Unexpected Solidlike Fracture in Simple Liquids • Hacker News Board

Re: Unexpected Solidlike Fracture in Simple Liquids

#61

Post by rcxdude » Sun, Jul 12, 2026, 4:16 PM UTC

dataflow wrote: post #29

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?…

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.

Re: Unexpected Solidlike Fracture in Simple Liquids

#62

Post by kevin_thibedeau » Sun, Jul 12, 2026, 4:24 PM UTC

kulahan wrote: post #39

autoexec wrote: post #32

Earlier quoted context omitted.

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.

Society flourished without lots of stuff we have today. It just flourished less. And people aren’t failing to migrate away from plastic because “somebody would make less money”, they’re using plastic because everything else basically sucks in comparison. It’s tough, cheap, light, stable, easy to shape, doesn’t often break dangerously, can have all of its basic properties modified, and more. Nothing else is THAT good.…

Waxed paper was fine for a lot of food wrappers until the penny pinchers abandoned it.

Re: Unexpected Solidlike Fracture in Simple Liquids

#63

Post by dataflow » Sun, Jul 12, 2026, 4:42 PM UTC

dataflow wrote: post #25

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?

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?

Re: Unexpected Solidlike Fracture in Simple Liquids

#64

Post by dataflow » Sun, Jul 12, 2026, 7:36 PM UTC

dataflow wrote: post #63

dataflow wrote: post #25

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?

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 de…

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

Re: Unexpected Solidlike Fracture in Simple Liquids

#65

Post by klustregrif » Mon, Jul 13, 2026, 5:24 AM UTC

autoexec wrote: post #33

klustregrif wrote: post #18

Earlier quoted context omitted.

That’s a misconception. Glass does not flow over time; it is a rigid, amorphous solid. The uneven thickness seen in old cathedral windows is a result of historical manufacturing. Glass was spun into discs that naturally became thicker at the edges, and builders installed the heavier side at the bottom for stability. Physicists calculate that it would take longer than the age of the universe for room-temperature windo…

> That’s a misconception. Glass does not flow over time;...Physicists calculate that it would take longer than the age of the universe for room-temperature window glass to visibly deform under gravity. so then it does flow over time, just not on a scale where it matters to us.

How do you go from “calculate that it would take longer than the age of the universe for room-temperature window glass to visibly deform” to “so the. It does flow”?

Glass flows a higher temperatures where it does act like a liquid, you can study glass blowing for examples, however no, room temperature glass is not a liquid and does not flow, for any practical definition of what flowing is.

Re: Unexpected Solidlike Fracture in Simple Liquids

#66

Post by kulahan » Tue, Jul 14, 2026, 9:41 AM UTC

Asmod4n wrote: post #46

kulahan wrote: post #39

Earlier quoted context omitted.

Society flourished without lots of stuff we have today. It just flourished less. And people aren’t failing to migrate away from plastic because “somebody would make less money”, they’re using plastic because everything else basically sucks in comparison. It’s tough, cheap, light, stable, easy to shape, doesn’t often break dangerously, can have all of its basic properties modified, and more. Nothing else is THAT good.…

All we need to do is to replace all plastics with bio degradable ones. But I guess that will take some time since we don’t have replacements for all petroleum based plastics yet. Hopefully this will get us recycling friendly plastics for foods in the long run since those just get burned nowadays cause you can’t recycle those we have today for that job.

I’m not sure that simply replacing one type of crude oil byproduct with something else does much on its own, since they still need all the other products produced before and after plastics are made.

Re: Unexpected Solidlike Fracture in Simple Liquids

#67

Post by kulahan » Tue, Jul 14, 2026, 7:53 PM UTC

kevin_thibedeau wrote: post #62

kulahan wrote: post #39

Earlier quoted context omitted.

Society flourished without lots of stuff we have today. It just flourished less. And people aren’t failing to migrate away from plastic because “somebody would make less money”, they’re using plastic because everything else basically sucks in comparison. It’s tough, cheap, light, stable, easy to shape, doesn’t often break dangerously, can have all of its basic properties modified, and more. Nothing else is THAT good.…

Waxed paper was fine for a lot of food wrappers until the penny pinchers abandoned it.

I don’t think wax paper is the dividing line between climate change and a happy planet, if I’m being honest

Re: Unexpected Solidlike Fracture in Simple Liquids

#68

Post by kulahan » Sun, Jul 19, 2026, 2:18 AM UTC

nervousvarun wrote: post #53

Asmod4n wrote: post #46

Earlier quoted context omitted.

All we need to do is to replace all plastics with bio degradable ones. But I guess that will take some time since we don’t have replacements for all petroleum based plastics yet. Hopefully this will get us recycling friendly plastics for foods in the long run since those just get burned nowadays cause you can’t recycle those we have today for that job.

Agreed but for it to happen implies altruistic, non-profit based corporate decision making R&D & subsequent manufacturing etc. No doubt the innumerable shareholder overlords out there who place the basic good of humanity over profit are pushing for it as we speak!

It sucks you’re the only person on earth who is altruistic enough for this thing that would definitely work but you’re choosing not to enact it despite it being so easy it’s a simple choice.

Because your statement sure leaves exactly zero room for anything else. Kind of a stupid comment at the end of the day. Either that, or you’re such an incredible jerk that you’re specifically choosing not to make these very easy changes that would save the world.