8 ms·

Unexpected 'Black Swan' defect discovered in soft matter for first time

126 points by dnetesn 5y ago

deleted 5y ago
[deleted]
Chris2048 5y ago
> In biology, we know that even a single defect in DNA, a mutation, can cause a disease or some other observable change in an organism And this would relate to material science?
- thisismyswamp 5y ago
  In the way that molecules are so fast that they go past each other frequently, making global effects possible to arise from small perturbations.
  - acjohnson55 5y ago
    One thing that comes to mind is prions, which cause diseases like mad cow and CJD. "Prions are misfolded proteins with the ability to transmit their misfolded shape onto normal variants of the same protein." https://en.m.wikipedia.org/wiki/Prion https://en.m.wikipedia.org/wiki/Prion
    - icoder 5y ago
      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.
  - gus_massa 5y ago
    That's incorrect. Molecules collide when they are close enough. (There is a small probability of tunneling, but it's really small.) Small perturbations in a crystal are call "defects" https://en.wikipedia.org/wiki/Crystallographic_defect https://en.wikipedia.org/wiki/Crystallographic_defect and they are quite stable, and don't move too much. The effect is very local. The defects in DNA can have a huge effect if they are in an (un)lucky spot, and they are completely unrelated to material science.
    - trutannus 5y ago
      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.
    - DrJokepu 5y ago
      Depends on the type of defect. Dislocations can move around quite a bit and they do affect the structural integrity of the material. This is why if you bend a fork, you will never be able to fully unbend it (without heat treatment), there will always be a S-shaped bend it it.
    - kragen 5y ago
      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.
- sandworm101 5y ago
  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.
  - optimalsolver 5y ago
    >A single defect can impact the entire field Just ask Boeing.
deleted 5y ago
[deleted]
thisismyswamp 5y ago
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 https://www.goodreads.com/book/show/242472.The_Black_Swan
- amelius 5y ago
  What is the relevance of the term here?
  - mohanmcgeek 5y ago
    That it's in the title? GP is pointing out that it's being used incorrectly
    - meepmorp 5y ago
      The term isn't used incorrectly
    - gumby 5y ago
      except that, this being the Internet, the observation is not in fact correct. (I think we've all been "guilty" of this at one point or another)
  - agilob 5y ago
    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.
  - dkarl 5y ago
    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.
cinquemb 5y ago
> 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. " [0]: https://arxiv.org/abs/1401.0960 https://arxiv.org/abs/1401.0960
- phonethrowaway 5y ago
  > At either side of the twin juncture, the molecular networks abruptly transformed their handedness. this seems rather intuitive to me, and unsurprising. for every action there is an opposite and equal reaction. a spinning cue ball changes directions when it bounces off a rail. it's the same reason circular polarizers let you see through reflections in glass.
deleted 5y ago
[deleted]
pjungwir 5y ago
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.
- Enginerrrd 5y ago
  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.
  - hinkley 5y ago
    Probably a different amount of dissolved gasses as well.
- hinkley 5y ago
  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.
- hyperpallium2 5y ago
  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.
CositaS 5y ago
The actual article this story is about: https://www.pnas.org/content/118/12/e2018977118 https://www.pnas.org/content/118/12/e2018977118 (the link was there but buried at the bottom of the page)
deleted 5y ago
[deleted]

126 points by dnetesn 5y ago

deleted 5y ago

[deleted]

Chris2048 5y ago

> In biology, we know that even a single defect in DNA, a mutation, can cause a disease or some other observable change in an organism And this would relate to material science?

thisismyswamp 5y ago
In the way that molecules are so fast that they go past each other frequently, making global effects possible to arise from small perturbations.
- acjohnson55 5y ago
  One thing that comes to mind is prions, which cause diseases like mad cow and CJD. "Prions are misfolded proteins with the ability to transmit their misfolded shape onto normal variants of the same protein." https://en.m.wikipedia.org/wiki/Prion https://en.m.wikipedia.org/wiki/Prion
  - icoder 5y ago
    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.
- gus_massa 5y ago
  That's incorrect. Molecules collide when they are close enough. (There is a small probability of tunneling, but it's really small.) Small perturbations in a crystal are call "defects" https://en.wikipedia.org/wiki/Crystallographic_defect https://en.wikipedia.org/wiki/Crystallographic_defect and they are quite stable, and don't move too much. The effect is very local. The defects in DNA can have a huge effect if they are in an (un)lucky spot, and they are completely unrelated to material science.
  - trutannus 5y ago
    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.
  - DrJokepu 5y ago
    Depends on the type of defect. Dislocations can move around quite a bit and they do affect the structural integrity of the material. This is why if you bend a fork, you will never be able to fully unbend it (without heat treatment), there will always be a S-shaped bend it it.
  - kragen 5y ago
    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.
sandworm101 5y ago
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.
- optimalsolver 5y ago
  >A single defect can impact the entire field Just ask Boeing.

deleted 5y ago

[deleted]

thisismyswamp 5y ago

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 https://www.goodreads.com/book/show/242472.The_Black_Swan

amelius 5y ago
What is the relevance of the term here?
- mohanmcgeek 5y ago
  That it's in the title? GP is pointing out that it's being used incorrectly
  - meepmorp 5y ago
    The term isn't used incorrectly
  - gumby 5y ago
    except that, this being the Internet, the observation is not in fact correct. (I think we've all been "guilty" of this at one point or another)
- agilob 5y ago
  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.
- dkarl 5y ago
  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.

cinquemb 5y ago

> 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. " [0]: https://arxiv.org/abs/1401.0960 https://arxiv.org/abs/1401.0960

phonethrowaway 5y ago
> At either side of the twin juncture, the molecular networks abruptly transformed their handedness. this seems rather intuitive to me, and unsurprising. for every action there is an opposite and equal reaction. a spinning cue ball changes directions when it bounces off a rail. it's the same reason circular polarizers let you see through reflections in glass.

deleted 5y ago

[deleted]

pjungwir 5y ago

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.

Enginerrrd 5y ago
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.
- hinkley 5y ago
  Probably a different amount of dissolved gasses as well.
hinkley 5y ago
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.
hyperpallium2 5y ago
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.

CositaS 5y ago

The actual article this story is about: https://www.pnas.org/content/118/12/e2018977118 https://www.pnas.org/content/118/12/e2018977118 (the link was there but buried at the bottom of the page)

deleted 5y ago

[deleted]