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September 1

Inorganic chemistry: crystal field theory and ligand field theory.

Crystal field theory came 1st. Is CFT something that explains a good 40% of something, and the ligand field theory explains another 55%? Is there something that CFT explains that LFT does not? And then, is there a 3rd theory that continues from the 2, or were the 2 considered complete?

There is also, charge-transfer band, at 2 types: ligand-to-metal (LMCT) and metal-to-ligand (MLCT). This is very independent of the above 2, right, as the above 2 were for metal-metal only? D metals. Thanks. 67.165.185.178 (talk) 02:49, 1 September 2022 (UTC).[reply]

Pharmacology and foods.

The body has about 4 receptors and 7 neurotransmitters. Are there any drugs that reacts with all 4 receptors and all 7 neurotransmitters? Somewhere out there, there should be data on what the average drug does, like maybe the average drugs only reacts with 2 receptors and 3 neurotransmitters. Can there be drugs that react with receptors, but with 0 transmitters, or react with transmitters, but 0 receptors? Would water be something that reacts with 0 and 0?

Well, I've heard that humans have 40 neurotransmitters in use in the nervous system, and that the immune system has those 40 plus 1. And the number of receptors is huge, perhaps 1000? All cells are capable of expressing anything any other cell can do, even though some are specialized to produce more. I've also heard that every cell in the body expresses every gene, even long-dead pseudogenes, at least once per day, presumably by accident. Abductive (reasoning) 05:09, 1 September 2022 (UTC)[reply]

There are already five major groups of receptor molecules (ionotropic receptors, G protein-coupled receptors, tyrosine kinase receptors, enzyme-linked receptors, nuclear receptors), which have many members. From our article Neurotransmitter: "The exact number of unique neurotransmitters in humans is unknown, but more than 100 have been identified." --Lambiam 08:35, 1 September 2022 (UTC)[reply]

Also for a food question. Can there be foods A and B, A is healthier than B at low amounts, but not at higher amounts. Sounds like to the extent the answer is yes, is to the extent the food is not 100% food. 67.165.185.178 (talk) 02:53, 1 September 2022 (UTC).[reply]

Many a vitamin is needed for survival at low concentrations and will kill you at higher concentrations. Abductive (reasoning) 05:09, 1 September 2022 (UTC)[reply]

Even drinking too much water (Water intoxication) can be fatal. 2603:6081:1C00:1187:A5DC:BD71:B7B:5DB6 (talk) 06:15, 1 September 2022 (UTC)[reply]

The healthiness of a food can only be considered in the context of a person's typical diet. For someone who usually only consumes meat and potatoes, Brussels sprouts are very healthy, but for someone who only munches cabbage, an extra serving of Brussels sprouts will hardly be an improvement. --Lambiam 08:00, 1 September 2022 (UTC)[reply]

The dose makes the poison - Paracelsus. --Jayron 32 10:44, 1 September 2022 (UTC)[reply]

You know what for my own question I'ma go with spinach and lettuce. Small amounts of spinach should objectively be healthier than a filler-food like lettuce. But too much spinach can lead to too much iron, nothing much with too much lettuce. 67.165.185.178 (talk) 03:41, 5 September 2022 (UTC).[reply]

The idea that spinach is a good dietary source of iron is basically a myth. Spinach has a moderate amount of iron, but very little of the iron is absorbed by the body when it eaten. [1] CodeTalker (talk) 07:18, 6 September 2022 (UTC)[reply]

Something of an accumulation of myths according Iron in Spinach from McGill University. It seems that Popeye never claimed that it is a good source of iron, and the false suposition that it is, didn't come from a decimal point error, as is widely believed. Alansplodge (talk) 10:28, 6 September 2022 (UTC)[reply]

Should COVID-19 survivors be careful or better not?

I heard someone on the radio claim that people recently recovered of COVID-19 are better off not being careful. The argument was that they have high immunity and therefore do not get sick from contact with an infected person, but then their immunity gets a boost. I don't know if the speaker was a doctor. Is this a known theory? A doctor at the hospital said she didn't know the theory and didn't know if it was true, but it sounded plausible to her. Thank you. Hevesli (talk) 16:57, 1 September 2022 (UTC)[reply]

So, there are a million complicating factors to consider. From an individual patient point-of-view, we have no way to assess their potential health outcomes from a second infection without knowing what their first infection was like. Have they fully recovered? Which strain was each infection? How healthy are they otherwise, in terms of immune system, lung function, etc. etc. etc. To say that any one patient can feel safer or not having been already infected by COVID-19 us impossible; only that patient's doctor knows enough about their particular health situation to answer that, and that one patient should get that information from a doctor that can assess their particular unique health situation. From a public health point of view, the ultimate goal is to minimize transmission in all forms; that's because the virus reproduces by transmission, the more people get it the more opportunities the virus has to mutate, and the more the virus mutates, the greater chance it could mutate into some new strain which could be more resistant to vaccines and treatments, more transmissible, and more deadly. The mutation rate is of great concern, and so minimizing re-infections can only help public health in that way. On the balance we expect people to be less likely to catch it a second time, and on the balance we expect reinfections to be generally less severe, but those are not the only consideration here, and regardless of whether or not we are talking about a single individual, whose response to a second infection may or may not go the way that the average person does (getting ill in any form always carries risks!), AND from a public health point of view, looking at an entire population, there is no conceivable way in which more COVID infection is beneficial. --Jayron 32 18:14, 1 September 2022 (UTC)[reply]

So one thing that I will say, which may be being confused here, is that there is a concept called the Hygiene hypothesis, for which there is some evidence, which says that exposure to some kinds of pathogens to people early in life may provide for a stronger overall immune system. It's not really that closely related to what you're talking about here, but I can see how someone could extrapolate some of the tenets of the hygiene hypothesis and overapply it to something like what you heard. --Jayron 32 18:19, 1 September 2022 (UTC)[reply]

As an aside, the Hygiene hypothesis really only applies to autoimmune disorders and likelihoods of allergies, from an immune system looking for challenges, not in the other direction of having a "stronger" immune system that is better at fighting off diseases. This whole notion of a "strong immune system" is rooted in concepts of independence and toughness and is one reason people refuse vaccines. Abductive (reasoning) 23:52, 1 September 2022 (UTC)[reply]

Yes, thanks for that clarification. I should have made that point stronger. --Jayron 32 14:16, 2 September 2022 (UTC)[reply]

There are two ways to understand the assertion/question.

One is whether it is beneficial to deliberately expose oneself to further infection, ceteris paribus. This could be scientifically tested (randomize a group of patients, spray the control group with water and the intervention group with covid-laced water, see if the latter group lives longer/better). The procedure and choice of follow-up period etc. might be simple (by the standards of a clinical trial), but it is likely that getting approval from the relevant ethics committee would be somewhat difficult. While ~~Jayron32 presented informed speculation that it could be beneficial under certain hypotheses~~ it might be beneficial for some individuals under some special circumstances, my speculaguesstimate is that on average and probably in almost all cases it is not: [probability of reinfection by the spraying] times [negative effects of reinfection] is probably higher than [probability the spraying avoids another later infection] times [negative effects of that avoided infection].

Another interpretation is that certain actions aimed at avoiding covid infection are on the whole detrimental (at least for some patients). For instance, if you don’t move from your home at all, you might not get covid, but you might get thrombosis. That can also be studied - take a cohort of patients, ask them before and after a study period about their habits, score them on a one-dimensional "covid carefulness" scale, correlate that with healthiness (including covid and non-covid problems). Ethics approval will be easy (the patients just have to fill out a questionnaire), but making a proper protocol and eliminating cofounding variables will be tricky. People who do motorsports / take drugs / do [insert any dangerous activity here] are more likely to have a non-covid health problem than the general population (because of that activity), and also more likely to score low on covid avoidance (because they generally do not worry much about their health). The setting of the study might push people to lie on the questionnaire in a non-uniform manner: for instance, smokers might get into the habit of lying to their physicians about how much they smoke, and that causes some people with a highly-significant medical characteristic (smoking habits) to score fictitiously high on the covid carefulness scale.

I think it is unlikely that either interpretation has been studied with enough care about the protocol and statistics to produce a result I would trust, and a quick look at Google Scholar turned up nothing. In the absence of any such study, I am not trusting what you heard at the radio, irrespective of who said it. Tigraan^{Click here for my talk page ("private" contact)} 15:24, 2 September 2022 (UTC)[reply]

Note, "While Jayron32 presented informed speculation that it could be beneficial" is 180 degrees opposite of what I said. What I said was "regardless of whether or not we are talking about a single individual, whose response to a second infection may or may not go the way that the average person does (getting ill in any form always carries risks!), AND from a public health point of view, looking at an entire population, there is no conceivable way in which more COVID infection is beneficial." (bold added to quote for clarification). I'm not sure how you went from my saying there was "no conceivable way in which more COVID infection is beneficial" to me claiming it was. --Jayron 32 15:29, 2 September 2022 (UTC)[reply]

Sorry, I certainly did not meant that you advocated for the infection policy, and I do not think anything you wrote was unreasonable (otherwise I would have said so). I have struck that part and put something in my own words. Tigraan^{Click here for my talk page ("private" contact)} 15:43, 2 September 2022 (UTC)[reply]

It's all good man. Yeah, individual health outcomes are, well, individual, and to say that zero people would benefit from reinfection is different from saying that, as a matter of either public health policy or medical best practice, intentional reinfection should be recommended. Could we find at least one person on the planet who had a better health outcome because they were so reinfected? I have no doubts we could. Does that mean policies should be changed to advocate for that? Hell-to-the-effing-no, because there are far more important considerations than any potential benefits to a single person. --Jayron 32 15:57, 2 September 2022 (UTC)[reply]

@Tigraan and others... instead of spraying one group with covid-laced water, supposedly to give them more antibodies, why not give them (another) booster vaccine? It seems that's what the original question is trying to get at... 71.228.112.175 (talk) 01:29, 7 September 2022 (UTC)[reply]

Actually, the OP asked specifically about "not being careful" and intentionally being in "contact with an infected person" (their words). That's not a booster shot. Those of us that responded provided answers to the questions actually asked. Your question involving booster shots is a different question. --Jayron 32 14:39, 7 September 2022 (UTC)[reply]

Time between successive COVID-19 illnesses

A related question. After recovering from COVID-19, the healed patient can fall ill again, but not immediately. How much time is left between at least? Thank you. Hevesli (talk) 16:59, 1 September 2022 (UTC)[reply]

As far as I know, there is no guaranteed minimum time limit between reinfections with COVID-19, indeed if we are dealing with substantially different strains, a person can be reinfected in fairly short order; or even be infected by multiple strains simultaneously, see here. --Jayron 32 18:07, 1 September 2022 (UTC)[reply]

Coronavirus (COVID-19) Infection Survey, characteristics of people testing positive for COVID-19, UK: 20 July 2022 notes that reinfection with the Omicron variant was five times more likely than with previous variants (in the UK). Alansplodge (talk) 12:52, 2 September 2022 (UTC)[reply]

September 2

Median of a binary star and general relativity

Imagine a binary star with two stars of the same mass. Between them there is a path where gravity cancels out for an object with a speed well above their orbital speed and coming from infinity (almost a straight line). In this case, what does the theory of general relativity predict? For the object, the curvatures of the space-time that it undergoes on its way between the two stars add up or cancel each other out? — Preceding unsigned comment added by Malypaet (talk • contribs) 20:16, 2 September 2022 (UTC)[reply]

Sorry, it's more complex. On the median in question there is an equal attraction of the two stars, in the distance they add up and in the middle (barycenter) they cancel each other out. Malypaet (talk) 21:25, 2 September 2022 (UTC)[reply]

See Lagrange point L1, which for a binary system of two bodies of the exact same mass and which orbit a common barycenter, will be at that barycenter. In any two-body problem, there are always 5 points where gravity "cancels out", those are the Lagrange points. --Jayron 32 14:37, 7 September 2022 (UTC)[reply]

September 4

Empathy as a finite resource

Is there scientific evidence that the empathy we can feel with other life forms is finite and being used up? 2A02:908:424:9D60:0:0:0:4A03 (talk) 10:06, 4 September 2022 (UTC)[reply]

Can You Run Out of Empathy?

Journal of Patient Experience - Empathy

Alansplodge (talk) 11:12, 4 September 2022 (UTC)[reply]

In Empathy§Neuroscientific basis of empathy we read that empathy is both affective and cognitive. An example is shown here.--Askedonty (talk) 11:40, 4 September 2022 (UTC)[reply]

Skull anatomy

I remember reading or hearing some time ago that the Australian aboriginal populations had sutures of the cranial bones different in number (one more or less) from the rest of the world population. However, do I not find this detail anywhere. Is there something like this? --37.162.33.97 (talk) 13:39, 4 September 2022 (UTC)[reply]

The following journal study analyzes cranial morphology of Aboriginal Australians; the abstract doesn't mention a distinction in the number of cranial sutures; however, further reading might reveal otherwise.

Curnoe, Darren (20 January 2011). "A 150-Year Conundrum: Cranial Robusticity and Its Bearing on the Origin of Aboriginal Australians". International Journal of Evolutionary Biology. 2011: e632484. doi:10.4061/2011/632484. ISSN 2090-8032.{{cite journal}}: CS1 maint: unflagged free DOI (link) --136.56.52.157 (talk) 19:19, 4 September 2022 (UTC)[reply]

It does mention suture abnormalities, specifically premature suture closure, possibly related to mastication. --Lambiam 05:47, 5 September 2022 (UTC)[reply]

Tangent Alert

I wonder what's the highest single-season mastur to mastic ratio by a human in history. Sagittarian Milky Way (talk) 13:01, 5 September 2022 (UTC)[reply]

The best to know is to tune in. The best are naturally vintage Bakelite, azn. Artificial cranial prototypes, in a sense. --Askedonty (talk) 13:35, 5 September 2022 (UTC)[reply]

@Sagittarian Milky Way, Askedonty: I tried to make sense of your comments, but unfortunately failed. @Sagittarian Milky Way: What exactly are you referring to by "single-season mastur to mastic ratio" here? @Askedonty: Why are you talking about plastic radios in the context of a question regarding craniology? Seriously, I'm at a real loss, and hope you can enlighten me on the actual meaning of these posts. (Please be so kind as to ping me if you like to reply. Thanks in advance.) Best, Hildeoc (talk) 13:40, 6 September 2022 (UTC)[reply]

@Hildeoc I'm afraid Sagittarian Milky Way (who is absolutely welcome to confirm that opinion) may be uttering his apparent nonsense because he is making of the subject the same interpretation than you. I'm taking 136.56.52.157's wording but "cranial morphology" is only wrongly evocative of craniology, considering that word as relating to pseudo-science Phrenology. --Askedonty (talk) 14:33, 6 September 2022 (UTC)[reply]

@Hildeoc, you may not be aware that there is a long-standing tradition on the Ref desks of using small type for jokes and other side-track material not germane to the main discussion. Apologies if you knew this and were merely seeking to understand the jokes above as jokes (which I think involve puns on mastication, mastic as a glue or plastic component, and the results of another word starting with 'mast-'). {The poster formerly known as 87.81.230.195} 90.201.73.43 (talk) 22:36, 6 September 2022 (UTC)[reply]

I apologize if someone felt their time wasted trying to find wit that didn't exist in a puerile comment (though I wouldn't have truncated any words if I wasn't almost given my first ban a good chunk of a decade ago for a clump of risqueness in a possibly excessive long-term average. If someone said something like "maybe tone it down, we're a little higher-brow than YouTube comments" or "what if a female's first RD impression is this and she doesn't like it" then this confusion wouldn't have happened. Or if I had enough foresight to realize a level and random risqueness distribution and my non-influence of what others ask doesn't excuse an unusually risque week then whoever tried to get me banned probably wouldn't have). Explanation: In US sports (and maybe other countries too, I don't know) sometimes we say things like Tom Brady has the highest single-season touchdown to interception ratio of all time. About 100 billion humans have ever been born so out of the 1XX billion (if lots of infant mortality) to several trillion (if not) calendar years of human life (let's say Greenwich Mean Time proleptic Gregorian calendar) one of them has the highest ratio of seconds spent masturbating to seconds spent masticating. I was wondering how high that ratio was. Maybe infinite for someone fed though a tube or IV with a destroyed jaw? The world may never know. Sagittarian Milky Way (talk) 22:55, 6 September 2022 (UTC)[reply]

September 6

European prosperity

Does one have to consider it rather a coincidence or not that Europe as the still by far most prosperous continent for centuries, at least in relative terms, at the same time is the continent with the least rate and probability of severe natural disasters (such as earthquakes, tsunamis, volcanic eruptions, tornados, floods) in comparison to other continents? Hildeoc (talk) 13:16, 6 September 2022 (UTC)[reply]

(PS: Please do let me know if there's any grammatical flaw in the wording of this question, so I can improve my feel for language. Thanks in advance!--Hildeoc (talk) 13:24, 6 September 2022 (UTC))[reply]

I think "the lowest rate" is better. Also, since in this context "probability" can only be interpreted as frequentist probability, which is directly related to the rate of occurrence, the words "and probability" are superfluous. IMO it is better to leave them out. --Lambiam 19:12, 6 September 2022 (UTC)[reply]

A minor improvement to readability would be to hyphenate the term still-by-far in this particular grammatical context. (I won't try to define it because grammatical analysis has radically changed since my 1970's schooling). {The poster formerly known as 87.81.230.195} 90.201.73.43 (talk) 22:39, 6 September 2022 (UTC)[reply]

You ask a very complex and subjective question, friend. Is Europe the most prosperous? In recent years, leading European economies have been struggling, whereby China has become a leading economic power in the world. Natural disasters? Every Spring can bring flooding in central Europe, and we can get severe weather in the Winter and Summer (this year was no different), however, there are no tectonic plate boundaries or large bodies of water that could lead to earthquakes or tornadoes or the like; however, Iceland has some volcanoes that can be pretty troublesome (like in 2010), but otherwise it's not that bad. It's a geographic coincidence really, but Your question is really quite general and subjective, as I said. I have taken the liberty to close Your small text with the appropriate flag (is that called a flag? command? word?) so the rest does not come out small as well. --Ouro (blah blah) 14:38, 6 September 2022 (UTC)[reply]

Thanks a lot for your comment and fixing my formatting negligence (I guess they call that a tag, by the way). If you don't mind, I would first like to wait for some more replies before going into your arguments. Best, Hildeoc (talk) 14:51, 6 September 2022 (UTC)[reply]

Australia has the highest GDP per capita and the most first worlders (percent), Europe has the most first worlders (millions), North America has the richest billionaires, Asia has the most billionaires, most GDP, most high-tech looking cities and the first first world country (though it is poor now), Africa has the first first world area if all areas in the same league as the most prosperous are considered first world. For we were once all in Africa and relative prosperity differences are smaller the further back in human prehistory you go. It also has Ancient Egypt which had the world's grandest architecture for a very long time. Sagittarian Milky Way (talk) 02:54, 7 September 2022 (UTC)[reply]

More people died in Europe in human-made disasters (both WWI and WWII) than in any continent as a consequence of natural disasters. That by itself suggests any correlation is coincidental. European earthquakes can be severe, examples being the 365 Crete earthquake, the 1755 Lisbon earthquake (see also the BBC special "The earthquake that changed history"), the 1761 Lisbon earthquake and the 1816 North Atlantic earthquake (hitting Lisbon again), the 1908 Messina earthquake, the 1963 Skopje earthquake and the 1977 Vrancea earthquake. They tend to be indeed relatively rare. But civilization blossomed in the earthquake-prone Middle East well before it took hold in Western Europe. Before the industrial revolution took off, Europe was not particularly prosperous; the initial industrialization was financed with the proceeds of the Atlantic slave trade. I see no plausible way of relating this to the relative rareness of natural disasters. --Lambiam 21:53, 6 September 2022 (UTC)[reply]

Have you seen Guns, Germs and Steel? manya (talk) 04:29, 7 September 2022 (UTC)[reply]

A society can survive without being prosperous. Diamond's notion of success is that of survival, of not collapsing; his books on the topic do not deal with causes of prosperity. --Lambiam 09:52, 7 September 2022 (UTC)[reply]

Part of the reason why Europe seems less affected by natural disasters is that it uses its wealth to limit the effects of such disasters. Devastating floods are prevented (or made less devastating) with extensive flood protection works (Zuiderzee Works, Delta Works, Thames Barrier, Venice flood barrier, the systems of dikes and pumping stations along many large rivers), which couldn't be built in places like Pakistan or Mozambique for lack of money or political will and determination to built such defences. In the same way, Japan and Chile are much less affected by earthquakes than Afghanistan or Iran, which suffer similar earthquakes, as those rich countries can afford buildings that can withstand them. If there's a connection, it's that being rich makes natural disasters less devastating. PiusImpavidus (talk) 10:55, 7 September 2022 (UTC)[reply]

It has the wealth to do so though. It's not like other places had the same wealth and squandered it through bad choices. There is a saying in the U.S. "Being born on third base and thinking you hit a home run", indicating that one attributes one's success (reaching home plate and scoring in a baseball game) with one's own actions (the hitting a home run), when in fact it has more to do with the advantages one had which one had nothing to do with (being born on third base). Europe was in a similar position. Europe (for whatever reason) had a head start in technology, and that head start was largely used to add to its own power by leveraging the potential from other cultures and preventing them from advancing themselves. Europe basically used its advantage to extract (largely labor and raw materials) from other areas of the world, and then simultaneously prevented those areas from using those resources to those area's own benefits. When we ask "Why did Europe have that advantage", there is a real danger in extrapolating any answer we get to "Europe was then justified to using that advantage in the way it did" or even "Europeans should not be held to account for the way they used their advantage" or "Europe shouldn't be held accountable for the harm they caused others if natural happenstance gave them advantages other cultures didn't have". If you doubt that is where such questions are going, you haven't been paying attention to the historiography of European history for the past several thousand years. It's not just China that has the mandate of heaven philosophy regarding the right to power... --Jayron 32 11:59, 8 September 2022 (UTC)[reply]

Just last night on the PBS show NOVA, there was a discussion of literacy, in particular how the European development of printing enabled Europe to leap ahead of other cultures which lacked it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:10, 8 September 2022 (UTC)[reply]

Well, borrowing or adopting of printing. Again, the western perspective is often "until a thing is discovered by European people, it doesn't exist". Literally every part of Gutenberg's press, except its use of Latin text, had been in existence for hundreds of years in other parts of the world. Both the printing press itself, and Movable type, both often erroneously attributed to Gutenberg, had been in existence in China since the 700s AD (printing press) and 1000s AD (movable type). Both Chinese and Arabic peoples had been using the technology for quite a while before Gutenberg. --Jayron 32 13:16, 8 September 2022 (UTC)[reply]

Developmen in monkeypox management

The latest decisions to prevent complications — Preceding unsigned comment added by Howard thanduxolo dube (talk • contribs) 17:21, 6 September 2022 (UTC)[reply]

It might be better to ask at Talk:Monkeypox, but the CDC suggests [2] patients at risk be given tecovirimat. Abductive (reasoning) 02:27, 7 September 2022 (UTC)[reply]

September 7

Can Marker degradation be performed with ozonolysis rather than hexavalent chromium?

As a trans person in STEM / going to medical school, the ability of the business decisions of one or two companies to disrupt the hormone supply chain in the US concerns me, so I like to keep abreast of "the state of the art," just in case I have the ability to influence the situation in the distant future. Marker degradation is an old procedure, so I wonder if it's still performed with hexavalent chromium. Maybe I'm searching wrong, but I can't find any new methods that use a substitute for hexavalent chromium, which is environmentally toxic (and just uncool).

What happens if one uses ozonolysis instead of chromic acid to open the cyclic enol ether "furan" ring in the second step of the Marker degradation? The oxidative workup of ozonolysis typically results in carboxylic acids. Can one obtain esters with either the reductive or oxidative workup? The ester group is hydrolyzed in the third and final step of the Marker degradation anyway, with the 16-OH eliminated. Yanping Nora Soong (talk) 17:38, 7 September 2022 (UTC)[reply]

The difference between oxidative and mild reductive workup (dimethyl sulfide) of ozonolysis is whether an alkene carbon that has an H on it becomes an acid as an "over-oxidation" beyond the simple carbonyl (aldehyde). So in the case of the classical Marker degradation, the dihydrofuran ring does not give the opportunity for oxidation beyond the simple carbonyl. There are many alkene-cleavage reactions, several of which are potentially chemoselective for the electron-rich enol alkene rather than other alkenes in the structure. DMacks (talk) 18:29, 7 September 2022 (UTC)[reply]

@Yanping Nora Soong.. Over the years, there have been many process studies to improve the Marker degradation. One 2003 paper doi:10.1021/op0200625 available as a .pdf uses potassium permanganate, for example. Mike Turnbull (talk) 20:20, 7 September 2022 (UTC)[reply]

September 8

Amount of information in analog vs digital

If we define amount of digital information in bits 0/1, how can we define amount of analog information?

When you convert any analog signal into digital (taping a human talking or taking a picture of a landscape) can you calculate the amount of information lost? In case of audio, for example, through sampling you could get a file of n MB, but it's there a point when you can say you captured all the sound? I don't mean all meaningful sound, but all the sound? It's clear that for us humans there's a point when we can't hear any difference anymore. Bumptump (talk) 09:03, 8 September 2022 (UTC)[reply]

I think what you are after is the Nyquist–Shannon sampling theorem. This tells you the sampling rate needed to capture information up to a certain frequency. For audio a sampling rate of 44,100 Hz is often considered as capturing all the information, as it allow frequencies within the human hearing rage of 20-20,000 Hz to be perfectly reconstructed, though as the article states some humans can hear sounds above that range, and reconstruction would require a perfect low-pass filter, so in theory some people (particularly children) could hear the artefacts produced by this rate of sampling. For the maximum possible frequency of sound (regardless of human hearing) you would need someone more knowledgeable than me to verify but some non-authorities sources suggest a limit of [3GHz for sound travelling in air], which would require a 6Ghz sampling frequency. -- Q Chris (talk) 10:20, 8 September 2022 (UTC)[reply]

Is it just audiophile nonsense that because 44.1k can't accurately reproduce the timbre of the 20k then a human could tell the difference? Sagittarian Milky Way (talk) 12:04, 8 September 2022 (UTC)[reply]

A great question. My understanding is that unless your ears can react to frequency changes over 20k then it will not be able to detect any differences in timbre. However some people, particularly children and younger people, can hear frequencies above 20k in ideal laboratory conditions, humans can hear sound as low as 12 Hz and as high as 28 kHz, though sounds at this level are greatly attenuated. I would say that I could definitely not hear any difference at over 60 years old, I think it possible that a young person could. That's why dvd audio and a lot of other formats support a higher bitrate. A sampling rate of over 56khz should cover everyone though. -- Q Chris (talk) 13:31, 8 September 2022 (UTC)[reply]

Some more info here: Sample-rate conversion. 41.23.55.195 (talk) 10:25, 8 September 2022 (UTC)[reply]

The information content of an analog signal is not only restricted by channel bandwidth but also by the signal to noise ratio. If you had an continuous analog signal in the range 0V to 31V changing slowly enough that bandwidth were irrelevant but with 1V of noise, you wouldn't be able (roughly speaking) to distinguish more than 32 different values corresponding to 5 bits of information. 2A01:E34:EF5E:4640:64E1:E668:BA81:4F87 (talk) 13:58, 8 September 2022 (UTC)[reply]