There is an equal reaction for every action according to the third law. It has reassured us for 400 years, explaining why we don't fall through the floor and why paddling a boat makes it glide through water. When a system is in equilibrium, there is no energy going in or out. Statistical mechanics is the branch of physics that explains how collections of objects behave. When one state of matter transforms into another, such as when water freezes, this allows researchers to fully model the conditions that give rise to phase transitions.
Many systems persist far from equilibrium. Life is perhaps the most glaring example. Our metabolism converts matter into energy. A dead body is a human body that settles into a state of equilibrium.
The third law becomes meaningless in such systems. Equal-and-opposite falls apart. A interacts with B in a different way than it does with A, said Vincenzo Vitelli, a Condensed Matter theorist at the University of Chicago. In systems like neuron networks and particles in fluids, there are nonreciprocal relationships. Prey doesn't eat its predator.
The University of Chicago's Vincenzo Vitelli helped find a new way of thinking about phase transitions in nonreciprocal systems.
Statistical mechanics doesn't represent phase transitions for unruly systems. Nonreciprocity dominates. The law is easy to break because birds can't see behind them. The way bird A interacts with bird B is different from the way bird B interacts with bird A. Cars stuck in traffic or barreling down a highway are similar. Engineers and physicists who work with metamaterials have harnessed nonreciprocal elements to design acoustic, quantum and mechanical devices.
Many systems are kept out of equilibrium because they have their own power sources. A complex dynamical system is made up of extra energy sources and reactions that are not statistical mechanics. How can we understand phases in changing systems?
The answer is seen in mathematical objects called exceptional points. An exceptional point in a system is a place where two or more characteristic properties become indistinguishable and collapse into one. At an exceptional point, the mathematical behavior of a system changes dramatically from nearby points, and it can be described as lasers in which energy is gained and lost continuously.
The team has found that these exceptional points control phase transitions. Physicists and mathematicians have studied exceptional points for decades. They have never been associated with this type of transition. Cynthia Reichhardt is a physicist at Los Alamos National Laboratory in New Mexico. You can bring all the machines that we already have to study these systems.
For years, a range of areas and phenomena have not seemed to have anything to say to each other. Robert Kohn of the Courant Institute of Mathematical Sciences at New York University believes that their work represents rich territory for mathematical development.
Symmetry breaks.
The work began with quantum weirdness. Ryo Hanai, a researcher at the University of Chicago, and Peter Littlewood, Hanai's adviser, were investigating a kind of quasiparticle called a polariton a few years ago. wood is on the scientific advisory board of the Flatiron Institute, a research division of the Simons Foundation.
A quasiparticle is not a particle. A collection of quantum behaviors look like they should be connected to a particle. A polariton shows up when the particles responsible for light interact with each other. The Bose-Einstein condensate is a state of matter in which atoms all collapse into a single quantum state, because of the low mass of polaritons.
