The possibility of producing non-perturbative low-scale gravity states in collider experiments was first discussed in 1998. The ATLAS and CMS experiments have searched for non-perturbative low-scale gravity states using the Large Hadron Collider (LHC) with a proton--proton centre of mass energy of 13 TeV. These experiments have now seriously confronted the possibility of producing non-perturbative low-scale gravity states which were proposed 20 years ago. I will summarise the results of the searches, give a personal view of what they mean, and present some models in which low-scale gravity would not have yet been seen at the LHC.

简历：Doug Gingrich received his PhD from the University of Toronto in 1988, then spent time as a College Lecture and Research Associate at the University of Oxford. Doug has been a professor at the University of Alberta since 1993. Doug has researched with several international experiments in particle physics and gamma-ray astronomy. He has been active on ATLAS since the signing of the Letter of Intent in 1992. He had involded in the R&D on switch-capacitor arrays for the LAr calorimeter, and is respobsible for the Monte Carlo production management. Doug spent about three years developing the phenomenology for the LHC to search for low-scale gravity non-perturbative states, such as quantum black holes and high-excited string states. In the last ten years, he has been active as either an analyser, editor, contact, EB chair, or supplier of the MC signal samples for essential all 14 ATLAS papers searching for low-scale gravity. He has also been involved in the analysis of several Beyond Standard Model Higgs papers.