Wikipedia:Reference desk/Archives/Science/2016 February 9

= February 9 =

Synthetic turquoise
Is there such a thing as fully synthetic turquoise (as opposed to imitation turquoise)? If so, how is it synthesized? 2601:646:8E01:9089:14B5:216D:30B1:F92 (talk) 06:02, 9 February 2016 (UTC)


 * The second sentence of the lede in our article Turquoise says "In recent times, turquoise, like most other opaque gems, has been devalued by the introduction of treatments, imitations, and synthetics onto the market. - so evidently, there are synthetic stones out there. Geology.com says "A small amount of synthetic turquoise was produced by the Gilson Company in the 1980s...It was a ceramic product with a composition similar to natural turquoise." - so I guess it's arguable that this was not truly a synthesis of a material identical to the real thing.  It goes on to say: "Synthetic turquoise, and turquoise simulants have been produced in Russia and China since the 1970s." - but no clue as to the manufacturing methods. SteveBaker (talk) 13:40, 9 February 2016 (UTC)


 * I found the Gilson name also - searching brings up a chemical analysis of a different synthetic - seems like this one is not perfect somehow - not sure how to define a yes or no answer about it though. Wnt (talk) 15:59, 9 February 2016 (UTC)


 * Whew! So from what I gather, so far nobody made the real thing in the lab?  That's good news for me, thanks! 2601:646:8E01:9089:A082:3561:E888:76F (talk) 01:02, 10 February 2016 (UTC)


 * Maybe. "The Real Thing" is a little tricky here.  Just how close do you have to get before you say it's "real"? SteveBaker (talk) 15:33, 10 February 2016 (UTC)


 * A real gem comes from a little yellow idol, or the Cold Lairs, or is waiting for you behind the ranges... DuncanHill (talk) 15:44, 10 February 2016 (UTC)

Weight of paper
What will be the weight in kilograms of 0 r5eams of 60gsm paper having dimensions 10'x11x1' is this paper of A4 size.223.176.51.205 (talk) 12:09, 9 February 2016 (UTC)
 * This looks like your homework question. Wikipedia doesn't do students' homework for them because that would negate the benefits of practicing at home. If there is some part of the question that you don't understand, or you have got stuck part way through, ask a relevant question about the part you don't understand and we will try to point you in the right direction. Dolphin  ( t ) 12:21, 9 February 2016 (UTC)


 * Also look up 'ream of paper' as it says how many sheets you have, the dimensions don't tell you that. Dmcq (talk) 12:50, 9 February 2016 (UTC)

No this is not a home work problem I a not a paper technologist I know 1 ream has 500 papers but I don't understand the basis weight concept and please tell me what is the weight of 1 ream paper or 1 of the 500 papers or how to calculate the weight because I cannot make it out from websites.223.176.51.205 (talk) 12:57, 9 February 2016 (UTC)
 * A4 sized paper is .297 metres times .210, so a single sheet of paper has an area of approximately 0.062 square metres. Each square metre weighs 60g (as in 60 gsm: grammes per square metre).  Thus 500 sheets weigh 500 x 60 x .210 x .297 = approx 1.87 kg.--Phil Holmes (talk) 13:02, 9 February 2016 (UTC)
 * A4 is exactly a sixteenth of a square metre (0.0625) (see ISO 216 for details), so the weight is 500 divided by 16 times 60 g which is exactly 1.875 kg. In practice, Phil Holmes might be more correct because of the slight loss in cutting.    D b f i r s   22:10, 9 February 2016 (UTC)


 * Really? If you're a "paper technologist" then you sure as hell ought to know OK so you need to know that 'gsm' stands for 'grams per square meter'.  You can easily calculate the total area of 500 sheets of paper of whatever size (length x width x number of sheets), convert to square meters.  Then multiply by the gsm number to get the weight in grams.  Then divide by 1,000 to get kilograms. SteveBaker (talk) 13:31, 9 February 2016 (UTC)


 * Steve, the OP said they were not a paper technologist. I'm not a linguist, but I know what "not" means. DuncanHill (talk) 13:36, 9 February 2016 (UTC)
 * Ooops! Sorry!  My bad! SteveBaker (talk) 13:42, 9 February 2016 (UTC)

FWIW, a "ream" used to be 20 quires - or 480 sheets. Blame the British . Collect (talk) 16:37, 9 February 2016 (UTC)
 * NB, by definition a sheet of A4 paper has surface area of $$ { 1 \over 2^4 } $$ m2, or one 16th of a square metre. LongHairedFop (talk) 22:18, 9 February 2016 (UTC)
 * Knowing that, don't you just wish they'd put 512 sheets into a ream? SteveBaker (talk) 15:32, 10 February 2016 (UTC)
 * I do, it would be 2^5 square meters exactly.--Lgriot (talk) 20:25, 10 February 2016 (UTC)

Widely distributed species
Phrynobatrachus ogoensis is a species of frog from western and central Africa. According to the article, which correctly reflects the IUCN Red List source, it's found in a small area of central Gabon and near Robertsport in Grand Cape Mount County, Liberia. How can a species be found in both spots, yet nowhere in between? I understand the concept of a species existing in disconnected locations that were once connected, e.g. the freshwater eel species (can't remember which one) found both in Europe and North America, and a species that's been human-transported from one spot to another, e.g. rats and house sparrows, but I don't imagine people transporting just another frog species in this manner, and what about the climate/topography would prevent the frog from spreading any farther from its current limited habitats in these highly rainforested regions? Nyttend (talk) 14:04, 9 February 2016 (UTC)
 * Without knowing the specifics of frog distribution in Africa off the top of my head (man, if I had a dime for every time I said that phrase) there are a variety of elements in play that restrict species' expansion. As you note, the two areas may once have been contiguous and the species just died off in the middle areas. That (and the lack of further outward expansion) could be the result of many things, including direct human action altering waterways, draining marshes, and so on, or by various forms of pollution. Frogs are an indicator species (not in our article yet, so ref), which means that they are particularly susceptible to pollutants. In other words, the area between their current habitats might seem pristine to us and many other animals, but not to the froggies. It would also be interesting to see if there are other frog species that compete directly against ogoensis within the same ecological niche. Matt Deres (talk) 15:18, 9 February 2016 (UTC)


 * The obvious answer is that the two locations probably represent two distinct species. The two populations were treated as the same species back in the 40s (before DNA was known) and that conclusion has persisted given the lack of any subsequent scientific effort to confirm or deny whether these two populations are from a single species.  IUCN itself says they probably aren't a single species, but that more investigation is needed.  Dragons flight (talk) 15:37, 9 February 2016 (UTC)


 * It's entirely possible that the range was much broader, but has shrunk. Relict_(biology) describes this case. Think of how we have only small isolated patches left in the USA of old growth forest or Tallgrass_prairie . There are several species that may not exist only in those remnants, but will have very low density anywhere else.
 * I don't know specifically what's up with this one particular frog, but the situation you describe is entirely consistent with how we think about species distributions in a conservation/management context, and it's all too common of a story. While the CA tiger salamander is not so extreme, check out the isolated pockets in the distribution here . Many other redlisted amphibians will have similarly disconnected distributions, as their habitats are degraded and they become extirpated from all but the most remote and inaccessible environs. SemanticMantis (talk) 18:50, 9 February 2016 (UTC)

The extinction of sandboxes
It looks like kids these days do not have access to sandboxes anymore (unless it's a sandboxed browser). When and how did this shift took place? Who decided that they should go? I suppose they were deemed unsafe, but was this move absolutely necessary? --Scicurious (talk) 14:04, 9 February 2016 (UTC)
 * I'm sure it frustrated cats in the neighborhood. ←Baseball Bugs What's up, Doc? carrots→ 14:34, 9 February 2016 (UTC)
 * This site declares "If there’s one thing that kids love more than slides and swing sets, it’s the sandbox! These can be found in all parks and playgrounds and kids can safely play all kinds of games in there, or build sand castles and other cool thing with the sand." However maintaining the sandbox requires protecting it from rain and from all animals and pets, including insects. Observing a child's play with toy models in a small sandbox is a form of non-directive Play therapy attributed to child psychologist Margaret Lowenfeld. AllBestFaith (talk) 14:54, 9 February 2016 (UTC)


 * (EC) 1) Plenty of kids have access to sandboxes. I think you must mean the decline of public sandboxes at children's parks, or perhaps you haven't noticed that small (coverable) backyard sandboxes like this are still fairly common in the USA. 2) Very little is absolutely necessary. 3) Here is a selection of articles that describe some of the safety concerns   . I'm not sure about necessity and sandboxes, but exposing kids to Toxoplasma gondii seems like a good thing to cut down on, and that's just one of the more famous pathogens that can linger in sand... SemanticMantis (talk) 15:03, 9 February 2016 (UTC)


 * Yes, I mean the public ones, it seems that they are more difficult to protect than a little one in your backyard. Scicurious (talk) 15:36, 9 February 2016 (UTC)


 * Well put. The question also implies that this was an organized decision; toys fall in and out of fashion just like anything else. Matt Deres (talk) 15:20, 9 February 2016 (UTC)


 * I think it could be a Health Hazards Regulation. They could have been prohibited, in the same way that not wearing a seat belt was banned. Scicurious (talk) 15:43, 9 February 2016 (UTC)


 * The OP's premise is patently wrong, nearly every public park in my metro area, including those built or renovated in the past 10 years has a large open sand play area or sandbox in it. You can still buy sandboxes at Walmart and Target, and they sell large bags of "play sand" at Home Depot and Lowes.  So the answer to the OPs "why?" question is "we can't tell you why, because the question makes no sense, because your premise is wrong". Unless the answer is " you aren't looking hard enough "-- Jayron 32 16:16, 9 February 2016 (UTC)


 * This is why I sometimes ask the OP, "Who says so?" Which I should also have done here, but failed to. ←Baseball Bugs What's up, Doc? carrots→ 16:24, 9 February 2016 (UTC)


 * Having observed a few new sand boxes in your area proves nothing about the trend. Let's see some sources, please. StuRat (talk) 17:15, 9 February 2016 (UTC)
 * First, the OP needs to provide sources to support his own premise. ←Baseball Bugs What's up, Doc? carrots→ 17:58, 9 February 2016 (UTC)
 * No, our job, should we choose to volunteer our time, is to provide references. OPs can ask whatever questions they like. In the places I've lived, I've think WP:OR I've seen a decline in public sandboxes for children. Put more carefully, I think less new playgrounds constructed in the USA since 2000-2015 have sandboxes than e.g. those constructed in 1965-1980. Of course my observation could be incorrect too, so I've included a reference that gives some numbers below. In any case, demanding refs from OP is not something we really should do. While we may appreciate refs, we really can't demand them. Providing references is kind of what we're supposed to do here, isn't it? I think you've also expressed a desire to see less policy commentary on the ref desks, so please feel free to start a thread on the talk page if you'd like to discuss it further. I am collapsing this thread because it isn't terribly relevant to the OP, but feel free to uncollapse if anyone thinks it needs full visibility. SemanticMantis (talk) 18:38, 9 February 2016 (UTC)


 * In regard to the premise, here is a NYT article from 1995 that gives some numbers, and says there were far more sandboxes included in city parks in the past. To wit "Since the 1970's, no new or renovated city playground designs have included sandboxes unless requested and lobbied for by the community, which also must maintain them."  If anyone wants to find other stats for other areas, I'm sure they'd be appreciated. It seems as though the prevalence of sandboxes may change throughout time and place, which should really surprise nobody. It is clear that at least in NYC, there has been a precipitous decline in public sandboxes since the 1970s. SemanticMantis (talk) 18:38, 9 February 2016 (UTC)
 * The time between when that article is written and when it is referring to as the halcyon days of sand box glory is as long as the time between now and when the article is written. An article from 20 years ago saying how awesome life was 40 years ago isn't all that relevant to our discussion today.  -- Jayron 32 01:05, 10 February 2016 (UTC)
 * So what? Do you really think there has been some resurgence of sandboxes since 1995? For that matter, OP never gave a timeline, he could be thinking in comparison to 10 years ago, or maybe 50. Here's another article about NYC that says "the number of sandboxes has dwindled from a peak of seven hundred to only fifty or so today" . That article is from 2010, so I don't think it's fair to say the numbers are out of date. I only looked for NYC because it's a big famous city with a large parks dept. I don't disbelieve that your metro area still makes new sandboxes with new parks, but it seems like you're trying very hard to disbelieve the fact that public sandboxes do seem to have declined in many areas. This seems to be coincident with increasing awareness of some health concerns, and in 2008 the national sanitation foundation did an extensive study. That study and others are reported on here in 2015, where parasitic roundworms are also mentioned to have been found in 2/10 daycare sandboxes. It is indeed hard to find good references on numbers of municipal sandboxes. But the references I do have show a decline. They also show an increasing concern from public health officials and doctors. Given these references that I found, along with my personal observations, those of the OP, and those implicit in many of the public safety articles, I conclude that there has been a change in public sandbox incidence in many places in the USA. This does not preclude any new sandboxes being built in your neighborhood this year. SemanticMantis (talk) 16:46, 10 February 2016 (UTC)


 * Wikipedia has an article about Playground surfacing and there are dozen options besides sand. The article does not mention a tendency towards other materials, but sand has all drawbacks, expecting cost, which is low.The Americans with Disabilities Act was passed in 1990, and sand does not comply with its requirements. So, it's clear to me that some communities could choose other materials for their playgrounds. And that's without entering into the Toxoplasmosis issue. Llaanngg (talk) 19:22, 9 February 2016 (UTC)
 * Yes, this is the big issue. Sand gets very dirty. Modern playgrounds are more likely to use rubber surfacing or maybe bark chippings. Blythwood (talk) 06:09, 10 February 2016 (UTC)


 * Sand isn't just used as a surface in a sandbox, it's used as a building material to build sand castles, etc. StuRat (talk) 20:56, 9 February 2016 (UTC)
 * Indeed. We're almost surely talking about sandpits here, not the open areas under/around whole playgrounds of equipment. DMacks (talk) 21:59, 9 February 2016 (UTC)


 * I don't know about in the US but, since retiring from my original occupation, I have worked as a relief caretaker in a number of local authority schools in the UK. One of the requirements of nurseries and early years units is that they must have provision for the children to play with sand and with water (usually both together). They often have facilities for this, both inside and outside and it is one thing that drives you mad when you have to clean it all up every evening - would you let your kids play with sand and water in a room with carpets? I have even worked at one nursery school where they had a one ton bag of soil and they asked me to regularly bring in a couple of buckets so the kids could mix it with water and sand and make mud pies - you can imagine the mess that made on the nursery carpets when they came back inside. The outside sandpit was always covered at night to stop cats and birds crapping in it but, obviously, in a public park it would be difficult to keep it covered and of course the public could drop sharp objects in it. However, the premise that children don't get to play in sand anymore certainly doesn't apply in the UK. Richerman    (talk) 22:11, 10 February 2016 (UTC)


 * Clearly the problem there is not with the requirement that kids get to play with dirt, sand and water - but that they should do it indoors. Why not let them do it outside - when weather permits - and not otherwise? SteveBaker (talk) 19:15, 11 February 2016 (UTC)


 * They have automated catboxes that can comb the "lumps" out now. I wonder if a larger version could clean and then seal a sandbox at night. StuRat (talk) 22:24, 10 February 2016 (UTC)


 * No doubt such a thing could be devised - it could filter, wash and dry the sand at intervals and return it to the sand box - but the cost of building and running such a contraption would likely be prohibitive. Personally, I doubt that would be a good idea, even if it was plausible.  There is undoubtedly a trend in trying to keep children super-clean and far from all bacteria and other such nastiness - but sadly, it starts to look like doing that causes them to fail to gain immunity to a lot of the things they encounter.  There are suspicions that this may explain the increase in some diseases such as asthma - which is especially prevalent in children that are kept "too clean".  As humans, our children evolved to sit around in dirt, sand, etc - it's dangerous to assume that cutting them off from those situations is a net advantage.  SteveBaker (talk) 19:13, 11 February 2016 (UTC)


 * For which, see hygiene hypothesis. Matt Deres (talk) 02:10, 12 February 2016 (UTC)


 * Yes, some level of exposure to microbes may be healthy, but that doesn't mean we should let our kids play with cat poop. There's an appropriate balance.  StuRat (talk) 05:13, 12 February 2016 (UTC)
 * Indeed, "moderation in all things" (especially cat pooh) SteveBaker (talk) 03:37, 13 February 2016 (UTC)

Starkiller Base superweapon
In Star Wars: The Force Awakens, General Hux gives the order to fire Starkiller Base's superweapon, which emits an energy beam strong enough to destroy entire planets. When I first saw the film, my suspension of disbelief was briefly dropped, when I thought "there's no way that energy beam can travel lightyears in minutes", but then I thought "Hey, I'm watching a film with interstellar spaceships and talking aliens", and kept on with the story.

Now, onto my question. Suppose such an energy beam is possible. Ignore its power, it doesn't have to destroy anything, just get at its destination without getting too much spread out and diluted. It can be just a fancy light show. But it has to be visible to the naked eye.

How would the people on the destination planet see it coming? Would it appear as a slowly-moving bright spot in the sky, getting gradually brighter, until it illuminated the whole sky? Or would the people just suddenly find the sky all illuminated? J I P &#124; Talk 20:11, 9 February 2016 (UTC)


 * If it travels at the speed of light - they wouldn't see it at all until it arrived. If it travels faster than light then all bets are off because the laws of physics as we know them say that it's impossible - so any "What if..." answers would be nothing better than wild speculation.
 * In the real world, even a visible-light laser is invisible as it crosses a vacuum - and unless it has enough power to ionize the air and make it glow, it'll be more or less invisible all the way until it hits it's target (maybe it might vaporize a few dust motes or something). If it is powerful enough to make the air glow, it still wouldn't be visible until it hit the air - it would basically pop into view as a glowing shaft of light in such a tiny fraction of a second - that it would appear to be instantaneous.
 * But if it's fictional...it can look like whatever the director and the special effects department can imagine!
 * SteveBaker (talk) 20:44, 9 February 2016 (UTC)


 * OK, so it would go as I imagined, not as it was actually depicted in the film. I always thought the effect of a beam moving at light speed would have instantaneous effects when it's finally seen. Not like in the film where people can harmlessly watch it slowly approach for a few minutes, until it finally destroys the entire planet in a few seconds. I think the director made it move so slowly for dramatic effect. J I P  &#124; Talk 20:50, 9 February 2016 (UTC)


 * I haven't seen the film, but the effect sounds totally unlike a laser, and more like a plasma ball, as in Ball lightning, but perhaps containing a Quark–gluon plasma to carry that sort of energy. It would have to cover most of the distance via a created Wormhole.  I suspect that the film-makers were more worried about the impression on the viewer than they were about explaining the exact physics.    D b f i r s   21:55, 9 February 2016 (UTC)


 * Haven't seen the film, but if the region of space the beam passes through glows with ordinary light, and if the beam follows a spacelike path, then the beam would appear to emanate on the planet struck and move up into the sky. One way to see this is that if the beam is "instantaneous", linking the two planets at a single moment in their shared rest frame (assuming they're not moving relative one another) then it really isn't moving from one planet to the other - its appearance is symmetrical as seen from either world.
 * However, it is conceivable that the design of the beam would call for it to build up in a large spacelike path while the energy accumulated, but then one end gradually moves at a sublight speed toward the planet until it discharges, etc. As a rule, you can write apologia for the worst sci fi plots if you think them through carefully. Wnt (talk) 22:41, 9 February 2016 (UTC)
 * I see what you're saying - if the beam arrives faster than the light it emits along the way, then it's tempting to say that it's first visible where you are - then starts to appear backwards towards the source as the light from it's passage catches up with it's ultimate effect. But because the laws of physics don't allow for things that go faster than light, all bets are off.  We can't make any reasonable statement about the physical reality of the square root of a negative number - and that's what the Lorentz transformation requires:


 * $$ \gamma = \frac{1}{ \sqrt{1 - \frac{v^2}{c^2}}}$$


 * When v2 is greater than c2, the v2/c2 is greater than one - and we have the square root of a negative quantity. So the mass, length, time-dilation and energy of this superluminal 'effect' are all impossible to calculate.  We know that in the real world, we never see the square root of a negative number in an actual result.  It always cancels out somewhere else.  So there is really very little likelyhood of anything physical, that can transmit information, travelling faster than light...and if it did, the consequences are a mathematical impossibility.  Causality itself falls by the wayside.  Making any statement whatever about what that might look like is entirely unreasonable in light of what we know.
 * Possibly the only reasonable speculation relates to the (not-real) concept of tachyons - which hypothetically might travel at beyond the speed of light. The kind of crazy math that results from this is that tachyons would require infinite energy to slow down to the speed of light (a kind of mirror image of regular particles that need infinite energy to reach the speed of light) - and that their lowest energy state would be when they were travelling at infinite speed.  So even if we take a BIG stretch into the most hypothetical physics, we end up with a weapon who's effects would travel at infinite speed and not take the time that the beam weapon in StarWars takes.
 * All bets are off. This is a fictional thing - and the appearance of it is whatever your imagination (or the plot) needs it to be. SteveBaker (talk) 15:30, 10 February 2016 (UTC)
 * Well, the laws of physics allow phenomena to go faster than light, just not information. For example, the owners of this death-ish star might have launched a bunch of probes to line up along the trajectory of the intended attack years in advance, then ceremoniously press the button at the exact time they were all timed to go off ... in which case you would see the closest ones to the planet light up first.  (Just ask a 9/11 truther ... they put explosives inside the planet, and the death star firing at it is just a misdirection...) Wnt (talk) 17:58, 10 February 2016 (UTC)
 * There is, in fact, a detailed cannon explanation for why the beam from Starkiller base appeared in the manner that it did, but as it is pure science fantasy, I shall not sully the reference desk with such dribble. Anyone curious can look up the weapon's entry on the Star Wars Wikia. Someguy1221 (talk) 22:41, 10 February 2016 (UTC)
 * Indeed, it is possible for a phenomenon of some kind to travel faster than light - but not in this case since the beam carries the information that someone on the death star pressed the "DESTROY THE PLANET!" button (and when and in which direction it was aimed and a whole lot more besides). Since information cannot travel faster than light, neither can a functional death ray.  So, yes, it is indeed still hogwash. SteveBaker (talk) 15:12, 11 February 2016 (UTC)