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June 28

Rhizophoraceae, could it be narrowed down taxonomically?

Hi Ref Desk,

I just found some photos I could stitch to a panorama of mangroves I took 5 years ago at Anse du Canal near Petit-Canal on Grande-Terre, Guadeloupe, Lesser Antilles. The family of mangrove plants is the Rhizophoraceae, but I was wondering if the identification could be further narrowed down to the genus level or perhaps even species level based on the photo alone and the location? -- Slaunger (talk) 07:12, 28 June 2015 (UTC)[reply]

Great photo! Using the photo for species level ID would require an expertise I don't think we have here. Fortunately, the specific location will help you rule out several genera. Just a note, Mangrove#Taxonomy_and_evolution lists several other families in addition to Rhizophoraceae that also have species known as mangroves in them, you might want to browse through those also. SemanticMantis (talk) 14:35, 29 June 2015 (UTC)[reply]

Resolved Thanks, SemanticMantis. I decided to search for scientific papers dealing with mangroves in Guadeloupe and found a researcher (Daniel Imbert, Université des Antilles et de Guyane.), whom I asked by email for identification. He had no doubt it was red mangrove (Rhizophora mangle). -- Slaunger (talk) 18:41, 30 June 2015 (UTC)[reply]

How can one induce sleep paralysis?

I read the article on sleep paralysis but it doesn't say how to induce it. I'd really like to experience it for myself. Thanks — Preceding unsigned comment added by 117.169.218.7 (talk) 11:59, 28 June 2015 (UTC)[reply]

You can't induce it, there are just certain things that make it more likely [1]. Mikenorton (talk) 12:22, 28 June 2015 (UTC)[reply]

Have your doctor strap you into your bed. That should do the trick. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:32, 28 June 2015 (UTC)[reply]

Why did birds survive the extinction of other dinosaurs?

It seems to be generally accepted that modern birds are descended from the dinosaurs, I'm left wondering why specifically the birds survived the dinosaur extinction event? It seems very surprising that no other kinds of small dinosaur made it through the mass extinction alongside the birds, reptiles and mammals that seemingly had similar lifestyles, body size and diet to small non-avian dinosaurs.

What feature of birds enabled them to get through the catastrophe?

SteveBaker (talk) 14:50, 28 June 2015 (UTC)[reply]

"My answer to a related question about aquatic dinosaurs may help, I at least point to a Radio Lab episode where they discuss the KT impact with geologists. Basically, anything that was on the surface of the Earth got cooked, but anything under a few inches of soil would be ok. This favored small mammals, birds, and reptiles that nested underground. While modern birds don't typically bury eggs, ancient birds may have, to hide them from predators. – user137 Nov 18 '14 at 20:52" Count Iblis (talk) 15:53, 28 June 2015 (UTC)[reply]

Sure, but surely there were small dinosaurs (comparable in size and lifestyle to mammals and reptiles) that weren't adapted to flight at the time? Seems unlikely that ALL small dinosaurs were birds...and clearly you didn't need any of the special bird adaptations such as flight or egg-laying in order to survive. So if birds could survive - then why no tiny dinosaurs or other kinds? SteveBaker (talk) 17:16, 28 June 2015 (UTC)[reply]

This is probably related to bird's capability of flight. Ruslik_Zero 17:35, 28 June 2015 (UTC)[reply]

But the mammals and reptiles that survived couldn't fly. Why did the dinosaurs need to be able to fly in order to survive? SteveBaker (talk) 19:15, 28 June 2015 (UTC)[reply]

Wasn't it the less the case that birds survived as such, but that birds later evolved from the small number of dinosaur species (or one species even?) that managed to survive the extinction? --87.112.205.195 (talk) 17:38, 28 June 2015 (UTC)[reply]

No, that was my first thought too - but when I was trying to figure this out for myself, I discovered that the evolution of birds happened long before the extinction event. Microraptor was around 120 to 125 million years ago and was capable of powered flight and looked a lot like a modern bird (except for the small matter of having four wings!). But the rest of the dinosaurs didn't go extinct until 66 million years ago - so birds had been evolving for 55 to 60 million years before the rest of the dinosaurs vanished. SteveBaker (talk) 19:14, 28 June 2015 (UTC)[reply]

it might be that a few kinds could fly higher that other dinosaurs so they survived

We don't know. We lack a complete understanding of the events of the impact, or of the ecology that existed before and after the event. We do know that at least some mammals and birds survived, though far from all of either. We also know that non-avian dinosaurs went extinct, but a variety of other reptiles (e.g. alligators, turtles) survived. Some of the differences is undoubtedly due to adaptation, lifestyle, and flexibility, but some of the difference between who died and who survived is also probably down to dumb luck. Imagine killing 99% of all individual animals alive and then seeing which survivors manage to form successful breeding populations, not an easy thing if your species is large and sparsely populated. It also isn't very clear how much differentiation already existed prior to the event. For example, if small burrowing mammals were already more successful than small dinosaurs in occupying the burrowing niches, there may have been few or no dinosaurs designed for hiding underground during the event. Cretaceous–Paleogene extinction event provides some detail on the speculations about the role that traits like small size, burrowing, swimming, ectothermy v. endothermy, etc. may have played in favoring some groups over others. Dragons flight (talk) 22:38, 28 June 2015 (UTC)[reply]

Agreed we don't (and likely can't) know for sure. Paleoecology is hard stuff. It's probably not even deterministic - when you get to low population levels after Disturbance_(ecology) , things like allee effects and founder effects pose a serious challenge to any kind of long-term, deterministic prediction of how competition will sort out the community ecology of a certain clade. It's not so much about who survived the first few years after impact, but also about who was able to have positive growth rates in the new world - it's not just existence, but species coexistence in the community context that matters. There's also the extremely likelihood of multiple basins of attraction in the population processes, known as Alternative stable states in ecology. Even in homogenous worlds, we can see evidence of emergent endogenous heterogeneity and non-deterministic competitive outcomes over time. And of course the real world has lots of heterogeneity that further complicates deterministic prediction.

That being said, there is indeed speculation on why things worked out the way they did, though it doesn't always get published in reputable journals. This [2] is a nice write up of the specifics of kill mechanisms. This [3] is a nice general perspective piece on extinction vulnerability, with some discussion of K/T. This one [4] might be your best bet at getting a view of how morphology is thought to play into the sauropod/avian evolution around the K/T. Incidentally, there is still at least some debate over when the avian radiation occurred, and how many birds or birdlike things survived. These two papers seem to be part of the emerging consensus that avian radiation was well underway before the K/T extinction [5] [6]. If you believe that there were many birds around before the asteroid hit, then they would have already gone through several iterations of Niche_differentiation, and that by itself is enough to suggest that most extinction mechanisms would have a selective effect, even though it doesn't tell us exactly why any one clade was selected. SemanticMantis (talk) 15:04, 29 June 2015 (UTC)[reply]

Some good stuff above; I would only caution/reaffirm that a) it's honestly unknown at this point b) palaeontology is undergoing huge shifts in understanding and has been for the last few decades, and c) the dividing lines between birds and dinos, such as they exist right now, are being routinely re-written. Experienced dino guys, like Robert Bakker, have asked similar questions about other groups of animals: what catastrophe is big enough to kill off all the dinosaurs but too small to kill off the frogs? We know using present day data that frogs and other amphibians are great indicators of the health of an ecosystem - they don't tolerate much change - yet they apparently had no problem with the global catastrophes we associate with the KT extinction. Matt Deres (talk) 19:22, 29 June 2015 (UTC)[reply]

Memory question

During the day when you do something you typically remember doing it. Can you tell me what chemical is released into the brain at night that prevents you from remembering your dreams? Also, how is it so fast acting that one can wake for a few moments in the middle of the night and remember doing so, but not remember the dreams either side of the awakening? — Preceding unsigned comment added by 183.217.239.165 (talk) 17:20, 28 June 2015 (UTC)[reply]

I've read somewhere that this has to do with the way memories are stored in the brain. When you dream, your memory works differently, similar to how it works in animals and small children. At the age of about 5 the memory starts to work differently due to the development of language. When the vocabulary of the child becomes rich enough, memories are filed in the brain using abstract language more instead of the primary experience. It has been found that events in early childhood could be clearly remembered by children until about that age of about 5 and then all of a sudden the child will fail to be able to recollect the event. This is then purely a matter of the brain starting to use a different filing system to store and recollect memories, old memories filed according to the old system then become untraceable.

Now, when we dream, we revert back to using the old system for memory again, because in dreams we typically don't use language a lot. Then, when you wake, your brain will use the usual language based system form memory recollection, and then you'll have difficulties remembering the dream. You can also notice this effect when you remember another dream inside a dream, or memories from early childhood inside a dream. Count Iblis (talk) 17:53, 28 June 2015 (UTC)[reply]

Another point of view (because this is an area of active research), dreams are not transferred from short term to long term memory. Short term memory lasts a few minutes. If you talk about your dream as soon as you awake, you can remember what you said, but you will forget the dream. 75.139.70.50 (talk) 19:34, 28 June 2015 (UTC)[reply]

Who says so? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:55, 28 June 2015 (UTC)[reply]

First, to summarize... Norepinephrine appears to be required to move memories from short-term to long-term memory. I have not seen any studies that satisfactorily explain the full mechanism. It appears to be more complicated than just triggering the hippocampus to move the memories - though that is certainly used because people with cancer or damage to the hippocampus fail to move memories into long-term memory. It appears, across many VERY easy to find studies in psychiatric journals, that the prefontal cortex is also used to decide which memories the hippocamus should move and norepinephrine is used in the process. While sleeping, levels of norepinephrine drop. Without norepinephrine, memories are not moved from short-term memory to long-term memory. When you wake up, norepinephrine levels rise and your ability start remembering things returns. So, WHO says so: Try Fricke and Mitchison from Berkeley, Crick and Kotch from CalTech, Hartmann from Tufts, and pretty much anything in the Journal of Sleep Research.

As for your comment below that you can "remember" a dream by concentrating on it - that falls into false memories. There are countless experiments that expose how false memories work. I recently saw a television program in which a "crime" took place and witnesses were questioned. They were asked to concentrate and remember the event. They convinced themselves that they were remembering the criminal's jacket, hat, and shoes (he wasn't wearing a hat). They remembered the color of the victim's dress (she had on a shirt and slacks). As I mentioned above, if you think about a dream as soon as you wake, you can remember thinking about the dream and move those thoughts to long-term memory. However, you will forget the actual dream. With false memories, you can fill in all the gaps in your memory and convince yourself that you have remembered your dream, but you are actually just remembering thinking about the dream - not the dream itself. 199.15.144.250 (talk) 11:55, 29 June 2015 (UTC)[reply]

The TV series "Brain Games" often has segments showing how unreliable and incomplete witness memories can be. And I should clarify that I usually don't remember an entire dream, just the parts that made a strong impression; at the same time realizing there was more to it, but it's gone. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:59, 29 June 2015 (UTC)[reply]

Sleep study experts would likely tell you that you are remembering the impression that the dream had on you and not the dream itself. Another way I've seen it described is that you are vividly remembering your reaction to the dream that you had once you woke, but you are not remembering the dream itself. Your reaction likely contains short-term memories of the dream, which then are transferred to long-term memory because they are part of the reaction. In the end, there is a muddy definition of "remembering the dream." Is remembering a memory of the dream the same as remembering the dream? For the scientific studies done at the sleep lab in our hospital, memories of memories don't count as remembering the dream. Side note: study of dream recall is getting more funding now that it is moving into general studies of memory storage and recall. If you are really interested in this area and have a related degree, check with your local sleep lab. There will likely be opportunities for research. 209.149.113.185 (talk) 16:01, 29 June 2015 (UTC) — Preceding unsigned comment added by Baseball Bugs (talk • contribs) [reply]

I'd like to see a citation for the claim that "...you typically remember doing it." Unless you're like Carrie Wells, your routine activities will fade from memory. For example, driving to and from work every day for thousands of work days, you'll remember the route, but you're not likely to remember any particular drive to or from, unless something unusual happened and made an impression. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:01, 28 June 2015 (UTC)[reply]

I wrote a blog post about this a few months ago, The frustrating puzzle of dream amnesia. The basic message is that we rather surprisingly don't know the answer. Looie496 (talk) 03:00, 29 June 2015 (UTC)[reply]

In contrast to the OP's claim, it is possible to remember dreams, at least in part, by concentrating on them. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:41, 29 June 2015 (UTC)[reply]

Yes, though it's impossible to say how much is legitimately remembered and how much is just false memory (how would you even know?). I've read and can back up based on experience that the ability to recall is severely hampered by movement. Lying perfectly still and concentrating on the dream may give you some impressions, but it's usually a lost cause once you stand up. Matt Deres (talk) 19:36, 29 June 2015 (UTC)[reply]

Asteroids

If some asteroids collided with one of the solar system gas giants like Uranus, would there be an ouflow of matter or would it just be bottled up and increase the pressure? --109.149.199.246 (talk) 18:24, 28 June 2015 (UTC)[reply]

Something similar happened with Comet Shoemaker-Levy 9 and Jupiter. --TammyMoet (talk) 18:56, 28 June 2015 (UTC)[reply]

Actually more than one time: Category:Jupiter_impact_events. Ruslik_Zero 20:01, 28 June 2015 (UTC)[reply]

We know that asteroid impacts with Mars were enough to cause chunks of rock to be thrown all the way to impact on Earth (See: Martian meteorite). The fact that we've found 132 of them so far suggests that this is not an uncommon thing. Less remarkably, we've also seen chunks of moon rock arrive here on earth via the same mechanism. That being the case, it wouldn't surprise me if gasses from Uranus wouldn't also reach the escape velocity of that planet never to return. Uranus' escape velocity is about four times greater than Mars - but that would also result in impacting asteroids being accelerated to higher speeds as they head inwards to the surface.

Uranus has 27 moons and a bunch of rings that might also capture ejected material and prevent it from returning to the planet itself without it having to reach escape velocity.

It doesn't seem likely that the total mass lost in this manner would be likely to exceed the mass of the incoming impactor...but I think that would be hard to prove conclusively. SteveBaker (talk) 21:14, 28 June 2015 (UTC)[reply]

Mars and the Moon are rocky bodies, and rock shatters on impact. Jupiter is a gas giant, and Uranus is an ice giant. If matter were ejected due to impact, it wouldn't be in a form capable of impacting another planet such as Earth. I haven't researched it, but I would think that the gassy or icy nature of a giant planet would minimize the amount of ejected matter as opposed to a collision with a rocky planet. Robert McClenon (talk) 00:52, 29 June 2015 (UTC)[reply]

I wasn't suggesting that the matter from Jupiter or Uranus would be capable of reaching Earth - I was merely pointing out that there is clearly enough energy present in a falling asteroid to propel rocks outwards at speeds beyond escape velocity. Therefore, an impact with a gas giant could easily propel gasses outwards at similar speeds and result in a total loss of that material.

If you need a mental image of this - consider that if you toss a brick into a swimming pool, the splash goes way higher than if you drop it into a sand box from the same height.

Furthermore, you don't need to push the material outwards as fast as escape velocity if it can be pulled towards another body before it falls back...and Uranus has a rich set of moons that could capture sub-escape-velocity material.

There is no doubt that material will be lost in this way...the question is whether the amount of material that's lost exceeds the mass of the asteroid itself...which is a tougher thing to estimate.

SteveBaker (talk) 04:39, 29 June 2015 (UTC)[reply]

I seem to recall that the recent impacts on Jupiter shot fireballs back out. I believe the mechanism was that the impactor displaced the atmosphere, leaving a vacuum in it's wake, which then collapsed as superheated gases from the sides rushed in, creating a higher pressure, resulting in the fireball. Now high far out those gases were blown, I do not know. StuRat (talk) 04:34, 30 June 2015 (UTC)[reply]

Commercial space flight mishaps

Today's launch of a SpaceX Falcon 9 suffered a catastrophic explosion that destroyed the launch vehicle and its payload. This event was originally described as an "anomaly" by NASA. Later, at the first press conference, an FAA spokesperson described the occurrence as a "mishap." This terminology has specific meaning in the context of commercial space flight (it is defined by 14 CFR §437.75).

How were previous SpaceX failures categorized? Do we yet have a Wikipedia article listing anomalies and mishaps during commercial space operations?

Nimur (talk) 20:58, 28 June 2015 (UTC)[reply]

Have you seen this article^[1]? The 'See also' and the 'External links' section; might help you...I haven't checked... -- Space Ghost (talk) 18:55, 29 June 2015 (UTC)[reply]

References

^ https://en.wikipedia.org/wiki/SpaceX_CRS-7

Do these new driverless cars comply with the three laws of robotics?

(see Three Laws of Robotics)

Q as topic. It seems that we're coming to a point where this is becoming an important issue. With something like a Roomba, it doesn't matter so much, but robots/AI/whatever being in charge of road vehicles with the potential to kill humans seems different.--87.112.205.195 (talk) 21:04, 28 June 2015 (UTC)[reply]

No. They almost certainly lack the intelligence to reliably identify human beings, and have no abilities to 'obey orders' beyond their designed purpose - driving on roads, in traffic. They aren't 'robots' in the general sense that Asimov describes, and don't need to be to do the job required of them. AndyTheGrump (talk) 21:11, 28 June 2015 (UTC)[reply]

Asimov's laws are exceedingly subtle in their wording and implications. For example, the first law says that a robot may not allow a human to come to harm because of it's own inaction. Arguably then, it should drive itself off and help the underprivileged rather than drive you to work this morning! On the other hand, because even with perfect software, there is a non-zero chance of you dying in a car wreck when you are driven by it, it might simply refuse to drive anyone anywhere.

The second rule says that says that a robot must obey the orders of any human providing it doesn't result in it infringing the first rule...so a car thief can order it to drive away and be dismantled for parts...maybe...depending on the fuzzy definition of "come to harm". The third rule requires the car to protect itself...but not if that would infringe the first or second rules...so that rule doesn't help here.

But it's very hard to understand these rules - what does "come to harm" mean for a human? Is loss of money "harm"? If not, then the robot will drain your bank balance in order to obey the command of a random vandal who thinks it's fun to tell cars to crash themselves into the nearest brick wall. If loss of money does constitute "harm" then the car might feel that it's better if you take a taxi today in order that it can protect it's own existence by not wearing out it's parts by driving you to work.

So no, for sure not. I don't think any robot of any kind will ever truly be able to follow these rules...and if it could, I think it would be an entirely useless device - so I doubt anyone will even try to implement them.

If you read the Isaac Asimov books that explore the three laws that he proposed, virtually every story is an example of a robot that does something exceedingly bad because it's following the three laws. In some cases, he claims that the robots can balance relative strengths of the three laws - but that seems to imply a complicated equation between "harm" as in loss of money, "harm" as in minor scratches and scrapes or "harm" as in death balanced against verbal orders that rage from outright demands to mere suggestions from humans.

The laws aren't even all that useful. Should a car save your life by driving into a crowd of 100 small children - doing so with enough care to ensure that they all live, despite losing limbs and spending the rest of their days in wheelchairs? That's a difficult ethical decision - and the laws don't help the robot to decide in the slightest.

SteveBaker (talk) 21:38, 28 June 2015 (UTC)[reply]

Isaac Asimov wrote some great stories, but they were science fiction. More specifically, his robot series were very old science fiction. How old? So old that when Asimov conceived of his Three Laws of Robotics, he never considered that robots would have computers in them! Asimov wrote some very excellent stories about robots, and some very excellent stories about computers, but I am not aware of any story where he connected the facts together: his robots are not programmed using computer software! (If anybody can cite any Asimov story which even slightly contradicts this, I will happily rescind my assertion!) Instead, Asimov posited a special machine, a positronic brain, which could not be reprogrammed: rules about decision-making were built into this machine. This is the opposite of how computers work! General purpose computing machines can be reprogrammed to follow any algorithm that we can describe as logical sequences of steps represented in a formal machine language!

If you would like to read a very interesting and much more modern robot science fiction story, The Robot and the Baby by John McCarthy explores software programming rules that govern the ethical behavior between robots and humans. The story was written only a few years ago, and its author was a foundational contributor to the field of artificial intelligence programming. Unlike Asimov's robots, this robot actually must follow a computer program to calculate how it interacts with a human when it is faced with an ethical conundrum. McCarthy's story provides a more accurate representation of the way a computer-software-controlled robot would behave, even down to the fact that every robot who runs the same software is expected to behave identically. Asimov's fictional stories about his U.S. Robots and Mechanical Men robots don't seem to follow this logic! If you want to know how Asimov envisioned robotic cars, and how his Three Laws would apply, we don't have to speculate: we can read Sally (1953)! Those cars are a lot more emotional than modern robotic cars (like Stanley), and their decisions never are described to be the results of calculation.

Nimur (talk) 21:53, 28 June 2015 (UTC)[reply]

I agree that Asimov didn't have software in his robots - but he very much did expect them to behave identically - in Little Lost Robot, Dr Susan Calvin tries to find one robot with a slightly modified design amongst 62 identical robots...and the job is tough because the odd one out has been ordered to "get lost" - which it does by impersonating the others. All 63 robots behave identically in almost every test.

His robots behave very much as if they were running software.

But, "...the fact that every robot who runs the same software is expected to behave identically" - only true in theory. In practice, robots only behave identically in identical circumstances. My robotic vacuum cleaner starts out from it's charging socket every day, and with the precise same software, trundles around vacuuming the house. But it doesn't take the exact same path every day. Microscopic variations in the floor make it diverge a little to the left and right as it drives along, and when it comes to the point where it has to turn left or right in order to avoid the opposite wall, it chooses (I think) based on how much it has to turn in either direction - sometimes the wall is at an angle of 89 degrees, other times it's at 91 degrees - so it's essentially random. Two AI robots will similarly have slightly different sensory inputs, slightly different initial circumstances. It's like identical twin humans. Sure, they start off with identical DNA - but before very long, they are living quite different lives.

The world is chaotic (in the mathematical sense of extreme sensitivity to initial conditions) - and robots are not immune to that.

But it is unfortunate that people who read Asimov's robot stories hold up these fictional rules as being a great starting point for real robots. It's certainly not true - and there is no evidence that Asimov ever believed that.

SteveBaker (talk) 23:52, 28 June 2015 (UTC)[reply]

What would be some good rules for real robots then, do you think? I know that people have suggested that all robots/AIs be taught the Ten Commandments. Which could either go very well, or very, very, very badly indeed. Another one (and probably the most important) should probably be NO SELF-REPLICATING MACHINES UNDER ANY CIRCUMSTANCES. --87.112.205.195 (talk) 00:20, 29 June 2015 (UTC)[reply]

Remember that Asimov started writing his robot stories in 1939 and formalized the Three Laws of Robotics in 1942. Computers in any sense that we know them had not been invented. The closest that there was to what we now call software was the early work of Alan Turing. In the 1950's, when Asimov was still writing robot stories, computers existed, but were so large and energy-intensive that they were not seen as an alternative to the hypothetical positronic brain. Asimov, like other science fiction writers of the Golden Age, was sometimes too optimistic and sometimes not optimistic enough in anticipating technology. Robert McClenon (talk) 00:40, 29 June 2015 (UTC)[reply]

The ten commandments are woefully inadequate - let's have a quick run-through:

You shall have no other gods before Me. -- Hmmm - probably not an issue.
You shall not make idols. -- Shame, with 3D printing, robots are pretty good at that.
You shall not take the name of the LORD your God in vain. -- OK - make a note of that in the vocabulary database.
Remember the Sabbath day, to keep it holy. -- Robots are good at remembering stuff: const char*sabbath="Sunday"; ...but "keeping it holy" evidently pulls in a whole raft of other rules about what exactly that means. I don't know that we want our robots to basically shut down and praise god on one day of the week.
Honor your father and your mother. -- Don't have those, so no problemo.
You shall not murder. -- Aha! A useful law finally! Not quite as good as Asimov's 1st law, but definitely A Good Thing. God evidently doesn't care if you allow someone to die through your inaction, or if you cause them non-fatal injuries during extreme torture sessions.
You shall not commit adultery. -- Um...yeah, that's probably a good one to toss in there, but until robots get considerably more anthropomorphic than they currently are, it's probably not an issue for anything fancier than an artificially intelligent dildo.
You shall not steal. -- Ooooh! Good rule! Asimov's robots are perfectly OK with stealing (depending on how you define "harm to humans").
You shall not bear false witness against your neighbor. -- OK, no problem there.
You shall not covet stuff. -- Not hard for an arguably emotionless device.

So it seems likely that a very few lines of code would take care of most of those things - but in truth the only useful protections these offer is that the robot won't murder or steal. But sadly, there is no prevention for maiming small children or deliberately driving into other cars on the freeway just to see how much damage they'll take. Since the robot doesn't have to follow anyone's instructions, you could get into your car at the end of a long day at work and discover that it just doesn't feel like driving home today.

The ten commandments are totally useless here. Asimov's rules work better - but they're still nowhere near adequate.

We'll need *SO* many rules. First of all, the robot must ingest the entire corpus of the constitution and laws of the places it's going to visit - including case law and 'common law'. It'll have to know that driving at the speed limit on a freeway is going to upset all the humans behind it - and breaking the law by driving 10% faster is considered acceptable. It'll have to follow customary rules of politeness..."Thou shalt not yell 'FUCK YOU' at maximum audio volume and/or raise robotic middle finger at persons who cut you off in traffic - even though your owner does exactly that when in 'MANUAL DRIVE' mode."...for example.

The rules and customs of life are vastly more complex than can possibly be encapsulated in a small, convenient number of rules. Robots will either need hundreds of millions of lines of code to cover all of the eventualities (which, I guarantee will be bug-ridden as all hell) - or they'll have to learn, making many horrible mistakes along the way...just like people.

SteveBaker (talk) 03:10, 29 June 2015 (UTC)[reply]

Industrial robots are "made safe" by prohibiting humans from getting within their reach while they are on. Many guided missiles are designed to self-destruct if they lose target guidance. Of course they are intended to harm humans, of the "other" political persuasion. Roger (Dodger67) (talk) 12:05, 29 June 2015 (UTC)[reply]

Indeed - but that tactic isn't going to work out so well with robotic cars! SteveBaker (talk) 15:08, 29 June 2015 (UTC)[reply]

Although the story of Light Verse (short story) suggests to get the identical behaviour the robots may have required adjustment in some cases. Nil Einne (talk) 13:42, 29 June 2015 (UTC)[reply]

Indeed - and when your computer starts misbehaving, the most common suggestion is to "Reinstall Windows" to return it to normal behavior...but suppose you've tweaked settings and installed a bunch of plugins and applications, and made your own folders and such. Doing a "recalibration" by reinstalling Windows will wipe out a bunch of positive characteristics that your computer has picked up over the years - and you might well be upset if someone did that without asking you first. That pretty much mirrors Asimov's story - so it's as true with simple computers as it is with "positronic brains". SteveBaker (talk) 15:08, 29 June 2015 (UTC)[reply]

I'm amazed that robotic cars were allowed without some type of national debate on whether we want to go in that direction. However, when inevitably a robotic car kills somebody (possible due to a glitch, or perhaps just something unavoidable as happens with human drivers), then I'd expect the debate will take place. Another example of a tombstone mentality. StuRat (talk) 20:07, 29 June 2015 (UTC)[reply]

Well, they aren't exactly "allowed" yet. The various states that have approved testing still require the car to have pedals and a steering wheel and that there be a human driver ready to take control at any moment. I saw a report a week or so ago that pointed out that there are more robotic 18 wheeler trucks being tested on US highways than robotic cars...which is not something that's being widely discussed.

But the "top-down" approach of testing complete, fully-autonomous cars is only one approach. Robotic cars are also subtly creeping in through a "bottom-up" route. We have cars out on the roads (that you can actually buy) that apply the brakes if you get too close to the car in front or if you reverse into a perilous situation. Cars that can parallel park themselves are becoming pretty common, so are cars with sensors that tell you if you're drifting out of the lane, or pulling out in front of another car. The 2008 Lancia Delta actually biasses the power steering to gently nudge the car back into it's lane if you start drifting over the line. Both BMW and Tesla are soon to launch cars that do lane changing automatically. According to Lane_departure_warning_system#Vehicles there are a whole slew of cars that will steer themselves on freeways due to appear this year.

This is "robotic-cars by stealth" - adding one small feature at a time, letting people gain confidence in them, until one day you realize that the human driver simply isn't needed anymore. The worrying thing is that people are going to start depending on these features - so the "robotic" nature of existing cars will sooner or later be the indirect cause of human deaths.

So don't expect to necessarily wake up one day and be able to buy "The First Ever Fully Autonomous Car"...more likely, by the time a fully autonomous car appears, we'll all be driving cars that allow you to sleep, read and use your phone as they drive down freeways - but which have to wake you up to turn off the freeway...we're probably only a couple of years away from being able to do that. Cars that are 70% then 80%, then 90% autonomous in more and more road conditions will make the journey to fully robotic cars in tiny, tiny steps. The day you can put your kid into the car and tell it to drive him/her to school while you get on with something else will be just a tiny additional step from a car that needed you to get through 4-way stops, but did everything else automatically.

But 90 to 95% of car wrecks are caused by driver error...and even fairly klutzy robots should be able to do better than that. It's just that publicity will show the rare (but terrifying) cases of software bugs killing people - and conveniently ignore the thousands of lives that are saved by the very same software. Humanity really has to get to grips with the nature of statistics and risk assessment...but we're really not very good at it.

SteveBaker (talk) 03:35, 30 June 2015 (UTC)[reply]

I'm not as confident as you that robotic cars will be safer, at least initially. Each driver needs to make thousands of decisions correctly to avoid an accident each day, and that seems like a high rate of accuracy for the first gen of robotic cars to match. Presumably the current crop is "going for the low-hanging fruit", and only driving in the easiest situations. To make them able to handle all situations, and do so at least as well as a human, could take quite some time. StuRat (talk) 04:25, 30 June 2015 (UTC)[reply]

Your argument is perfect for aircraft as well. A pilot has to make thousands of decisions to keep an airplane flying safely. It turns out that in the most modern aircraft, humans cannot keep up with the decision making. They lose control and crash. Computers can make decisions faster than humans. Multiple computers can work together to make multiple decisions at the same time. Returning to humans driving cars - humans are easily distracted. Humans make very poor decisions. Humans cause most accidents - relatively few are caused by things like a deer running into the road or a tire falling off a truck. Most are caused by humans being stupid selfish humans who care more about something trivial and pointless than they care about paying attention to the road. 209.149.113.185 (talk) 13:10, 30 June 2015 (UTC)[reply]

To my knowledge most passenger aircraft are still flown by humans, and even drones typically have remote pilots, so I'm not sure what you meant by "in the most modern aircraft, humans cannot keep up with the decision making". Perhaps you mean the pilot says to turn right and the computer then adjusts all the control surfaces to accomplish that goal ?

One problem with relying on computers for critical things is how often they break down. A human brain can hopefully last for decades without a major failure, like a stroke, but computers only seem good for a few years, typically. So, you would need to frequently replace all the critical bits (which then requires testing to establish that nothing went wrong during the replacement) and provide triple redundancy (so it can take whatever action 2 of the 3 suggest). StuRat (talk) 13:20, 30 June 2015 (UTC)[reply]

Correct - Jet aircraft (and especially fighter jets) are uncontrollable. Computer sensors make thousands of adjustments every second. The human has a joystick and gives general commands, such as "turn right, however that works, but I don't care how it works, I just want to go right if you don't mind." Drones are the same. A computer maintains GPS track, altitude, and stability. The human sends requests to the computer, asking it to do things. In cars, humans still have a very direct connection between the steering wheel and the tires. The connection between the brake pedal and the brakes is mostly direct (automatic-braking systems step in to try and keep the meat sacks from having an accident). The gas pedal is being slowly moved away from the engine. It is being sent to a computer that decides what is the best way to increase or decrease speed, primarily to increase fuel efficiency. Now, cars are coming with automatic braking to stop the car when the organ donor behind the wheel is too busy texting to pay attention to the cars stopped at the traffic light. Many also have automatic parallel parking assist because making all those decisions about turning the wheel and pressing the brake is far too difficult for a simple human brain to handle. In my opinion, there will always be a group of people who refuse to let a computer drive their car, just as there are still people who refuse to use automatic transmission because no computer could ever shift gears better than a human. 209.149.113.185 (talk) 14:22, 30 June 2015 (UTC)[reply]

Sounds like you are describing fly-by-wire. Yes, that's a type of automation, but not nearly as concerning as when the bots have total control. StuRat (talk) 18:12, 30 June 2015 (UTC)[reply]

On a typical 8 hour transatlantic airline flight, the pilot and copilot fly the plane for less than 5 minutes...and the plane could manage that by itself if it had to. They are there to cover the emergencies that the autopilot can't cope with...but most of the time, they are dead weight. The trouble with cars going the same way is that (just with airline pilots), it's hard not to get bored and fall asleep - so in that one time in 10,000 when you need to be alert to handle that emergency that the computer can't handle...you're not going to be alert enough to deal with it. So we find that there is an effect akin to the uncanny valley where the smarter the computers get, the more danger there might be - until they cross some magic threshold of intelligence when it's safer to let the computer handle the emergency than it is to expect a human to do it.

What's interesting about the 'bottom-up' approach to automating cars with increasing levels of 'gadgets' like lane-keeping is that we're actually using the computers to handle the emergency cases and NOT take over the routine driving stuff - which is the opposite of what happened in the airline industry. SteveBaker (talk) 03:50, 1 July 2015 (UTC)[reply]

I would think boredom would be more of a problem with pilots, since there are fewer decisions to make mid-flight. In a car, even on a straight freeway, there's still decisions on when to pass, etc. This might be another reason why a copilot is needed, just to keep the pilot occupied with conversation to keep him awake. StuRat (talk) 04:45, 2 July 2015 (UTC)[reply]

Big Bang

Are there any tests made for the Big Bang like Abiogenisis? -- Space Ghost (talk) 23:02, 28 June 2015 (UTC)[reply]

Observations are made, see Observational cosmology. Bubba73 ^{You talkin' to me?} 00:27, 29 June 2015 (UTC)[reply]

High energy particle accelerators (such as the Super Proton Synchrotron and the Large Hadron Collider, both at CERN, and the Relativistic Heavy Ion Collider at Brookhaven) create quark–gluon plasmas. These experiments replicate conditions during the quark epoch, when the universe was less than 10 milliseconds old. Detailed analysis of the results from these experiments have (so far) confirmed that the Standard Model of particle physics is correct. And the Standard Model allows cosmologists to make very precise predictions about the subsequent evolution of the universe that very closely match observational data such as the cosmic microwave background radiation and the relative proportions of elements in the universe. Gandalf61 (talk) 10:22, 29 June 2015 (UTC)[reply]

I just hope it doesn't take years to understand what you guys stated... Anyway thank you both

I'll read it soon. -- Space Ghost (talk) 19:02, 29 June 2015 (UTC)[reply]

Life form(s)

Have scientists yet come up with simulations of life forms that may be available at a Goldie lock zone of/in a planet, during a steller evolution? Say for example, a T Tauri Sun’s ray will destroy the Earth in its goldie lock zone. If we move Earth to a distance where it will receive the equivalent temperature of our yellow sun and rotate it like it rotates in this solar system, and so on. If so, what are the results of life forms of steller evolutions? -- Space Ghost (talk) 23:48, 28 June 2015 (UTC)[reply]

Just a minor point but it's spelled "Goldilocks" as in the character from Goldilocks and the Three Bears. Dismas|^(talk) 07:13, 29 June 2015 (UTC)[reply]

Agreed. It's from in the story where she found one bowl of porridge was too hot, another too cold, and one was "just right". StuRat (talk) 18:00, 29 June 2015 (UTC)[reply]

Sorry friends, I didn't know. I heard the word in a science telecast program once. -- Space Ghost (talk) 19:01, 29 June 2015 (UTC)[reply]

Current evidence, gathered by examining star and planet formation, is that the star forms before the planets are formed. Therefore, your question is based on something that is not expected: a planet forming before the star forms. 199.15.144.250 (talk) 11:35, 29 June 2015 (UTC)[reply]

[[File:|25px|link=]] I recalled, then again, computer simulations can do any kind of tricks these days. -- Space Ghost (talk) 19:01, 29 June 2015 (UTC)[reply]

It's not just the star's formation that could wipe out life on a planet. The Sun's expected red giant phase should do so on Earth, not to mention a nova or supernova. StuRat (talk) 17:58, 29 June 2015 (UTC)[reply]

But I thought the hotter the Sun becomes the different molecules it produces, considering a red giant and considering its a population I star, shouldn't it produce molecules which should satisfiy the hypothesis of alien life form(s)? -- Space Ghost (talk) 19:01, 29 June 2015 (UTC)[reply]

Stars don't directly produce molecules at all, as it's too hot for molecules, which are composed of 2 or more atoms joined together, to form. They do produce larger, more complex atoms (see chemical element) the hotter they get (although the heat isn't just the cause, but also the result). Life does require these larger, more complex elements, but they can be leftover from a previous generation of stars. In our case, our Sun mostly just produces helium now, and all of the heavy elements on which life relies come from some supernova long before the solar system was formed. StuRat (talk) 19:47, 29 June 2015 (UTC)[reply]

See Goldilocks zone. StuRat (talk) 17:56, 29 June 2015 (UTC)[reply]

Okay, thanks. -- Space Ghost (talk) 19:01, 29 June 2015 (UTC)[reply]

some discussion of users and policies moved to talk page. SemanticMantis (talk) 19:06, 30 June 2015 (UTC)[reply]

You should have notified users of this directly, including User:Russell.mo who posted this question. μηδείς (talk) 22:19, 30 June 2015 (UTC)[reply]

June 29

Identify a submarine

This photo of a submarine was found among a collection of documents and photos related to a South African warship, HMSAS Transvaal's trip to Australia in 1951. Unfortunately there is no other information about the encounter with the submarine, though we suspect it was probably Australian. Roger (Dodger67) (talk) 06:39, 29 June 2015 (UTC)[reply]

The silhouette is very similar to a British T-class submarine, a number of which operated from Australia during and after the war. WegianWarrior (talk) 07:00, 29 June 2015 (UTC)[reply]

A quick bit of research on Wikipedia suggests the Royal Australian Navy had no submarines in 1951. See Royal Australian Navy Submarine Service#1945 to present. (In fact, the RAN had no submarine from April 1931 when HMAS Otway (1927) and HMAS Oxley (1927) were returned to the RN, until HMAS Oxley (S57) et al were commissioned in the late 1960s.) Dolphin (t) 07:07, 29 June 2015 (UTC)[reply]

Thanks this info narrows down the research task considerably: Which Royal Navy T-class subs were in Australian waters during January 1951. Roger (Dodger67) (talk) 09:28, 29 June 2015 (UTC)[reply]

A March 1951 newspaper report of a Commonwealth naval exercise in Australian waters, in which two unnamed British submarines "acted as hares" for the combined surface fleet; Modern Submarine Main Danger. It might be difficult to pinpoint as the RN maintained a whole submarine flotilla at Singapore during the 1950s and early 1960s. Alansplodge (talk) 10:10, 29 June 2015 (UTC)[reply]

It was called "Operation Convex" according to The West Australian, 12 March 1951: "Big Naval Exercise". Alansplodge (talk) 12:05, 29 June 2015 (UTC)[reply]

Another photo of the sub has turned up, in Sydney Harbour, date not known but definitely early 1951. If anyone is interested, a forum discussion about the HMSAS Transvaal documents and photos is at http://www.saairforce.co.za/forum/viewtopic.php?f=18&t=8225&p=103962#p103962 -- Roger (Dodger67) (talk) 10:45, 29 June 2015 (UTC)[reply]

Just found that the Royal Navy's 4th Submarine Flotilla was based at HMAS Penguin in Sydney, the last British submarine leaving in 1969. According to The Royal Navy 4th Submarine Squadron Based in Sydney, AUSTRALIA, those based there in 1951 were: HMS Telemachus (P321), HMS Thorough (P324) and HMS Taciturn (P314). Alansplodge (talk) 12:25, 29 June 2015 (UTC)[reply]

But we can rule out HMS Taciturn, as she had been modernised in 1948 to look like this. Alansplodge (talk) 18:07, 29 June 2015 (UTC)[reply]

Thanks all I think the three names are as close as we're ever going to get unless another photo showing a hull number or other distinctive marking turns up. Roger (Dodger67) (talk) 18:06, 29 June 2015 (UTC)[reply]

What is relation of the bacterium "Helicobacter pylori" to the pylorus?

I don't find the answer In the article Helicobacter pylori "The bacterium was initially named Campylobacter pyloridis, then renamed C. pylori (pylori being the genitive of pylorus, the circular opening leading from the stomach into the duodenum, from the Ancient Greek word πυλωρός, which means gatekeeper.[110]). When 16S ribosomal RNA gene sequencing and other research showed in 1989 that the bacterium did not belong in the genus Campylobacter, it was placed in its own genus, Helicobacter from the ancient Greek hělix/έλιξ "spiral" or "coil".[110]" 192.117.186.252 (talk) 14:34, 29 June 2015 (UTC)[reply]

Found in the stomach, named for a part of the stomach? DMacks (talk) 17:07, 29 June 2015 (UTC)[reply]

Well, the article states that it is linked to duodenal cancers, leading to me to assume it's found in the duodenum as well as the stomach. It seems entirely reasonable that it was named pyloridis/ pylori simply be because of where it was first found, around the bottom of the stomach, top of the duodenum, in particular the pylorus. But that's just my guess' at present.

Now, for a reference that supports the claim, I got to this article [7] by searching for /pyloridis new/. That led me to the original describing article UNIDENTIFIED CURVED BACILLI IN THE STOMACH OF PATIENTS WITH GASTRITIS AND PEPTIC ULCERATION paywalled here [8] (you might be able to find an accessible copy by searching the title). In it, Marshall says

“

If

it is premature to talk of "Campylobacter pyloridis" perhaps the name "pyloric campylobacter" will do to define the site where these organisms are commonly found and to indicate the similarity to known Campylobacter spp.

”

- emphasis mine. So I'd say that we've now confirmed that it is named after where it is commonly found. If you want to thank me, you could do so by editing the H. pylori article to cite that ref for the claim that Marshall first detected it in the second sentence, and possibly later for a new sentence explaining the name :) SemanticMantis (talk) 17:08, 29 June 2015 (UTC)[reply]

Home-made air conditioner

The air-con projects I have seen so far are build based on ice (from the freezer) in some isolating box and blowing a fan on it.

Is there a home-made air-con project that would not work with the principle above? Something based on evaporating water could also work, couldn't it?--YX-1000A (talk) 17:01, 29 June 2015 (UTC)[reply]

Yes, evaporative cooling is our general article, the devices are commonly called swamp coolers in parts of the USA, though many names are used. These get a lot of use in greenhouses, where you might not mind exchanging some heat for humidity. I just recently saw a decent installation of one in an orchid house near Corpus_Christi,_Texas. Quite cooling indeed, even in a humid environment, despite reports that the maker of said cooler warned that it might not work well at that ambient heat and humidity. Might not be very suitable for in-home use in very humid climates though. Here's a homemade version I found on youtube [9]. SemanticMantis (talk) 17:21, 29 June 2015 (UTC)[reply]

An even simpler method is to drape a damp towel over a box fan (being sure to leave enough air flow to not overload the fan). You will need to rewet the towel often, though. You can toss it in the washing machine periodically with some bleach to avoid mildew. StuRat (talk) 17:51, 29 June 2015 (UTC)[reply]

Another way to make a homemade air conditioner would be to get a long hose (ideally thin-walled), connect to the faucet, loop the hose around the room, have it drain someplace safe, and turn the water on. This relies on underground water pipes supplying cooler water than the air temperature. Advantages are the simplicity and no electricity use. However, it is extremely wasteful of water, so would only make economic sense if you drain the water someplace you can use it anyway, like to irrigate a garden/crops, fill a bathtub (that would only take a few minutes, though), etc.

An alternate version could use a water pump and rain barrels (although the pump could be omitted if the rain barrels are elevated enough above the area you want to cool). Here it would only work early in the day, when the rain barrel water is still cool from night, but that water is free, so you don't have to worry about wasting it (although irrigating a garden or crops with it still makes sense). Both variations would likely only work to cool a small area, unless you are a farmer, and have need for massive amounts of water to irrigate your crops anyway, in which case the first method might cool the entire house (but a farmer is more likely pumping water out of a stream or underground reservoir, so there would be some increased electrical use to pump it through the house, too). StuRat (talk) 17:37, 29 June 2015 (UTC)[reply]

Swamp coolers are not very effective when evaporation is limited due to humidity (it just makes the room feel like a swamp by adding moisture to the air). The hose method is used in places where it is easy to cool water - such as Hawaii. Just run the hose extremely deep into the ocean to cool the water down and then loop it back up to the house. The actual system there is more complicated - but the principle is to send the house's heat into the ocean. Another method, not mentioned, is simply moving the air. If it is hotter at the top of a room than it is outside, automate a system of trapping the hot air at the ceiling and sending in slightly less warm air from outside - a rather poor version of a heat pump. Overall, none of those works as well as running coolant through a radiator and blowing air past it. Doing so also gives you the benefit of dehumidifying the air because condensation will collect on the radiator and drip down. 209.149.113.185 (talk) 17:47, 29 June 2015 (UTC)[reply]

And I suppose I should mention the method I actually use to cool my house. Put box fans (not those silly, tiny, underpowered twin "window fans" shown at the top of that article, but rather the large, single fan, shown below it) in windows, to blow hot air out and cool air in at night. Put all the fans blowing in at the lower floor and out on the upper floor to take advantage of the tendency of hot air to rise (or put fans pointing in on one side of the house and out on the other, for a single story home). Try to seal the area around each fan as well as possible to prevent local recirculation (air going the wrong way around the fan). I've cut a circular "mask" out of plastic sheeting for each fan, custom fit to each window opening, to do this. Don't leave any other windows open without fans. Can cool the house quickly when it is cool and dry at night and hot during the day. However, if it's humid out, say over 60°F dew point, the humidity getting inside makes it not practical. Also, you will have to make the house uncomfortably cold by morning to keep it cool all day, so wear a sweater to bed, and even then it's only good to keep the house maybe 10°F cooler than the outside temp. And if you leave the fans on too long in the morning you are paying to blow warm air into the house. Also, can't use this method when there's a risk of rain or bad fumes (like from cars in the driveway) that may be blown inside, or security issues with open windows. Still, with all these caveats, I can cool my house much faster than with A/C, under ideal conditions. Note that I mean the air is cooled quickly, but to cool the walls, floors, ceiling, furniture, etc., takes hours. If you don't cool those down, then the air temp quickly rebounds as soon as you turn the fans off.

One other caution is to always maintain positive pressure in the house, by having more fans blowing in than out. This means you turn the fans blowing in, on first, and off last. If you don't do this and create a negative pressure, it may suck exhaust (water heater, etc.) down chimneys, and you don't want that. StuRat (talk) 18:13, 29 June 2015 (UTC)[reply]

Number of bones and joints in human body

Ironically, Google search engine shows 360 joints according to non-reliable sources if you just type the following "number of joints in human body". However I'm really surprised why such very old question doesn't get interest of the scientific community to answer. I searched some other sites (like this), found that bones are about 206 in an adult human and about 250-350 joints. I assume that if a joint is linking two (or more bones unless there are two or more consecutive joints) and thus total number of joints should be always less than or equal total number of bones which should limit that of human body to 206 joint. Do you have an explanation?--Almuhammedi (talk) 21:18, 29 June 2015 (UTC)[reply]

A quick search on Google led me to Talk:Joint, where there are several links that try to explain this seeming contradiction in logic. Maybe it depends how one defines a "joint". ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:58, 29 June 2015 (UTC)[reply]

Please remember that some bones don't have precisely one or two joints; some bones have several suture-type joints, for example. Nyttend (talk) 12:16, 30 June 2015 (UTC)[reply]

Surprisingly, this is a question about Islam, not science. See [10] for example. --Dweller (talk) 12:22, 30 June 2015 (UTC)[reply]

June 30

How is it that one mole of any gas occupies 22.4 l?

How is it that one mole of any gas occupies 22.4 l at STP? Yogesh Khandke (talk) 03:26, 30 June 2015 (UTC)[reply]

Ideal gas law DTLHS (talk) 03:32, 30 June 2015 (UTC)[reply]

You mean V = NRT/P will always be constant = 22.4 l? I will have to do the numerical. Thanks Yogesh Khandke (talk) 04:32, 30 June 2015 (UTC)[reply]

OK, V = (1 x 8.314 x 273)/101325 = 0.0224 cu m, or 22.4 l, and also the since equation has only one intrinsic property which is set to 1, N = 1, whatever value we get, it will be constant for all gases. Still, physically I still don't get the "how"? See we have one mole being made up of 6.022 x 10^23 atoms/ molecules of carbon di oxide, oxygen, or whatever gas, what is I see is one atom the size of a foot ball, the other a golf ball, another a table tennis ball, at STP, how do these equal number of different sized balls fit in one size 22.4 L? Yogesh Khandke (talk) 05:00, 30 June 2015 (UTC)[reply]

I don't know the answer but I imagine that the size of the molecules is a very small percentage of the size of the distance between them in the gas. ----Seans Potato Business 12:21, 1 July 2015 (UTC)[reply]

Ask yourself, how much of the 22.4 L is actually occupied by gas molecules, and how much is occupied by the empty space between gas molecules? The actual size of the molecules doesn't matter because most of the volume is actually empty space. Dragons flight (talk) 06:27, 30 June 2015 (UTC)[reply]

Well, it matters some. It's the b parameter of the van der Waals equation. --Trovatore (talk) 06:33, 30 June 2015 (UTC)[reply]

Indeed. The OP's surprise that all gases occupy the "exact same" volume might be tempered when we explain that all gases are not ideal. For most gases - and in particular, near standard temperature and pressure conditions - the behavior is nearly ideal. Small non-idealities are introduced when we use other equations to enhance the ideal gas equation; and the perfect volumetric equivalence for all species of gas goes away. Nimur (talk) 12:43, 30 June 2015 (UTC)[reply]

Even more generally: Equation_of_state#Cubic_equations_of_state. Thermodynamics! shoy (reactions) 12:48, 30 June 2015 (UTC)[reply]

The ideal gas law can be derived from the kinetic theory of gases. As Dragons flight says, one of the assumptions of simple kinetic theory is that the size of each molecule is very much smaller than the average distance between molecules. Another assumption is that the average kinetic energy per molecule is proportional to the temperature of the gas. So if we increase the mass of each molecule by a factor of 4, but keep the temperature and volume the same, the average kinetic energy decreases by a factor of 4. And hence the average speed of each molecule is halved. Now that molecules are travelling at half of the original speed but with four times the original mass, each collision with the walls of the container imparts an average impulse (change in momentum) that is twice the original average impulse. But collisions happen only half as often as they did before because the molecules are travelling half as fast. So the pressure on the container walls (average force per unit area, which is average impulse per unit time per unit area) is unchanged - the increased impulse in each collision is balanced out by the smaller number of collisions per second. This is a "hand waving" explanation - for a more rigorous derivation, see our kinetic theory article . Gandalf61 (talk) 11:17, 30 June 2015 (UTC)[reply]

I need to digest the information provided, many thanks. Yogesh Khandke (talk) 02:39, 1 July 2015 (UTC)[reply]
- Take your time -- it's not simple. The easiest thing is just to assume that the gas is "ideal", which essentially means that molecules are points and that there are no inter-molecular attractions. Once you've gotten your head wrapped around the properties of ideal gases, you can get into situations that depart from the ideal gas behavior (referred to as "real" gases). These mostly have to do with low temperatures and/or high pressures. Short Brigade Harvester Boris (talk) 02:51, 1 July 2015 (UTC)[reply]
  - The answers above are excellent, but I might add that the ideal gas law is a model, an approximation; it works well in many of the situations we deal with frequently (ie RTP) but it gets further and further from reality when its assumptions begin to break down. One such breakdown is at very high pressure, where molecule size becomes relevant. Another is at low temperature, when intermolecular interactions become significant. And so forth. Vanamonde93 (talk) 01:35, 2 July 2015 (UTC)[reply]

Bose-Einstein condensates

Bose–Einstein condensation at 400, 200, and 50 nanokelvins. The peaks show that as the temperature goes down, more and more atoms "condense" to the same energy level.

This image appears at Bose–Einstein condensation (network theory) with the same caption. It confuses me: is left 400 and right 50 or vice versa? Saying "400, 200, and 50" sounds like they're going left to right, but it looks like more and more atoms "condense" to the same energy level as you go from right to left, i.e. it's 50, 200, and 400. Nyttend (talk) 12:30, 30 June 2015 (UTC)[reply]

It confuses me too! There are no axis labels, and the image description page and the articles do not directly explain what is being plotted. I could make assumptions that we're looking at a two-dimensional histogram, but I'm not sure if the horizontal axes represent position, phase-space, or something else. I'm not sure if the vertical axis represents particle count, particle energy, or something else. I'm even less certain what the three instances of the graphs represent, but this is the only item directly described in the caption (apparently the parameter that varies between each graph is temperature).

The graph was contributed by a Wikipedia editor nearly ten years ago, but it is not referenced from a publication. If we can find a suitable replacement, or a suitable reference to explain it, we should improve or replace the image. You could try contacting the image uploader via their talk page. Nimur (talk) 12:39, 30 June 2015 (UTC)[reply]

I remember reading a while back that the graph represents the number of atoms present in an energy level. From what I remember, the ‘higher’ the graph the more atoms are present at that energy level. The flat nature of the graph on the left indicates that the atoms are all relatively evenly distributed among energy levels (which is expected in normal conditions). The graph on the right (specifically the peak) indicates an extremely high number of atoms concentrated in a specific energy level.208.87.234.202 (talk) 13:15, 30 June 2015 (UTC)[reply]

...which corresponds to the lowest temperature, as the caption explains. Lowest temperature is on the right-hand side. 129.2.106.82 (talk) 13:54, 30 June 2015 (UTC)Nightvid[reply]

Yes, that description is consistent with that given here [11], it claims that that the images are of a velocity distribution, though it does not give explicit temperatures, nor the axis labels. A key point is that the right image is coolest. The right image has almost all peak, with very little variance around it. The center image has a peak, but also some variance. The left image has almost no peak, and reflects the "normal" variation of velocity. The page linked above is the lab web page of Prof.Dr. S.O. Demokritov, and I'm willing to call that reliable enough for these purposes. As a stop-gap until better images or sourcing can be found, I've slightly modified the caption. SemanticMantis (talk) 14:00, 30 June 2015 (UTC)[reply]

Yes. The key is the red. The more red, the more condensate. The peaks are an illusion since the temperature is lower on the right. They aren't larger on the right but the energy difference as a percentage is larger for the peak. Higher Q factor to borrow from a different field. --DHeyward (talk) 06:28, 1 July 2015 (UTC)[reply]

Fate of coronary artery plaques after rupture

When someone has a heart attack due to a ruptured plaque in a coronary artery, and then gets clot-busting drugs in the emergency room, why doesn't the clot re-form after the drug wears off? Isn't the rupture still there? 129.2.106.82 (talk) 14:03, 30 June 2015 (UTC)Nightvid[reply]

The "clot-busting drugs" you refer to are more commonly referred to as "blood-thinners." It is dangerous to stop taking a blood thinner at any time, not just after heart attack treatment. A study on Warfarin and Xarelto at Duke University in 2012 found that heart attack/stroke risk increased rapidly when ceasing blood thinner use. Further studies have both validated and partially contradicted that study. The contradictions have to do with further refinement of the population based on other treatments, history of heart attack/stroke, and end-results that are similar, such as pulmonary embolism or deep-vein thrombosis. For most patients, the blood thinner dissolves the plaque and allows for normal clearance in the urine. There are some, a vast minority, who become threatened. Therefore, new procedures are constantly being developed to break down and capture the plaque rather than release it into the heart or the rest of the blood stream. It would be best, of course, if cardiovascular disease was stopped before it began. As it is, most hypertension and cardiovascular specialists are simply trying to improve a very bad situation. 209.149.113.185 (talk) 15:48, 30 June 2015 (UTC)[reply]

I'm talking about the drugs used only for the acute MI, such as Tissue Plasminogen Activator, which are discontinued. If the different drugs such as thinners are enough to prevent a new clot, would they also have been enough to prevent the first one, if they had been taken early enough? 129.2.46.176 (talk) 01:46, 1 July 2015 (UTC)Nightvid[reply]

What do inspectors of nuclear facilities search for?

When foreigner inspectors of nuclear facilities visit a country, how can they know whether a bomb isn't hidden somewhere else? Or that more enriched plutonium is not hidden somewhere else? Atomic bombs don't have actually a huge volume that would be tricky to hide. --Bickeyboard (talk) 17:02, 30 June 2015 (UTC)[reply]

They look for blatant evidence of wrongdoing. The way it has worked in the past, primarily with Iraq and then Iran, they schedule a specific time to visit a specific installation. The date is set well enough into the future to ensure that there will be nothing questionable at the facility. Then, the inspectors do a walk-through. During the Iraq inspections, there was a lot more public information about the cleanup before inspections, including surveillance photos showing trucks moving "stuff" from the inspection facility to a non-inspection facility. With Iran, there is far less information, but the inspections are still scheduled well in advance and limited to specific installations. 209.149.113.185 (talk) 17:12, 30 June 2015 (UTC)[reply]

That's exactly the problem. How can they find anything this way? --Bickeyboard (talk) 17:31, 30 June 2015 (UTC)[reply]

Basically, they don't. It's a charade for political purposes mainly. The only concrete benefit to the inspector is that it prevents some wrongdoing. If the inspected facility knows they are going to be inspected, they will avoid doing what they are not supposed to do (at least temporarily). It is a way of getting minimal compliance when there would otherwise be zero compliance. Gnome de plume (talk) 17:35, 30 June 2015 (UTC)[reply]

While some of the responses above are quite cynical, they are also un-sourced commentary. Perhaps you would like to read about the IAEA's work, including work related to the Nuclear Nonproliferation Treaty, Monitoring in Iran, and Monitoring in the DPRK. Treaty compliance, inspection, and external auditing is not easy, but it's also not a "charade." Nimur (talk) 17:54, 30 June 2015 (UTC)[reply]

It's not that easy or bad. To separate out U235 you need large and complex machinery. Similarly for Plutonium. And these materials are relatively carefully accounted for, so it's not that easy to make some of it vanish. Checking the books is part of the inspection. Talking to the personell is part of the inspection. It is not very easy to keep a secret when a large number of people are necessarily involved in it. --Stephan Schulz (talk) 17:43, 30 June 2015 (UTC)[reply]

These inspections are of the nuclear power stations (while in Iraq, the inspections included buildings accused of housing chemical weapons). It is well-known where Iran built their enrichment facility and it is not included in inspections. 209.149.113.185 (talk) 17:54, 30 June 2015 (UTC)[reply]

Do you have a source for this information? If not, you should reconsider whether your comment merits inclusion in this encyclopedia's reference desk. First, to which inspectors do you refer? Secondly, to whom are these speculative facts well-known? Thirdly, which reliable source reported that the inspectors intentionally avoided such facilities? If you cannot directly attribute these allegations to anybody, you might need to read our guidelines on unsupported attributions and reliable sources. Nimur (talk) 17:58, 30 June 2015 (UTC)[reply]

The IAEA, already linked above, does not inspect the enrichment facility itself. They ask Iran to report on it, but never actually set foot in the facility. Further, it is well-known where the facilities are. You can get a list on Wikipedia: Nuclear facilities in Iran. How is this controversial? To be more correct... I must point out that an enrichment plant was built and shown to inspectors in 2009. It was not operational at the time and access has not been documented with the IAEA since. I am happy to be corrected with documentation tha the IAEA *has* been in an operational enrichment facility. Your complaint is that you just disagree. 209.149.113.185 (talk) 18:05, 30 June 2015 (UTC)[reply]

Implementation of the NPT Safeguards Agreement and relevant provisions of Security Council resolutions in the Islamic Republic of Iran, (29 May, 2015). The IAEA asserts that it has independently verified many facts. It asserts that several technical visits were arranged, conforming to the "Framework for Cooperation," including technical visits to centrifuge facilities and the Lashkar Ab’ad Laser Centre. The Agency asserts (in this and other reports) that it has physical access to numerous facilities in Iran: "Iran has continued to provide the Agency with managed access to centrifuge assembly workshops, centrifuge rotor production workshops and storage facilities." (Page 1 of the report). Non-proliferation inspection, in particular when conducted under the auspices of the United Nations and the IAEA, does not mean "unrestricted access to anything and everything in the nation;" there are rules about what is covered. For starters, read IAEA Safeguards to learn what they inspect, why they inspect it, and under what international legal frameworks these inspections occur. Here is a list of locations relevant to the implementation of safeguards in Iran. If you think something is missing, perhaps you should make a convincing case to the Commission.

IAEA's Director General stakes his professional reputation, and his funding, on the veracity of such public documentation. I would not be surprised if there have been many more confidential internal findings, technical visits, and reports; but these are the reports that are available to the casual, uncredentialed, unprivileged internet reader at no cost. Nimur (talk) 19:32, 30 June 2015 (UTC)[reply]

We are apparently seeing different information in the same document. I see "managed visits" to facilities to produce and store centrifuge parts. Those facilities are not the enrichment plants - those are just part factories and warehouses. This is important because the number of parts produced is directly related to the number of centrifuges in operation. If there are no hidden parts being used, the IAEA can make an assumption about the number of centrifuges in use and detect more being used. As for enrichment operations, it is stated that environmental samples are taken to determine the operations. What does that mean? I take it to mean samples of the environment: air, water, and soil. There are also many instances where it is stated that the claims being made are based solely on statements from Iran. I want to make it clear that it is obvious that the IAEA is inspecting Iran to the best of its ability. I simply believe (based on the wishy-washy language of IAEA reports) that its ability is limited when it comes to physical access to an operational enrichment centrifuge. 209.149.113.185 (talk) 19:53, 30 June 2015 (UTC)[reply]

All of these are fair critiques. International inspections are not easy and it is plausible that there could be corruption, incompetence, or oversight. We are all entitled to interpret the facts and publications subject to our own biases. I personally do not think there is significant corruption, incompetence, or oversight; I think the media poorly portrays the complexity of the problem, and presents a dramatically over-simplistic "good-guys and bad-guys" narrative with respect to nuclear safety. I imagine that if the tables were turned, and foreign inspectors showed up at your home, workplace, hospital, school, laboratory, or power station, carrying paperwork written in legalese in a foreign language, insisting that they had a right to inspect your things, you would not let them have free run of the place. You probably would call for your local or national government to help you kick these invaders off of your property! So it is with international inspectors in Iran. These international agencies run a very fine line between enforcing international laws (agreements, rather) - even when approved by the local government - and also complying with local laws.

You can find many opinion pieces and policy reviews that applaud the IAEA, and you can find many more publications that harshly criticize their work. Here's a perspective piece from the RAND Corporation, an organization that I find to be very well-informed and less susceptible to flimsy political biases than most media outlets: The Days After A Deal With Iran: Implications for the Non-Proliferation Regime. What irks me is not your bias or your opinions: I respect your right to those viewpoints. Surely I have my own biases and opinions...! But at least, when we contribute on the Reference Desk, we need to back up any claims with informed citations, so that all readers of our encyclopedia can form their own opinions.

Nimur (talk) 20:25, 30 June 2015 (UTC)[reply]

There was a computer virus released through Siemens I thought that gave a pretty good idea of the number of centrifuges Iran was using. The virus varied the spin rate too quickly and caused the centrifuges to become unstable and destroy themselves. There was quite a bit of data regarding repair that didn't quite jive with published accounts. --DHeyward (talk) 06:37, 1 July 2015 (UTC)[reply]

You are thinking of stuxnet. I'm not sure about gave a pretty good idea of the number of centrifuges Iran was using, I believe it was 'reverse engineered' to a degree, but I don't believe it "reported back" any information like number of centrifuges in Iran. In fact if I remember correctly, Iran was deduced to be the target mainly because that's where most of the infections were reported. Vespine (talk) 06:44, 1 July 2015 (UTC)[reply]

Nice video and lecture re IEAE at http://www.fourmilab.ch/documents/nuclear/plutonium.html and http://www.fourmilab.ch/documents/nuclear/uranium.html GangofOne (talk) 06:54, 1 July 2015 (UTC)[reply]

Correct, Stuxnet couldn't report back because the centrifuge facilities do not have any form of connection to the Internet. That is what made Stuxnet so special - it was designed to get to a network that it had no means of reaching (until someone broke security protocol and brought in Stuxnet on a USB drive). Also, the "released through Siemens" statement is most likely incorrect. While it is easy to find countless blogs that claim Siemens was involved, the evidence based on the language in the code of Stuxnet and the purpose of Stuxnet points towards Israel. It is important to note that Israel has denied any involvement with Stuxnet. 199.15.144.250 (talk) 12:44, 1 July 2015 (UTC)[reply]

There is even one more step involved. StuxNet infects PC's that are on the net - then installs itself onto memory sticks and USB music players. They bet that people would take these infected devices, put music on them and plug them into PC's that were NOT on the Internet so they could listen to music at work. Those PC's were then infected - but that's not what killed the centrifuges. Stuxnet actively seeks out PC's that were running a very specific application that the Iranians used to design software for the microprocessors that drive the centrifuges. That infected design software would then add extra code into every microprocessor application that the Iranians wrote that would check to see if it was controlling a centrifuge - and do to the nasty deed. It hid itself very well, so not even using the debugging software would find it...because the debugger was also infected. So not only were the centrifuges off-net, but so were the PC's used to write the software for the centrifuges. It required software engineers (who really ought to know better!) to bring infected memory sticks and music players from home to plug into security-sensitive machines at work. Very, very, clever - exceedingly hard to pull-off.

SteveBaker (talk) 22:31, 1 July 2015 (UTC)[reply]

I should have been more clear. Siemens didn't create it, but I think they helped isolate it. The amount of tech support needed from Siemens was the indicator of the damage and scope of the program. Siemens wasn't called out to fix one centrifuge controller and they know how many times Siemens went and how many techs. JTAG is a wonderful thing. --DHeyward (talk) 22:37, 1 July 2015 (UTC)[reply]

Star & Stellar Evolution

Hello, Can some check this two articles please, I believe its not done appropriately; information(s) might need to be migrated from one another... Regards -- Space Ghost (talk) 20:44, 30 June 2015 (UTC)[reply]

What exactly is the problem? I suggest that you post your suggestions to Talk: Star and Talk: Stellar evolution, or, if you know what the improvement would be, be bold and edit. Do you have a specific question? Robert McClenon (talk) 01:54, 1 July 2015 (UTC)[reply]

No, apology.

My English is not very good, therefore I'm not being bold enough to edit the articles...I don't wish to give out wrong information or make WP look like idiots English language usage type of thing, to others; if you know what I mean... Plus I have not come to English learning yet.

'Smoking' is my subject not 'science', so I always try to recheck with you guys as I'm learning... I've learnt most of it before, I'm learning it again in detail, and coming across some things, e.g., Star, Stellar Evolution, Star Formation, protostar and so on, all articles should be merged into one article named 'Star' and 'redirects' should be used for 'star formation', 'Stellar Evolution', 'protostar', 'pms' and so on. Because when someone wants to learn something it will be easier for them this way. I thought mentioning it here would give the upper hand...in what to do... -- Space Ghost (talk) 19:12, 1 July 2015 (UTC)[reply]

Does anyone know, to whom I can speak about this? This one (Star) article has 5 babies (extra articles), not required...Its just needs to be organised... -- Space Ghost (talk) 19:45, 1 July 2015 (UTC)[reply]

You can try at the talk pages, but a better place would be Wikipedia:Proposed_mergers. There you can propose the merges and your reasons. I think people will disagree with your proposal, but I'm not sure. I understand your perspective, but we have different articles for a reason. If one article covered all that, it would be huge and hard to navigate. Also, not everyone who looks up stars wants to know all the details about their formation and evolution. However, there is a lot of redundancy stellar evolution is discussed in star, so maybe you should take it to proposed mergers. It would be interesting if nothing else. Here's one thing you can easily do: make sure that each page has links to the other pages. For example I just went to star and searched for "stellar evolution" - the words do occur, but they are not wiki-linked! There is a later link, but I see no reason not to link it at first mention. That's a way you can improve articles without even writing any new English. Beware of WP:OVERLINK, but don't worry about it too much. Overlinking is better than underlinking. So you can go to these and help make WP better just by linking articles together. That way people who want to learn will find it easier to find other related articles. SemanticMantis (talk) 19:57, 1 July 2015 (UTC)[reply]

They are linked hierarchically but perhaps it can be more direct. For example, star has a section for formation. There is a main article for star formation that has a subsection for protostar that is also a main article. Wikipedia is generally built this way. Some degree of flattening the links (i.e. a protostar reference in the star article that short circuits the star formation article) is sometimes helpful but I don't think merging will be in WP's interest due to size. Sometimes, the "What links here?" function can help with navigation. WP can be a cyclic graph which is sometimes the bane and anathema to persons that prefer flatter or acyclic graphs. --DHeyward (talk) 00:55, 2 July 2015 (UTC)[reply]

July 1

How to dissolve/remove insulation film on magnet wire?

Resolved

Hello Everyone. I would like to know how to dissolve/remove the insulation film on magnet wire. Also can this be done using everyday household products? Thanks for your help in advance, —SGA314 I am not available on weekends (talk) 13:35, 1 July 2015 (UTC)[reply]

Probably most knives would work. Nil Einne (talk) 13:48, 1 July 2015 (UTC)[reply]

Yeah I already did that. The problem with using a knife is the knife ends up cutting off most of the copper strands. Although that does work, albeit not very well. Is there any sort of solution I can whip up to dissolve the coating? I also read that the coating can only stand up to so much heat. So I was thinking about throwing it in the oven with a temperature of 500°F(of course I would first strip off the black plastic exterior). But I would like to use this only as a last resort. —SGA314 I am not available on weekends (talk) 13:59, 1 July 2015 (UTC)[reply]

Most magnet wire insulation will either burn or melt off (depending on the composition), and cleaning small amounts with a butane torch is not uncommon. However, the combination of carbon monoxide and isocyanates in the reaction product is really bad to breathe, so unless you are talking about very small quantities, I wouldn't recommend using heat without proper fume protection. Dragons flight (talk) 16:47, 1 July 2015 (UTC)[reply]

@Dragons flight: I am only talking about a fraction of the length of a set standard headphone wires. So I think that fumes wouldn't be a problem. However, there is some sort of soft, white cloth that the wire is wrapped around. I think that might cause a problem. However, I don't know whats it made out of. —SGA314 I am not available on weekends (talk) 16:52, 1 July 2015 (UTC)[reply]

Maybe sandpaper of a high grit carefully rubbed would get away the clear insulation without being strong enough to take down the copper. 20.137.7.64 (talk) 14:23, 1 July 2015 (UTC)[reply]

Great idea. I will try that. I don't know if it will make a difference but I have 4 wires. 2 of then are clear insulation and the other have green and blue insulation on them. Does the color make a difference? —SGA314 I am not available on weekends (talk) 14:26, 1 July 2015 (UTC)[reply]

Are you aware of wire strippers? From a standpoint of stripping insulation, it's not clear to me that magnet wire is much different than any other insulated wire, and hence I think the standard tool for the job should work just fine. (p.s. knives also usually work fine, if much slower, given enough practice at not cutting the wire. It's just matter of knife handling skill. Sort of like how some people can peel a potato or onion in a few seconds, while others take minutes :) SemanticMantis (talk) 14:42, 1 July 2015 (UTC)[reply]

In this case, the insulation adheres to the wire, so wire strippers won't work very well. 199.15.144.250 (talk) 14:53, 1 July 2015 (UTC)[reply]

My point exactly 199.15.144.250. Yes I do know about wire strippers. But I am talking about coated insulation, not just plastic insulation. Read about it here: Magnet wire. Also, I am working with very light gauge speaker wire. Look at a pair of ear buds and see what I am talking about. —SGA314 I am not available on weekends (talk) 15:40, 1 July 2015 (UTC)[reply]

Ok, guess I was wrong, thought it couldn't hurt to point out. But I have stripped insulation from speaker wire using wire strippers without much problem; maybe different types adhere differently. SemanticMantis (talk) 16:06, 1 July 2015 (UTC)[reply]

Emery cloth (but I expect fine sandpaper would be all right). Thincat (talk) 15:34, 1 July 2015 (UTC)[reply]

Huh, never heard of Emery cloth. Good to know. —SGA314 I am not available on weekends (talk) 15:42, 1 July 2015 (UTC)[reply]

I did it! I figured out how to get the coating off. I just burned it off with a candle lighter. The trick is though not to heat the wire so much that it glows brightly and falls off. What I do is I slowly move the flame up and down the wire until it starts to glow. Then I stop and blow on the wire to cool it down. And that's it. Now you can twist the wire with other bare conductive wires and it will conduct. If the wire doesn't conduct, then repeat the process. and test wire again. Thanks everyone for all your suggestions. Special thanks to @Dragons flight: for his suggestion. —SGA314 I am not available on weekends (talk) 19:20, 1 July 2015 (UTC)[reply]

Some acids will do the job, but may also etch the metal, e.g. nitric acid, but that is not a household chemical. Martin451 20:28, 1 July 2015 (UTC)[reply]

If it's an enamel based insulation you can use acetone (nail polish remover). Other solvents may work as well (home depot has many). If using a lighter or soldering iron, put a clip-on heat sink (soldering kits usually have them. It will stop the heat from transferring as much down the wire. --DHeyward (talk) 03:17, 2 July 2015 (UTC)[reply]

Ape Ejaculation

(Moved from Entertainment desk by SemanticMantis (talk) 14:52, 1 July 2015 (UTC))[reply]

How does the quantity of ejaculation compare between different primates. For instance, people, chimpanzees and gorillas. Chimps, being smaller have the largest testicles whereas gorillas the smallest. People are in the middle. So who's load is the most? — Preceding unsigned comment added by 203.126.168.2 (talk) 14:23, 1 July 2015 (UTC)[reply]

Check out the book Reproductive Biology of the Great Apes: Comparative and Biomedical Perspectives here [12], maybe this book [13] the article Ejaculate quality, testes size and sperm competition in primates here [14], and the article Comparative Population Genomics of the Ejaculate in Humans and the Great Apes here [15]. If those don't have the info, it's probably in the refs cited therein. Some are freely accessible and some are not. You can ask me or at WP:REX if you can't get full access to an article (often doing a regular google search for the full title will bring up an available copy). SemanticMantis (talk) 14:50, 1 July 2015 (UTC)[reply]

Vinegar to clean glass - why?

Why is vinegar commonly recommended to clean glass? What are the chemical reactions intended? ----Seans Potato Business 16:52, 1 July 2015 (UTC)[reply]

Vinegar is mostly water and Acetic acid, which is a weak acid. Acetic_acid#Solvent_properties discusses the properties that make it a decent glass cleaner - in part it is because it can dissolve both polar and non-polar compounds. SemanticMantis (talk) 17:21, 1 July 2015 (UTC)[reply]

A few-percent acetic acid in water is pretty much "water" not "acetic acid", and is probably still a very poor solvent for non-polar materials. A petty common organic lab technique is to do a reaction in 100% acetic acid as solvent, then add water and the product precipitates out in good yield. It usually only takes 1–3 volumes of water vs the acid to accomplish it, which is still several times higher concentration of the acid than vinegar is. DMacks (talk) 19:23, 1 July 2015 (UTC)[reply]

(ec)Vinegar (like most acids) removes limescale (calcium carbonate), converting it into CO2, H2O, and a calcium salt - Calcium acetate in the case of vinegar. This salt is usually water soluble, and hence easy to remove. --Stephan Schulz (talk)

Or you can use hydrofluoric acid, which will leave the glass so clean it will look like there's no glass there at all ! :-) StuRat (talk) 04:37, 2 July 2015 (UTC) [reply]

Dead slow, or damn fast

Up ahead on the track you know your loco engine and train will have to cross a severely damaged bridge. If the bridge fails, you are dead. What is the best speed to crosss the bridge. Dead slow, or damn fast??--86.149.100.245 (talk) 19:54, 1 July 2015 (UTC)[reply]

On foot.

It depends on the bridge. Remove as much weight as possible from the train, and go slowly. You will be less likely to damage the bridge than going fast. If there is a reasonable chance of the bridge surviving, then this is the best strategy.

If it is certain that the bridge will fail, then again remove all weight, and go as fast as possible, hoping to clear the bridge before it collapses.

In all circumstances, get the passengers, unneeded crew to walk across first, carrying as much needed supplies as possible. Unhook unneeded carriages. Martin451 20:23, 1 July 2015 (UTC)[reply]

The question is "What speed?" not "What else could I do?". SteveBaker (talk) 21:07, 1 July 2015 (UTC)[reply]

I think it has to depend on how the bridge is damaged.

Suppose a critical bolt has worked itself loose and is just holding together by an inch or so? Going fast would presumably create vibrations that would shake the bolt loose and destroy the bridge - where going slowly might avoid that.
Suppose it's a key component that's got a small crack in it - the process of crack propagation might take time - so going slowly would spell disaster, where getting across before the crack propagates to a disaster point would save the train.
Suppose induced oscillation in the bridge would spell disaster? In that case, travelling at some particular speed at which the oscillations are at their worst would destroy the bridge and any other speed would be safe. With that possibility, there is no specific speed which is better than any other - unless you know a lot about the bridge and how it's failing.

My (admittedly intuitive) bet is that there is no one "right" way - it depends on the nature of the damage, the nature of the train, etc.

SteveBaker (talk) 21:06, 1 July 2015 (UTC)[reply]

Dead slow, to mitigate the Hammer blow forces.--Aspro (talk) 21:21, 1 July 2015 (UTC)[reply]

But the bridge could fail under sustained static loading. What Then??--86.149.100.245 (talk) 21:36, 1 July 2015 (UTC)[reply]

A train? Over a failing bridge? Trains need tracks that are smooth and uniform in the separation between rails. Unlike what you might see in movies, I don't think there is any way that going "damn fast" is going to allow a train to get across a failing bridge. Once it actually starts to fail, it will already be too late for the train regardless of its speed. The only hope is that you can cross the bridge without it failing, which for most failure modes will make slow the only practical option. Dragons flight (talk) 22:45, 1 July 2015 (UTC)[reply]

What then? Then it's your own fault for collapsing your bridge!

In the United States, railway bridges are 100% private - (unlike all other bridges - pedestrian bridges, automobile bridges...) - there is no government agency or public utility who oversees railway bridges or even vets them for safety. For example, have a read through this article on a new rail bridge route proposed near my childhood hometown: an LPG rail transport bridge over Watkins Glen State Park. So: if a train crushes a bridge and the bridge fails catastrophically, it's your own fault for owning a rail bridge and operating a railroad! (This is why the Watkins Glen issue is so controversial: how can we make sure a fiery explosion doesn't engulf our state park if our regulators have no authority?)

As I enjoy reading about railroads and federal regulations, I went digging into the details here, and I found this Explanation and Amplification of FRA's 'Statement of Agency Policy on the Safety of Railroad Bridges' . If you own or operate a railway, you should have a professional engineer with competency "in the field of railroad engineering" evaluate whether your bridge is safe at any speed. It is your responsibility to determine what speeds are safe! Specifically, the FRA recommends against returning rail track to operation over a suspicious bridge - even at restricted speed, until the actual structural problems with the bridge are diagnosed and resolved by a competent engineer. However, this is a recommendation and not a regulation! FRA Track Safety Standards Fact Sheet.

Nimur (talk) 22:49, 1 July 2015 (UTC)[reply]

But I thought "unsafe at any speed" wasn't applicable to choo-choos? Nyttend (talk) 23:29, 1 July 2015 (UTC)[reply]

One case where faster is better is the "Evel Knievel" jump (my name for it):

  ->
-------+
       |     +------
       |     |
       +-----+

Here there is a break in the track and a drop. If you go fast enough you will land safely on the other side, while if going too slow you will splat into the wall on the other side. I've seen this at work in the case of a car driving over a pothole. However, with a train, it would somehow need to get back on the track, although perhaps derailing on the other side would be less dangerous than crashing down into the ravine. StuRat (talk) 00:57, 2 July 2015 (UTC)[reply]

The only solution I can think that mitigates both dynamic and static problems (assuming the bridge is level), is to accelerate as fast as posible and coast across the bridge. Coasting should be a static load (though the rate of change of mass on the bridge could still be a problem). Under power, there is a also a lateral stress on the rails that isn't present wjile rolling except for the rolling friction force against motion). It's still not a tractable problem without knowing the mechanism of failure (i.e. damage). If the damage is exacerbated by cantilever or horizontal forces is a different solution than vertical load damage. Now, if you have a near lights speed drive....you probably don't need a bridge. --DHeyward (talk) 04:11, 2 July 2015 (UTC)[reply]

There is no point in risking being dead, so dead slow obviously. At the slow rate of one cm per day you will have time to have a crew work on getting the bridge fixed before you begin crossing. Otherwise enlist the help of Thor to hold it together if he is available. --Wetdreamshere (talk) 04:43, 2 July 2015 (UTC)[reply]

Guys, you all seem to be repeating a lot of pseudoscience, and without any reference at all! Have you got a professional engineering license with specialization in railroad engineering? Have you studied bridge design as part of your civil engineering curriculum? Have you even bothered to spend a half hour reading about this topic before speculating on it? Why do you think riding slowly is any safer? At least User:DHeyward has shifted the discussion towards static and dynamic loads, which is a step in the right direction towards an analytical solution. But without actually studying a specific bridge, performing detailed and rigorous analysis, we can't know that riding slowly is even slightly safer than riding fast. In fact, I've already provided a source which specifically calls out this fallacy as a contributing factor to many accidents!

Step back, find some reliable sources - like a textbook on railroad bridge engineering, or a website on Railroad Bridge Safety Standards. Read it. Exercise some critical thinking. Then you can provide informed commentary, instead of idle (and often wildly inaccurate) speculation. Engineers do not validate bridge safety using ASCII-art and unrefined gut intuition. Nimur (talk) 05:33, 2 July 2015 (UTC)[reply]

Thor and company doesn't really need a textbook because they will hire only the very best qualified bridge contractors. --Modocc (talk) 06:13, 2 July 2015 (UTC)[reply]

If I may digress into fiction: This exact situation occurs in Jules Verne's famous novel Around the World in Eighty Days. They decide to go as fast as possible; they get across, but the bridge collapses behind them. Of course Verne was a science-fiction/adventure writer, not an engineer! Incidentally, in the novel the speed they reach is 100 mph (and yes, even in the original French it's given in miles per hour): in fact the speed record for steam locomotives at the time was around 80–90 mph. But in the 1956 movie they changed it to 30 mph!

And back to real life: in 2005 there was a bridge that collapsed under a train in Italy, but the train got across—because the rails remained intact and supported it! See Eurostar 9410 derailment. --70.49.171.136 (talk) 07:08, 2 July 2015 (UTC)[reply]

No seasons

Is there anywhere in the world that experiences no significant meteorological seasons, places where the stars are the only part of nature that changes from month to month? Of course it would have to be on or close to the equator, since the amount of sunlight can't vary very much. But it seems like most equatorial regions have distinct dry and wet seasons; are there any exceptions? Just looking for locations on land, not oceanic locations. Nyttend (talk) 21:38, 1 July 2015 (UTC)[reply]

The answer here [16] seems useful. Dragons flight (talk) 22:13, 1 July 2015 (UTC)[reply]

Singapore may have the smallest seasonal amplitude of any well-known place. It has near-zero temperature seasonality and a modest annual cycle of rainfall due to the monsoon. Short Brigade Harvester Boris (talk) 01:08, 2 July 2015 (UTC)[reply]

I remember a professor in college saying that Quito, Ecuador - due to the combined facts that it is on the equator and its elevation is over 9000 feet - was mild and spring like all year round. According to Quito#Climate it looks like there is a little more to it than that. MarnetteD|Talk 03:22, 2 July 2015 (UTC)[reply]

Being on a small island in the middle of an ocean helps to moderate temperatures (as long as the ocean doesn't freeze over). So, I'd go with an island near the equator, for temperatures. Of course, hurricanes/monsoons/cyclones are still a possibility, but some spots seem relatively safe from those, too, as the pic of historic hurricanes and cyclones shows. StuRat (talk) 04:27, 2 July 2015 (UTC)[reply]

Based on people that have lived there, I have to go with Singapore as well. Ocean islands are temperate but the ocean is pretty seasonal everywhere. Another interesting place is the southpole. Not really a season as one long 6 month day followed by a 6 month night. No rain and the temperature is only cold. At "night" planes can't get there though. --DHeyward (talk) 04:50, 2 July 2015 (UTC)[reply]

"Cold" is a relative thing. South_Pole#Climate_and_day_and_night puts the lows at -20°F in summer versus -80°F in winter. That's the difference between relatively normal winter gear and something more akin to a space suit. StuRat (talk) 05:09, 2 July 2015 (UTC)[reply]

Ahhh but that's a day/night diurnal difference, not seasonal. :). Besides, for me, the difference between -20°F and -80°F is like the difference between dead and deader :). --DHeyward (talk) 05:44, 2 July 2015 (UTC)[reply]

July 2

[1] ttps://en.wikipedia.org/wiki/SpaceX_CRS-7

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