Wikipedia:Reference desk/Archives/Science/2016 June 15

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June 15

How do I initiate a discussion on a paper I've written explaining mass inertia?

I've written a paper that computes mass inertia. I'd like to discuss the paper with knowledgeable people who can point out any deficiencies in my thinking.

The last time I attempted this, I wound up "talking" to immature people with nothing but sex on their minds. I'd really like to discuss the subject with other adults.

I think I can explain mass inertia. Is anyone interested?

Zee99 Zee99 (talk) 00:09, 15 June 2016 (UTC)

Wikipedia is definitely not the correct place to challenge accepted science. The problem here is that LOADS of people "think" they've come up with a new theory in physics, it's actually a very common phenomenon, except that pretty much all of them are wrong, within a very small margin of error. They pretty much all have some fundamental misunderstanding of the existing accepted science, to a greater or lesser extent. I'm guessing you don't have a degree in physics, so I'm sorry if it sounds harsh but the overwhelming probability is that you just don't understand the current science well enough to challenge it, let alone "overturn" something that is already accepted by science. Here are two articles you should read, one from quroa and another from a famous physicist who's emailbox is literally inundated by people proposing "new theories", this is apparently a well known phenomenon for physicists who put themselves in the public sphere. The harsh truth is, there are no shortcuts, if you want to overthrow some existing science, no one is going to do it for you, YOU have to put in the years of study to figure out why your theory is wrong, and if you put in the years and the hard yards and the STILL think your theory is right, only then you might be in a position to start convincing other people. If you do really want to just go and talk to some proper physicists, register to attend a meeting of the American Physical Society. Vespine (talk) 04:17, 15 June 2016 (UTC)

Pretty much anyone can upload to arXiv, though from what I hear papers that don't have a "trusted" person to vouch for them get dumped into the "general" categories, which are pretty much the circular file for all the crank nonsense that gets submitted. What I would suggest is to contact a professor of physics. Be respectful and open to critique and there's a good chance they'll give you some attention, or refer you to someone who can. However I will echo what Vespine said. If you don't have a degree in the relevant fields, don't be at all surprised if your theory turns out to be flawed. Now this shouldn't be viewed as a mark against you. It's great that you're interested in science, and making mistakes is part of learning. But please don't go down the crank route of, when someone highly knowledgeable explains to you why you're wrong, deciding that you're right, everyone else is wrong, and all of science is a conspiracy against you. And hey, maybe you have figured something out, in which case you might be able to get your paper published and help advance scientific knowledge. --71.110.8.102 (talk) 08:47, 15 June 2016 (UTC)

Ok, go for it. Altho I have some ideas about the subject myself. I know mass inertia can be very dangerous. Coz if it lasts long enuff, you get Type 11 diabetes...Myles325a (talk) 06:57, 17 June 2016 (UTC)

Organic chemistry

hoffman bromide reaction mechanism — Preceding unsigned comment added by Tej Bogati (talk • contribs) 07:39, 15 June 2016 (UTC)

This, perhaps? Hofmann rearrangement - though if so, the word is bromamide, not bromide. Your question is very vague, and you really need to make it much clearer as to what you are actually asking. Wymspen (talk) 09:02, 15 June 2016 (UTC)

Adaptive value of mushroom toxins?

Today's featured article, on Amanita bisporigera, got me thinking about something I'd idly wondered about for a while.

Poisonous mushrooms seem to produce toxins that can be extremely complex molecules, and that affect megafauna in a wide variety of ways. Is this "on purpose", so to speak? Less anthropomorphically, do they get any selective advantage from it? It's a little hard to figure out how. I mean, I can certainly imagine that dying animals provide nutrients for fungi, but it takes quite a while before the animal dies; the benefit would seem to be shared with a whole lot of fungi that don't have the toxin. The Amanita ones interfere with RNA; could this be for some other "reason", with the bad effects on mammals being just a side effect? Intuitively that's hard to believe as well, but I suppose possible.

Similar questions for bacteria that produce extraordinarily toxic compounds — C. botulinum, C. tetani, Bacillus anthracis. Now with those, I really can't believe it's an accident — the molecules seem too specifically tailored to kill. I assume the first two kill animals that then provide an anaerobic growth medium for the bacteria, or some such. For anthrax, probably something similar, though it seems extraordinarily wasteful, given that most of the bacteria perish with the animal, and only a few that come out and sporify end up being able to infect other animals and pass on the genes. But nothing that I've read about them seems to address the question head-on. Has there been research specifically on this question? --Trovatore (talk) 09:25, 15 June 2016 (UTC)

Sure, the toxicity of Amanita spp. definitely seems to be "on purpose", insofar as it is widely regarded as an adaptive trait (i.e. one that confers a selective advantage, so I redirected that common phrase). It's not just toxic to megafauna, it's toxic to most eukaryotes. Here [1] is a paper that mentions that, but its primary purpose is examining the adaptations that allow fruit fly larvae to eat Amanita safely (That's why they work as fly traps, hence Fly agaric). Anyway, once you know the toxin defends the fruiting body from many/most potential enemies, then it's fairly easy to see that it has selective benefit, as those that are more toxic will tend release more spores than their less toxic siblings, etc.

For the Clostridium spp. I'm less sure. Honestly until just now I thought that tetanus was sort of a freak accident, but it's hard to say for sure. One thing is clear is that most Clostridium are not toxic to mammals, and even the toxin-generating ones are perfectly happy to do their thing in the soil and never get into an animal. Anyway, my guess/intuition may be wrong, so read these articles [2] [3] and refs therein to get to the bottom of it. One is about a interesting concept of "pathogenicity islands" in bacteria, and the other is "Genetic characteristics of toxigenic Clostridia and toxin gene evolution". They should have some comments on adaptive value of Clostridium toxins. SemanticMantis (talk) 14:57, 15 June 2016 (UTC)

Thanks, SM. I'll see if I can find some time and dig into them.

So your understanding is that the toxins in mushrooms are for defense rather than predation. That seems to have the same problem, though. The poison takes a long time to kick in, so the costs are concentrated and the benefits are shared with other fungi. Unless the animals learn to avoid the toxic ones, which they probably do, but often the toxic ones are hard to distinguish from the safe ones, which complicates the narrative.

When I read about how the bacterial toxins work, I can't believe it could possibly be an accident. There are just too many moving parts that have to work together. What advantage the bacterium gains from it still seems a bit obscure. --Trovatore (talk) 18:48, 15 June 2016 (UTC)

Yeah, maybe it's not an accident; I'm not so good at biochem, and I can't really judge an argument based on complexity or cost of synthesis. I do think some time with those papers will pay off though.

As for the shrooms- one thing to remember is that animals do learn. Not only within lifetime, but also as a selective process acting over generation, wherein things that eat smelly mushrooms die and don't have as many babies. That's why warning coloration works, right? It's not perfect and it doesn't help the odd poison arrow frog that does get eaten, but it's better than nothing , and it's good enough to independently evolve and persist across a wide range of clades, from plants to amphibians to mushrooms. And it's ok if the benefit is shared or if there are look-alikes too - see e.g. Batesian mimicry and Müllerian_mimicry, where aposematic cues can be shared among whole groups of organisms, many of which are fakers. There's limits to how many can fake it before the whole game is up, but that's getting far too lost in the details. One more ref: here [4] is a paper on olfactory aposematism that mentions Amanita's odor as being a deterrent to natural enemies. SemanticMantis (talk) 19:06, 15 June 2016 (UTC)

It might be relevant to bear in mind (as I'm sure you're well aware) that the mushrooms are not discrete organisms, but minor parts of a possibly extensive and long-lived subterranean mycelium which itself is not significantly damaged by individual fruiting bodies being eaten – this merely hampers its reproduction. Consequently, discouraging a particular animal from eating more of them (by noxiousness or toxicity) may well have a significant benefit for that particular mycelium. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:08, 16 June 2016 (UTC)

That is a very good point, thanks. SemanticMantis (talk) 16:06, 16 June 2016 (UTC)

The Bourne identity

Hi WP:RD/S people.
"Bourne" is the family authority for Flabellidae. See ITIS and WoRMS
Who is this Bourne? I did do my best to find out who this most probably notable zoologist may be. And I failed.
Turning it over to you all.--Shirt58 (talk) 13:44, 15 June 2016 (UTC)

A search for Bourne 1905 on Google Scholar finds "Report on the solitary corals collected by Prof. Herdman, at Ceylon, in 1902. by Bourne, G C." Searching for that or 'Flabellidae Herdman bourne' finds it's also mentioned here [5] [6] [7]. Notably [8] says "Published in Bourne, Gilbert C. 1905. Report on the solitary corals collected by Professor Herdman, at Ceylon, in 1902. In: Report to the government of Ceylon on the pearl oyster fisheries of the gulf of Manaar (Herdman, ed.), [Unspecified Publisher]: 187-242 + Pls. I-IV." Searching for 'bourne gilbert c ceylon' finds [9] and [10]] which mentions a Bourne, Gilbert Charles. Searching for that name finds Wikisource:Author:Gilbert Charles Bourne, Wikispecies:Gilbert Charles Bourne and [11]. Nil Einne (talk) 14:58, 15 June 2016 (UTC)

When do scientists predict we will have warp drive

When? 100 years from now? 200? 1000? When? — Preceding unsigned comment added by Uncle dan is home (talk • contribs) 18:26, 15 June 2016 (UTC)

Never. As best as anyone can tell such a thing is impossible. There are mathematical theories that allow such a thing, but they are math, not reality. The math may turn out to describe reality, or it may not, no one knows. See Alcubierre drive for more on this. Ariel. (talk) 18:36, 15 June 2016 (UTC)

Depends what you mean by "warp drive". If you mean some kind of magic engine that will accelerate your spaceship to a superluminal velocity, such a thing is impossible based on our current understanding of physics. There may be some (almost literal) loophole that lets you travel to distant locations by using a wormhole, but this is highly speculative and the technology required is far out of our reach. CodeTalker (talk) 19:39, 15 June 2016 (UTC)

As the article notes, the Alcubierre drive doesn't violate general relativity. This doesn't necessarily mean it's possible to construct one, but it's perfectly consistent with relativity. --71.110.8.102 (talk) 00:40, 16 June 2016 (UTC)

It's "consistent" with general relativity only inasmuch as you can take any differentiable spacetime manifold, plug it into the GR field equation, and get a stress-energy tensor. Finding a "solution" of this sort takes no effort; literally anything is a solution. In most cases, the stress-energy tensor bears no resemblance to anything that could arise from actual matter obeying physical laws. As soon as you add any physical constraint, by imposing one of the energy conditions for example, warp drives are excluded. For a longer rant on this subject, see my long post in this thread. -- BenRG (talk) 22:00, 16 June 2016 (UTC)

But hasn't something similar to warp drive been observed with galaxies moving further apart from us faster than the speed of light?Uncle dan is home (talk) 06:02, 17 June 2016 (UTC)

In cosmology, nothing ever outruns a light beam. Even in special relativity you can have more than 299,792,458 objects in a line, each moving at 1 m/s away from the objects next to it. If you add up those relative speeds, you get a value greater than c (= 299,792,458 m/s). (If you add the speeds using the special-relatlvistic formula, you get a value less than c.) Large cosmological recession speeds are likewise just the sum of adjacent speeds that are less than c, and the fact that the sum exceeds c doesn't really mean anything. (Unlike special relativity, there's no other way of adding the speeds to get a value less than c; instead, the relative speed of distant objects in curved spacetime is just not well defined.) -- BenRG (talk) 17:52, 17 June 2016 (UTC)

By warp drive, i mean ships that can warp space,creating a bubble that can travel faster than light. The spaceship itself doesn't move faster than light, it's the bubble that moves faster than light. — Preceding unsigned comment added by Uncle dan is home (talk • contribs) 21:44, 15 June 2016 (UTC)

Well, warp drive has a "Real-world theories and science" section... Dismas|^(talk) 00:30, 16 June 2016 (UTC)

Some scientists say "never". There's no reason to suppose a warp drive is necessarily possible. As noted, the Alcubierre drive has gotten a lot of attention, and is theoretically possible under general relativity, but there are a lot of problems that make many think it's not possible to actually construct one. It's quite possible constructing a warp drive is impossible, and we will always be limited by c. --71.110.8.102 (talk) 00:40, 16 June 2016 (UTC)

Your great great grand children may well be robots who can travel at the speed of light by uploading the information in their electronic brains via radio communications to some machine at a distant location. They probably won't bother attempting to build fancy spacecraft. Count Iblis (talk) 06:19, 16 June 2016 (UTC)

Household wiring

In a split-phase electric power system, is there an easy way to identify which outlets are line-to-line and which are line-to-ground (without having to rip up the drywall to examine the wiring itself)? 2601:646:A180:C88C:F88D:DE34:7772:8E5B (talk) 21:24, 15 June 2016 (UTC)

Assuming you're in the USA, see NEMA connector. The 120 V sockets have vertical blades, the 240 V sockets have horizontal blades. Tevildo (talk) 21:51, 15 June 2016 (UTC)

I've checked out NEMA connector, and the table actually shows that some of the sockets can be used with either 120V or 240V (and look like 120V ones). In these cases, how can I tell for sure? Do I have to check them with a voltmeter, or is there an easier way?

2601:646:A180:C88C:F88D:DE34:7772:8E5B (talk) 22:09, 15 June 2016 (UTC)

The NEMA-14 socket has four contacts (both phases, ground, and neutral), so can be used with both 120 V and 240 V appliances depending on the plug wiring; however, it'll always have both phases connected to it. There isn't a three-pole NEMA socket which can (legally) be connected either between phase and neutral or between phase and phase. If you're confident that you can use a voltmeter safely, that probably is the easiest way of checking any sockets you're not sure about. Tevildo (talk) 22:32, 15 June 2016 (UTC)

Just went down to the garage -- almost all of the sockets there are standard 5-15 120V type, but there's one which is different and is not one of the NEMA standard types -- it looks like a NEMA 10-30, but with an extra triangular hole in the center. And in the fuse box, there are 2 double-pole circuit breakers, one rated for 15 amps and the other for 30 amps -- the 30-amp one seems to correspond with the oddball socket and is labeled "Dryer", but the dryer is not plugged into the oddball socket but into one of the 120V ones along with the washer and the central vacuum. Is the oddball socket the 240-V one? (The other double-pole circuit breaker is labeled "Dishwasher" -- should I look for another non-standard socket under the kitchen counter?) 2601:646:A180:C88C:F88D:DE34:7772:8E5B (talk) 22:37, 15 June 2016 (UTC)

One of these? That's a 10-30R, the hole is to ensure the plug isn't inserted incorrectly. It will have (or, rather, should have) both phases and neutral, but no ground. Tevildo (talk) 23:11, 15 June 2016 (UTC)

Yes, exactly! So, the voltage would be 240V between the two diagonal slots, and 120V between either of these and the L-shaped one, right? 2601:646:A180:C88C:F88D:DE34:7772:8E5B (talk) 23:21, 15 June 2016 (UTC)

Yes. See, for example, this article. Glad to be of assistance! Tevildo (talk) 23:46, 15 June 2016 (UTC)

Thanks! 2601:646:A180:C88C:F88D:DE34:7772:8E5B (talk) 00:39, 16 June 2016 (UTC)

Regarding the dishwasher... In our house (in Canada) in the kitchen there are split duplex outlets, where the upper and lower outlets are on opposite phases. These are wired to a double-pole breaker since live wires from two circuits are in the same electrical box behind the outlet. This arrangement lets us draw up to 15 A from the upper outlet and 15 A from the lower outlet simultaneously. However, the same 15 A, 120 V circuit feeding one half of one outlet also powers the dishwasher. So the dishwasher is supplied through a double-pole breaker even though it runs on the normal single-phase 120 V. Possibly you have the same arrangement.  As to a socket, until recently all our dishwashers had screw connections and were directly wired into the circuit, but our newest one came with a standard plug and we therefore had a standard duplex socket installed inside the adjacent cupboard. --69.159.60.83 (talk) 09:35, 16 June 2016 (UTC)

Unless I've misunderstood you just measure the voltage. Ariel. (talk) 21:52, 15 June 2016 (UTC)

Assuming the OP is confident they can work safely with mains voltages. I would not encourage someone to stick things into electrical outlets unless they know what they're doing. If the OP has any doubt about their house wiring, they should contact an electrician (or their landlord). Tevildo (talk) 22:01, 15 June 2016 (UTC)

I'm shocked to hear that a clothes dryer runs from a 120 outlet.(Of course I have been shocked numerous times at circa 120 volts DC and AC). How many watts does the clothes dryer use? Edison (talk) 03:15, 16 June 2016 (UTC)

Berry punny. 120 V dryers do exist. It's fairly common for small apartment-sized units to run on 120 V. Shock Brigade Harvester Boris (talk) 03:53, 16 June 2016 (UTC)

Depends whether the dryer is heated by gas or electric. An old apartment of mine had one that was gas with 120V for timer and tumbling (and maybe gas ignition?). But behind it was an unused 240V/high-amps receptical because the landlord was planning to switch to all-electric instead of supplying gas. DMacks (talk) 18:14, 16 June 2016 (UTC)

While I agree that sticking multimeter probes into the outlet is probably a bad idea, they do sell receptacle testers, which are no more hazardous to use than plugging in a toaster. Talk to your local hardware store/home improvement center, and they hopefully should be able to point you to one that will work for your situation. (Fixing any problems identified, though, that might involve an electrician.) -- 160.129.138.186 (talk) 20:02, 17 June 2016 (UTC)

Already done (with a voltage tester, not a receptacle tester), and it works -- in fact, at first glance, it would seem to work too well, because the tester is showing 277V AC (out of 4 choices, the next higher one being 480V AC). I think it may be because the tester measures the peak voltage instead of the RMS -- is this true? 67.164.54.236 (talk) 04:15, 18 June 2016 (UTC)

As the article voltage tester says, an AC tester designed for mains voltage usually consists of a neon bulb connected in series with a ballast resistor. From your description, the one you used shows voltage ranges, meaning that several neon bulbs are used with resistive voltage dividers, just as the article says. A neon lamp lights (strikes) at 90 volts, so the appropriate neons will light for all dividers whose division results in 90 volts or more, even if that is at the peak voltage of the AC waveform. That is, the tester is a peak-indicating device in a bar-graph format. The voltage range indicated (277 V) suggests that the voltage at the outlet is 220-240 VAC (310-339 V peak - obtained from V_RMS x 1.414). Akld guy (talk) 23:55, 18 June 2016 (UTC)

It would be useful to know what the other choices on the tester are. 277 is 480/√3 and is therefore the RMS voltage between any two hot wires of a 480  3-phase feed. I think this is a system used industrially in some places but it certainly should not occur in a household supply. --69.159.60.83 (talk) 04:56, 19 June 2016 (UTC)

For non-electricians, I recommend the "Kill-O-Watt" meter: [12]. It's much easier to use than a multimeter, and there's no risk of damaging it by connecting it with the the wrong settings selected. StuRat (talk) 05:09, 19 June 2016 (UTC)

Badgers and mushrooms

(Inspired by the above question re Amanita). In Phallus impudicus#Spore dispersal, there's a rather confusing sentence - "the proximity [of the fungi] to badger carcasses entices the flies to lay their eggs and help ensure that they are more quickly eliminated, removing a potential source of disease." I'm not sure what "they" refers to, and what is being protected from disease - the badgers, the flies, or the fungi? The causality also seems the wrong way round - I could understand if the argument was that the dead badgers attract the flies, and the flies encourage the fungi, but that's (apparently) not what the article says. Any help would be appreciated: I've also asked on the article talk page, but I'm sure the Science desk will be more responsive. Tevildo (talk) 21:36, 15 June 2016 (UTC)

Badger carcasses? We don't need no stinking badgers! (Sorry, I couldn't resist.) CodeTalker (talk) 22:09, 15 June 2016 (UTC)

Tree < Lion = Kenya Wins

Yeah, that's a mess. TLDR: "they" means "the badger carcasses", and who is protected from disease is the surviving members of the colony. I skimmed this paywalled ref [13]. It says "The benefit to badgers of this relationship is that the blowflies would rapidly and efficiently remove badger cadavers, which are potentially dangerous as disease reservoirs for the rest of the badger social group."

So it goes like this: all these shrooms attract flies. Shrooms near a badger sett attract flies that then also have a relatively high likelihood of finding a nice carcass in which to deposit eggs. Shrooms are fly laxative, and so flies poop after eating shrooms, and so a colony of shrooms can build up near a badger set. Badger setts that have shrooms nearby are then relatively more protected from disease, compared to setts that have no fungal associates. In this manner, shrooms, flies, and badgers all benefit from a positive reinforcement based on proximity.

Can you fix up the article from there? I can provide a pdf of the ref if anyone wants it. (BTW, some badger sets in EU have persisted for several centuries, perhaps longer. I recall something about old abbey records used to date a colony to a very surprising age. Anyway, this happy poop-death-fly-mushroom loop probably helps that long-term stability. Social insects are vigilant about casting out their own dead to keep the colony clean, but I don't think badgers have figured that out - and why bother, if some neighboring shrooms and flies will take care of it for you?) SemanticMantis (talk) 22:47, 15 June 2016 (UTC)

Thanks very much! Sleeman's text is sufficiently clear (although I still think the theory sounds a bit dubious, but that's not an issue here). I've made some appropriate changes to the article; of course, further improvements are always to be encouraged. Tevildo (talk) 23:30, 15 June 2016 (UTC)