Wikipedia:Reference desk/Archives/Science/2018 September 19

= September 19 =

How to choose an expert?
If I want to solve an issue -- settling a dispute about an edit in an article in Wikipedia, deciding whether cell phones provoke cancer or taking homeopathic medication -- are we doomed to appeal to an authority to settle the issue? Wikipedia has a rather dismissive attitutde towards credentials, so, it makes the question even trickier. When we admit that we are not competent in a field, how to decide who is competent, when there's a huge body of knowledge in a science? --Doroletho (talk) 00:35, 19 September 2018 (UTC)


 * Wikipedia doesn't "choose an expert", it summarises what the majority of experts have published in WP:Reliable sources, giving both sides where there is wide disagreement.  Dbfirs  06:15, 19 September 2018 (UTC)


 * The leap of faith that Wikipedia makes is that, while it takes an expert to appreciate the validity, limitations etc. of the expert consensus on domain Foo, it does not take one to know what that consensus is. And that is what we describe (alongside significant minority views, public perception yada yada). We proceed exclusively by "appeal to authority". Tigraan Click here to contact me 09:07, 19 September 2018 (UTC)
 * I need to make one minor quibble, "dismissive attitutde towards credentials" is 100% wrong. Wikipedia has a strong respect for the writings of experts that have been published in reliable sources.  Indeed, ALL of Wikipedia is designed to be referenced to the writings of highly credentialed people who have been scrupulously vetted and who's writings are considered highly reliable.  What Wikipedia is (and is rightly so!) dismissive of is a) the claim that because a person in an argument says they have credentials, they should win any disagreement and b) that the existence of credentials (even if valid) in a discussion should override actual, published, reliable sources where the person fronting the argument disagrees with those sources.  Wikipedia loves credentials, it just dismisses people who use claims of credentials to win arguments in opposition to what is written in reliable sources.  -- Jayron 32 11:09, 19 September 2018 (UTC)


 * We have an encyclopedia article: an expert ..."has intense experience through practice and education..." and "is widely recognized as a reliable source."
 * That lede paragraph summarizes it! Expertise is developed by studying, and is established by peer-review.  Whether we are participating in editing or reading Wikipedia, or in any other aspect of our lives, we determine "expertise" by finding many other people who agree with us.
 * This may seem like an oversimplification; it may seem unstable or hazardous; but it works. Alternatives to this method have been proposed; you can study the theory of knowledge to learn about the meta-problem of trying to establish knowledge (and the related concept, "truth"), from first principles; but in short summary, even though many philosophers have proposed alternatives, Wikipedia is one exemplar of a working system in which all knowledge is established through community consensus - including the specific ouroboric knowledge about which members of our community carry even more knowledge.
 * Nimur (talk) 16:01, 19 September 2018 (UTC)


 * Society used to appeal to authorities to settle issues on all matters before the scientific revolution. For 300,000 years humanity has existed we didn't have cell phones, cars, satellites etc. etc., and that changed when the scientific revolution started about 300 years ago. The most important thing that allowed the scientific revolution to succeed was to stop to appeal to authority. Count Iblis (talk) 17:06, 19 September 2018 (UTC)
 * No, we still appeal to valid scientific authorities: Every individual person (like you, me, everyone else here) does not have enough minutes on earth to do every scientific experiment ever done. While what makes science different from other forms of knowledge-making is that one could re-do each experiment (and also that each experiment has the potential to disprove a hypothesis, what is called falsifiability, the ability of a hypothesis to be disproved by experimentation).  What has changed is the type of authority upon which we appeal: the appeal to a scientific authority is still necessary, because we literally cannot expect every citizen to do every experiment themselves; the same applies to authorities in other field: we cannot expect every human to read every historical text ever written; but they should be able to check the sources of reliable historians.  We still appeal to the authority of those scientists because they have a reputation of using valid scientific methods to make knowledge and we still appeal to the authority of historians because they have a reputation of using valid historical methods to make knowledge, etc. etc.  The reliance on valid authority in knowledge building is necessary because no one human can build all of that knowledge on their own from first principles.  At some point, they have to have reasons to trust that someone else is doing it right.  -- Jayron 32</b> 17:20, 19 September 2018 (UTC)
 * Yes, we do need to put our trust in a system, as even scientists cannot go about verifying everything they need to know for their own research. However, this is then the system involving rigorous reviews and independent reproduction/verification of results, so it's not about trusting the judgment of particular individuals. If it's at all possible to have doubts about some result, then such doubts will be the subject of further research. So, it's far more about the whole process making sure that researchers are not going to leave any stone unturned, that allows people to have trust in the results of scientific research. Count Iblis (talk) 20:33, 20 September 2018 (UTC)


 * The traditional approach has been a combination of authority, jury, evidence, and democracy. People expect "good papers" and "good journals" to be run by "the right people", based on ad hominem considerations, but then allegedly random researchers (chosen by authority) review papers and decide based on the text, and then we review the papers by doing a literature search and seeing who is mostly believed.
 * The modern issue is that some trolls might generate more comments than everyone else put together. Papers and whole journals might be the blathering of artificial intelligence.  Such mechanisms have the net effect of disrupting communication, so people retreat into "bubbles" by which they trust fewer opinions, even if less competent, to go through the mass of nonsense and try to pick out something that sounds logical and reasonable.  But then there's also the issue that while in the past a forged figure might be crudely copied and pasted in multiple papers, now we can picture some entities generating convincing forged video, so certainly a good faked PAGE gel.  So long as an honest mind trying to reconcile the logic behind the data can make sense of what is genuine, there might be hope, but how long can that last?  After that, all communication is lost and humans are back to where they were before the invention of speech, but with a superior species of machines occupying their former niche. Wnt (talk) 14:08, 20 September 2018 (UTC)
 * That's the problem of knowledge making in general, and in the end following your train of thought leads only to solipsism, which while logically consistent is not a practical way to live one's life. As soon as one places trust in any concept which cannot be perfectly proven (including, even, what your own senses tell you on a daily basis), one must take some leap of faith that the information one is assuming is real is actually real.  At some point, you have to just trust it, and you can set your own criteria for what is likely to be more trustworthy, but to follow perfect logic and demand that all information require perfect truth to be acceptable, ONLY solipsism works.  -- Jayron <b style="color:#090">32</b> 16:49, 20 September 2018 (UTC)
 * It depends how much effort you want to put into it.  The legal system has a highly-developed way of arriving at the truth.   Cases are originally heard in a court of first instance.   If there is any doubt you can appeal to a higher court, then a still higher court and so on.   At the end of the process you get a well-referenced decision which is very unlikely to be wrong. 92.31.140.53 (talk) 15:08, 20 September 2018 (UTC)
 * Hmmm, I would have said something more like "fifty-fifty". Wnt (talk) 12:28, 22 September 2018 (UTC)
 * Regarding trusting experts and science see our article on argument from authority. --Modocc (talk) 16:40, 20 September 2018 (UTC)

type of turbine in a dam
I have a hydroelectric question about two dams in western Washington, both described in Wiki: the Upper Baker Dam and Lower Baker Dam. Are both dams equipped with Pelton impulse turbines? If not, what kind of turbines are in use? Thanks for your help! It's a wonderful service. Rossroderick (talk) 03:17, 19 September 2018 (UTC)
 * They're 300' dams, so that's enough head for Peltons to make sense. I can't find anything on-line about them to confirm this, although  contains this tiny cross-section image of the new 30MW Unit 4 which looks more like a Francis turbine. Andy Dingley (talk) 11:32, 19 September 2018 (UTC)

Are there any bacteria that are hydrophobic?
My understanding is bacteria in general all thrive in wet/moist conditions, so are there any bacteria that don't like water? Then, are there any bacteria that are neutral in water (don't actually thrive more). Otherwise, bacteria is generally 100% hydrophilic right. 12.239.13.143 (talk) 18:58, 19 September 2018 (UTC).
 * "Hydrophobic" and "hydrophilic" are not typically used to describe organisms. All known cells are bags of water, so in that sense (if you don't consider viruses and prions to be alive) you could describe all life as "hydrophilic", because all life needs water. But not all bacteria are adapted to wet environments. Bacteria or archaea live in every terrestrial environment we've checked, including bone-dry deserts, acid mine drainage, salt lakes, and rock miles underground. Bacteria adapted to those environments will often not do well in others because other bacteria will out-compete them. As you may see, the reason those terms aren't used is they don't have much descriptive power when you try to apply them to organisms. They're too reductive. Plus, it risks confusion with their typical usage in chemistry. --47.146.63.87 (talk) 06:45, 20 September 2018 (UTC)
 * Lipophilic bacteria may be helpful, although I think that article would benefit from some work. Klbrain (talk) 22:48, 22 September 2018 (UTC)

type of hydroelectric turbine in use
Yesterday I asked this:

I have a hydroelectric question about two dams in Western Washington, both described in Wiki: the Upper Baker Dam and Lower Baker Dam. Are both dams equipped with Pelton impulse turbines?

This was the very good answer:

They’re 300’ dams, so that’s enough head for Peltons to make sense. I can’t find anything on-line about them to confirm this, although [16] contains this tiny cross-section image of the new 30MW Unit 4 which looks more like a Francis turbine. Andy Dingley (talk) 11:32, 19 September 2018 (UTC)

I have since learned that the turbine vanes in at least one of the dams have streams of water directed at them, through nozzles, that are controlled by hydraulics, i.e., by oil under pressure controlling the motion of pistons. The hydraulics are used to determine the direction of the flow and possibly the pressure of the flow.

Would that information tend to indicate Pelton impulse turbines or the Francis turbine?

And a second question: Do you know which dam the new 30MW Unit 4 is installed in: the upper or lower dam?

Thanks very much.

Rossroderick (talk) 03:28, 20 September 2018 (UTC)


 * Atleast the technology of the last unit 4 turbine is pretty clear because of its unique feature of being "fishfriendly". All conventional hydro turbines are fischkillers and on top allow only one direction since no fish is fast enough to swim up in them.


 * That it is the newest also gives a clue, because altho it is one of the oldest turbine principles of all, it has only recently become very popular again in modern hydroelectric powerplant constructions.


 * They are called vortex-, low head- or very low head turbines (VLH-Turbines). Seems they are still so brand new and uncommon (altho i had already read about them (wrongly described) as "new innovation" 4-5 years ago) that we actually still dont have an article about them, nomatter they are definitely worth one. I am a little puzzled with the 2 dams tho because these vortex turbines actually dont need a dam and the mentioned sidenote about the benefit for the fish should mean there are 2 of these or the one in the lower dam somehow circumvents the upper to let the fish pass tru both. --Kharon (talk) 04:43, 20 September 2018 (UTC)
 * A Gravitation water vortex power plant is one of the types mentioned in the Low head hydro power article. DMacks (talk) 05:16, 20 September 2018 (UTC)


 * Construction- and engineering-firms still seem in a contest about how to call these. I learned about them under the name vortex hydro turbine. I am pretty sure many more will be build in the future because they are actually very simple and easy to build, yet surprisingly effective and versatile and on top very ecological. So guess some common name will crystallize out in some years. --Kharon (talk) 06:18, 20 September 2018 (UTC)


 * I'm kind of surprised they need a special turbine to spare fish. I mean, haven't any of these engineers heard of FACS sorting? :) Wnt (talk) 13:57, 20 September 2018 (UTC)


 * Lots of methods have been tried to reenable natural diadromous fish migration. Unfortunately only with limited success no matter the serious effort and investments. These new old vortex turbines actually promise a very good solution to that which is surprisingly cheap and effective enough for power generation on top. Besides Hydro power is pretty abundant anyway so dependent on POV it may actually look a bit silly to take such huge investments, just to tinker out a few more % efficiency. --Kharon (talk) 18:02, 21 September 2018 (UTC)