Wikipedia:Reference desk/Archives/Science/2016 February 23

= February 23 =

Updates on Desert Varnish?
Is Desert Varnish alive? I haven't seen any updates. If this is considered alive will this mean that the shadow biosphere is more probable? 199.19.248.47 (talk) 02:13, 23 February 2016 (UTC)


 * That would depend on whether the microbes in the desert varnish are similar to known microbes. StuRat (talk) 03:17, 23 February 2016 (UTC)


 * As I understand it, there are few if any detected bacteria or other 'normal' lifeforms in the varnish. The huge question is whether there is any other kind of highly atypical life living in there and responsible for the otherwise-hard-to-explain chemistry of the varnish.  So, the idea occasionally shows up that there might perhaps be some completely different forms of life in there.  Stuff that's maybe not DNA or even RNA-based.  Such a thing would go a long way to explaining the unlikelyhood that abiogenesis seems to have happened only once...by proving that it actually happened more than once.  If that were found to be the case, then the conclusion would have to be that life would always form with near 100% probability in any suitable environment - and from that we would extrapolate that there is life everywhere in the universe - and from that we get into the Fermi Paradox and the Great Filter - and from that we can deduce that humanity is doomed to be wiped out within a couple of generations as all other intelligent life in the universe evidently has been.   Big BIG conclusions would likely emerge from the discovery that there is some kind of non-DNA/non-RNA life living there.


 * But we haven't found it yet. I presume scientists have looked there - but detecting that life exists, based on unknown chemistry - and evidently being very, very slow lived - would be exceedingly difficult. On the other hand, we don't have an alternative explanation for the varnishes' peculiar chemistry - and an exotic lifeform would be a possible explanation for that.


 * So - conclusion so far? We don't know.
 * SteveBaker (talk) 03:42, 23 February 2016 (UTC)


 * Quoting from "Biogeological Analysis of Desert Varnish Using Portable Raman Spectrometers" published in Astrobiology (journal):
 * "Desert varnish, also known as rock varnish or desert patina, is a thin skin (often only microns in thickness) comprising iron(III) oxides, manganese(IV) oxides, and clays on the outer surfaces of rocks located in either hot or cold desert environments (Potter and Rossman, 1979). The first suggestions that desert varnish might have a biological origin were made independently by White and Laudermilk (White, 1924; Laudermilk, 1931), both of whom postulated that botryoidal nucleation could arise from epilithic manganese-oxidizing bacteria, fungi, and algae in desert conditions. This was later confirmed by Krumbein and Jens (1981) and by Dorn and Oberlander (1981). A comparison of desert varnish morphologies (containing biomineralized manganese oxides) with microstromatolites was performed by Raymond et al. (1992), and the incorporation of biomineralized silica by bacterial colonies was reported by Westall et al. (1995)."
 * Indeed, one study even found manganese oxidizing bacteria in desert varnish, and that's from 1981. There are also various spectroscopic studies easily found on pubmed that find common metabolic products in desert varnish. I think at this point the evidence is extremely compelling that at least some desert varnishes are of organic nature, and the causative organisms are no more unusual than other extremophiles. There is a possibility that some desert varnishes do not arise in the same fashion, but at this point I would take Occam's Razor and assume they're all caused by normal life forms. Someguy1221 (talk) 09:00, 23 February 2016 (UTC)


 * For example, the extremophile life by a black smoker is quite strange. StuRat (talk) 14:35, 23 February 2016 (UTC)


 * This is a student paper on the topic, but it seems to cover most of the bases nicely, and has a bibliography that includes both many recent studies and some of the older key works. SemanticMantis (talk) 17:08, 23 February 2016 (UTC)


 * Awesome - I've updated my response. SteveBaker (talk) 17:13, 23 February 2016 (UTC)


 * Interesting question! This looks like a good source if the Google Copyright Gods smile on you.  More generally, the thing that gets me is the statement going back to this paper that desert varnish is nucleated.  What I haven't seen is whether there is any useful genetics to this nucleation.  Can you create nuclei of different morphologies of varnish (lamellar, botryoidal I think were examples given) and have the regions grow up that way?  If so, then the varnish would seem to have genetics.  But I didn't see reference to such an experiment.  (A pity ... you'd think it would be a money-maker for construction and other stoneworking to select out forms that would have desirable properties, e.g. transparency, and to pretreat stone surfaces with them) Wnt (talk) 17:53, 23 February 2016 (UTC)
 * It's definitely interesting - but not just for practical applications. If we could show that there exists life here on earth that shares no evolutionary history with life-as-we-know-it - then...
 * We'd know that abiogenesis is a commonplace thing.
 * Which implies that the numbers in the Drake equation change drastically in favor of more life elsewhere in the universe.
 * Which lends teeth to the Fermi paradox.
 * Which means that the Great Filter is alarmingly real.
 * Which means that humanity is almost certainly doomed to near-extinction within a handful of generations.
 * Better hope it's not there. SteveBaker (talk) 16:14, 25 February 2016 (UTC)
 * This really isn't that obvious to me. We see all sorts of "life" that has a 1-bit genetic code - fire, salt crystallization, that kind of stuff.  If it counts, prions are sort of more than that - I remember there's an apparent difference between kuru and Creutzfeld-Jakob disease, AFAIR, said to be based on some mysterious variation in what misconformations of the protein are possible.  (here's an approachable reference about that)  It's at least conceivable that there could be several kinds of "life" with ten bits of genetic code on the average planet, that were incapable of progressing further, while biological life is preposterously unlikely.  (But no, I think there's a Great Filter ... at least, if you're using the term right, from the article I get a different gloss.  I mean, how long can you live with nuclear weapons pointed at you and not think...) Wnt (talk) 02:20, 27 February 2016 (UTC)

Rorschach's mask
Kovacs Rorschach.png - Rorschach with and without his mask

A fictional character called Rorschach has a mask that is described as follows:

"Rorschach's mask, which he considers his true "face", is a part of fabric made from a material derived from the technologies of Dr. Manhattan, and it is blank except from the front, where two viscous liquids, one black and one white, are between two layers of latex. The liquids continually shift in response to heat and pressure, which explains why the liquid only animates when Rorschach puts it on his face. The black liquids form symmetrical patterns like those of a Rorschach inkblot test while never mixing with the white color of the mask, thus never producing a gray color, much like Rorschach's view of morality and the world."

- Rorschach (comics)

Would it be possible to create something like that in real life? How? The restriction on non-symmetrical patterns can be ignored.

The Quixotic Potato (talk) 18:44, 23 February 2016 (UTC)


 * Sure, if you're willing to ignore the symmetry. Miscibility gives some information on when liquids do mix. When you have two or more liquids that won't mix, you call it a Multiphasic_liquid. A common example is Vinaigrette. Emulsion is what would happen if Rorschach slept on a vibrating bed or otherwise was subjected to long-term agitation, though often emulsions will settle out and unmix if given enough time. Here's eight minutes of slow-motion video showing a multiphasic mix of water, oil and milk that illustrates the immiscibility of oil and water.   SemanticMantis (talk) 19:21, 23 February 2016 (UTC)
 * Also, there are temperature-sensitive liquid crystal applications. See, for example Liquid crystal thermometer.  Something like that could be impregnated in the mask, and could perhaps produce the desired results.  -- Jayron 32 19:34, 23 February 2016 (UTC)
 * It should be quite easy to achieve this effect with help of the upcomming OLED-technology, including building advanced masks with it. Certainly much more impressive stuff even like personifying other people. You can find this in nature too. Cameleons, octopuses and squids have brought this beyond perfection including surface changes and using this to hypnotize prey youtube sample. It should be possible to build something alike a squid skin with technology but you will need a Billionair to pay the bills. --Kharon (talk) 21:14, 23 February 2016 (UTC)
 * To clarify, I think it will be hard to make an actual mask that looks cool and "works" like the one described. But milk, motor oil and clingfilm should illustrate that the concept works just fine, even with cheap, easily accessible materials. SemanticMantis (talk) 21:40, 23 February 2016 (UTC)
 * In concept, this is essentially a lava lamp. Making one work in 2D is a bit demanding in that both liquids have to wet the containing surfaces equally well, I think.  In a stereotypical lava lamp, the wax balls are permitted to totally avoid contact with the containing surface, but if the liquids are very black and very white, that would make the visible surface all one color, or at least tinged with it.  Wnt (talk) 21:53, 23 February 2016 (UTC)
 * I think current EPaper solutions would work here too. They have the advantage of being flexible and reacting to sunlight appropriately - it would also make getting the symmetry to work easy.  But if you truly want the mixing of fluids per the description of how it works, kinda like a 2D lava-lamp - then that's harder - and if it has to react to the skin beneath and stay symmetrical - then I think it's impossible without electronics. SteveBaker (talk) 16:05, 25 February 2016 (UTC)

I love the Reference desk. Thanks everyone, very interesting answers! I will have to do some research. The Quixotic Potato (talk) 16:56, 27 February 2016 (UTC)