Unexpected Solidlike Fracture in Simple Liquids

https://www.quantamagazine.org/we-know-simple-fluids-can-flow-turns-out-some-can-fracture-20260710/

by Anon84 • 12 days ago

99 62 12 days ago

https://journals.aps.org/prl/abstract/10.1103/t2vy-32wr

Someone tell me the industries that are going to benefit the most from this in the short and long term and what I can expect to see in the next 30 years as a result of this discovery.

helpfulclippy• 12 days ago

That sounds like a lot of work for someone to go do for a quanta article about something neat a researcher noticed.

calrt• 12 days ago

I worry that this sort of request will become the norm in the age of AI where people forget that people aren’t there to serve them.

lostlogin• 12 days ago

You made an account to say that?

lstodd• 11 days ago

he had his llm to make an account to post this.

rixed• 11 days ago

He made an account to add an offensive comment that would make many infuriated HNers engage with, thus improving the rank for the article?

gmueckl• 12 days ago

Maybe it will not have any mmediate application. But guess what? It's still cool! And that can be its very own reward if you let it.

Oh, btw: electricity was a novelty toy for several long decades with no major practical applications. But that eventually changed because people kept researching it. And it changed the world.

JumpCrisscross• 11 days ago

It’s a new, generalizable material-science property at STP. Those almost always find practical uses.

(Off the top of my head, a material that dissipates tension below a certain rate but fails when it is applied faster than that rate seems to resemble a mechanical breaker. As in not an electrical breaker that works mechanically. But one that decouples when you pull on it super hard. Being able to do that in fluids means one can potentially do that at very tiny scales.

More broadly, if simple fluids have a quasi-elastic mode, that has fundamental implications for hydrodynamics. I'd be super curious to know, for example, if anything similar to this occurs in air or water.)

labbeth• 11 days ago

Maybe I'm wrong or too naive... but isn't it related to "cavitation"?

dgoldstein0• 11 days ago

From reading the article, it does sound like that's a top hypothesis. Pulled fast enough, a bubble from cavitation can form and serve as the nucleation site of the crack

dd8601fn• 12 days ago

This looks like silly putty behavior.

jdlshore• 11 days ago

Oobleck (corn starch and water) will do this too. But presumably they already knew that. The article describes it as being known to happen in “complex fluids,” but that it was news that it happens in “simple fluids.” Presumably silly putty and oobleck are “complex fluids?”

EA-3167• 11 days ago

Specifically they're the subtype of non-Newtonian fluids, and it's also a colloid, and certainly is very elastic.

nelox• 11 days ago

Turns out glass has been known to be a fluid and to fracture for quite some time.

[edit: but glass is not a simple fluid.]

helltone• 11 days ago

I thought glass was a solid?

vlovich1232• 11 days ago

Nope, lots of fluids that just flow over such a long period they appear solid.

Eji1700• 11 days ago

It's an amorphous solid last time I dove into this.

The "well it's technically a liquid!" because it "flows" is really not telling the whole story. Like most science, it's just more complex than can be quickly summarized with one sentence, and doesn't quite map to just high school simplifications.

evaneykelen• 11 days ago

I lived in a house built around 1605 in the Netherlands, with some of the windows being hundreds of years old, based on expert opinion. The glass had started to droop downward in certain places, almost like the resin you see in trees. It made me realize that glass is not as rigid as I thought.

jzer0cool• 11 days ago

This seems more of inertia, Newton's first law. "An object at rest stays at rest,...". What comes to mind say there is some threshold acceleration (e.g. or at extreme, accelerate to c within some short time, t), then essentially you have a body at rest and breaks at the weakest point. Interesting would be seeing this effect with varying viscosity.

immmmmm4• 11 days ago

a project in collaboration with the oil and gas company Exxon Mobil

I find it a bit dark that, at a time people, crops, forests and biomes are dying due to extreme heat caused by the fossil fuel industry’s reckless behaviour the last 50 years, the said fossil fuel industry funds research on exotic rheology.

thorncorona• 11 days ago

well unless you figure out how to replace plastic..

autoexec3• 11 days ago

We could replace a large number of plastics right now and be just fine. Society flourished and thrived before we used plastic for everything in our lives. Some people would make less profit though, so of course it's impossible to make those kinds of changes, but we could.

MengerSponge• 11 days ago

They care about rheology because that expertise enables fracking, and they're smart enough to understand that you have to fund basic science to get (valuable) applied science.

immmmmm4• 11 days ago

I have worked half of my life in both fundamental and applied science, I know how this work. In particular you can refuse jobs you deem unethical.

Why not funding energy transition research for instance. It’s know to science for half a century we’ll cook to death if we don’t phase out fossil fuel energy.

And by know, I mean there’s literally millions of papers on the topic.

godwinson__4-8• 11 days ago

This is the same company whose research funding was among the first to produce forecasts of these affects. Yet that didn't stop them.

Can't get more "dark" than that.

https://en.wikipedia.org/wiki/ExxonMobil_climate_change_deni...

immmmmm4• 11 days ago

Oh yes, they had some of the best climate scientists back then.

It’s somewhat a scale up of what the tobacco industry did, same strategies, etc

dzhiurgis• 11 days ago

The disease is consumerism, not industry. As long as there is demand - there will be supply. AFAIK no people weaned themselves off fossil fuels yet. Even basics haven’t been solved yet in most parts.

mjevans2• 11 days ago

At scale that is never going to happen.

Stop even thinking of conservation, start thinking of how to produce the desired effects using alternate sources and then apply regulation to move to those sources.

Solar, wind, tidal, geothermal, nuclear of any sort that's safer than coal or oil? Build it ALL.

Inexpensive energy is the cornerstone of advancing quality of life.

brador• 11 days ago

Should be called semi-rigid fluids. They have a structure, it’s just weak and breaks at weak points as you would expect.

dataflow5• 11 days ago

I must be missing something.

If something is a fluid... or at least a liquid... that means it... flows, right?

Flow speed isn't infinite, so whenever you pull apart a liquid, you'll see some remnant of the pre-flow state. The thicker the liquid, the slower you need to pull it apart to see that.

Is this surprising? Why wouldn't every liquid do this? In what way is this somehow special to some liquids and not others?

kulahan5• 11 days ago

Cavitation can be another “out” for that energy.

madaxe_again2• 11 days ago

Your intuition is correct, and what you’re describing is cavitation - which the article goes on to mumble about a little. Honestly, I am also struggling to see what the novel result here is. You can snap off a drip of pitch by pulling on it - if you shear it, it will probably just bend - yank on the droplet and it comes off with a satisfying snap.

But then again I suppose if you lead a cosseted life, never played with the contents of a shed, and had your first practical experience of actual hands on behaviour of viscous liquids in a lab… you might shout “Eureka”.

chupasaurus• 11 days ago

Pitch is a viscoelastic polymer while simple fluids are non-elastic, that's the whole point.

dataflow5• 11 days ago

Another issue I don't see how to solve is: how do you even gather the data?

That is: how do you even know if someone (a) is doing the same job as a graduate of your program would do, (b) actually skipped a program or its equivalent, and (c) is making more than a graduate of your program?

All of these are personal and private information. If I apply to a startup tomorrow and get hired without listing my engineering degree on my resume, then are they supposed to add me to some national database of uneducated engineers, list my compensation, and explain that they would've hired a graduate for the same role too? If I apply to another company and list my degree then is that gonna overwrite the database? How the heck would this actually work?

dataflow5• 11 days ago

Whoops, looks like I somehow posted on the wrong page.

dataflow5• 11 days ago

Second comment for a semi-off-topic question: does the state of matter depend on the gravity?

Thought-experiment: take any solid, put it in an infinitely strong cup, and crank up gravity. At some point gravity overwhelms the forces holding the substance together and thus the substance ends up breaking apart and.. filling the cup just like a liquid, no?

Does everything become liquid-like at sufficiently high gravity? How does one distinguish what's a solid or a liquid when gravity seems to make them behave similarly?

madaxe_again2• 11 days ago

It really depends on what’s in your cup at relatively low gs - some things will deform, others will brittle fracture, others yet will just stubbornly sit there, but if you keep on cranking that gravity dial you’ll get degenerate matter, which behaves quite a bit like a liquid.

Mielin• 11 days ago

https://i.pinimg.com/originals/a1/fb/66/a1fb663d7d2942c1988d...

If you put a cup of water in a strong enough gravity, lower part of the cup will have higher pressure, and that part will turn to unusual ice types. While top of the cup will remain liquid. Cranking up a gravity will only change the ratio. This is why people use pressure instead of gravity, pressure is what defines the state.

Your main point is something like "material becomes weak compared to gravity, conforms to the cup, as if liquid", or "cant have long range structure". But we already have solids that are like that - sand. Sand doesnt resist change to its shape, it just slides in a new position. And yet we still consider sand to be solid. Angle of a pile in particular.

Even a neutron star likely has surface level irregularities on a scale of centimiters. While a liquid can flow to submicron level smoothness even in a diy experiment.

Material gets stronger as pressure is increased. Unusual crystal structure becomes available. Superconductors and some other weird properties can exist only when crystal structure is compressed. And this tendency continues all the way to degenerate matter, as in neutron stars. Material from inside of a neutron star is likely the strongest a material can be in this universe.

So in the end, "solidness" continues to fight back, presenting enough properties to differentiate it from a true liquid, even if it could look somewhat similar, "shallow pile of material", all the way to degenerate matter of neutron stars.

dataflow5• 11 days ago

Interesting, thanks!

rcxdude• 11 days ago

A solid will put up some resistance to shear forces, up to the plastic limit. A liquid gives zero resistance to a constant shear force after enough time. What this means is that a solid might approximate a sphere but it will still at the limit have some level of roughness (even with something as extreme as a neutron star), while a liquid will in principle always move towards a perfect sphere under gravity alone.

Unexpected Solidlike Fracture in Simple Liquids

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