The latest advances in microparticle physics as exemplified by ... pancakes

To bake delicious pancakes, you need a good dough, which is a mixture of very different ingredients: water, flour, sugar, eggs and butter. And behind it has long been noticed a stan-like property - this substance, when mixed, strives to begin to move in the direction opposite to the one in which it is directed. Recently, Harvard researchers published their research on this issue, describing new discoveries in the physics of the motion of granular microparticles using pancakes as an example.

A team of physicists led by graduate student Lisa Lee found that there is a direct relationship between the composition of the mixture and the direction of motion. If the density of the substance is low, then the granules will tend to repeat the vortex motion entraining them. But with an increase in density, the direction is reversed. The reason for this is friction, since the more particles in the mixture, the more each of them interacts with others, which reduces their freedom of movement.

The greatest scientific interest here is the fact that, under certain conditions, a liquid mixture begins to behave like a solid. For example, ordinary sand - in an hourglass it sprinkles like water, but on the beach you can safely walk on it. Scientists have found that the main factor in this case is the number of particles in a given volume - the more there are, the higher the friction force. And at some critical indicators, the probability of moving becomes equal to zero - in fact, a liquid substance becomes a solid.

But another conclusion can be drawn from this: if friction is eliminated, then the particles will never stop. Using computer simulations, Lisa Lee's team proved that there is a theoretical possibility to create a fluid with a near-zero coefficient of friction of particles, which will never solidify, no matter how many of these particles are in it.