Quanta Physics World  June 2022

Seen and heard

Weird and wonderful stories from the world of physics

(Courtesy: Public domain via Wikimedia Commons)

Let’s do the twist

When it comes to eating an Oreo, some of us can’t resist twisting the two biscuits apart and licking the filling off. That’s because most – if not all – of the filling ends up stuck on one biscuit or the other. Crystal Owens, a PhD student at the Massachusetts Institute of Technology, has now tackled the physics of how that mysterious separation occurs. She and her colleagues created an “oerometer” – a rheometer that grasps the two biscuits and gives the cookie a twist until it separates into two. They confirmed that the filling always ends up on one biscuit, suggesting the effect doesn’t depend on precisely how an Oreo is twisted (Physics of Fluids 34 043107). The amount of filling doesn’t affect the separation process either, although what does make a difference is the twisting speed, with a slow twist being better for a clean break. Unfortunately, the research doesn’t explain why the filling always ends up on one side, though Owens reckons it could be linked to how Oreos are manufactured. Yeah, but what about custard creams?

Taste the difference

Still on confectionary, researchers in the Netherlands claim to have designed the perfect piece of chocolate by exploiting the science of “metamaterials”. Usually the domain of optical physics, metamaterials are artificial materials with internal structures that create specific properties, such as a certain optical response. But by heating chocolate and then creating various metamaterial-like structures using a 3D printer, the researchers – led by André Souto and Corentin Coulais at the University of Amsterdam – were able to improve the all-important “mouthfeel” of chocolate (Soft Matter 18 2910). They found that how the chocolate cracks when chewed, for example, can be controlled by altering the design of the metamaterial arrangement. In fact, chocolate pieces with more cracks have a better mouthfeel, testers found. Who said physics can’t be tasty?

No trousers, please

Social media went into meltdown last month from an unexpected source: the 13th International Particle Accelerator Conference, due to be held in Bangkok on 12–17 June. Delegates planning to attend the opening ceremony – presided by Thai Princess Maha Chakri Sirindhorn – were astonished to be told that only “crisp, neat, pressed and never wrinkled” attire would be permitted. Men were required to wear “dark or subtly patterned suits with matching jacket and pants”, along with “plain colour or conservative patterned ties”, “dark leather dress shoes” and “dark-colour socks”. Women had it even worse. Trousers were banned, with women required to wear a skirt that was a “little below the knee and never shorter than above the knee”. Make-up had to be “minimal” and “conservative”, with “nude (skin-tone) or dark coloured pantyhose”. The outcry led to a swift U-turn from the organizers, who say the dress code will now conform to “international standards”. Whether physicists will get away with “scruffy academic”, though, isn’t clear. 

 

(Courtesy: CC BY-SA 4.0 Harsh Goswami)

Sticking together 

Birds can be notoriously picky when foraging for nesting material and can be seen poking or shaking a candidate stick before deciding to add it their growing nest – in effect testing its mechanical properties. Now researchers in the US have carried out experiments and simulations to model how wooden twigs pack together in a nest-like structure. The team found a certain set of properties that make a twig or collection of twigs become optimal nesting material (10.48550/arXiv.2112.00784). This includes having a nonlinear stiffness as well as undergoing a “quasi-static hysteresis”, referring to how the material maintains equilibrium while undergoing a delayed response to stress. The researchers found that these features arise in a nest-like structure from the interplay of friction as the sticks are arranged. They reckon their work could improve our understanding of other complex structures such as the formation of underground fungal mycelium networks. Sounds fantastick.