Wikipedia:Reference desk/Archives/Science/2016 June 4

= June 4 =

Concorde
How many pages was the checklist for the Concorde jet? 2601:646:A180:C88C:F88D:DE34:7772:8E5B (talk) 00:55, 4 June 2016 (UTC)


 * I'm sad that the admins in your facility won't allow you to use google. It rarely does much harm. Greglocock (talk) 03:15, 4 June 2016 (UTC)


 * If you don't want to answer, then don't answer, but PLEASE CUT OUT THE RUDENESS! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 05:26, 4 June 2016 (UTC)
 * And for the record, I DID try to look it up on Google, but all of the hits had to do with the checklists for the FSX Concorde, not the real-life Concorde! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 05:29, 4 June 2016 (UTC)
 * Oh, the youtube of the braniff concorde was for a flight simulator? In that case, and that case only, I apologise. Greglocock (talk) 07:10, 4 June 2016 (UTC)
 * The youtube has NOTHING to do with my question -- I was asking SPECIFICALLY about the CHECKLIST! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 22:53, 4 June 2016 (UTC)
 * And the youtube shows the pilot and engineer going through the checklist. So you are wrong, ungrateful and shouty. Greglocock (talk) 00:45, 5 June 2016 (UTC)
 * I did not watch the video, because I know that Braniff Airlines never did have any Concorde jets in its inventory -- so I naturally assumed that the video was either a fake or was one of an FSX flight mission, not a real flight! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 03:43, 5 June 2016 (UTC)


 * Well to be honest I had overlooked or forgotten that little oddity as well "Braniff became the registered operator of the planes while on U.S. domestic service, and the planes were physically re-numbered with temporary adhesive vinyl. Registration was then returned to Air France or British Airways on the trans-Atlantic leg. Over American soil, the Concorde was limited to Mach 0.95, though crews often flew just above Mach 1; the planes flew at Mach 2 over open water."Greglocock (talk) 04:03, 5 June 2016 (UTC)
 * Considering how it ended, we might assume the checklist was at least one page short. ←Baseball Bugs What's up, Doc? carrots→ 12:35, 4 June 2016 (UTC)
 * Always check the runway for strips of metal that have fallen of the aircraft infront of you? LongHairedFop (talk) 14:36, 4 June 2016 (UTC)

Anyway, there seem to have been several seperate checklists: the "flight deck check" checklist, the "pre-startup" checklist, the "post-engine startup" checklist, the "taxi" checklist and the "pre-takeoff" checklist are all described in Air Crash Investigations: The End of the Concorde Era, the Crash of Air France Flight 4590 by George Cramoisi (pp. 222 - 224). Alansplodge (talk) 22:04, 4 June 2016 (UTC)
 * Thanks! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 22:53, 4 June 2016 (UTC)

Species identification (tree)


The uploader supplied information for this states they weren't show if this tree was what they were told it was called. In context it's not clear if the name was a species common name or a locality one.

What's the species shown, preferably the taxonomic name?Sfan00 IMG (talk) 13:11, 4 June 2016 (UTC)
 * Possibly a Banyan tree? ←Baseball Bugs What's up, Doc? carrots→ 13:29, 4 June 2016 (UTC)


 * I google-imaged "banyan tree in Havana" and several items came up, some of which look to be this very same tree. ←Baseball Bugs What's up, Doc? carrots→ 13:35, 4 June 2016 (UTC)
 * Florida strangler fig (Ficus aurea) is native to the area. Rmhermen (talk) 23:39, 4 June 2016 (UTC)
 * Our article for Ficus aurea gives higuerón as an alternative name for the species (the reference for that refers to Costa Rica) which is not too dissimilar to "Holguín" which the poster of the image thought was the name. Also our banyan article lists the Florida strangler fig among the "many banyan species". Alansplodge (talk) 17:34, 5 June 2016 (UTC)

Hydrogen apocalypse
According to Hydrogen, it "is very rare in the Earth's atmosphere (1 ppm by volume) because of its light weight, which enables it to escape from Earth's gravity more easily than heavier gases". So if hydrogen were a bit heavier, like oxygen or nitrogen, and thus stayed on Earth, and considering its hazards, the life on Earth would have been in danger (assuming that if the hydrogen weight is theoretically increased to permit its stay on Earth, it would still be hydrogen)? 93.174.25.12 (talk) 18:01, 4 June 2016 (UTC)
 * Why would a proton be any heavier in hydrogen than in other atoms/molecules? ←Baseball Bugs What's up, Doc? carrots→ 18:10, 4 June 2016 (UTC)
 * dreams of possible armageddons. what if HIV became airborne, what if worldwide anti-social sentiments and philosophies became dominant...FAMASFREENODE (talk) 18:38, 4 June 2016 (UTC)
 * What has that got to do with the mass of a proton? ←Baseball Bugs What's up, Doc? carrots→ 19:10, 4 June 2016 (UTC)


 * The problem with hypotheticals is they're hypothetical. To make hydrogen heavier you'd have to do one of two things: add particles to the hydrogen atom, or change the mass of the proton and/or electron. Considering the first case, if you add neutrons you get heavier isotopes of hydrogen, but all except deuterium are unstable. Adding electrons gives you hydrogen ions, but that doesn't change the atom's weight to any meaningful degree because electrons have a tiny mass, and you can only add so many before the nucleus can't hold on to any more. If you add other particles you wind up with something that's not hydrogen anymore. In the second case, you'd change all of physics and chemistry, so it's hard to make predictions about what the universe would look like. But, it's worth noting that we already have a fairly dangerous gas present in large quantities on Earth. It's called oxygen. You're only able to survive around large amounts of oxygen because you're descended from life that adapted to it. When photosynthetic organisms started producing oxygen in large quantities, it killed all the life that couldn't adapt to it or hide from it. And even still, too much oxygen can injure or kill you. Oxygen is so reactive we have to station people throughout our communities to jump into action when it starts reacting too vigorously with things. --71.110.8.102 (talk) 20:01, 4 June 2016 (UTC)


 * With excess hydrogen Earth may have turned into a planet looking more like Uranus. Some lifeforms can make use of hydrogen using hydrogenase enzymes, so life may still be possible. Graeme Bartlett (talk) 22:44, 4 June 2016 (UTC)


 * I didn't really think about that aspect, but you point out another issue. Terrestrial planets like Earth are, well, terrestrial because they form closer to their star(s) where it's too hot to for hydrogen and helium to condense. Planets that form beyond the frost line can hold onto these gases. Since most "ordinary matter" in the universe is hydrogen and helium, they get huge. Since the resulting planets have no solid surface, they're not generally believed to be capable of supporting life, although some exotic ideas have been floated. So if proto-Earth had been able to hold onto hydrogen, life probably wouldn't exist on Earth. --71.110.8.102 (talk) 07:37, 5 June 2016 (UTC)


 * If we think of a planet with greater mass but a similar size to Earth (say, a heavier core) so that its escape velocity is higher, then the hydrogen gas may be prevented from escaping the atmosphere. (Rather than hypothesising some new form of hydrogen, upping gravity seems to me more in line with the OP's intent.)  Now, if the H2 level gets high enough for sustaining combustion / explosion in air, then lighting a match could be pretty devastating.  If the level of H2 were kept sub-explosive, however, say by more hydrogenase-using organisms, then living with hydrogen would be possible.  We get by with 1 ppm at the moment, a higher but stable level from a balance of consumption / loss and production is not unreasonable, IMO.  Also, a planet with high H2 but little if any O2 would be unsuited to life on Earth as it is now, but there was life on Earth without much O2 before, so it isn't impossible.  EdChem (talk) 09:09, 5 June 2016 (UTC)


 * This is almost off topic for the RD, since it's one of those how much wood would a woodchuck chuck kind of questions. Still, we have a somewhat comparable situation with atmospheric methane, which is heavy enough to mix much more with the atmosphere.  The reason why we don't get a 'methane apocalypse' is that fire is not truly all or nothing; there is a little bit of the essence of fire (by which I mean combustion, really) throughout the atmosphere.  What I mean by this is that free radicals, in this case specifically the hydroxyl radical, get produced by the continual impact of ultraviolet rays from the Sun (in this case this is indirect, I think, via excited oxygen reacting with water).  There is a whole wild layer of dilute free radical chemistry, including the famous ozone layer, high above the Earth, but actually the hydroxyl radical is much more widely distributed, and lasts only a short time wherever it is found.  So what would happen in a fire happens above the Earth, but much more slowly and without the drama.  Similar processes exist in many other systems, such as our bodies - but it is only in a few rare systems, like the degradation of unsaturated oils in rags, where this can cross the boundary to spontaneous combustion. Wnt (talk) 13:08, 5 June 2016 (UTC)


 * So if you're tired of your train rails taking years to burn put them in pure oxygen. Fwoosh! Sagittarian Milky Way (talk) 01:07, 8 June 2016 (UTC)

this user enquires the signs and symptoms of a serotonin-devoid nervous system
replies should contain as much data in-reply and not collections of external linksFAMASFREENODE (talk) 18:34, 4 June 2016 (UTC)
 * Replies should contain links to sources. ←Baseball Bugs What's up, Doc? carrots→ 19:11, 4 June 2016 (UTC)
 * "This user" could always go somewhere else if they aren't happy about this being a reference desk. Nil Einne (talk) 02:08, 5 June 2016 (UTC)
 * Interesting article, cites :
 * "'To do this, they developed “knockout” mice that lacked the ability to produce serotonin in their brains. The scientists ran a battery of behavioral tests. Interestingly, the mice were compulsive and extremely aggressive, but didn’t show signs of depression-like symptoms. Another surprising finding is that when put under stress, the knockout mice behaved in the same way most of the normal mice did. Also, a subset of the knockout mice responded therapeutically to antidepressant medications in a similar manner to the normal mice. These findings further suggest that serotonin is not a major player in the condition, and different factors must be involved. These results could dramatically alter how the search for new antidepressants moves forward in the future, the researchers conclude.'"
 * Also see (2012, the older idea) Wnt (talk) 13:14, 5 June 2016 (UTC)