Physicists say they’ve produced the first ‘supersolid’, and it’s even stranger than predicted

At its most simple, matter can come in the form of a solid, a liquid, a gas, or plasma. But what if you could combine the fundamental properties of these separate states to create a strange, hybrid form of matter that somehow exists as both a solid and a liquid?

More…

…In a sense, they’d created matter that can flow through itself, and with zero resistance.

CrazyNeutrino said:

…In a sense, they’d created matter that can flow through itself, and with zero resistance.

How cool is that.

:)

CrazyNeutrino said:

Physicists say they’ve produced the first ‘supersolid’, and it’s even stranger than predicted

At its most simple, matter can come in the form of a solid, a liquid, a gas, or plasma. But what if you could combine the fundamental properties of these separate states to create a strange, hybrid form of matter that somehow exists as both a solid and a liquid?

…In a sense, they’d created matter that can flow through itself, and with zero resistance.
How cool is that.

:)

“a supersolid – an exotic state of matter that has the crystalline structure of a solid, but flows like a liquid”

It’s been known for ages that the borderline between amorphous solids and liquids is blurred, for example in glasses, but this is a crystalline material that flows like a liquid. That seems impossible, unless …

“It’s solid in the sense that there is a certain rigidity to it, just like an everyday solid. But it has this very strange property that the matter can flow without any viscosity at all,”

That seems to be contradictory. No viscosity means no resistance to shear forces. But rigidity requires resistance to forces. A “torsional oscillator” produces shear forces.

Helium vs Bose-Einstein condensate. “The idea of a supersolid is so strange because superfluid and solid states compete, and in most materials, atoms are forced to choose one or the other. But in Bose-Einstein condensates, these two states can more easily live together in harmony, making the weird materials less counterintuitive than supersolid helium-4 would be.”

You have to read the link. It reads like a story, with different researchers producing different results.

I’m sitting on the fence.

So what’s a material called that flows like a liquid until force is applied then it becomes a solid

Cymek said:

So what’s a material called that flows like a liquid until force is applied then it becomes a solid

Rheopectic fluid.

btm said:

Cymek said:

So what’s a material called that flows like a liquid until force is applied then it becomes a solid

Rheopectic fluid.

Yep.

Dilatant fluids show higher viscosity when the magnitude of the stress is high (for example, when you run on wet sand it behaves as a hard surface)

Pseudoplastic fluids show lower viscosity when the magnitude of the stress is high (for example, ketchup flows easily when the bottle is hit or shaken hard)

Rheopectic liquids increase their viscosity as the time of application of stress increases (for example, cream and egg whites harden as they are beaten for a period of time).

Thixotropic liquids decrease their viscosity as the time of application of stress increases (ketchup and nail polish are examples of thixotropic fluids because they get thinner when you shake the bottle for a period of time). They return to their normal viscosity after a period of time after the stress stops being applied.

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Note time component of Rheopectic as opposed to Dilatant.

:)

macx

Dilatant fluids, also known as shear thickening fluids, are liquids or solutions whose viscosity increases as stress is applied . They are an example of non-Newtonian fluids, as they do not have a linear shear stress versus shear rate rate, which is unique to Newtonian fluids (see graph). This means that some dilatant fluids have the unique property of being able to turn from liquid to a solid just by having stress applied.

There are also such things as shear thinning fluids, or pseudoplastics, which display the opposite properties of dilatant materials; as more stress is applied to pseudoplastics the viscosity decreases (or shear rate increases),

Natural non-Newtonian fluids

A number of non-Newtonian fluids can be found naturally, although most of them are pseudoplastics as opposed to dilatants. A famous example of a non-Newtonian fluid is quicksand. At first it seems solid but as the victim walks onto it, thereby applying stress and causing it to become more viscous (as quicksand is a pseudoplastic), they sink in as they struggle, applying more stress to the quicksand, which then thins causes them to sink faster. Another example of a pseudoplastic is ketchup, which will not flow until it is squeezed or shaken . There are not as many natural dilatants, although certain proportions of sand and water mixed together can display dilatant properties. For example at a beach, if you stand on the wet sand, your feet will sink in slightly, but if you run across the sand (thus applying greater stress to it), it will behave as a solid and your feet will not sink in. A dilatant fluid can easily be made by making a 2:1 mixture of cornflour and water. It is a liquid, but when stirred it becomes thicker and more difficult to stir. If hit with a hammer, it will shatter like a brittle solid; but if left it will return to a liquid.

Rheopecty

Dilatancy is not to be confused with rheopecty, even though both properties have increased viscosity as a result of applied stress. The difference between dilatant and rheopectic materials is that rheopectic materials’ viscosity is time dependant and thus increases the longer the stress is applied , whereas dilatant materials’ viscosity increases just with an increase in stress. An example of a substance that displays rheopecty is cream; which becomes stiff only after prolonged beating.

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(from the web somewhere)

macx

> Dilatancy is not to be confused with rheopecty, even though both properties have increased viscosity as a result of applied stress. The difference between dilatant and rheopectic materials is that rheopectic materials’ viscosity is time dependant and thus increases the longer the stress is applied , whereas dilatant materials’ viscosity increases just with an increase in stress. An example of a substance that displays rheopecty is cream; which becomes stiff only after prolonged beating.

Nicely put.

An example of a dilatant fluid is wet sand. The amount of stress carried by grain-grain contact depends on the stress, but doesn’t increase with time. So it’s not rheopectic.