When you squeeze ketchup out of a bottle, you're battling its stubbornness: it sits still at first, then suddenly shoots out in a blob. That's typical non-Newtonian behavior — resistance to flow changes with how hard you push. But the authors of a new study found a way to almost completely eliminate that resistance. They proposed coating the tube walls with an ultra-thin lubricating film — something like oil on a frying pan. And then ketchup, paste, or even wet clay starts moving inside as if it were water: easily, smoothly, and predictably.
The secret is that motion now concentrates not throughout the entire fluid mass but only in a thin layer near the walls — where the film is. Think of a crowd on an escalator: if the steps glide smoothly, people ride calmly without jostling. Here, the lubricant plays the escalator's role. The bulk of the material simply slides, barely deforming, and its complex internal structure stops affecting the flow. The scientists calculated and modeled this effect: in this regime, even materials that usually require powerful pumps can be driven by gravity, and the pipe's throughput increases by tens or hundreds of times.
The practical implications are huge. In nature, a similar mechanism helps blood move through capillaries and mucus protect stomach walls. In engineering, it promises pumping oil, construction mixes, or food masses with minimal energy expenditure. Essentially, we're learning from living systems: a thin slippery layer can completely rewrite the rules of transporting complex fluids, turning a viscous plug into a docile stream.
If you coat the tube walls with lubricant, thick honey will flow 100 times faster under the same gravity than without it.
In Peter Watts's novel Blindsight, an alien ship uses layers of different viscosity to move without friction — similar to the described effect, but on a cosmic scale.