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July 16

Telescope mount

Back in the day, fancy amateur telescopes used equatorial mounts, which were mechanically complicated but straightforwardly tracked the stars' apparent motion as the earth rotated. X-Y mounts were (and are) mechanically simpler, but figuring out how to point them required intricate calculations.

Now that there are computers in everything, are X-Y mounts displacing equatorial ones, say in the midrange amateur segment? Is XY used at all in the high/professional segment? Thanks. 67.164.113.165 (talk) 05:45, 16 July 2019 (UTC)[reply]

According to our telescope mount article, computerized positioning has enabled the simpler design of an altazimuth mount to be used for all levels up through professional. DMacks (talk) 06:17, 16 July 2019 (UTC)[reply]

Thanks! Yes that is what I meant by XY mount. It looks like the right thing. This stuff is very expensive ready-made but it seems more DIY-able than an equatorial mount. 67.164.113.165 (talk) 06:33, 16 July 2019 (UTC)[reply]

I remember trying to aim a heavy small field of view scope 0.7 degrees north of Polaris in the day without even a protractor, making small adjustments by picking it up and putting it back down and trying to get a nondescript axis of tiny weightlifting weights to point my latitude degrees up and 28.9 degrees left of the street grid which is 28.9 degrees right of real north. The Sun drifted where it shouldn't every half hour or hour cause this is very hard. Fun times. (at night you can look through a monocular in the rod the weights are on with a map of the Polaris area they make for this and aim to within 0.1 degrees in a snap) Sagittarian Milky Way (talk) 16:59, 16 July 2019 (UTC)[reply]

Figure skating jump energies

Out of curiosity, I derived a minimum lower bound on the amount of energy needed to do a figure skating jump with n rotations.

Specifically, the additional kinetic energy needed to both jump into the air and spin is the sum of the necessary translational and angular kinetic energies,

$K={\frac {1}{2}}(I\omega ^{2}+mv_{vert}^{2})$ .

where $v_{vert}$ denotes the vertical component of the takeoff velocity. The minimum angular velocity needed is ${\frac {\pi ng}{v_{vert}}}$ (as derived from the kinematics equation for constant acceleration and the fact that these n rotations must be done in the time between takeoff and landing).

Under these assumptions, by differentiating K with respect to the vertical takeoff velocity, the needed kinetic energy injection is found to be $K=\pi ng{\sqrt {Im}}$ . This is only a lower bound, since additional air time is needed for the needed angular acceleration due to the snap and body inefficiencies (the body doesn't convert all food energy to mechanical energy).

I've heard of a study that says a quintuple jump is the maximum theoretical limit. However, the sky seems to be the limit in practice, and the linear growth of this formula in weight and number of rotations suggests that the limit will really be the force needed, since all this extra kinetic energy needs to be injected in just two stages – the takeoff impulse, and the snap (where conservation of angular momentum is used for getting the rotations needed).--Jasper Deng (talk) 08:46, 16 July 2019 (UTC)[reply]

Dunno about jumping harder, but maybe they could wear weighted gloves to get more angular momentum during the arms-out pre-jump spin. 67.164.113.165 (talk) 09:21, 16 July 2019 (UTC)[reply]

Using equipment other than skates on the ice is frowned upon in this sport except for training purposes, such as ankle weights which help the legs snap together on takeoff.—Jasper Deng (talk) 10:46, 16 July 2019 (UTC)[reply]

The limit is certainly not the sky, rather, the energy best athletes can muster in explosive feat like high jump, or sprint. Or, even better, pole vault, which probably sum up the max energy (aka height, in this instance) that can be turned into something. Then you need calculate the best split of the energy into the jump (determines the time up) and the spin (given the time up, the number of spin). (edit). Long jump will also help, for the maximum jumping time. Gem fr (talk) 10:28, 16 July 2019 (UTC)[reply]

The ideal split calculated in my model is about half angular and half translational. It’s really an apples to oranges comparison to cite other sports since I know of virtually no other sport that uses angular mechanics as much. The phenomenon of angular acceleration by reduction of the moment of inertia is pretty unique to figure skating. What can be known based on weight distribution is the maximum proportional change in it, since one’s moment of inertia about the vertical axis is bounded below by that of the air position. It may not look like it but skaters virtually never have zero angular momentum while moving, especially in jump takeoff situations. Every jump takes off from an edge which is on the circle. This is not the only source of angular momentum, though.—Jasper Deng (talk) 10:48, 16 July 2019 (UTC)[reply]

Not surprised at all by that equipartition (see related equipartition theorem). Both long jump and pole vault involve angular mechanics (although their axis is horizontal, as opposed to vertical in spinning), but that is not my point. The point is, the skater cannot build up significant spinning energy before the jump, so it has to come from the jump impulse (be taken from translation) (edit: while he wont be able to zero the useless horizontal movement energy), meaning, the max energy of vault jumper is a pretty good approximation of the max spinning+ translational energy of the skater. Gem fr (talk) 11:31, 16 July 2019 (UTC)[reply]

Not so. The angular acceleration does significant work: when decreasing the moment of inertia, the angular velocity rises by a factor of the multiplicative inverse of the ratio of the new and previous moments of inertia, and thus so does the angular kinetic energy. Also, especially on toe jumps (the toe loop, flip, and lutz), a very significant amount of energy is injected by the tap on the ice, so it’s not really just the conversion of horizontal translational motion to vertical. If you watch skaters’ toe jumps, even quadruple jumps diminish skaters’ horizontal linear momentum by little.—Jasper Deng (talk) 18:13, 16 July 2019 (UTC)[reply]

The record breakers at pole vault are able to rise their center of mass up to ~5 m, which translate into a maximum vertical speed of (2gh)^0.5= ~10 m/s; which, not strangely at all, is close to the horizontal maximum speed of top running sprinters, meaning, pole vault is pretty efficient at turning horizontal speed into vertical; not sure skaters can be as efficient.Gem fr (talk) 11:51, 16 July 2019 (UTC)[reply]

The pole must store energy. Thus when more bendy better energy storing poles are invented the world record rises. Sagittarian Milky Way (talk) 22:34, 16 July 2019 (UTC)[reply]

Skaters can achieve significantly higher on-ice speeds than the best runners simply due to having less resistance, so they also have much more translational energy to work with.—Jasper Deng (talk) 18:13, 16 July 2019 (UTC)[reply]

OK, you are right, then, you probably should rely on speed skating max speed as a better approximation of max energy. List of world records in speed skating mention 54.40 km/h (15 m/s, which is slightly less than 50% more speed than sprint, but more than 2x as much available energy; it is also a speed at which the air is a significant drag). However, if the skater cannot really tap on the horizontal energy (as per your just above added observation) and must rely on his jumping impulse, then for the really available energy you are back at the same as long jump, that is, sprint, that is, ~10 m/s; or even high jump, where the vertical max speed will be ~5m/s. In any case 15m/s is an upper bound. Gem fr (talk) 22:35, 16 July 2019 (UTC)[reply]

Even if we use 10 m/s, my model predicts an upper bound significantly greater than five rotations – well over a dozen rotations. That is, if no translational energy is converted. Edge jumps like the salchow and loop jump do convert significant translational energy into rotational (by tightening up the edge, that is, lowering the turning radius), at the cost of not being able to inject as much energy anew (a significant amount is still injected new by the legs themselves, though not as much as with toe jumps).--Jasper Deng (talk) 22:55, 16 July 2019 (UTC)[reply]

Intuitively, I think the skater will be able to transform significant part of the horizontal speed/energy into rotation speed/energy, but not into vertical motion. While equipartition would be the best, I doubt the skater will actually achieve it. He will be limited by vertical impetus, which will be of the same magnitude, at best, as a high jumper (~5 m/s; this value is reasonable since I found ref for 4.5m/s). This would make flying time the strongest limit to the number of spin. Gem fr (talk) 00:50, 17 July 2019 (UTC)[reply]

A takeoff velocity of 5 m/s does not seem like a reflection of real limits; air time is given by

{\frac {2v_{vert}}{g}}

which yields only a bit more than a second of air time for that vertical velocity, but I have seen skaters in the air for significantly longer. But yes, real skaters are currently not that close to equipartition. Instead, the limit probably is the maximum possible angular acceleration, since the moment of inertia is bounded below and above. Then that links into the amount of angular momentum one can have while still on their edge (remember, skaters basically never have zero angular momentum even while "gliding straight"). --Jasper Deng (talk) 01:36, 17 July 2019 (UTC)[reply]

one second is pretty long, actually. It can be extended by a small fraction by ending lower than started. And I just watched Javier Sotomayor record breaking jump; I cannot precisely figure his flying time, but it seems shorter than 1.5 s. And skaters do no better; this hints at air time only slightly longer than 1 second. Gem fr (talk) 07:41, 17 July 2019 (UTC)[reply]

This is not the best resource for maximum airtime; skaters known for their air time can get almost two seconds. —Jasper Deng (talk) 08:18, 17 July 2019 (UTC)[reply]

The phenomenon of angular acceleration by reduction of the moment of inertia is pretty unique to figure skating. -- it's a defining feature of the pirouette in ballet, and is probably used in other forms of dance as well. Also in diving and gymnastics, it seems to me. In the "tuck" it's done by pulling the knees towards the chest. 67.164.113.165 (talk) 16:13, 16 July 2019 (UTC)[reply]

Debateable whether ballet counts as a sport as much as I enjoy it. Diving and gymnastics don’t have even close to the same magnitude of angular acceleration; of those, only ballet has comparable angular acceleration.—Jasper Deng (talk)

Since a coin flip is in the realm of Lagrangian mechanics, I think this would be too, though I have no experience applying it myself.—Jasper Deng (talk) 18:39, 16 July 2019 (UTC)[reply]

Honeybee subspecies - A. m. carnica or A. m. carpatica?

Moved from Wikipedia:Teahouse § Honeybee subspecies - A. m. carnica or A. m. carpatica?

https://link.springer.com/article/10.1134/S1022795416020058 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872275/ https://link.springer.com/article/10.1134/S1022795418030109

The carpatica subspecies seems to be discussed by the russian federation and carpathian arc, but not accepted by the overall scientific western community. How much higher is the genetic variance threshold for naming a subspecies in the scientific community and what would A.m.carpatica have to show to be included in the categorization? — Preceding unsigned comment added by Anbu95 (talk • contribs) 12:37, 16 July 2019 (UTC)[reply]

Subspecies#Monotypic_and_polytypic_species looks relevant. The variations have to be nonrandom AND distinct geographically, so there may be too much geographical overlap between carnica and carpatica to consider them subspecies. 70.67.193.176 (talk) 14:39, 17 July 2019 (UTC)[reply]

Rotating black hole

If the gravity field around the black hole is spherically symmetrical, how can the rotation of the bh drag the surrounding spacetime around? It is exerting the same radially directed force in all direction, yes? — Preceding unsigned comment added by 86.8.200.199 (talk) 19:21, 16 July 2019 (UTC)[reply]

Short answer: No it’s not radially directed because it’s spinning.—Jasper Deng (talk) 20:30, 16 July 2019 (UTC)[reply]

So it is not radially directed because of the rotation? Can you quote a reference for that assertation,? — Preceding unsigned comment added by 86.8.200.135 (talk) 23:14, 16 July 2019 (UTC)[reply]

Motion around a rotating, uncharged black hole is modeled by the Kerr metric, which is rotationally but not spherically symmetric. I couldn't give you a straightforward equation for the non-radial acceleration from the perspective of a distant observer, but maybe someone else can, or you can find one in one of the references to that page. Someguy1221 (talk) 23:22, 16 July 2019 (UTC)[reply]

Can you explain why? In traditional Newtonian gravity, a symmetrical rotating mass can be modeled the same as a non-rotating mass. I assume that's what inspired the question. ApLundell (talk) 23:18, 16 July 2019 (UTC)[reply]

In general relativity, gravity is a manifestation of spacetime curvature, which is itself a function of mass/energy and momentum. The gravity of a rotating object is thus not even expected to be the same as that of a non-rotating object. Someguy1221 (talk) 23:27, 16 July 2019 (UTC)[reply]

General topic: frame-dragging. --47.146.63.87 (talk) 03:14, 17 July 2019 (UTC)[reply]

can this be explained by vector field theory at all?86.8.201.96 (talk) 19:44, 17 July 2019 (UTC)[reply]

It can expressed using a tensor field, of which a vector field can be seen as a special case. Someguy1221 (talk) 20:02, 17 July 2019 (UTC)[reply]

Moon umbra lighter around the edges

I'm watching the lunar eclipse tonight and it seems that the part of the Moon in the umbra is a little brighter around the edges. Is this due to eye's perception of contrast or just a chance alignment of the maria, or is it a real optical effect? I've observed it several hours ago when the eclipse began and now at a different part of the Moon, which leads me to think it's not the placement of the maria. 93.136.63.164 (talk) 22:21, 16 July 2019 (UTC)[reply]

That part is being lit by brighter parts of twilight. The edge is lit by sunrise and sunset which is why the penumbra is so bright, part of the Sun is above the horizon there. Sagittarian Milky Way (talk) 22:39, 16 July 2019 (UTC)[reply]

Oops I wasn't precise enough. I meant the lunar limb (didn't know the word for it). I agree with your reason for the edges of the umbra, that's also because Sun's radius is non-zero, and because of Earth's atmospheric refraction etc. For instance see here or here, the contrast is weaker than what I perceived visually this night but you can clearly see that none of the darkest parts are at the limb. 93.136.63.164 (talk) 03:47, 17 July 2019 (UTC)[reply]

I'm not sure if libration can ever make the limb a mare from Earth. The limb is generally Maria-free. The umbra radius shrinks slightly from middle of moon to limb with most of that near the limb which should help sharpen the horns a bit. Since the limb is a half percent further. Even an uneclipsed crescent also has sharper horn tips than you'd expect, one would assume a photograph of a crescent phase on a sphere would look like 2 perfect circles of different sizes overlapping but the horn tip would actually be slightly sharper than that. I can't visualize the geometry well enough to see if the geometric reason for this would also help sharpen the horns in a lunar eclipse. Sagittarian Milky Way (talk) 04:24, 17 July 2019 (UTC)[reply]

Thanks, that makes sense. I was kind of hoping for a more esoteric explanation, kind of like opposition surge, but then again it seems opposition surge is also mostly just shadows of a not-quite-2D lanscape. 93.136.58.135 (talk) 05:41, 18 July 2019 (UTC)[reply]

I've remembered something which should cause the horns to be sharper, the umbra is elliptical. The sharpest part of the umbra transition has been experimentally determined to be most closely correlated with the altitude of the tropopause (inside gets cloud blocked, scattered, refracted and dispersed too much) and this is more meters above sea level at Earth's equator than its poles which are already closer to the center of the Earth. Even Alaskan mountains have noticeably thinner air than Himalayan ones of the same altitude, this starts below the tropopause. This horn sharpening subportion is generally unsymmetrical though of course. Sagittarian Milky Way (talk) 12:19, 18 July 2019 (UTC)[reply]

July 17

Coffee and insomnia

Can drinking coffee cause insomnia? FreeKnowledgeCreator (talk) 03:28, 17 July 2019 (UTC)[reply]

Our article on insomnia cites this NIH website: "Commonly used substances also can cause insomnia. Examples include caffeine...", which is present in ordinary coffee.

Any specific individual may have different experiences, but there we have one reputable source that says it's possible.

Nimur (talk) 03:36, 17 July 2019 (UTC)[reply]

Caffeine § Adverse effects: Yes, coffee contains caffeine, and insomnia is a potential adverse effect of caffeine. Decaffeinated coffee still contains some residual caffeine. (I think this question is acceptable; it's not asking for medical advice.) --47.146.63.87 (talk) 03:44, 17 July 2019 (UTC)[reply]

I mean that's the point, isn't it? Srsly it has a half-life of maybe 6 hours depending, so if you have a cup in the morning it will be mostly out of your system by bedtime, but if you have any in the afternoon it can keep you up at night. 67.164.113.165 (talk) 04:36, 17 July 2019 (UTC)[reply]

That could depend on your tolerance level. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:36, 17 July 2019 (UTC)[reply]

The problem is that once caffeine starts to interfere with sleep, you'll tend to drink coffee later in the day as the whole point of drinking coffee was to make you more wakeful. So, what started as coffee on Monday morning at work to deal with social jet lag, can later become coffee at 4 pm to be able to be awake enough to forge ahead with work until 6 pm. The more this affects sleep, the more coffee you'll drink later in the day, because sleepiness will become stronger later in the day if you didn't sleep well. Count Iblis (talk) 15:23, 17 July 2019 (UTC)[reply]

Yes, it's somewhat addicting, or "habit-forming" as the saying goes. I once worked with someone who drank plenty of coffee and for variety they started consuming Jolt Cola. I don't recall observing any impairment later in the day, but that was quite a while ago so I can't say for sure. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:55, 17 July 2019 (UTC)[reply]

And if they then start taking sleeping pills to get to sleep, then more coffee to wake up, then more sleeping pills, etc., it can become dangerous. SinisterLefty (talk) 20:58, 17 July 2019 (UTC)[reply]

Once they get fired, they can sleep as much as they want. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:09, 17 July 2019 (UTC)[reply]

Or if they die, then they can sleep all they want. SinisterLefty (talk) 22:41, 19 July 2019 (UTC)[reply]

Andrew J. Wakefield

I have an issue with your article on Andrew J. Wakefield, my first and main issue is that the article opens up with the statement that he is against vaccinations. I have listened to him speak and read his book, he is only against the MMR vaccination being administered together. Why is there no edit points in this article, I would think if WikiP was as unbiased as they purport to be, there would be edit points in this article, and above and beyond that your staff would research his standings on vaccinations, and not let them be published if they were in fact contrary to his studies. Autism is beyond a serious problem today and the future looks even dimmer. I nor anyone of my family at present have been afflicted, but that is not to say it will not happen. I commend Andrew Wakefield for his willingness to stand up to the Phamaceutical Companies which I am sure are behind his being blackballed and discredited. Please advise me if I am able to publish this in the article Andrew Wakefield as I see no edit points available. — Preceding unsigned comment added by Dan Baroni (talk • contribs) 11:47, 17 July 2019 (UTC)[reply]

Hello Dan Baroni, unfortunately you can’t edit this article because it is semi protected, instead you can request an edit by clicking on ‘View source’ at the top of the page and then click ‘Submit an edit request’. You might also want to discuss the problem on the talk page of the article where there are specialists on the subject who can talk to you. You can edit the page when you are an autoconfirmed user, but it is best to discuss what you would like to do with others. Please contact me if you have anymore questions on my talk page. Reagrda, Willbb234 (talk) 12:16, 17 July 2019 (UTC)[reply]

Hi Dan Baroni (talk · contribs). Your memory of what Mr Wakefield has said in talks is not acceptable as a reference in Wikipedia, but his book can be quoted within limits. Even better, if you can find reports in independent WP:Reliable sources, then these will help when you request material to be added via the talk page. Dbfirs 12:29, 17 July 2019 (UTC)[reply]

(edit conflict)Provided you can source your edit, feel free to do them. Be aware, though, that

the +20 years old claim of a link between vaccination and autism have been investigated and debunked [1] [2] [3] etc. (besides the fact that MMR kills, autism doesn't, so even if a vaccine did caused a few autism case -- which, again, is not true -- it would still be worth it).
conspiracy theories about [insert favorite big money scapegoat] blackballing and discrediting [insert favorite lunatics] are not welcomed on wikipedia, and spreading those is frowned upon.
wikipedia is not, and doesn't claim to actually be, unbiaised. It only tries to. Anyone is welcome to edit, there are no morality check and obviously, biased person can edit (for instance, I find you quite biased, and still invite you to edit so that Wakefield ideas are more accurately described).
when topic is hot, you may not be allowed to directly edit, but you can always make your point in the talk page

Gem fr (talk) 12:33, 17 July 2019 (UTC)[reply]

Agree, Dan Baroni (talk · contribs) do mind that promotion of fringe views is not appreciated, see WP:LUNATICS. Tgeorgescu (talk) 12:34, 17 July 2019 (UTC)[reply]

Googling the subject "Andrew J. Wakefield vaccinations", many sources call him an anti-vaxxer, while also pointing out that his bogus study was about the MMR vaccine. It would be incumbent upon the OP to find some valid sources where he supports other vaccines besides the MMR. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:04, 17 July 2019 (UTC)[reply]

I mean, I maybe see a slight point here. The lede of the article calls him "an anti-vaccine activist", with "anti-vaccine" linked to Vaccine hesitancy. Someone like Wakefield would probably argue they're not "anti-vaccines"; they just challenge the standard vaccine recommendations made by public health bodies. But, in public discourse, "anti-vaccine" has become a metonym for "questions the standard vaccine recommendations", encompassing everyone from the person who thinks all vaccines (and possibly other medical treatments) are a government mind-control plot to the person who thinks current standard vaccine schedules recommend too many vaccines at the same time or possibly too early. Wikipedia can only report what other sources say, and if mainstream sources describe him as "an anti-vaccine activist", that's what the article should say. Perhaps there should be a source cited for such a label, since such a label is a bit controversial (as demonstrated here). Personally, I think another issue in the lede is describing him as "a discredited former British doctor". The "discredited" seems to me an unnecessary bit of opprobrium, trying to give the reader the impression right away that he's a Bad Guy. Omit needless words; let the article speak for itself. --47.146.63.87 (talk) 22:30, 17 July 2019 (UTC)[reply]

A guy who forge a false research finding, that led a lot of people to skip MMR vaccination, resulting in fatalities, IS a bad guy; a guy who gets his paper retracted and is banned of practice, IS discredited. Now, I agree that questioning a single vaccine (MMR is his case) and questioning each and every vaccine is not the same thing and should not come under a single antivax umbrella. Even for a bad guy. "an anti-MMR-vaccine activist" would be more accurate. Gem fr (talk) 23:29, 17 July 2019 (UTC)[reply]

Nah, he's just plain anti-vax. He definitely beats the MMR drum harder than any other, but he opposes all vaccination, unless he's getting paid for it [4]. Someguy1221 (talk) 01:14, 18 July 2019 (UTC)[reply]

OK. I guess, either the OP was wrong, or he radicalized views since OP checked. Anyway. The cringe is not worth it. Gem fr (talk) 14:13, 18 July 2019 (UTC)[reply]

@Dan Baroni:: if you want to consider the validity of Wakefield's claims of autism being caused by post-birth vaccinations (whether particular ones or generally), you might want to look at this recent report of a scientific study. {The poster formerly known as 87.81.230.195} 2.122.177.55 (talk) 23:31, 17 July 2019 (UTC)[reply]

July 18

I am wondering . . . . .

I sent an inquiry through the talk page, I think. I do not frequent facebook, for a number of reasons, 1. I do not post comments on it, it seems frivolous and shallow. 2. Messages coming from people who I do not know and not responding in a timely fashion when I answer/ask a question that they have sent to me. The concept of wikipedia seems to be an ultra intelligent type of facebook. Granted I use wikipedia, 100's of times more than facebook, of course facebook is not a fact finding venue.

So the reason I am posting? or asking? this question is: was my first comment about Andrew Wakefield, only read by Wiki Staff or was it on an open talk forum? Were all the responses to my comment from Wiki Staff or from users also? How do I determine who is staff and who is a user? Is the talk forum exclusive to the Andrew Wakefield page or is it in some cyber universe forum where it floats around to be seen by the millions of people who might type in a key word such as autism, Wakefield, MMR Vaccine?

I do appreciate the quick response to my comments.

Also, it seems there may be a symbol or flag for conflict and agree with the comment??

Do my posts contain my name??? I do not care, that is the username I chose, so I do not hide behind numbers or symbols.

In conclusion, I hope the four thingees I am putting in are the correct way to sign this question?

Thanks again.

Dan Baroni (talk) 00:38, 18 July 2019 (UTC)[reply]

"Staff" and "Users" greatly overlap here. Basically all staff (Admins, etc.) are also users. Some users just read and post Q's, but anyone is allowed to edit articles, as well (except for some protected articles), so any user can become an editor simply by picking the Edit button on an article. And an editor is normally considered to be "Staff", in other publications. Of course, nearly all staff here are unpaid. SinisterLefty (talk) 00:44, 18 July 2019 (UTC)[reply]

Dan Baroni—you say "So the reason I am posting? or asking? this question is: was my first comment about Andrew Wakefield, only read by Wiki Staff or was it on an open talk forum?" It is visible to all editors as well as all readers. Bus stop (talk) 01:14, 18 July 2019 (UTC)[reply]

Wikipedia is more open than most websites, in that you don't even have to be a registered user to do editing. At least one reply in the previous section was posted by a non-registered user, i.e. an IP address. As to who might be "staff", you can get a pretty good indication by checking individuals' user pages to see what they have to say (or don't). ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:52, 18 July 2019 (UTC)[reply]

This is the science reference desk, where questions/topics should usually be about science, answered by helping editors with links to relevant Wikipedia articles or other resources. There are noticeboards (WP:NOTICEBOARDS) that are more appropriate to address Wikipedia and content issues. Also helpful may be the WP:Teahouse or WP:Helpdesk. —Paleo Neonate – 03:15, 18 July 2019 (UTC)[reply]

Maybe to clarify a couple of answers: Nearly all pages on Wikipedia are completely open for the public to read. All non-protected pages are in principle open for the public to change. In particular, everybody can normally "post" something on a talk page. Wikipedia does not have "staff" in the traditional sense. The Wikimedia foundation runs the web servers, but does not usually interfere with the contents. Wikipedia editors are unpaid volunteers (and everybody who has edited Wikipedia is included under that label). Some editors have been granted advanced privileges via a community process. The most frequent of these are "administrators". Again, these are unpaid volunteers, and they have no special role with respect to content. If you want to change a page, either change it, or convince someone else to change it. The best place to reach interested people is via the talk page of the article. Especially if the change may be controversial, it's a good idea to first read WP:V, WP:RS and WP:NPOV. --Stephan Schulz (talk) 13:07, 18 July 2019 (UTC)[reply]

Where in the world has the highest average dew point?

And what is this number? What about average heat index? Sagittarian Milky Way (talk) 12:24, 18 July 2019 (UTC)[reply]

I googled "highest average dew point world" and this is one item that came up.[5] ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:33, 18 July 2019 (UTC)[reply]

according to dew point

{\begin{aligned}T_{\mathrm {dp} }&\approx T-{\frac {100-\mathrm {RH} }{5}};\\[5pt]T_{\mathrm {dp} }&\approx T+{\frac {\mathrm {RH} }{5}}-{\frac {100}{5}};\end{aligned}}

That would be a place at the highest pressure (ie at sea level; because lower pressure means easier evaporation, lower relative humidity) and highest average humidity (without a mountain screening wind and creating a Foehn wind, which would decrease humidity more than it would increase temperature), with as high temperature as possible, and the sea/ocean itself at as high as possible average temperature all year long. As mentioned in the ref found by Baseball Bugs, no place qualify more than Persian Gulf or Red Sea (well, I cannot think of one, at least; Dead Sea lacks humidity; places with Tropical rainforest climate, like Singapore, have high humidity yearlong, but their average temperature would be lower).

Gem fr (talk) 14:10, 18 July 2019 (UTC)[reply]

That dew point of 88 must have been unbearable. Here it starts feeling pretty bad about 73, and the highest I've seen it this summer has been 79. Right now it is 93 degrees, 56% humidity, dew point 75, heat index 104. Bubba73 ^{You talkin' to me?} 20:15, 20 July 2019 (UTC)[reply]

26% relative humidity here in So Cal right now…*applies more hand lotion* --47.146.63.87 (talk) 21:17, 20 July 2019 (UTC)[reply]

See here: "In 2003, Dhahran, Saudi Arabia, saw the highest heat index ever recorded at 81 °C (178 °F) with a temperature of 42 °C (108 °F) and a 35 °C (95 °F) dew point." Count Iblis (talk) 21:51, 20 July 2019 (UTC)[reply]

OP is not asking for record, but for highest average (yearlong, I guess). Although, according to its average quality (high temp and high relative humidity), the place of record surely qualify as a worthy competitor Gem fr (talk) 00:08, 21 July 2019 (UTC)[reply]

Is it possible to grow a fruit from a seedless fruit?

If I have a seedless fruit, can I grow a plant and other fruits from this seedless fruit only without using seeds? Does fruits have DNA outside the seeds? 93.126.116.89 (talk) 16:44, 18 July 2019 (UTC)[reply]

I would expect that parts of it have DNA, like the skin/rind/stem. But that's not sufficient to grow a plant. Fruit is highly specialized, and only the seeds are designed to start a new plant (although other parts of the fruit tree, like roots and stems, may also be able to grow new plants). Also note that some supposedly seedless fruit does have seeds, like "seedless" watermelon. They are just smaller and fewer, but still may be able to grow new watermelons. SinisterLefty (talk) 17:09, 18 July 2019 (UTC)[reply]

Essentially any cell in the plant will have DNA. There are very few exceptions to this (mammalian red blood cells are one of the very few examples of cells not containing DNA). --Stephan Schulz (talk) 17:57, 18 July 2019 (UTC)[reply]

doi:10.1038/219329b0 is an interesting 1968 Nature note about some E. coli colonies in which many of the cells do not have DNA. No idea off-hand what has been discovered since then. DMacks (talk) 18:06, 18 July 2019 (UTC)[reply]

(Curious) What about cloning a plant from a cell or more from the fruit and making it make a fruit? Is that possible? Theoretically? Practically? Usedtobecool ^✉️ ✨ 17:35, 18 July 2019 (UTC)[reply]

cloning a plant from a cell is routinely done. Gem fr (talk) 11:43, 20 July 2019 (UTC)[reply]

Vegetative propagation

This is very commonly done for commercial fruit species. Not so much because they're seedless or can't be propagated from seeds, but because they are very highly specialised fruit varieties, and a non-seed reproduction of them will 'breed true', whereas using seeds might give a plant with different results. Sometimes those results are better, mostly they're not so good.

However you might need to grow from a tree (by taking cuttings, or whatever), rather than from a fruit. Andy Dingley (talk) 17:48, 18 July 2019 (UTC)[reply]

(ec)According to this,[6] you can't grow watermelons from the seeds of a "seedless" variety. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:49, 18 July 2019 (UTC)[reply]

Well, for sure, a biologist could probably grow a plant out off a single living cell, but I guess this is no what you mean.

Also, it will somewhat depends on your definition of a fruit. With the strictest definition, a "seedless fruit" just doesn't exist. I guess you use a broader definition, which would include, say, banana and pineapple. You CAN grow a pineapple plant out of the "fruit" (using the top leaves, without seeds); you CANNOT do that out of a banana, AFAIK. So, again, it will depends on the plant.

Gem fr (talk) 17:42, 19 July 2019 (UTC)[reply]

Gem fr, Actually, I'd argue that that's exactly what they meant: Does fruits have DNA outside the seeds? Usedtobecool ^✉️ ✨ 21:52, 19 July 2019 (UTC)[reply]

You may be right, but asking that require absolutely no idea what DNA, or even a cell, is. So everything is possible. Gem fr (talk) 11:36, 20 July 2019 (UTC)[reply]

July 20

How fast are we moving through space?

Is it possible to accurately measure how fast we are moving at any one time?

the earth spins the earth orbits the sun is the sun moving? the galaxy spins and moves? and on and on.

do we require reference points to calculate movement? — Preceding unsigned comment added by 79.65.5.120 (talk) 13:29, 20 July 2019 (UTC)[reply]

It is possible to compare velocity using the Cosmic microwave background#CMBR dipole anisotropy. 368 km/s. Graeme Bartlett (talk) 13:42, 20 July 2019 (UTC)[reply]

In any one (duration-less) instant of time, Zeno's arrow is neither moving to where it is, nor to where it is not. Since everything is motionless at every instant, and time is entirely composed of instants, motion is impossible. DroneB (talk) 15:17, 20 July 2019 (UTC)[reply]

If you wonder what DroneB means, see Chronon. I think the OP was intending to ask the question in a Newtonian model of reality. Dbfirs 17:30, 20 July 2019 (UTC)[reply]

We DO require reference points (or, rather, reference frame) to calculate movement. Once a reference frame is chosen you can calculate movement pretty accurately Gem fr (talk) 15:52, 20 July 2019 (UTC)[reply]

On the grand scale of things, the earth's motion around the center of the galaxy is going to be pretty much in sync with the sun's orbit around the center of the galaxy. Just a smidgen of retrograde motion by the earth and the other planets relative to the sun, if you were at the center of the galaxy and could see the solar system. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:23, 20 July 2019 (UTC)[reply]

An interesting Q is, if there are multiple big bangs, could we tell if our "universe" is moving with respect to the others ? Since the cosmic background radiation is left over from our big bang, it won't do. Is there any more universal frame of reference ? SinisterLefty (talk) 17:38, 20 July 2019 (UTC)[reply]

The very definition of a Universe means that, if there is something greater than our "our universe", then the universe is the greater thing, not the part you currently call "our universe". Comics' definition of "multiverse" with people moving between is just nonsense. Gem fr (talk) 19:19, 20 July 2019 (UTC)[reply]

Hence the term "science fiction". ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:22, 20 July 2019 (UTC)[reply]

But a multiverse consisting of many, or perhaps infinite, universes is a valid scientific theory. SinisterLefty (talk) 21:05, 20 July 2019 (UTC)[reply]

It's a hypothesis, lacking any evidence. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:52, 20 July 2019 (UTC)[reply]

Yes, and so much so that it stops being scientific: there is no experimental findings that would prove or disprove such hypothesis Gem fr (talk) 06:28, 21 July 2019 (UTC)[reply]

That's true of many theories in physics, such as string theory. There were also many earlier such theories, like the existence of the Higgs boson and black holes, that took many years to verify (48 years and perhaps centuries, respectively). SinisterLefty (talk) 06:41, 21 July 2019 (UTC)[reply]

What test would you recommend for detection of a parallel universe? ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:09, 21 July 2019 (UTC)[reply]

If another universe expands into ours, then we will eventually find out about it, but it could be billions of years, or trillions, etc. Other than that, I have no idea. Also, the simplest solution is an infinite number of universes with all possible physical laws. This explains why the physical laws in ours support the evolution of life (those with incompatible laws never have anyone there to wonder about it). If there is only one universe, then you would need to explain why the physical laws just happen to be right for life to evolve, as the probability of that happening at random is extremely low.

What test would you suggest for string theory ? If you have none, does that make string theory science fiction ? SinisterLefty (talk) 16:32, 21 July 2019 (UTC)[reply]

It might be, but at least it's trying to explain observed facts. What facts have ever been observed to suggest a parallel universe? ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:08, 21 July 2019 (UTC)[reply]

I already said that the observed physical laws are oddly "just right" to permit life. For example, if there was an even amount of matter and anti-matter, they would annihilate each other and destroy everything. So we end up in a universe with a difficult to explain lack of anti-matter. SinisterLefty (talk) 00:12, 22 July 2019 (UTC)[reply]

"Oddly just right"? Who says? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:30, 22 July 2019 (UTC)[reply]

Max Tegmark, for one: "Going from our universe to the Level I multiverse eliminates the need to specify initial conditions, upgrading to Level II eliminates the need to specify physical constants, and the Level IV multiverse eliminates the need to specify anything at all... A common feature of all four multiverse levels is that the simplest and arguably most elegant theory involves parallel universes by default. To deny the existence of those universes, one needs to complicate the theory by adding experimentally unsupported processes and ad hoc postulates: finite space, wave function collapse and ontological asymmetry." SinisterLefty (talk) 07:01, 22 July 2019 (UTC)[reply]

That premise sounds suspiciously like creationism. ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:48, 22 July 2019 (UTC)[reply]

Indeed, this is just sophisticated theist metaphysics. Metaphysics is OK, but should never be mistaken for physics. Gem fr (talk) 07:59, 22 July 2019 (UTC)[reply]

Your example of matter/anti-matter is very bad. Reality is no good at perfectly balancing things, so, what would strange is that they be in perfectly equal quantity for ever. You don't need an explanation for inequality, you would need one for their being perfectly balanced. Gem fr (talk) 07:59, 22 July 2019 (UTC)[reply]

String theory is not science. It may qualify as math (which is OK) or science-fiction (which is NOT OK) depending on whether you claim things could be so, or you claim they are really are so. Very different from the theories predicting Higgs boson or black holes, which took time to be confronted to observational facts, but could be. Gem fr (talk) 07:42, 22 July 2019 (UTC)[reply]

Forbes has a pretty great answer - at least to a nonscientist; I got a bit lost at the end there. 1700 km/hr rotation at the equator. 30 km/s around the Sun. 200–220 km/s around the galactic centre. Add galactic movement and the article came up with 627 ± 22 km/s relative to the comic microwave background. Great pics too. 70.67.193.176 (talk) 17:49, 20 July 2019 (UTC)[reply]

Reference. Gråbergs Gråa Sång (talk) 17:56, 20 July 2019 (UTC)[reply]

The numbers cited in the Forbes article are the same as those in the article which Graeme Bartlett linked to above. As I understand it, the relevant number (i.e. of Earth relative to the CMB) is 368 ± 2 km/s; 627 ± 22 km/s is for the local group as a whole, but being anthropic we don't care about that, do we? Henry ^Flower 21:06, 20 July 2019 (UTC)[reply]

I think we do. But we may differ, it doesn't matter much. Gem fr (talk) 21:54, 20 July 2019 (UTC)[reply]

FWIW - Excellent Question - Answer: "Nearly Two Million Miles Per Hour" => I've tried to answer (or, respond to) this question several times over the years - some of my efforts were published (FaceBook and The New York Times) - and are copied below if interested - hope this helps in some way - in any case - Enjoy! :) Drbogdan (talk) 22:09, 20 July 2019 (UTC)[reply]

The velocities should, of course, be added as vectors, not as scalars, though there may be times when they are all in approximately the same direction? Dbfirs 17:47, 21 July 2019 (UTC)[reply]

@Dbfirs: yes - agreed - adding velocities as vectors may be better - in which case, "nearly 2 M mph" may be an upper limit, I would think - also - the overall trajectory may at first seem to be linear over time to some - but may actually be a bit non-linear - due to the different directions of motion (including a combination of linear and/or circular/orbital directions) - perhaps in some helical (corkscrew?) fashion - in any case - Enjoy! :) Drbogdan (talk) 19:28, 21 July 2019 (UTC)[reply]

https://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Science#How_fast_are_we_moving_through_space?

How Fast Are We Moving Through Space? => "Nearly Two Million Miles Per Hour"
(ie, 1.892 x 10⁶ mph = 0.066 x 10⁶/orbit sun + 0.043 x 10⁶/sun + 0.483 x 10⁶/orbit galaxy + 1.300 x 10⁶/galaxy )
July 20, 2019

REFERENCES:
ASP: How Fast Are You Moving When You Are Sitting Still?
https://web.archive.org/web/20181226060625/http://www.astrosociety.org/edu/publications/tnl/71/howfast.html
https://www.researchgate.net/publication/261562461_How_Fast_Are_You_Moving_When_You_Are_Sitting_Still
https://nightsky.jpl.nasa.gov/download-view.cfm?Doc_ID=238 = NASA
https://nightsky.jpl.nasa.gov/docs/HowFast.pdf = NASA (BEST?)
The Astronomical Society of the Pacific is an international nonprofit scientific and educational organization founded in 1889 ...
https://astrosociety.org/
No. 71 - Spring 2007
How Fast Are You Moving When You Are Sitting Still?
By Andrew Fraknoi
Foothill College & the Astronomical Society of the Pacific
Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, CA 94112.

FACEBOOK
My Related Published FaceBook Comments are copied below if interested --
https://www.facebook.com/drbogdan/posts/170616344726
https://www.facebook.com/drbogdan
https://en.wikipedia.org/wiki/User:Drbogdan

Dr. Dennis Bogdan
November 6, 2009
MIND-BOGGLING? We've *All* Come A Long, Long Way From Where We Were When We Were First Born! - In Fact, Each Year, "Spaceship" Planet Earth Travels Nearly 20 Billion Miles Through The Universe! - Actually, We're All Hurtling Towards Andromeda Galaxy At Nearly Two Million Miles An Hour ( https://web.archive.org/web/20181226060625/http://www.astrosociety.org/edu/publications/tnl/71/howfast.html )! Kind Of Mind-Boggling - At Least To Some Perhaps! :)

ALSO

THE NEW YORK TIMES
My Related Published NYT Comments are copied below if interested --
https://www.nytimes.com/2014/11/13/science/space/european-space-agencys-spacecraft-lands-on-comets-surface.html?comments#permid=13314862
https://www.nytimes.com/2014/11/13/science/space/european-space-agencys-spacecraft-lands-on-comets-surface.html

Dr. Dennis and Joanne Bogdan
Pittsburgh, PA
November 12, 2014
Thank you for an Excellent article - Yes - a spacecraft landing on an astronomical object, Comet 67P, going 84,000 miles an hour ( https://en.wikipedia.org/wiki/Comet_67P ), is quite an accomplishment - however - for perspective - seems that airplanes routinely land on an astronomical object, spaceship planet Earth, going much, much faster - nearly 2 million miles an hour according to astronomers => https://web.archive.org/web/20181226060625/http://www.astrosociety.org/edu/publications/tnl/71/howfast.html - in any case - Thanks again for the Excellent article - and - Enjoy! :)
Dr. Dennis Bogdan
http://en.wikipedia.org/wiki/User:Drbogdan
1 Recommend

C.Blacksmith commented Spain November 13, 2014

Speed is not an absolute measure. Planet Earth has a relative speed of 0 for airplanes (referring to its original position, the runway).
84,000 miles an hour is the relative speed of Comet_67P refering to Rosetta's original position.
Three big diferences:
- the acceleration process (which lasts 10 years)
- the distance (rendezvousing with the comet required travelling a cumulative distance of over 6.4 billion kilometres.)
- The automation (It will take the radio signals from the transmitter on Rosetta 28 minutes and 20 seconds to reach Earth, and the same to return to rosetta)
2 Recommend

Dr. Dennis and Joanne Bogdan commented Pittsburgh, PA November 14, 2014
Yes - I *Entirely* Agree - Thank You *Very Much* For Clarifying - Landing On The Comet Is A Truly Great Technical Accomplishment Of Course - Enjoy! :)

Heteromorphosis

Hello. I came across this term while modifiying Morphosis (disambiguation), and found that the article's lead sentence is unintelligible due to false syntax. However, I couldn't figure out how to appropriately fix it – without having the cited sources at hand. Can anybody perhaps help out? Regards--Hildeoc (talk) 19:56, 20 July 2019 (UTC)[reply]

It might be simpler to start from scratch with a (cited) definition from someplace like here: heteromorphosis. (n.d.) Farlex Partner Medical Dictionary. (2012). Retrieved July 20 2019 from https://medical-dictionary.thefreedictionary.com/heteromorphosis —107.15.157.44 (talk) 21:38, 20 July 2019 (UTC)[reply]

I edited according to my understanding. Is that better? If not, feel free to edit yourself. Gem fr (talk) 21:50, 20 July 2019 (UTC)[reply]

July 21

Diet and rate of fingernail growth

Hello. Is it true that if one eats certain foods, one's fingernails grow more quickly than they otherwise would, and if so, which foods are they? FreeKnowledgeCreator (talk) 08:29, 21 July 2019 (UTC)[reply]

check Nail_(anatomy)#Growth and Nail_(anatomy)#Effect_of_nutrition Gem fr (talk) 08:57, 21 July 2019 (UTC)[reply]

They don't mention specific foods. FreeKnowledgeCreator (talk) 09:10, 21 July 2019 (UTC)[reply]

They did mention that protein is the basic building material. Therefore, a lack of protein would slow growth down. However, more protein won't increase the growth rate unless you were deficient in protein/amino acids. That is, fingernails have a certain maximum growth rate, and more protein won't change that. Protein can be found primarily in fish, poultry, meat, dairy/milk, eggs, beans/lentils & seeds/nuts. Similarly, eating more of the micro-nutrients they listed won't help, unless you were deficient in those. SinisterLefty (talk) 12:41, 21 July 2019 (UTC)[reply]

Knox gelatin used to advertise that their product promoted nail growth. The following article states that according to MayoClinic.Com: "what you put in your mouth will have no effect on your nail growth"; it also includes much information on the subject:

Sefcik, Lisa (July 18, 2017). "Knox Gelatin for Nail Growth". Our Everyday Life. —107.15.157.44 (talk) 20:26, 21 July 2019 (UTC)[reply]

"what you put in your mouth will have no effect on your nail growth" must be understood as "you cannot grow nail faster", as it only depends on the cells making the stuff, with their own agenda, provided they are healthy. However, poisoning or nutrient deficiencies, WILL have effect on your nail growth, of course. Gem fr (talk) 07:22, 22 July 2019 (UTC)[reply]

July 22

Luna 15 flyby video: real of hoax?

I just watched a YouTube video on Luna 15 and it included a brief clip that was claimed to be a flyby of the Luna 15 caught on Apollo 11 film or video. It is at 5:33 Race for the Rocks - Apollo 11 vs Luna 15 on the Moon. It is also found here: Luna 15 over Eagle Apollo 11. Several things struck me as odd and made me suspect that this a fake video.

The camera angle is wrong, showing the equipment bay on the backside of the lander from the quadrant III direction.
The flag is in the wrong place, also in quadrant III.
I didn't think the camera exposure level was set to be sensitive enough to be able to detect such a flyby.

I first searched snopes but found nothing. A further search turned up little except this stack exchange article, which in turn mentions that the clip was included in a 2005 BBC documentary "Space Race". Can anyone here find more information to confirm or debunk the authenticity of this clip? Perhaps the angle and flag position can be matched to photography of a later mission. -- Tom N talk/contrib 01:32, 22 July 2019 (UTC)[reply]

Actually, BBC's "Space Race" was not a documentary, it was a docudrama -- if the clip was from there, then its fake. —107.15.157.44 (talk) 02:21, 22 July 2019 (UTC)[reply]

docudramas usually make extensive use of real footage, when available (besides, those come for free when public domain). -- if the clip was from there, then its fake. — is just wrong. The 6:07 dust figuring the crash of Luna is obviously not the real thing (nobody was there to film it) and the clip doesn't claim it is (it just suggests so). OTOH, I see no reason to doubt the explicit claim that the clip at 5:33 shows Luna flyby Apollo Gem fr (talk) 07:09, 22 July 2019 (UTC)[reply]

This Stackexchange thread discusses the video and whether it would have been possible. People seem to think not. --69.159.11.113 (talk) 07:59, 22 July 2019 (UTC)[reply]