A University of Birmingham scientist has built a “mini-universe” that takes a step toward answering one of science’s biggest questions: “What is time?” Publishing his findings in Physical Review Research, Professor Giovanni Barontini shows how it is possible to measure the flow of time without using a clock at all. The new findings provide a scientific model in which a version of time emerges from the experiment itself.

Two independent research teams have achieved a longstanding goal in physics: building a working nuclear clock. The devices, developed by Beichen Huang and colleagues at Tsinghua University and by Luca Toscani De Col and colleagues at the Vienna Center for Quantum Science and Technology in Austria, exploit the nucleus of a thorium-229 atom to keep time with extraordinary precision—possibly surpassing even the best atomic clocks available today.

Birds in flocks, bacteria and cells: In many collective systems, individual elements respond to only part of their surroundings, seemingly defying Newton’s third law of motion—action equals reaction. These exceptions are known as nonreciprocal interactions. A Dresden physics team working with Roderich Moessner, a founding member of the Würzburg–Dresden Cluster of Excellence ctd.qmat, has now developed a theory that makes it possible to describe these interactions efficiently and simulate them far more precisely.