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June 25

Anaphylaxis and cardiac arrest

What is the actual physical mechanism that leads to cardiac arrest and death in anaphylaxis? I know blood pressure drops and airways can swell, which leads to less oxygen reaching the blood. But how do these 2 things and other symptoms which I may have missed actually lead to a cardiac arrest? 90.194.63.148 (talk) 17:18, 25 June 2019 (UTC)[reply]

Presumably fluids leakage and airway obstruction lead to low oxygen supply to the heart, which eventually stops beating regularly i.e. fibrillates. Ruslik_Zero 20:30, 25 June 2019 (UTC)[reply]

Anaphylaxis#Cardiovascular has links to what happens Gem fr (talk) 20:46, 25 June 2019 (UTC)[reply]

Black holes

If and when the Big Rip happens, what will happen to black holes? Will they “survive” Rich (talk) 18:28, 25 June 2019 (UTC)[reply]

I don't think that is something our current understanding of physics can answer. But they won't survive forever - Hawking radiation will make them evaporate. --Stephan Schulz (talk) 19:25, 25 June 2019 (UTC)[reply]

@Richard L. Peterson: Very hard to say what will happen; we are talking about an event that may happen in roughly 22 billion years. The Big Rip article states that atoms, spacetime etc. will all be torn apart, so roughly speaking, black holes will not 'survive'. You also have to remember that this is hypothetical - the universe might end in a Big crunch, Big Chill, or several other possibilities, including religious ends to the universe. Even the cause of a Big Rip (Dark energy) is barely understood. Willbb234 (talk) 19:53, 25 June 2019 (UTC)[reply]

In a Big Rip scenario, black holes will lose all their mass due to accretion of phantom energy, see here and here for details. Count Iblis (talk) 15:57, 26 June 2019 (UTC)[reply]

June 26

DNA Replication

Help from biologists required:

File:DNA Replication, an introductory video.ogg

I am in the process of generating a video to show the basics of DNA replication. The video will (in acceptable volume) be published in a relevant article of the en:WP.
As I am not sure that I understand the concept of 3´to 5´vs 5´to 3´I need some WP editor with specific knowledge to verify that my little film shows a correct process of replication.
Thank you for any help / critique and advise.
--Cookatoo.ergo.ZooM (talk) 13:48, 26 June 2019 (UTC)[reply]
PS: I may have to split the video into shorter, maybe 60" clips to achieve some reasonable quality, but that is temporarily irrelevant.
PS2: You may have to click twice; for unknown reasons, the fist click shows but a black window.

Our article didn't have a figure I wanted, so I numbered the one we had and put it at the right. Polymerases work by breaking off some phosphates and linking the remaining phosphate of a nucleotide to a 3' end, so DNA strands grow at the 3' end under nearly all situations where replication is going on. The strands form a double helix pointing in opposite directions. Oh ... and as for the video, I'm afraid you have to scrap it entirely. It's just not the way it works -- you don't have large regions of side-by-side "double helix" without the helix. Wnt (talk) 15:40, 26 June 2019 (UTC)[reply]

Besides, the nucleic acid double helix contains a major groove and minor groove of different widths Gem fr (talk) 16:35, 26 June 2019 (UTC)[reply]

Hi, User:Wnt and thank you for the advice. I will modify the design and resubmit. The first attempt at abiogenesis was a total failure.
And for all we know, the current attempt (executed in online reality) may be doomed, as well 😈
--Cookatoo.ergo.ZooM (talk) 13:07, 27 June 2019 (UTC)[reply]
PS: I will ignore that helices are not symmetrical and uneven gaps / grooves are the result. This is not an exercise in molecular geometry. --Cookatoo.ergo.ZooM (talk) 13:14, 27 June 2019 (UTC)[reply]

Obviously you have to decide what level of detail to include and what the academic level of your target audience is. One confusing aspect is that in the polymerase reaction, there are dozens of loose A/T/G/C diffusing into the active site and then the correct one attaches with the rest simply dissapearing. It's true that there are lots of available bases of all types, but either they should bounce in and out (with only the correct one sticking) or else only the correct one should ever come in. You've also lost the whole visual idea of the need for the polymerase activity, which as you note is important for getting the strands to build. As illustrated, it seems its role is just to get the correct base-pairing, not also for attaching the new base to the previous part of the chain. Maybe retain the backbone, so it can "bond to the backbone" once it pairs with the base? If the backbone is made of arrows (rather than just a tube), then you can even illustrate the antiparallel difference between leading and lagging and the directionality of the replication, which you mention and is a major idea. DMacks (talk) 13:57, 27 June 2019 (UTC)[reply]

Thank you, user:DMacks.
I like your suggestion of switching the tubular backbones to antiparallel helical arrays of arrows to indicate the 3´/ 5´ logics of leading (continuous) / lagging (Okazaki) strand replication. This seems intuitive visual semantics. I have to experiment how to achieve that, but that is my problem. I expect a spot of brain storming in my Gothically vaulted regular winebar next to our cathedral will provide divine inspiration (or, at least, medication for ensuing frustration) 🤢.
And yes, the A/T/C/G blobs floating in and miracolously evaporating is clumsy and dilletant rubbish. This needs to be tightly modelled. A spot more brainstorming.
Your comments have been very constructive. Muchly obliged. --Cookatoo.ergo.ZooM (talk) 16:10, 27 June 2019 (UTC)[reply]

Have you see the WP:Videowiki tool? Doc James (talk · contribs · email) 19:21, 27 June 2019 (UTC)[reply]

Note abiogenesis is the original origin of life, not any replicative process. Likely some RNA-like nucleotides were involved, but certainly not helicase! Wnt (talk) 14:53, 28 June 2019 (UTC)[reply]

Re abiogenesis: Sorry, this was just an infantilistic joke. Humour, I perceive, is a non-overlapping magesterium to the Popperian school of scientific methodology. --Cookatoo.ergo.ZooM (talk) 16:41, 29 June 2019 (UTC)[reply]

June 27

Hypertension, isolated

There is a disease called isolated systolic hypertension. But why there doesn't exist a disease called isolated diastolic hypertension? --It's gonna be awesome!✎Talk♬ 17:09, 27 June 2019 (UTC)[reply]

There is: [1]. And also there's isolated diastolic hypotension: [2], and isolated systolic hypotension: [3]. As for Wikipedia not having articles on all of them, some conditions are more common and/or more problematic than others, and hence more notable. SinisterLefty (talk) 17:29, 27 June 2019 (UTC)[reply]

Thanks for the impressive and excellent points!! --It's gonna be awesome!✎Talk♬ 18:43, 27 June 2019 (UTC)[reply]

Can likely be redirected to hypertension and a sentence or two written about it there. Doc James (talk · contribs · email) 19:22, 27 June 2019 (UTC)[reply]

Thanks!--It's gonna be awesome!✎Talk♬ 05:18, 29 June 2019 (UTC)[reply]

@Doc James: how to quickly tell if https://www.ncbi.nlm.nih.gov/pubmed/30226658 is an peer-reviewed article? I didn't see the term "review" in the MeSH terms or Publication type beneath. --It's gonna be awesome!✎Talk♬ 13:48, 30 June 2019 (UTC)[reply]

Hi, dear Sir or Madam. Can I ask you a question? How to tell if an article on PubMed is an peer-reviewed/reviewd article? Thank you! --It's gonna be awesome!✎Talk♬ 13:04, 30 June 2019 (UTC)[reply]

Usually on can look under MeSH terms for the work "review article". That is correct more than 95% of the time, but sometimes it is not and sometimes it is missing.

With respect to https://www.ncbi.nlm.nih.gov/pubmed/30226658 I think it is an okay source to use to discuss isolated diastolic hypertension. Doc James (talk · contribs · email) 18:43, 30 June 2019 (UTC)[reply]

Ahh, I get it! Gratitude! --It's gonna be awesome!✎Talk♬ 08:30, 1 July 2019 (UTC)[reply]

Actinide Questions and Info needed

I'm writing a binder of every Fact, use and Compound of every element and I need some info on some Actinides if you could give some. I also have some questions to ask If anyone can help. I'd appreciate it. Porygon-Z (talk) 21:15, 27 June 2019 (UTC)[reply]

See actinide series. Then follow up with all the links and sources you find there. After finishing that, come back here with any further questions. SinisterLefty (talk) 22:11, 27 June 2019 (UTC)[reply]

Well I do have a question. How do we Know more about Cn than Es-Lr? Porygon-Z (talk) 22:51, 27 June 2019 (UTC)[reply]

You mean Cm (curium) ? SinisterLefty (talk) 22:46, 27 June 2019 (UTC)[reply]

No We know more About Cn Than we do Md, No, and Lr. I'm making a binder on the facts, uses and compounds of every element. Can you give me more info about Fm-Lr. Porygon-Z (talk) 22:51, 27 June 2019 (UTC)[reply]

You mean copernicium? Why do you say we know more about it ? Our article on it is about as long as the rest, and all are over 30k characters, with separate articles on the isotopes of each. SinisterLefty (talk) 22:56, 27 June 2019 (UTC)[reply]

Because we know more about an element that only lasts 5 seconds and has a compound (Cn) compared to an element that we only know its chemistry in solution and it oxidation states with no compounds (Md,No,Lr). I did go through each article even listing facts uses and compounds. I don't have much. Porygon-Z (talk) 23:18, 27 June 2019 (UTC)[reply]

Not sure. In some cases, they may not have been studied for chemical reactions, as they are dangerous and expensive to work with and there is very little benefit, since they have short half lives. The same applies to Cn, but somebody might just have happened to get a grant to study that one. There's also a theoretical island of stability, which may include Cn, leading to more study to verify if that is actually the case. SinisterLefty (talk) 23:28, 27 June 2019 (UTC)[reply]

But What about Mendelevium What do we know about it that I don't already have? Porygon-Z (talk) 23:34, 27 June 2019 (UTC)[reply]

We have this link to the chemistry of Md: [4]. SinisterLefty (talk) 23:38, 27 June 2019 (UTC)[reply]

It doesn't give much, but what little it does have, I already either have, don't care about, or don't understand. What else can you find? Porygon-Z (talk) 23:47, 27 June 2019 (UTC)[reply]

You should include that electron configuration diagram, and ask about those parts you don't understand. I'm not sure if there is any more info out there. You can try Google searches, but, as I said, such artificial elements are of limited use so aren't studied much. SinisterLefty (talk) 23:53, 27 June 2019 (UTC)[reply]

Do you have any idea what the Electrochemical Equivalent of Mendelevium even means? Porygon-Z (talk) 23:57, 27 June 2019 (UTC)[reply]

They have a link that attempts to explain it. I don't know anything about it beyond that. SinisterLefty (talk) 00:09, 28 June 2019 (UTC)[reply]

OK, then what about nobelium? What facts can you give there? Porygon-Z (talk) 00:16, 28 June 2019 (UTC)[reply]

Did you look at isotopes of nobelium ? Lots of info there. SinisterLefty (talk) 00:30, 28 June 2019 (UTC)[reply]

Lots of info on how to make it. What about its chemistry? Porygon-Z (talk) 01:04, 28 June 2019 (UTC)[reply]

They do have extensive info on decay processes, too. Same comments apply as above: "may not have been studied for chemical reactions, as they are dangerous and expensive to work with and there is very little benefit, since they have short half lives.". To give an analogy, there's lots of info on the speed at which various fish swim, because that's what they do. But not so much info, say, on how fast an elephant swims, as that would be a rare occurrence for them. So, rather than looking for that info, how fast an elephant walks is more relevant. Similarly, for unstable laboratory elements, the nuclear processes are far more significant than the chemical processes. SinisterLefty (talk) 01:14, 28 June 2019 (UTC)[reply]

There is a fair bit of nobelium chemistry, described in that article. Much more so than for the trans-actinides. Graeme Bartlett (talk) 11:17, 28 June 2019 (UTC)[reply]

Well that recycles into the question; What do we know about it ? Porygon-Z (talk) 01:54, 28 June 2019 (UTC)[reply]

You cannot really tell the limits of knowledge by looking in a Wikipedia article. As yo cannot tell what is missing by looking at it. But there is a tendency for the topics about which less is known to have a higher proportion of that knowledge in the article. If you want a more recent review see https://link.springer.com/article/10.1007/s10967-014-2971-y and The Chemistry of the Superheavy Elements Structural Characteristics, Population Analysis, and Binding Energies of [An(NO3)2+ (with An = Ac to Lr)]

and Chemistry Of The Heaviest Elements Graeme Bartlett (talk) 11:32, 28 June 2019 (UTC)[reply]

OK thank you. — Preceding unsigned comment added by Porygon-Z474 (talk • contribs) 16:28, 28 June 2019 (UTC)[reply]

June 28

chemistry reference

Are all the physical and chemical properties of matter governed by its chemical composition? Suyogya1 (talk) 04:23, 28 June 2019 (UTC)[reply]

No. See for example Phase transition, Allotropy, and Microstructure.--Wikimedes (talk) 05:19, 28 June 2019 (UTC)[reply]

@Wikimedes by chemical composition i just not mean proportion of atoms only, but also their molecular structure, orientation, configuration, bonding type, bonding strength, etc. because for a particular proportion of atoms there exist these fixed properties. see The topics referred by you are just having those properties i.e., allotropy is structural modification, microstructure is highly magnified structure.Suyogya1 (talk) 07:23, 28 June 2019 (UTC)[reply]

Yes: its chemical composition govern the physical and chemical properties of matter;

No: other things than its chemical composition also govern the physical and chemical properties of matter. Temperature for instance. Or electronic state. Many other.

And, in science, it is important to define properly what you are talking about, and to use common definitions. You cannot stretch the definition of chemical composition so as to include, say, effect of temperature on the molecule. Chirality (chemistry) give you examples of molecule with the very same chemical composition, but different properties. Gem fr (talk) 08:27, 28 June 2019 (UTC)[reply]

Allotropy is, of course, a chemical change (oxygen and ozone are two different things). Microstructure also is plausibly chemical in nature -- two diamonds, each a single molecule, are different because they contain different numbers and arrangements of carbon atoms. However, a group of microscopic diamonds could be stacked in different ways without changing their chemistry, so sometimes this could be non-chemical. But yes, surely temperature and phase are counted as physical rather than chemical changes. Wnt (talk) 16:12, 28 June 2019 (UTC)[reply]

@Suyogya1, I was thinking you had meant more than just composition (the relative amounts of each element) in your question. If you expand the question to include all chemical interactions, then the range of properties determined by the interactions also expands, and Gem fr and Wnt have given some good answers. Physical extensive properties are probably not considered to be determined by chemical interactions, and as Gem fr has said, other things can also affect properties. For example the Flexural rigidity of an I-beam is different from the flexural rigidity of a cylinder, but regardless of these geometric effects, at room temperature and pressure the flexural rigidity of iron is going to be a lot higher than the flexural rigidity of oxygen.--Wikimedes (talk) 22:33, 28 June 2019 (UTC)[reply]

I'm trying to understand this from the Hybrid Synergy Drive Article

High gear (equivalent): When cruising at high speed, the engine turns more slowly than the wheels but develops more torque than needed. MG2 then runs as a generator to remove the excess engine torque, producing power that is fed to MG1 acting as a motor to increase the wheel speed.

Surely the speed is a function of torque at the wheels (overcoming friction), and you will not be able to do anything with a generator->motor that you couldn't do by changing the gear ratio? -- Q Chris (talk) 09:23, 28 June 2019 (UTC)[reply]

According to the article "the torque/speed conversion uses an electric motor rather than a direct mechanical gear train connection". They say the goal is for the engine to run at a single "optimal speed" without having to vruuum-vruuum-vruum up the gears like a usual car accelerating, or having to suffer losses at a continuously variable transmission. Wnt (talk) 10:27, 28 June 2019 (UTC)[reply]

(edit conflict) you will not be able to do anything with a generator->motor that you couldn't do by changing the gear ratio? - True, but the gear ratio usually changes by fixed increments - e.g. European cars have 5-6 gear ratios. Having (essentially) two motors in parallel allow you have any gear ratio in some range, so to speak, which can more than compensate for the losses in the mechanical power -> electricity -> mechanical power conversion (because you then optimize the torque/speed point for higher engine efficency). Tigraan^{Click here to contact me} 10:32, 28 June 2019 (UTC)[reply]

"True, but the gear ratio usually changes by fixed increments - e.g. European cars have 5-6 gear ratios" - I can see that this might be the case to fill in the gaps between gears in nacrs with fixed ratios. The Hybrid Synergy Drive has a Continuously variable transmission though, so that shouldn't be necessary. -- Q Chris (talk) 10:37, 28 June 2019 (UTC)[reply]

I have just re-read the article and now understand. It is not a CVT but classed as one for regulatory purposes: "This is why Toyota describes HSD-equipped vehicles as having an e-CVT (electronic continuously variable transmission) when required to classify the transmission type for standards specification lists or regulatory purposes.". The combination of electric motor and planetary gears acts like a cvt. -- Q Chris (talk) 11:55, 28 June 2019 (UTC)[reply]

Glad you are sorted out, but it is a CVT, just not a mechanical one. The actual architecture, using a differential driven by an engine generator and an MG was proposed (and built, and tested) in the 70s. By Americans.Greglocock (talk) 00:09, 29 June 2019 (UTC)[reply]

Copper cementation

After copper ions have been removed from solution by depositing them on solid iron metal, how do you get the iron out of the copper to get pure copper? 182.0.150.151 (talk) 11:02, 28 June 2019 (UTC)[reply]

I don't know how it's done in a manufacturing process, but at home you could rust it away. That is, expose the iron to air and saltwater until it turns to iron oxide powder and breaks off. You would then want to polish the copper to remove any remaining rust, and any corrosion of the copper. SinisterLefty (talk) 15:01, 28 June 2019 (UTC)[reply]

You don't. If your goal was pure copper, you would have deposited them electrolytically onto copper cathodes, directly from the solution. If you have copper on iron as a mixture, you would then dissolve one of them, and if you wanted the copper to emerge pure, then it might be the copper that you dissolved. Andy Dingley (talk) 15:59, 28 June 2019 (UTC)[reply]

More in Copper extraction, Copper_extraction#Electrorefining and included links Gem fr (talk) 17:08, 28 June 2019 (UTC)[reply]

Conceivably you could be trying to get a copper cast of an iron object. Why I don't know. I think hydrochloric acid could be used to dissolve the inner iron without touching the copper cast, but I don't know that's really workable. Wnt (talk) 21:39, 28 June 2019 (UTC)[reply]

If you are a pro you know how to do it. If you are not, copper is sold in general stores at a price low enough, the copper you'll get this way is not worth the acid (despite it also being so cheap). But if for some reason I wanted to do that, I'll rather heat the thing, copper melting temperature is hundreds of K lower than that of iron and easily produced (with a blowtorch nowadays). Gem fr (talk) 06:53, 29 June 2019 (UTC)[reply]

Just to add to the chorus that home extraction of copper is not worth it, watch the YouTube chemist NileRed, who did a video on extracting pure gold from jewellery. When he extracted the gold, he also spent time and materials recovering silver from his extraction solutions, but didn't even bother with the copper, as the cost of materials meant it wasn't even worth it, so he just pitched them. It can be done rather easily, however, much easier using hydrochloric acid and powdered zinc, if you really want to do it. You'll need a large excess of HCl to react away any excess zinc, but you do get a nice, relatively clean copper dust in the end. I do the experiment with my AP chemistry students, it's part of a standard series of reactions called "copper to copper" where you dissolved copper metal with nitric acid, then do a series of reactions to it that so turn successively difference colors, and the last step is to recover the original copper. You can find the procedures online easily enough. But the zinc/acid method is a much cleaner method than the plating process the OP is attempting.--Jayron 32 12:45, 29 June 2019 (UTC)[reply]

Gold and silver (and to some extent platinum) are precious metals. This means those metals which have, since antiquity, been easily smelted. They also have the usual shininess and avoidance of corrosion, but mostly they were adopted as valuable so early on simply because they were the metals which were available. In places where native copper was available that had a similar veneration and of course native iron even more so (but that's extremely rare).

So it's just easy to smelt gold and silver into bullion form. When I do it, I just use a crucible loosely filled with coffee grounds (the nearest finely-powdered organic medium) and pop it into the gas forge for a bit. It's not even too fussy about the flame chemistry.

Copper's much harder. Harder to separate from iron by this route, and hard to smelt without burning off more than you're producing. But still, the bronze sword people (Neil Burridge) and the experimental archaeologists do it regularly. Similarly for tin. Zinc though can't be done this way, hence why metallic zinc wasn't available in Europe until the mid-eighteenth century (WP's coverage is pretty inaccurate for this though). Andy Dingley (talk) 13:16, 29 June 2019 (UTC)[reply]

I could imagine a case where depositing copper on iron, then removing the iron, might make sense. Let's say there was a decorative iron mask that still looks decent from the front, but due to improper storage is almost rusted through from the back. If we assume it's of little value, in part due to this condition, then creating a copper version, in better shape, that could be displayed without requiring a coat of oil to prevent rusting, might be desirable. (Obviously if it was museum piece, they would want to preserve the original no matter what the condition.) SinisterLefty (talk) 13:04, 1 July 2019 (UTC)[reply]

But why would you remove the iron?

If you're looking at electroforming copper onto steel (and mostly onto a graphite-coated wax former) look at the water cooling jackets on the cylinders of many water-cooled aircraft engines of WWI. Andy Dingley (talk) 14:29, 1 July 2019 (UTC)[reply]

You'd remove the rusty iron, in my scenario, because it's heavy and unpleasant, leaving a trail of powdery chunks of iron behind. Rust also stinks. If they wanted to wear the mask for some type of event, then wearing it with rusty iron against their face would be a particularly bad idea (although copper could still give them green skin, so a lacquer coating, or some type of pads to offset the mask from the face, would also be a good idea). SinisterLefty (talk) 15:04, 1 July 2019 (UTC)[reply]

Lion

Please, our article does not appear to contain this information. What is the natural lifespan of an African lion. Thanks Anton 81.131.40.58 (talk) 12:52, 28 June 2019 (UTC)[reply]

According to [5]: "Lions in zoos may live into their late teens or early 20s. In the wild, a lioness may live up to 16 years, but males rarely live past the age of 12." Incidentally, there are two subspecies of lions in Africa:

Panthera leo leo − includes the lion populations in West and northern parts of Central Africa.
Panthera leo melanochaita − includes lion populations in East and Southern African regions.

I don't know if there's a significant difference in lifespans. SinisterLefty (talk) 13:48, 28 June 2019 (UTC)[reply]

Note that LiOns have a much shorter lifespan. :-) SinisterLefty (talk) 14:50, 28 June 2019 (UTC)[reply]

June 29

Melting and boiling points of francium and astatine

Did anyone ever actually measure these, or do we only have predictions? The articles francium and astatine list them all as calculations or estimations in the body, and the At article even mentions that some experimental data suggests that the predictions are wrong. Double sharp (talk) 10:44, 29 June 2019 (UTC)[reply]

Don't know, but it must be a difficult thing to measure, since the actual temperature is difficult to control. This is because the highly radioactive nature of those elements generates more heat in the interior than on the surface, making it difficult to keep a sample at a constant temperature. SinisterLefty (talk) 10:52, 29 June 2019 (UTC)[reply]

I managed to get the text of the paper our astatine article cites for the experimental indications (10.1524/ract.1982.31.34.201): it indeed confirms the difficulty due to radioactive heating, inability to get a large quantity, and boiling point elevation due to polonium impurities that keep getting generated from astatine decay. So it simply gives an estimate based on semi-empirical theory on retention volumes from radio-gas chromatographical experiments (which is, of course, much better than just extrapolating from the halogen trend). As for francium: the closest I have been able to get is this paper, which quotes some estimations from its citres [6] and [7] (with a value of 871 K for the boiling point of Fr that seems more in keeping with the periodic law than the 950 K we currently quote), but I can't find those original sources for them to see if the values therein are just calculated or have any experimental basis behind them as well. Double sharp (talk) 12:28, 29 June 2019 (UTC)[reply]

There are some interesting papers around this locus. Will try to leave them, morrow. ∯WBG^converse 19:19, 30 June 2019 (UTC)[reply]

With R8R's help I've been trying to track down better figures for Fr at his talk page: we have found some figures (m.p. 8.0 or 20±1.5; b.p. 620 or 640), but I suspect that they are probably predictions (the set 20±1.5/640 is certainly calculated by Mendeleev's method). Double sharp (talk) 04:52, 2 July 2019 (UTC)[reply]

July 1

Time to space in Gemini 8

I was watching First Man and noticed that the sequences from liftoff of Gemini 8 to reaching space (or orbit, I don't remember) lasted a few minutes, they seemed as if intending to represent real time. The Gemini 8 article has March 16, 1966, 16:41:02 UTC as launch time and March 16, 1966, 22:14 UTC for the docking with Agena. But I don't see the time for reaching the space (or orbit). Do space flights usually take just some minutes to reach space?

Launch and Early Orbit phase is very small. Space launch says:

the edge of space is defined by convention, often the Kármán line of 100 km. Other definitions have been created as well, in the US for example space has been defined as 50 miles.

I do not have a preference for a definition. Anything that works in a movie to establish "the ship reaches space" is enough for me. It also says:

It is not generally recognized by the public that the increase in potential energy required to pass the Kármán line is only about 3% of the orbital energy (potential plus kinetic energy) required by the lowest possible Earth orbit (a circular orbit just above the Kármán line.) In other words, it is far easier to reach space than to stay there

--Error (talk) 00:19, 1 July 2019 (UTC)[reply]

Orbital objects are going some 17,000 mph in LEO. While they are not going that fast earlier in flight, they are still booking. Depending on your definition of the boundary of space and your launch vehicle, it only takes a couple minutes to reach space. Kees08 (Talk) 01:07, 1 July 2019 (UTC)[reply]

Reaching space (using whatever definition of space) usually isn't very interesting. It's about reaching orbit, which is when the engines are shut off and (apparent) microgravity begins. On some launches there may be a half-orbit coast phase followed by a few seconds circularization burn. From launch to orbital insertion last somewhere between 8 and 15 minutes on most launches.

The Titan II GLV used in Project Gemini had a rather high acceleration (up to about 6g, according to our article), so it reached orbit quickly. Our article mentions 156 seconds first stage and 180 seconds second stage burn, indicating it reached orbit in slightly less than 6 minutes. PiusImpavidus (talk) 08:42, 1 July 2019 (UTC)[reply]

(edit conflict)Depends if the vehicle is manned or not. If not, like a Minuteman, around 3 minutes are needed. But this require too much acceleration for a human being, so it takes ~3x more time, for instance, for Space_Shuttle to reach orbit. This is still less than 10 minutes. Gem fr (talk) 08:45, 1 July 2019 (UTC)[reply]

To see how long it takes to reach space (as defined however you would like to define it yourself), you can watch an old live stream of a SpaceX launch on youtube such as this one. 139.194.66.147 (talk) 11:19, 1 July 2019 (UTC)[reply]

In the case of STP-2, at T+00:03:13 the vehicle reached an altitude of 100km. At T+00:08:27 it reached a speed equal to LEO velocity. So the answer to whether space flights usually take just some minutes to reach space, yes, space is reached within minutes. 139.194.66.147 (talk) 12:49, 1 July 2019 (UTC)[reply]

Thank you all. Your answers satisfied my curiosity. --Error (talk) 23:01, 1 July 2019 (UTC)[reply]

Oddly enough, there was a comedy movie once where this bit of rocket science formed a plot point. In The Mouse on the Moon (1963), the spaceship from Grand Fenwick takes off slowly and intends to take weeks to get to the Moon. And Prof. Kokintz explains that they have no need to hurry because they have plenty of energy available from their special fuel. (That's not a direct quotation, but it's the essence of his point.) Real-life rockets generally accelerate rapidly to their final speed because fuel burned for any purpose other than accelerating the payload is essentially wasted, and if there is fuel available to waste, more fuel is spent accelerating it. This all ties in with the Tsiokovsky rocket equation. --76.69.117.113 (talk) 06:15, 2 July 2019 (UTC)[reply]

Just a science question if there's an official record

Hi all, is there an official source stating the weight of Kim? I read articles about him having problems with one of his legs and guessed this. Is that information available? Thanks all. --LLcentury (talk) 02:39, 1 July 2019 (UTC)[reply]

Kim who?--Shantavira|^{feed me} 05:53, 1 July 2019 (UTC)[reply]

I suspect the OP probably means Kim Jong-un. I doubt there is any reliable official source because the North Korean government generally just makes up whatever they feel suits. I mean the situation in North Korea is nuts enough that it's hard to know whether even Kim knows his weight, or his doctors have a proper record of it or they were afraid of annoying him in some way and so use a purposely miscalibrated scale or whatever. Kim has traveled to various places but recording the weight of leaders visiting your country isn't something countries tend to do at least officially. (I mean theoretically the Russians, Chinese, Singaporeans, Vietnamese etc could have hidden scales in stuff he stood on, but they're not going to tell us what they learnt.) According to [6] South Korean intelligence have actually tried to track his health including weight from video footage and estimated it was 130kg at one time but I'm doubtful that sort of thing is any more accurate to within 20% or so, and probably less. Nil Einne (talk) 08:20, 1 July 2019 (UTC)[reply]

I suppose rapid weight loss could be a sign of serious illness, and since him dying and leaving NK's nukes in the hands of somebody potentially even more crazy than him would have serious implications, I wouldn't put it past a security agency to put strain gauges under the floor of a hallway he was to walk down during a visit, to measure his weight as accurately as possible. Of course, they wouldn't publicize this fact, nor the results. SinisterLefty (talk) 12:55, 1 July 2019 (UTC)[reply]

Yes, my apologies, I was referring to Kim Jong-un. - --LLcentury (talk) 10:38, 1 July 2019 (UTC)[reply]

Crossing Over in Genetics

I'm trying to teach myself the basics of genetics. One very basic question that I'm not clear on is whether (let's limit to humans for simplicity) genetic diversity is always a matter of combination of individual chromosomes or whether alleles from different chromosomes can be mixed together. E.g., suppose we have chromosome C1 and the Father's genome is C1F1 and C1F2 and the mothers C1M1 and C1M2. My understanding is that in Meiosis we get four haploid daughter cells with the values for C1 being: C1F1, C1F2, C1M1, and C1M2 and that the new fertilized egg will have one of these from the father and one from the mother. However, it also seems there is something called Crossing Over where alleles from one chromosome get swapped with the homologous (I think that's the correct term) alleles from another. So that the child could end up with a C1 chromosome that was a combination of say C1M1 and C1F1. I hope my question is clear and I'm not butchering the terminology. Also, just to be clear, I'm aware there are also other factors that are very important such as epigenetics, the environment in the womb, etc. but I'm just trying to make sure my basic understanding of Meiosis in humans is correct. Thanks for any help. --MadScientistX11 (talk) 22:25, 1 July 2019 (UTC)[reply]

You have it correct. This is diagrammed in the image at the top of Meiosis, for a hypothetical organism with two chromosome pairs. For ease, in that diagram the paternal and maternal chromosomes are different colors. As you can see, the gametes that come out of meiosis have one full copy of each chromosome, but it is a mix of red sections and blue-grey sections. In that diagram, as is actually very typical, crossing over only happened on one member of each pair of sister chromatids. However, that is not actually a rule. It could happen by chance, but both sister chromatids can experience crossing over. Someguy1221 (talk) 22:52, 1 July 2019 (UTC)[reply]

did you read chromosome allele Chromosomal crossover Unequal crossing over ?

Gem fr (talk) 23:02, 1 July 2019 (UTC)[reply]

Thanks. I read the Chromosomal crossover article but not the others, I'll take a look at them. Part of the reason I was confused is that a professor told me the opposite, but she was not a biology professor and she was teaching genetics as one part of a larger class. And it's such an important concept (it really increases the combinatorics of possible genotypes) that I wanted to make certain I was understanding it correctly. Thanks a lot for the quick response. --MadScientistX11 (talk) 03:09, 2 July 2019 (UTC)[reply]

What do you mean, she told you the opposite? What specifically was she talking about, do you remember? I might know what she meant. Someguy1221 (talk) 04:28, 2 July 2019 (UTC)[reply]

July 2

@@ Line 223: / Line 223: @@
 :::Thank you all. Your answers satisfied my curiosity. --[[User:Error|Error]] ([[User talk:Error|talk]]) 23:01, 1 July 2019 (UTC)
+Oddly enough, there was a comedy movie once where this bit of rocket science formed a plot point.  In ''[[The Mouse on the Moon]]'' (1963), the spaceship from Grand Fenwick takes off slowly and intends to take weeks to get to the Moon.  And Prof. Kokintz explains that they have no need to hurry ''because they have plenty of energy'' available from their special fuel.  (That's not a direct quotation, but it's the essence of his point.)  Real-life rockets generally accelerate rapidly to their final speed because fuel burned for any purpose other than accelerating the payload is essentially wasted, and if there is fuel available to waste, more fuel is spent accelerating it.  This all ties in with the [[Tsiokovsky rocket equation]]. --[[Special:Contributions/76.69.117.113|76.69.117.113]] ([[User talk:76.69.117.113|talk]]) 06:15, 2 July 2019 (UTC)
 == Just a science question if there's an official record ==