It reminds me of PNP & NPN transistors. Could these liquid "defects" have applications too?
Ever since childhood I've wondered why the water behind a rowboat stays flat for so long. You'd think the surrounding water would flow in and make it as wavy as everything else. Then a few years ago I was on Thera and saw the same thing with the cruise ships coming in. Their flat glassy trails would last for hours. Why does it take so long for them to vanish? It is a liquid transition that is weirdly persistent. Does anyone have an answer? If not, maybe this can be someone's wobbling plate.
If I recall correctly, I think this is usually explained as a thermocline effect where as deeper water gets churned up and mixed in the wake, it is a different temperature than the surrounding water outside the wake. This water has ever-so-slightly different fluid characteristics and so it presents a bit of a barrier to the usual diffusion and mixing you might expect.
There's also the potential for a very thin layer of some type of hydrophobic substance (like an oil) to be left behind that can dramatically reduce waves in that area. There's youtube videos around for that effect.
IDK but one factor is most of the water filling the gap would come from underneath (it's at higher pressure), moving up to the surface. Its momentum carries it slightly too high, so it flows outward, then down and inward again, forming a vortex on either side. The surface looks smooth and the twin vortices woukd tend to persist.
WAG: does it have anything to do with dissolved gases slightly changing the physics of the water, making it a case of the waves seeing it as a transition between materials.
Start simple. Take a bucket of legos and run your finger through it. It will do the exact same thing - but much slower. When you embark on these super complex differential equations (people barley understand) - just go backwards.
> While the researchers were not actively looking for any particular defect in the material, the advanced imaging technique uncovered a surface defect, called a twin boundary. At either side of the twin juncture, the molecular networks abruptly transformed their handedness.
Reminds me of Q1D models that simulated glassy dynamics[0]:
"We describe numerical simulations and analyses of a quasi-one-dimensional (Q1D) model of glassy dynamics. In this model, hard rods undergo Brownian dynamics through a series of narrow channels connected by $J$ intersections. We do not allow the rods to turn at the intersections, and thus there is a single, continuous route through the system. This Q1D model displays caging behavior, collective particle rearrangements, and rapid growth of the structural relaxation time, which are also found in supercooled liquids and glasses. "
A single defect can impact the entire field. One unambiguous result could throw the entire standard model out the window. It has happened in astronomy, the father of physics, multiple times.
I think you and parent came up with a possibly better example than the one in the article quoted by the grandparent comment, more so than it being a clarification of how single DNA mutations ripple out to be big problems.
Basically, insofar as the perturbation does not impact more than the local lattice structure (sometimes just a few NM across), the overall lattice (therefore properties) will be rather unaffected. I know pure crystals will often have embedded impurities (ie: precursor residues in the product). The impact for the DNA change is that DNA is used to create downstream materials, whereas materials are generally used because of their properties directly. As long as a defect does not impact to a great extent the general properties of the material, it is irrelevant.
In terms of movement inside a lattice structure, the only real movement is vibrational and rotational movement, so global effects because of particles moving about has far lower influence.
an iron whisker with a single crystal defect in it has dramatically different macroscopic properties, especially tensile strength, from an iron whisker without a single crystal defect.
A Black Swan is an "unknown unknown", something you don't just lack understanding of, but don't expect or predict. The statistical interpretation of the term was popularized by Nassim Taleb in the book of the same name: https://www.goodreads.com/book/show/242472.The_Black_Swan
A black swan is not "an unknown unknown." It's something very rare, possibly non-existent - the phrase has been part of the English language for centuries (from Latin), and is clearly not being used in reference to Taleb's book:
> "This defect is like a black swan—something special going on that isn't typical," said Dr. Edwin Thomas, professor in the Department of Materials Science and Engineering
Isn't that the point? Before English-speakers had seen one, 'black swan' was a nonsense impossibility, like water flowing uphill. After Brits saw them in Australia, the phrase changed from 'total impossibility' to 'extremely unlikely but what do you know, actually true!'
I'm not sure I agree with anything you have said here.
"Black Swan" was in use before Taleb's book, at a similar frequency as it is today (Google Trends scores 2 vs 3, where 100 is when the book was released).
"Black swan" as a phrase dates at least to Roman times, often referring to the philosophical idea that the observation of a single black swan would prove their existence. (I've heard 'black sheep' used for this as well, although that has other more popular meanings).
The interesting part is that this did come to pass, for black swans: which are only native to Australia.
So, in my mind, it refers to something which is conceivable, but not believed to exist and not (yet) observed.
The Roman writer Juvenal is the origin of the phrase [1]. Neat to see pictures of them. [2] And humbling to think it took almost two thousand years for them to find out that the proverbial phrase was wrong.
The term black swan as it appears on the book actually comes from a philosopher. I think it is from David Hume. Does anyone here on HN knows? Its basically the concept in science that the connection between cause and effect is an ilusion. I remember reading the thought experiment from a philosopher in that context. Since google stopped working finding these things has proven more difficult.
This subthread is an illustration of the HN tendency to seize on whatever aspect of the article we think we can sound smart about, which, despite seemingly being an isolated comment that the scientist did not clarify or expand on at all, the journalist cleverly elevated to the headline.
Black Swan event is always unexpected, unpredictable, with no prior recorded history of such event, so no one could prepare for such event. It's always catastrophic as a system couldn't be possibly ready for it.
The article seems is too shallow in details of their seemingly very important discovery. Atleast nothing I could decipher. What do you think is relevant in their finding?
This has nothing to do with black swans, the birds... this has to do with unexpected results that are easy to explain in hindsight after the truth is known.
"Taleb's "black swan theory" refers only to unexpected events of large magnitude and consequence and their dominant role in history. Such events, considered extreme outliers, collectively play vastly larger roles than regular occurrences.[2]:xxi"
This discovery (unexpected behavior of matter) seems like it'll have a surprising and large magnitude.
"Materials can be broadly classified as hard or soft matter. Hard materials, like metal alloys and ceramics, generally have a very regular and symmetric arrangement of atoms. Further, in hard matter, ordered groups of atoms arrange themselves into nanoscopic building blocks, called unit cells. Typically, these unit cells are comprised of only a few atoms and stack together to form the periodic crystal. Soft matter can also form crystals consisting of unit cells, but now the periodic pattern is not at the atomic level; it occurs at a much larger scale from assemblies of large molecules."
Ever since childhood I've wondered why the water behind a rowboat stays flat for so long. You'd think the surrounding water would flow in and make it as wavy as everything else. Then a few years ago I was on Thera and saw the same thing with the cruise ships coming in. Their flat glassy trails would last for hours. Why does it take so long for them to vanish? It is a liquid transition that is weirdly persistent. Does anyone have an answer? If not, maybe this can be someone's wobbling plate.