We propose a formalism of standard timers in tracking the evolution of the Universe. By studying the evolution of the dynamic systems in the Universe, their physical evolution time can be extracted. Meanwhile, their observational signals encode the cosmological redshift.  Accordingly the redshift-time relation can be obtained from the observable of the cosmological dynamic systems, which helps the understanding the evolution of the Universe. In a practical description of the cosmological standard timer, we use the Hawking radiation from the Primordial Black Holes (PBHs) clustering and the gravitational waves from PBH binaries as the examples to show how to extract the redshift-time relation from the observables, which also shows the great potential of standard timers in measuring the Universe.

个人简介：Ding Qianhang, a current PhD candidate at the Hong Kong University of Science and Technology and a research assistant at the HKUST Jockey Club Institute for Advanced Study. He focuses on studying the cosmology and high energy physics through the multi-messenger astronomy, especially, including the topics about gravitational wave cosmology, primordial black holes, void cosmology and cosmological collider physics. 

Contact联系人 王少江