency intracardiac injection of epinepherine in the movie Pulp Fiction to keep the person's heart beating, but it was after the person had overdosed on heroin, not during a heart attack. Also, the heart injection was fictional: those injections are usually given in a leg muscle. See epipen. I wonder if you may have been remembering that scene. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 08:32, 1 February 2021 (UTC)[reply]

Are you thinking of pericardial tamponade? It can cause cardiac arrest, which is technically not a Heart attack (disambiguation) but is often colloquially called one. Pericardiocentesis, a treatment for pericardial tamponade, could be rather inadequately described as stabbing someone near the heart. Pericardiocentesis can be lifesaving, but it is ideally administered before the patient goes into cardiac arrest. If you want medical advice, take an advanced first aid course that includes first aid for firearm wounds (being shot in the heart is a common cause of pericardial tamponade). HLHJ (talk) 03:54, 2 February 2021 (UTC)[reply]

Assuming the blade doesn't directly enter the heart - which would cause instant death - the two would compound each other. A heart attack causes decreased heart oxygenation, while stabbing causes blood loss. Less blood means even less oxygen going to the unharmed parts of the heart. So the answer is, very likely, the person would die. Red Panda 25 21:12, 3 February 2021 (UTC)[reply]

The OP specifically said stabbed "in the heart". ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:29, 3 February 2021 (UTC)[reply]

Did you intend to find an answer from a legal perspective? Like what happens if you kill someone, who was dying within seconds? — Preceding unsigned comment added by Bumptump (talk • contribs) 21:46, 3 February 2021 (UTC)[reply]

Since the OP has only made the one edit, we may never know. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:30, 3 February 2021 (UTC)[reply]

Unlimited bandwith for over-the-air broadcasting

If everyone in my city had a radio they tuned to the same station at once, or a broadcast TV tuned to the same channel, we could all watch/listen simultaneously with no bandwidth or capacity issues (ignoring weather, antenna location, distance from the source, etc.) But if we all tried to make a mobile phone call or use the internet at once, we would have capacity issues. My guess is because of the two-way nature of phones and the internet, and also physical constraints such as the towers and the fiber and cable wiring. But is there a better explanation for this and would it also apply to satellite TV/radio?174.16.121.131 (talk) 00:59, 1 February 2021 (UTC)[reply]

I do not think that this is correct. In electronics, if you add more resisters in parallel, eventually the total resistance would be reduced to the point that the voltage would not be measurable. In other words, each receiver adds to the load on the transmitter until the transmitter is no longer able to drive the signal through the noise.

Another way to look at it is that each receiver also is a transmitter which transmits a signal roughly opposite (but smaller in magnitude) to the primary transmitter and partially cancelling it out. JRSpriggs (talk) 01:48, 1 February 2021 (UTC)[reply]

Basically as the signal to noise ratio decreases, the ability to extract information from the stuff coming into the receiver also decreases. If there are 1000 transmitters on a frequency and you're trying to listen to just one of them, the other 999 are "noise". The theoretical limits are established in Shannon's noisy channel coding theorem and modern spread-spectrum modulation schemes (like in current mobile phone systems) are really very good. By comparison, old-school broadcast radio is terrible. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 07:48, 1 February 2021 (UTC)[reply]

In a radio broadcast, there's a single transmitter sending the same signal to everybody at the same time. When using modile phones, the transmitters have to send a different signal to each separate user, so the total amount of signal is much higher. PiusImpavidus (talk) 08:45, 1 February 2021 (UTC)[reply]

The term "bandwidth" has two different meanings. In signal processing, "bandwidth" refers to the size of the portion in the frequency spectrum taken up by the signal. It can be related to the maximum rate of information transfer, but is a property of the signal, not coupled to a notion of channel. In networking, "bandwidth" is a property of a channel, directly specified as the maximum rate of information transfer. So the best explanation, I think, is that the set-up conflates these two notions. --Lambiam 11:41, 1 February 2021 (UTC)[reply]

Yes, modern satellite TV and satellite radio is duplex just like cellular service or the Internet; satellite receivers and the transmitters on the satellite communicate back-and-forth. One reason for this is to encrypt the signals, so free riders can't pick up the broadcasted content. --47.152.93.24 (talk) 18:51, 4 February 2021 (UTC)[reply]

^{[citation needed]} on the claim satellite TV or radio is duplex. I'm sure they exist, but I've never heard of them, nor any part of the world where they are common. Unencrypted satellite TV is generally just some variety of DVB-S. Encrypted satellite TV is generally just some variety of DVB-S with some form of encryption in the mix. While it is theoretically possible someone would require two-way communication for that, nearly all do not, even the infamous NDS VideoGuard. The smart card does require regular updates, but it doesn't need outward communication for those. (If you take out the smart card for a very long time, it's possible it won't work, in that case some outward communication maybe required either by the STB or end user.) For stuff like Pay-per-view, two way communication can be required but even then only in a limited way. In particular, for PPV purchased from the set top box or similar, there is some need for the box to communicate the purchase decision, but this was traditionally via modem and nowadays often via wired ethernet or Wi-Fi. For PPV purchased over the internet or phone, there's generally no need for the STB to communicate outwards as the provider simply signals the STB ~~a few times~~ and assumes it's received. Nil Einne (talk) 11:45, 5 February 2021 (UTC)[reply]

Who predicted an Analemma (position of the sun in the sky) before it got photograph in 1990s?

Wiki page of Analemma didn't mention history of Analemma clearly well. If Albert Einstein predicted Gravitational waves then who predicted Analemma? Rizosome (talk) 06:21, 1 February 2021 (UTC)[reply]

This article (which is given as a reference in Analemma, so anybody could have found it) mentions Jean Paul Grandjean de Fouchy as the "inventor" of this particular type of representation in 1740. It is based on the concepts of equation of time and mean solar time. --Wrongfilter (talk) 07:31, 1 February 2021 (UTC)[reply]

Although in principle it could be predicted by someone who knew enough about the Earth's motion around the Sun and orientation in space, it can in fact be observed very simply (by plotting the position of, for example, the shadow of a fixed object on a fixed surface every few days over the course of a year), so it was known about long before before such knowledge was developed. Sundials, an ancient technology, generally take it into account. According to this, the 1st-century BCE Roman architect Vitruvius utilised the concept in his work (in order to know where shadows of buildings would or would not fall) and described its calculation and use in Book 9, Chapter 7 of his work De Architectura Libri Decem, though he didn't claim to have discovered it, and it was likely known to scholars at least several centuries earlier. {The poster formerly known as 87.81.230.195} 90.200.40.9 (talk) 10:07, 1 February 2021 (UTC)[reply]

As I understand it, Vitruvius' analemma was not identical to the figure that Rizosome asked about. For that figure to become apparent one needs a certain way of reckoning time (at what time of day do you have to take the indivdual exposures that go into the photograph?) – that's why I mentioned mean solar time, which is a concept that Vitruvius did not know about. Nevertheless there is obviously a relation between what Vitruvius did and what de Fauchy did. --Wrongfilter (talk) 10:45, 1 February 2021 (UTC)[reply]

In any case, the annual north–south swinging of the solar position has been observed and known since antiquity. To observe the much smaller east–west deviations requires sufficiently accurate timekeeping devices, such as the pendulum clock, invented in 1656. By the time of Fouchy (who deserves an article), the biannual east–west movement must also have been detected. No one (as far as we know) can be said to have "predicted" it; the observation preceded the explanation. Fouchy's role is that of an inventor: he invented a graphical method to relate the position of the Sun in the sky (giving the apparent solar time) to the mean solar time. --Lambiam 11:20, 1 February 2021 (UTC)[reply]

Lambiam From here, Analemma is developed by the French astronomer Grandjean de Fouchy. But in Analemma his name is missing. Is 1730 in science vandalism? Rizosome (talk) 15:45, 1 February 2021 (UTC)[reply]

Sources disagree about the year. Here we read "since 1730", but here we see "1740". Without extensive investigation, it is hard to tell which is wrong. --Lambiam 16:06, 1 February 2021 (UTC)[reply]

In his 1797 treatise De la mesure du temps par les horloges, scientist and watchmaker Ferdinand Berthoud writes that he knew of three analemmata having been drawn, the first being by Grandjean de Fouchy at the Count of Clermont, and two more he drew himself in 1737.^[3] This makes the date 1740 too late. It may be impossible to assign a precise date, because it seems that Fouchy has not published his invention but merely told others, such as Berthoud. Several French sources give an imprecise date, writing "vers 1730" ("around 1730" or "circa 1730"). --Lambiam 11:03, 2 February 2021 (UTC)[reply]

Lien de courtoisie: fr:Jean-Paul Grandjean de Fouchy. -- ToE 19:36, 1 February 2021 (UTC)[reply]

A number of churches in Italy have an analemma inlaid in the floor, and a pinhole in the south wall so that an image of the sun at noon falls thereon. One day in 200x, the sun was partially eclipsed for Italy at noon, and someone put out a call for photographs of the image of the crescent sun on such churches' analemmata. I supposed when I saw this gallery that the analemmata were made in the Renaissance, but perhaps not? —Tamfang (talk) 02:29, 3 February 2021 (UTC)[reply]

~~This would have been the solar eclipse of October 3, 2005.~~ It is possible that the traced figure and its significance was discovered independently several times, and it is not strictly impossible that some of these inlaid analemmata stem from the Renaissance. Some clock towers had striking clocks that were accurate enough already then; they would have struck the sexts every day at the same mean solar time. It would be interesting to historians of timekeeping to know the earliest construction dates. --Lambiam 09:32, 3 February 2021 (UTC)[reply]

Perhaps the solar eclipse of August 11, 1999, which passed as a partial eclipse over Italy around 10:45 UTC = 11:45 CET. (I had the privilege of watching its glorious totality that day from Amasya.) --Lambiam 17:08, 4 February 2021 (UTC)[reply]

February 3

Single use plastic

I've recently bought a disposable water filter for a jug and the package says "Reduce single use plastic". Since the filter itself is plastic and assuming it's the manufacturer's responsibility to produce non-plastic filters, I consider "reduce single use plastic" directed towards consumers a bit taunting and mocking. And per Brita (company), the manufacturer in question, "the filters can be recycled", which also makes that reduce plastic warning redundant. So does it make sense? 212.180.235.46 (talk) 12:28, 3 February 2021 (UTC)[reply]

I believe the message is about plastic water-bottles. Between the lines they're stating that decanting from a Brita into a re-usable bottle is a good thing, and well done you, rather than buying those one-use plastic water bottles. I agree it's a poorly directed message and reads like an accusation. Zindor (talk) 12:53, 3 February 2021 (UTC)[reply]

Context Is for Kings. The context here is a product that you use for filtering tap water. Britas aren't meant to be used to filter bottled water. So, by using a Brita instead of bottled water, you are reducing the amount of single use plastics since you aren't using single use plastic water bottles. Even the Brita filter itself isn't really a single use product; you use it to filter water again and again for months. The amount of water going through it is far greater than the amount of water that would be contained in single use plastic water bottles with an equivalent amount of plastic. --OuroborosCobra (talk) 18:24, 3 February 2021 (UTC)[reply]

Just in case there's any doubt, their website makes it clear that they're talking about the waste generated by bottled water.

“Single-use plastic bottles are destroying our planet. With Brita, you can enjoy great-tasting water without the waste.[4]”

ApLundell (talk) 23:43, 3 February 2021 (UTC)[reply]

Are you sure this was the literal text? If so, it is a bit crummy; it should be "single-use plastic waste" – what is being reduced is not the plastic (the incredible shrinking bottle) but the plastic waste. If this was not the literal text, perhaps it said, "reduces single-use plastic waste". --Lambiam 10:18, 4 February 2021 (UTC)[reply]

One important thing to note about bottled water. Unless you live in an area without access to safe drinking water (and there are a LOT of people in that situation, so don't get me wrong), bottled water is basically pointless. If you live in a major western city with a municipal water supply, the water in your bottled water is just drawn from the same water supply as your kitchen tap gives you. It's going to be produced in a local bottling plant, which may (but often does not) do some rudimentary filtering such as would be done by a Brita-type filter (but on a larger scale). When you buy bottled water, you're basically paying for just the bottle, and if you have containers in your house that can hold water, and a kitchen tap that delivers water from your local municipal water source, there's no conceivable advantage to drink bottled water. --Jayron 32 14:08, 4 February 2021 (UTC)[reply]

This may be true in the USA, but isn't true elsewhere. Our (UK) tap water has detectable chlorine in it. The bottled water we can buy comes from many different places and contains differing levels of minerals, so will taste different. The one I usually buy is from Evian in France.--Phil Holmes (talk) 08:16, 5 February 2021 (UTC)[reply]

Note that here "detectable" means: detectable by the unaided human sense of smell. --Lambiam 10:21, 5 February 2021 (UTC)[reply]

It is also true in many parts of the U.S.; you can get any number of different kinds of bottled water for your own purposes. If it is important enough for you to increase plastic waste and excessive shipping pollution to have French water, good for you! You should be proud. The shareholders and marketing executives of that corporation thank you heartily for doing your part to increase their wealth at the expense of the environment. --Jayron 32 14:46, 5 February 2021 (UTC)[reply]

February 4

drawing planets orbits around earth

I wish to produce the like of this image. I want it to make it myself so I can release it as creative commons. Preferably, I would like to include the orbits of Venus and Mercury as well. Is there a tool for this job? אילן שמעוני (talk) 01:11, 4 February 2021 (UTC)[reply]

The tool XEphem is capable of calculating and charting ephemerides, but I don't know if it will directly display this kind of chart. The calculation part has been isolated and made available in the form of the Python library pyephem. I have not examined its precise functionality, but our article Ecliptic coordinate system gives formulas for converting between equatorial and ecliptic coordinates, if necessary. List of information graphics software lists many apps that can convert a data set to a chart. --Lambiam 10:06, 4 February 2021 (UTC)[reply]

Vertical bar in chemical formula

The chemical formula given for lazurite is (Na,Ca)₈[(S,Cl,SO₄,OH)₂|(Al₆Si₆O₂₄)]. What does the vertical bar represent? –LaundryPizza03 (d c̄) 14:22, 4 February 2021 (UTC)[reply]

This discussion forum has some ideas. --Jayron 32 15:33, 4 February 2021 (UTC)[reply]

Almost every source presents a different formula. I saw this specific version in the 1992 book A Guide in Color to Precious & Semiprecious Stones.^[5] A 2000 research article in American Mineralogist has (Na,Ca)₈[Al₆Si₆O₂₄](SO₄,S)₂.^[6] --Lambiam 16:51, 4 February 2021 (UTC)[reply]

Cloning using CRISPR/gene editing question

Do you believe that it would ever become possible for us to edit the genes from any cell from our bodies (for instance, a skin cell)--saying, using CRISPR or whatever--and transform this cell into a zygote/embryo? Not into a sperm or egg, but rather into a zygote/embryo. Futurist110 (talk) 22:05, 4 February 2021 (UTC)[reply]

Yes. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:13, 4 February 2021 (UTC)[reply]

Would that also apply in regards to successfully transforming non-human bodily cells (for instance, a cat's or dog's skin cells) into human zygotes/embryos using gene editing? Futurist110 (talk) 01:38, 5 February 2021 (UTC)[reply]

Maybe. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:57, 5 February 2021 (UTC)[reply]

If I peel and mush some bananas, hollow out an orange and stuff it with the banana mush, have I successfully transformed the orange into a banana? --Lambiam 10:15, 5 February 2021 (UTC)[reply]

No, but it's a poor analogy, because the banana mush doesn't actively manufacture more banana structure and banana metabolism proteins, whereas human genes inserted into a non-human cell do generate human-cell proteins and might indeed, if done right, cause the cell to transform into a human zygote.

That said, while I concur with Bugs' "maybe", Futurist110's proposal of using non-human cells apparently adds pointless difficulty to the exercise: why, in the real (future) world would one use non-human cells when human cells would surely be available? Well, Futurist110 is (I understand) kicking around ideas for a science fiction novel, so there might be plot or background details that necessitate it, such as the exploitation of a loophole in laws forbidding human zygote gene editing. {The poster formerly known as 87.81.230.195} 90.200.40.9 (talk) 23:19, 5 February 2021 (UTC)[reply]

Calculating the distance range of commercial over-the-air FM radio stations

Now, I know the internet is full of forum questions of similar types, where people are being answered there would be too many undefined variables in their question than to really give an answer. However, I'm trying to find a simple online calculator (or maybe a formula, but I'm afraid it won't be easy to calculate on paper) for the following given specific conditions:

Let's assume we have a fully flat area for hundreds and hundreds of square miles, like a desert or prairie, without any forests, hills, or mountain obstacles.
We have a number of FM radio towers. Each being a simple, omnidirectional isotropic radiator, which sets antenna gain at 0dB on the transmitter side. They all broadcast at or around a frequency of 100 MHz. The towers only differ in height and watt power.
We know the exact individual height of every tower above sea level (in metric MASL), ranging between c. 60 to c. 250 meters.
We know the individual watt power of every tower, ranging from 0.01 kW to 20 kW.
The receivers are simple car or home kitchen radios with small whip antennas (which probably gives them an antenna gain of c. 2 to 3 dB), all at c. 1 to 2 meters above ground.
We define the limit of transmission range as the area within which the signal quality or strength for the receivers does not drop off below 50dBuV per meter.

So, what I'd like to calculate would be the individual distance range of every single tower, based on those factors and atmospheric path loss, while ignoring specific weather conditions. And no, I'm not asking about radio aka radar horizon, as that limit is most likely far above the capacities of those towers, anyway. --46.93.157.63 (talk) 23:48, 4 February 2021 (UTC)[reply]

Since you already give a strength limit of 50dBuV per meter a lot of your other assumptions are not required. So your volts per meter, can convert to watts per square meter (V/m)²/377, which for you is 2.65×10⁻¹⁰. You can then work out the size of the sphere 4πR² so your power flux: P/(4πR²) > 2.65×10⁻¹⁰. Substitute your transmitter power in P and solve for R. For 10000 watts I get 1730 km. This may sound big, but don't forget that the Earth is curved and there are hills and trees that absorb. So reality will be less. Due to reflection from the ground, the signal can also be doubled in some places, (and zeroed in others). Also consider that the transmitter will not be isotropic, and will avoid transmitting power down into the ground, and up into the sky. Graeme Bartlett (talk) 00:57, 5 February 2021 (UTC)[reply]

This does not take the path loss into account that is due to signal attenuation in the atmosphere. I further notice that Friis' transmission formula involves the wavelength, so presumably this should be of some significance. --Lambiam 10:09, 5 February 2021 (UTC)[reply]

Yeah, I was about to say that quite a lot of sources and websites make a huge deal out of path loss, Friis formula, wattage, and antenna gain (both on the transmitter and the receiver side), and there are even some websites with tables that claim you can calculate range from kW and HAAT, such as [7] ("How far will my signal go?", source: professional electronics dealer Broadcast Warehouse), and [8]. (Granted, with the first website, the power wattage examples are much smaller, and with the second, the figures are for highly directed transmitters.) (Although some sources claim you have to convert kW into effective radiated power first, not the actual power used or emitted, and that the results from kW (or ERP) and HAAT would be officially grouped into so-called "station classes" designated by the FCC, such as A, B, C, etc., where each FCC "station class" would equal a broadcast range class.)

To the contrary, quite a lot of *OTHER* sources even pretty much claim in response to "How many miles per watt?" questions that power wattage would have no impact at all once you have a tower, and then you could simply take the height of the tower in feet, and 75% of that or so would be the range in miles, acting as if 1 Watt would carry all the way to the radio horizon unchanged once you're 20 feet high. That's rather confusing, as you seem to have radicals on both sides: There seems to be a camp that says HAAT would be everything, and then there's a camp that says it would be entirely up to path loss, Friis formula, wattage, and antenna gain. And all over the internet, both camps seem to be entirely ignoring the other camp's existence, actively denying that the factors given by the other camp have much of any effect at all upon range, or they say those other factors would be far too diverse in real life that you can't really calculate them.

Anyways, from loooooooots of googling and reading, I've found two different solutions to my problem:

a.) Nautel’s Radio Coverage Tool: [9] It's free (though requiring registration). All you have to do is pick your location conveniently from a global map, then enter frequency in MHz, power wattage in kW, HAAT, and pick your type of receiver, and there you go. The thing has access to massive databases of global terrain data to calculate and draw your actual range as a circle around your tower on a map for you at the click of a button. You can also additionally download Google Earth to make the results look really neat, make even more realistic range calculations, and do lots of other stuff.
b.) I've found that there are official, publicly accessible FCC databases for pretty much every single commercial FM station in the USA that also list ranges in miles for every single station. Wikipedia even has a short list like that on its own at List of North American broadcast station classes#Station class description (where Wikipedia even claims that you can calculate ERP from HAAT and kW somehow, though without giving a formula). Unfortunately, no such official lists seem to be available for Germany, which is the actual area I'm trying to find this out for, and when you google for terms such as "FM radio technical broadcast range" in German, all you'll get is results not in miles, but in number of potential listeners, as if listeners would be the official physical electronic measure unit of "technical range". However, I've now come upon an amateur website where thousands of radio enthusiasts have reported FM bandscans from all over Germany to, and the site has used that data to draw rather detailed, confusing maps with ranges depicted as circles, either for every commercial or public broadcaster or for every radio tower used by that station, and are listing the rough broad range radius of every single station or tower derived from all that amateur data also in rough numerical values of kilometers. --46.93.157.63 (talk) 14:07, 5 February 2021 (UTC)[reply]

February 5

Substance in cardoon stalk

I boiled an cardoon stalk. The boiling water, after the addition of vegetable bouillon cube (therefore substantially salt, glutamate and flavorings), was kept in the pot for a few hours, and from clear as it was (slightly yellowish, color substantially due to the addition of the bouillon cube) has turned green! I would have expected to find at the limit a brown liquid, almost black, having had all the time to oxidize, but that color just I would never have expected. To which I think: "... is it pH sensitive?" (the cooking water is particularly calcareous, so the broth should be slightly basic). I add a splash of lemon juice and the broth turns yellow. And adding baking soda turns green again. And here is the question: which substance (or chromophore group) could be responsible for the color change? --87.0.134.53 (talk) 10:26, 5 February 2021 (UTC)[reply]

It's most probably one or more anthocyanin responding to the pH change. Roger (Dodger67) (talk) 14:18, 5 February 2021 (UTC)[reply]

Per Roger, some pigment or combination of pigments is responsible. Anthocyanins are generally blue/red indicators (antho=red, cyan=blue), while something like Curcumin is a yellow/red indicator (the main coloration of turmeric). I am not familiar with a "yellow/green" indicator natural to plants, but clearly they exist. Not sure what specific chemical these are in this case, but such types of compounds are common enough. --Jayron 32 14:25, 5 February 2021 (UTC)[reply]

Carbon emission of rail vs air

If you look at the greenhouse gas emissions of the whole system over a period of time (for example 50 years), are electric trains still much better then air travel? Has this been modelled? 2A02:C7F:C42F:6400:E1C2:D924:23F8:470E (talk) 17:18, 5 February 2021 (UTC)[reply]

Cecil Adams provides a nice overview to this question here.

I believe the paper he mentions at the start of the article is this one. I think that paper, and its citations could provide a very detailed answer to your question. ApLundell (talk) 19:14, 5 February 2021 (UTC)[reply]