Wikipedia:Reference desk/Archives/Science/2023 July 10

= July 10 =

If an interstellar black hole passed 1 km from sea level?
As slow relative to ground as possible without continuing to be interstellar (~42 km/s solar escape velocity @ 1 AU minus ~30 km/s for moving with Earth's orbit and 0.46-0.47 km/s for moving with Earth rotation equals slightly over Earth escape velocity of 11.2 km/s) then what mass-distance combo would cause the least harm without being invisible to naked eye at closest approach? (Hawking radiation, blindness, Hawking radiation making other stuff radioactive, sucking air etc) Maybe on a high mountain the right amount of intervening air could allow a decent view without radiation poisoning? Sagittarian Milky Way (talk) 19:43, 10 July 2023 (UTC)


 * It feels like it'd be hard to add anything more scientific beyond this response to a similar question, some years ago:
 * "The answer to this type of physics question always depends: how would [the black hole arrive to this trajectory]? If you can specify that, we can follow through with the consequences by solving the equations of motion [or the black hole dynamics] for the system.
 * "On the other hand, if you just want to make something up, "just imagine" that the [black hole] magically [appears at this location], all bets are off. We can't meaningfully speculate what consequences follow when one law of physics breaks "because of magic." Anything could happen. Everything we know about the way [black holes interact with nearby matter] depends on the rules of physics as we currently understand them.
 * "So - does that answer your question? Anything. Anything could happen."
 * Nimur (talk) 22:42, 10 July 2023 (UTC)
 * By orbiting the galactic center from the net gravity of galactic dark matter and billions of stars and passing equatorial parts of Earth on the outside @ ~12 km/s relative to the ground at minimum altitude of 1 km as previously said? More specifically Earth could be @ perihelion, hole 1 km above the central Pacific on the "lunar eclipse side" of the Sun-Earth line, Moon on the "solar eclipse side" of that line, hole velocity vector at that instant is parallel to orbit of the Earth-Moon barycenter around the Sun and in the same direction but just fast enough to have come from and return to galactic orbit without gravitational assist from another body i.e. Moon. Not exactly the same galactic orbit post-solar perturbation as pre- of course but still a galactic orbit. Sagittarian Milky Way (talk) 23:58, 10 July 2023 (UTC)
 * I think Roche limit will be interesting/useful to read. I don't think there will be a sea level well before you reach 1 km. Rmvandijk (talk) 08:22, 11 July 2023 (UTC)


 * What mass do you have in mind? Are we talking about a stellar black hole or what? --Amble (talk) 13:32, 11 July 2023 (UTC)
 * Something that doesn't do more than it has to to be seen. A stellar mass would fuck up the Earth (negligible Hawking radiation though). I do not know if this size range exists in the universe, primordial ones might exist but have never been seen blowing up as evidence for their existence (the detection range would be big by H-bomb standards and small by astronomical) Sagittarian Milky Way (talk) 15:37, 11 July 2023 (UTC)
 * There are papers that look into detectability of close encounters of small black holes with Earth (either a collision or nearby pass). Here is an example: . They conclude that the seismic signature is the most likely to be detectable, and this is consistent with what I've seen considered in other work. As you scale up the mass of the black hole and the energy released, it seems the only thing you'd notice without any special instrumentation would be the increasingly destructive earthquake. --Amble (talk) 18:23, 11 July 2023 (UTC)


 * For ordinary mass black holes passing through the solar system, the most noticable effect would be the X-rays. Through Bondi accretion, the BH collects quite a bit of gas from the solar wind, turning it into X-rays, making the BH a dangerously bright X-ray source. When taking a lower mass BH, the safe distance decreases and tidal forces will eventually get more dangerous than X-rays, but that's for very low mass, primordial BHs. If a one-solar mass object passes through the solar system at typical interstellar velocity, it has to get relatively close to a planet (compared to the distance from that planet to the sun) to significantly affect that planet's orbit, else there's not enough time to exchange significant momentum. PiusImpavidus (talk) 19:01, 11 July 2023 (UTC)

What is the chemical class of Acitretin?
I'd like to read on very very similar molecules. Is this molecule of any specific group, more specific than just "Retinoids"? Thanks. 2A10:8012:7:1FEE:4051:9C9D:C970:2285 (talk) 19:54, 10 July 2023 (UTC)
 * Retinoids are a class of chemical compounds that are chemically related to vitamin A. The first-linked article shows molecular diagrams for the four generations of retinoids. Philvoids (talk) 09:29, 11 July 2023 (UTC)
 * It seems like retinoids are the most specific class acitretin belongs to. If you want to find highly similar compounds try searching PubChem or other chemical compound databases you have access to. &#8213; Synpath 16:50, 11 July 2023 (UTC)

Integrated science
how to  make  a  functional  simple  distillation  apparatus. 105.161.231.62 (talk) 21:00, 10 July 2023 (UTC)
 * You might find some useful info in the Moonshine article. ←Baseball Bugs What's up, Doc? carrots→ 23:09, 10 July 2023 (UTC)
 * Does that mention moonshine explosion accidents and how toxic improperly distilled moonshine can be? Sagittarian Milky Way (talk) 00:08, 11 July 2023 (UTC)
 * Of course functional simple distillation can also be used for non-moonshine purposes like seperating seawater into fresh and something even worse to drink and seperating urine into water and concentrated urine. Sagittarian Milky Way (talk) 00:25, 11 July 2023 (UTC)
 * Then eventually (a thousand or more gallons later), phosphorus, as Hennig Brand discovered. Card Zero  (talk) 05:46, 11 July 2023 (UTC)
 * Which is coincidentally also very flammable. Sagittarian Milky Way (talk) 11:19, 11 July 2023 (UTC)

Distillation is the process of separating the components of a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a Still. The simplest example is a Pot still consisting of a single heated chamber and a vessel to collect purified alcohol, as used for batch production of Cognac brandy and Malt whisky. Philvoids (talk) 09:16, 11 July 2023 (UTC)

Before undertaking any distillation, ensure that you have considered the legal and safety aspects. For example distilling alcohol requires a license in many jurisdictions and distillation of flammables (eg for the recovery of solvents from used washings) must be done with great care. Martin of Sheffield (talk) 09:33, 11 July 2023 (UTC)


 * The title is 'Integrated science'. They're probably just interested in doing some chemistry at home. In which case they'll want a glass condenser and the rest of the usual school apparatus and they're not going to be able to supply Al Capone amounts of anything. Copper for moonshine is easier and can be used for a large still - but it is unsuitable for chemistry experiments. One can start learning how to do glass blowing but this is fairly intricate and the equipment is pretty cheap on the web. NadVolum (talk) 11:47, 11 July 2023 (UTC)


 * The question makes no mention of alcohol. When I was in high school, we made a still to separate liquids. It can be used to separate many types of liquids. My memory is that we had to identify which solution was just one liquid, which was a mix of two liquids, and which was a mix of three liquids. The setup was easy. Put a two hole rubber cork in a beaker full of liquid. Shove a thermometer in one hole to measure the temperature of the liquid. Shove that curly glass tube in the other hole. Put the beaker over the lab table flame to heat it up. Liquid starts to drip out of the glass tube. Identify when the temperature suddenly increases - that means it finished one liquid and it is on to the next one. At no point in the lab did we create moonshine. 12.116.29.106 (talk) 12:22, 11 July 2023 (UTC)


 * Well "Integrated science" doesn't really mean much - presumably tying physics and chemistry together?  The OP doesn't mention any substances, all I advised was to be careful over legal and safety issues.  Here in the UK you don't need to be making "Al Capone amounts" to gain the attention of HMRC.  Again, here in the UK, very many years ago I worked in a school lab and we had a continuous still to generate the supply of distilled water for the three sciences.  At the back of my mind I've a feeling that the still had to be registered or something, just to prove we weren't making moonshine, but this was 40 odd years agon and I can't be certain now. Martin of Sheffield (talk) 13:11, 11 July 2023 (UTC)
 * Integrated Science refers (in this context) to an approach or curriculum dealing with the 'natural' sciences as a broad whole rather than as separated disciplines of Physics, Chemistry, Biology etc., often for school and other students who are not going to pursue science-oriented further education to higher levels, and therefore do not need (at that point in their education) to study science to the depths that separate science courses go. Back in the last millennium I used to edit textbooks for IS courses. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 14:32, 11 July 2023 (UTC)
 * Thx, sounds like what used to be called "general science" where all three sciences were handled as a single GCSE. Martin of Sheffield (talk) 15:39, 11 July 2023 (UTC)
 * I think we called it general science as well and joked that you learn two things. Everything poops. Don't mix an oxidizer with an acid (only because that was a day that kept your attention long enough to learn something). 12.116.29.106 (talk) 16:12, 11 July 2023 (UTC)