Wikipedia:Reference desk/Archives/Science/2021 October 24
| Science desk | ||
|---|---|---|
| < October 23 | << Sep | October | Nov >> | October 25 > |
| Welcome to the Wikipedia Science Reference Desk Archives |
|---|
| The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
October 24[edit]
Anti-Stokes %.[edit]
What are some examples of things that have a highest % of anti-Stokes shifts? Like most emissions is like 95% Stokes, 5% anti-Stokes. What phenomenon have some of the highest percentage of anti-Stokes shifts? 67.165.185.178 (talk) 01:10, 24 October 2021 (UTC).
- Presumably you're again talking about Stokes shift? ←Baseball Bugs What's up, Doc? carrots→ 07:26, 24 October 2021 (UTC)
- Yes, last time I forgot to include the word shifts. But I am not aware of anything anti-Stokes in chemistry that are not shifts. 67.165.185.178 (talk) 12:58, 24 October 2021 (UTC).
- Stokes vs anti-stokes can't really be defined by most things being "95% stokes, 5% anti-stokes." An anti-stokes shift takes place if the thermal population is high enough that some molecules in a sample are in an excited state (usually first excited state), rather than in the ground state. This portion is governed by things like a Boltzmann distribution, and therefore the energy of the excited state, Boltzmann's constant, and temperature. This is why, for example, the ratio of Stokes and anti-Stokes Raman scattering can be used to determine the temperature of a sample. The lower the energy of the excited state, the higher portion of molecules will be in said excited state for any given temperature. --OuroborosCobra (talk) 00:37, 25 October 2021 (UTC)
- But did you just basically say, the hotter the temperature, the higher % of anti-Stokes shifts (or scattering) happens? 67.165.185.178 (talk) 01:18, 25 October 2021 (UTC).
- Yes. At least anti-Stokes shift Raman scattering. --OuroborosCobra (talk) 01:34, 25 October 2021 (UTC)
- Raman basically means it happens in the IR region, right? And scattering is just an emission without an absorption? There is Compton scattering which happens in the clouds, which I believe happens in cold temperatures, so maybe Compton scattering is the example of the coldest anti-Stokes. 67.165.185.178 (talk) 02:09, 25 October 2021 (UTC).
- Yes. At least anti-Stokes shift Raman scattering. --OuroborosCobra (talk) 01:34, 25 October 2021 (UTC)
- But did you just basically say, the hotter the temperature, the higher % of anti-Stokes shifts (or scattering) happens? 67.165.185.178 (talk) 01:18, 25 October 2021 (UTC).
Total volume of human population[edit]
I've seen a social media post claiming that if the entire human population of the world [presumably, except the person who pushed the button...] was put in a liquidiser and poured out, it wouldn’t fill a basin the size of Windermere. Is that about right? Has the calculation been done? Ghmyrtle (talk) 11:04, 24 October 2021 (UTC)
- According to List of lakes of the Lake District, the volume of Windemere is 314.6 m³ x 106, if that helps with the maths. Alansplodge (talk) 11:43, 24 October 2021 (UTC)
- (ec) Very crude order-of-magnitude estimate: The body volume of the average human being is on the order of 0.1 m3 or so, and there's about 10 billion of them. The total volume of mankind is therefore 109 m3, which may be a bit of an overestimate (don't know what the outcome of the liquifier is, and I'm not sure I want to know). Lake Windermere has a surface area of around 10 km2 and an average depth on the order of 10 m, so a volume of 108 m3, which may be a bit of an underestimate. So, the volumes are indeed of comparable size. --Wrongfilter (talk) 11:47, 24 October 2021 (UTC)
- According to Human body weight, the worldwide adult average is 62 kg, but "about 26 percent of the world is under 15 years of age" [1] so you might have to do some guesstimating to find a mean human mass. Alansplodge (talk) 11:57, 24 October 2021 (UTC)
- If we go for 50kg (≈50 litres or thereabouts) for the sake of simplicity. World population is 7.9 billion [2] so total liquidised volume is 395 billion litres, so Windemere might overflow a bit, if I've done the sums right (never my strong point). Alansplodge (talk) 12:06, 24 October 2021 (UTC)
- According to Human body weight, the worldwide adult average is 62 kg, but "about 26 percent of the world is under 15 years of age" [1] so you might have to do some guesstimating to find a mean human mass. Alansplodge (talk) 11:57, 24 October 2021 (UTC)
- (ec) Let's put it at 30 kg then (using half orders of magnitude). At the density of water that corresponds to a volume of 0.03 m3, or 3·108 m3 for the entire human population, which agrees with your more precise lake volume, and confirms my feelings of over- and underestimates. Incidentally, this is a good example of a Fermi problem. --Wrongfilter (talk) 12:10, 24 October 2021 (UTC)
- We're in the roughly the same ballpark anyway. Alansplodge (talk) 12:46, 24 October 2021 (UTC)
- Where else would we be? ;-) --Wrongfilter (talk) 12:47, 24 October 2021 (UTC)
- :-) Alansplodge (talk) 12:48, 24 October 2021 (UTC)
- That is some weird question. I can't quantify how weird it is. scope_creepTalk 13:34, 24 October 2021 (UTC)
- I think it is ideal for Fortean Times. scope_creepTalk 14:01, 24 October 2021 (UTC)
- Before the Internet, I read that all of humanity would not fill the Grand Canyon, so the idea has been around a while. Abductive (reasoning) 15:59, 24 October 2021 (UTC)
- Over here, it was said that all of humanity could fit on the Isle of Wight. However, this 2013 newspaper article debunks the idea by calculating that the island is too small by a factor of ten. Of course, this is without the effort of liquidising everyone. Alansplodge (talk) 20:55, 24 October 2021 (UTC)
- Manhattan has 22.something square miles of land, I don't know if that includes the small Roosevelt, Governors, U Thant, Mill Rock, Randalls and Wards Islands and Marble Hill. At 28 million square feet per square mile and less than 50% being covered with floors you'd need an illegal whole island floor area-to-footprint ratio of low tens to hold everyone without intrafloor stacking. New York City has 303 square miles of land. Since standing humans can hexagonally close pack and you can fill the spaces with babbies you could probably barely fit everyone on in 1 layer if there were no crap like walls to take up space but where would everyone poop? For today's population to stand one-deep on 1 NYC's worth of flat land the sexes might have to alternate every 2 ranks with the women squeezing their breasts into each others' cleavage. Also if you did this billions of people would die, they would starve or thirst to death before escaping the worst traffic jam ever, even if they were all teleported there at the same time. If this ever happens and you're near the edge steal a car and FLEE! Drive as fast as you can control just in case, each time it runs dry steal another car, gas stations and traffic lights are good places to find running cars when everyone's raptured. Sagittarian Milky Way (talk) 02:21, 25 October 2021 (UTC)
- That sounds like https://what-if.xkcd.com/8/ PrimeHunter (talk) 03:22, 25 October 2021 (UTC)
- Manhattan has 22.something square miles of land, I don't know if that includes the small Roosevelt, Governors, U Thant, Mill Rock, Randalls and Wards Islands and Marble Hill. At 28 million square feet per square mile and less than 50% being covered with floors you'd need an illegal whole island floor area-to-footprint ratio of low tens to hold everyone without intrafloor stacking. New York City has 303 square miles of land. Since standing humans can hexagonally close pack and you can fill the spaces with babbies you could probably barely fit everyone on in 1 layer if there were no crap like walls to take up space but where would everyone poop? For today's population to stand one-deep on 1 NYC's worth of flat land the sexes might have to alternate every 2 ranks with the women squeezing their breasts into each others' cleavage. Also if you did this billions of people would die, they would starve or thirst to death before escaping the worst traffic jam ever, even if they were all teleported there at the same time. If this ever happens and you're near the edge steal a car and FLEE! Drive as fast as you can control just in case, each time it runs dry steal another car, gas stations and traffic lights are good places to find running cars when everyone's raptured. Sagittarian Milky Way (talk) 02:21, 25 October 2021 (UTC)
- Over here, it was said that all of humanity could fit on the Isle of Wight. However, this 2013 newspaper article debunks the idea by calculating that the island is too small by a factor of ten. Of course, this is without the effort of liquidising everyone. Alansplodge (talk) 20:55, 24 October 2021 (UTC)
- Before the Internet, I read that all of humanity would not fill the Grand Canyon, so the idea has been around a while. Abductive (reasoning) 15:59, 24 October 2021 (UTC)
- :-) Alansplodge (talk) 12:48, 24 October 2021 (UTC)
- Where else would we be? ;-) --Wrongfilter (talk) 12:47, 24 October 2021 (UTC)
- We're in the roughly the same ballpark anyway. Alansplodge (talk) 12:46, 24 October 2021 (UTC)
- (ec) Let's put it at 30 kg then (using half orders of magnitude). At the density of water that corresponds to a volume of 0.03 m3, or 3·108 m3 for the entire human population, which agrees with your more precise lake volume, and confirms my feelings of over- and underestimates. Incidentally, this is a good example of a Fermi problem. --Wrongfilter (talk) 12:10, 24 October 2021 (UTC)
Bacterium lactis[edit]
Hi Folks!! Is that bacteria this bacteria Lactococcus lactis? It is a question regarding Joseph Lister, who apparently isolated B. lactis and grew it. The first time apparently. scope_creepTalk 13:32, 24 October 2021 (UTC)
- The first bacterial pure culture on earth, obtained and scientifically described by Joseph Lister (1873) was Lactococcus lactis, at that time called: ‘Bacterium lactis’. [3] Alansplodge (talk) 15:12, 24 October 2021 (UTC)
- Coolio. @Alansplodge: Thanks. scope_creepTalk 15:30, 24 October 2021 (UTC)