Wikipedia:Reference desk/Archives/Science/2016 February 27

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February 27

Rietdijk–Putnam argument

I was reading the article on Rietdijk–Putnam argument, specifically the Andromeda paradox and it got me thinking. So the car driver can see the Andromeda galaxy one entire day ahead of the pedestrian. If he were to slam on the brakes or make a U-turn, wouldn't he see the events in the Andromeda galaxy slowing down significantly or even unfolding backwards in time, and wouldn't that create pretty much the mother of all Doppler shifts? 93.136.14.136 (talk) 01:55, 27 February 2016 (UTC)

Your intuition about planes of simultaneity going backwards in time is correct, but you don't see events on a plane of simultaneity. What you actually see is events on your past light cone, and your past light cone at a given moment doesn't depend on your speed at that moment, so changing your speed doesn't instantaneously change what you see.

The redshift/blueshift you will see if you're moving at velocity v toward/away from Andromeda is ${\sqrt {\frac {1+v/c}{1-v/c}}}$. Acceleration doesn't affect that except inasmuch as it changes your velocity. The speed of everything is changed by the same factor—a factor-of-2 blueshift not only doubles the frequency of all light but also makes clocks appear to be running twice as fast and so on. The factor is never negative so time never appears to run backwards.

Rietdijk and Putnam's argument only demonstrates that they don't understand special relativity. Planes of simultaneity are physically meaningless. There's no experiment that can detect the "present existence" of things on a plane of simultaneity. In fact a "computer running the universe" can store just the present state of the universe on some spacelike surface. It doesn't have to keep earlier states around. That's not to suggest that the universe really works that way, but the existence of that model means that any argument that the past must still exist is wrong. -- BenRG (talk) 08:32, 27 February 2016 (UTC)

The main confusing thing about relativity is that different things change at once. Suppose for ease of illustration you walk toward a galaxy at relative rest to you (not Andromeda). Your light cone tips toward it, and "the same time" there (for you) becomes earlier. And the distance to the galaxy becomes less (Lorentz contraction). And the rate at which time is passing on it changes (time dilation). And the light reaching you from it seems bluer, which represents a general fast-forward in how events on it seem to be playing out (which is different from the time dilation, because your view of the light depends on the galaxy's apparent motion toward you). Keeping track of all these things is challenging, but somehow the math all works out. But when we say simultaneity is "meaningless", what that really gets at is that there's nothing to calculate - you can't see time reverse this way, once all the other factors are considered. Wnt (talk) 09:27, 27 February 2016 (UTC)

The light cone doesn't tip. Its direction is fixed by the geometry of spacetime. There's a different light cone for every spacetime point, but not for different speeds.

The rest of what you said is mathematically true, but physically meaningless. It's exactly analogous to the following in Euclidean geometry: draw a straight line (Andromeda's worldline) and a curve (your worldline). Then draw lines perpendicular to the curve and see where they intersect Andromeda. When your curve bends away from Andromeda, the intersection with Andromeda moves rapidly forward in Andromeda time. When your curve bends toward Andromeda, the intersection with Andromeda moves rapidly backward in Andromeda time. When your curve is straight but not parallel to Andromeda's, the intersections with Andromeda are spaced farther apart than the intersections with you (time dilation). This is all true, but why were you drawing those perpendicular lines? The two worldlines represent the locations of two physical objects in spacetime, but the lines between them represent nothing. Absolutely nothing. I always have trouble convincing people of this because every introduction to relativity assigns enormous importance to these perpendicular lines. But they are 100% human inventions. -- BenRG (talk) 22:24, 27 February 2016 (UTC)

Heh, you're indeed right about the light cone per se not tipping. It's only this imaginary "waist" of the light cone that tips, and if the "waist" can tip without the cone tipping I guess that would be a clue that something is very peculiar. :) Wnt (talk) 11:17, 28 February 2016 (UTC)

Names of newly discovered taxa

The question was asked previously, but having read I think it missed the point when it comes to novel species discovered in modern era. For example, crested eagle described by French Daudin in 1800 is known in French as "harpie huppée" and in Russian as "гвианская гарпия" (literally, Guinean harpy). Obviously Daudin wasn't the one who gave it English or any other non-French common name. Who gives such common foreign names? Or the family Mimid (introduced by Bonaparte in 1853), which in Russian is called Пересмешниковые (literally, the mockingbirds). What authority usually assigns foreign-language common names in such cases? Brandmeister^talk 09:54, 27 February 2016 (UTC)

1) English is not the default language of the world, and "foreign language" is not subservient to English. 2) Common names are not necessarily assigned by any authority in every known language in the world. No one decided that the Spanish word for dogs would be "perro" and it would be "chien" in French and 犬 in Japanese. There is not a central committee in the world which decides what every language will use for its own words. --Jayron32 16:27, 27 February 2016 (UTC)

That's obvious, I mean new species for which there was no prior knowledge and consequently, a common name. Who gives them common names in languages other than that of scientific description? Brandmeister^talk 20:01, 27 February 2016 (UTC)

But from Bengal to Belize and Las Vegas to Lahore, the language of the sceptered isle is rapidly becoming the first global lingua franca. AllBestFaith (talk) 18:25, 27 February 2016 (UTC)

Short answer is which ever name in that language serves to identify a new creature and comes into 'common' usage. As François Daudin was a well know zoologist, the name he gave to this bird served to distinguish it from any other bird and thus passed into common usage. A resent example is the 'Bondo Mystery Apes'. First re-discovered near to the Congo town of Bondo and then near the Congo town of Bili. As both these are in the Bili Forest, Bili ape is quickly becoming the common name – and both are easy to pronounce. So it is a case of survival of the fittest names. A another common feature to 'common names' apart from pronunciation is catchiness. For an example of catchiness, is the suppose 'wood ape' of North America. Native Americans have many names for it according to their own languages but 'Bigfoot' quickly became the common name in the 1950's but remained as Yeti in the Soviet Union; despite them also having big feet.--Aspro (talk) 14:43, 28 February 2016 (UTC)

The above are all correct, and it's largely just the first word that catches on. If anything catches on at all, which it usually doesn't. Here's some additional info you might find helpful. There simply is no naming authority for common names. We have IUPAC for formal chemical nomenclature and ICZN for formal animal names and even International_Cultivar_Registration_Authority for naming your club's prize roses. But none of that matters at all. "Daddy long legs" can mean a harvestman, a spider, a fly, or even a plant, depending on who you ask and where. Some places it even means all of these! Nobody can tell people they can't call a crane fly a daddy long legs if they want to.

The other thing to remember is that most species never get common names, because they never get talked about enough to gain one. You may be interested in reading up on neologism, slang, and word formation, which all have have relevant infor about how new words, including names, develop organically. Here [1] is an image gallery proposing alternate common names for various animals. The goal their is humor, but they are not wrong names either. The moment I say cat snake or trash panda and you know I mean a ferret or a raccoon, then that is a perfectly valid common name. SemanticMantis (talk) 18:30, 28 February 2016 (UTC)

Science papers with photographs of the authors on the first page

Today I came across this weird paper with color photographs of the authors on the first page[2]. I've never seen something so bizarre before.

How common is this? I.e. what percentage of scientific papers have photographs of the authors on the first page?Johnson&Johnson&Son (talk) 12:29, 27 February 2016 (UTC)

Very uncommon. If you read German, de:Metalurgia International has the story of this particular paper and journal - basically, the journal is known as a pay-to-publish vanity press without proper quality control, and the paper was written as a sting operation to uncover this. --Stephan Schulz (talk) 12:44, 27 February 2016 (UTC)

In mathematics, the College Mathematics Journal, published by the Mathematical Association of America, has color photos of authors on the first page. So the practice is not entirely limited to the vanity press. Loraof (talk) 15:00, 27 February 2016 (UTC)

By coincidence, just today when researching for a WP article, I found this[3] (note the photos). This journal has been around since 1992 and I doubt very much it would be described as a vanity journal. I don't know whether photos appear on a hard-copy of the journal.DrChrissy ^(talk) 16:57, 27 February 2016 (UTC)

Follow-up. It looks as though the photos are inserted by ResearchGate, rather than the journal.DrChrissy ^(talk) 17:01, 27 February 2016 (UTC)

It's fairly common for posters at conferences to have pics of the author(s) at the top. In that case the pics have practical value, so that you can recognize the authors in the crowd and ask them about their work. But that obviously doesn't apply for a journal article. Honestly, I can't see any point whatsoever in having pics of the author in a journal article other than ego and flashiness. For better or worse we'll probably see more and more of this as journals try to jump on the social media bandwagon. Shock Brigade Harvester Boris (talk) 17:14, 27 February 2016 (UTC)

It depends on the field and journal, to some extent. Generally speaking, I've found it's rare to see it on research papers, but it does sometimes happen with review and perspective articles. For example, Angewandte Chemie (a highly respected journal in chemistry) doesn't do anything like it for its research papers, but all of its review articles have photographs and short biographies of all the authors as part of the article itself. (As does ChemBioChem, from the same publisher.) Chemical Society Reviews and some of the other journals from the Royal Society of Chemistry do this as well. ACS Chemical Biology doesn't attach pictures and biographies to the papers themselves, but does have a separate "Introducing Our Authors" section, which has selected pictures and bios for both review and research authors. In contrast, the Journal of the American Chemical Society (by the same publisher as ACS Chemical Biology) normally doesn't provide any sort of biography or photographs at all. - To make an unsupported generalization, I'd say including photographs and biographies on reviews tends to be more prevalent in European journals, and less so for American ones, though that's not hard-and-fast. -- 160.129.138.186 (talk) 20:22, 27 February 2016 (UTC) (by edit request) ―Mandruss ☎ 20:35, 27 February 2016 (UTC)

As I recall, IEEE papers have tended for a very long time to have a black-and-white photo with a one paragraph bio for each author at the end.

Question: which Open Access journals do this, and should we be copying the photos to Commons? Jheald (talk) 21:01, 27 February 2016 (UTC)

Does this mean articles in Open Access journals are not subject to copyright?DrChrissy ^(talk) 21:08, 27 February 2016 (UTC)

DrChrissy That depends on what kind of Open Access :-) PLOS use CC-BY [4]. There's a fair amount of discussion of gratis vs libre at our article Open access. Jheald (talk) 21:14, 27 February 2016 (UTC)

Thanks for the reply. I was thinking about copyright in terms of using images from Open Access journals. I'll raise it as a specific question at Commons next time I feel the need to use an image. DrChrissy ^(talk) 21:17, 27 February 2016 (UTC)

You need to check the terms for the particular journal; possibly even the particular article in some cases, I think. Commons has (or had) a c:Commons:Open Access File of the Day, though I don't know whether or not that's still running; there's also c:Category:Open access (publishing) which contains categories of images from different OA journals; while here on Wikipedia there is Wikipedia:WikiProject Open Access. Jheald (talk) 22:10, 27 February 2016 (UTC)

Why is everyone whispering? Shock Brigade Harvester Boris (talk) 01:10, 28 February 2016 (UTC)

• Agreed it's not unheard of for review articles. I wrote an invited review for a new-ish but serious biomedical journal two years ago and was somewhat surprised to have them ask for photo and potted biography. Fgf10 (talk) 23:55, 27 February 2016 (UTC)

I know it's not in the scope of the OP's question, but paper that the OP links to is gibberish; perhaps it's computer-generated, posing as human-generated, as in some sort of Turing test? Robinh (talk) 19:18, 28 February 2016 (UTC)

• As Stephan Schulz rather cryptically pointed out above, that paper is a spoof along the lines of the famous Sokal affair -- see http://retractionwatch.com/2013/09/23/a-serbian-sokal-authors-spoof-pub-with-ron-jeremy-and-michael-jackson-references/ for a full account. Looie496 (talk) 15:18, 29 February 2016 (UTC)