时间：2025年10月9日（星期四）10:00-11:30
地点：西湖大学云谷校区E4-233
主持人：理论科学研究院 刘洪光
主讲人：Daniel R. Terno, Macquarie University
主讲人简介：Daniel R. Terno was born and grew up in Latvia, which was then actually a part of the USSR. He has completed his undergraduate and graduate studies at Technion in Haifa, Israel, with Asher Peres as the thesis advisor, finishing his Ph.D. in 2003. Between March 2003 and December 2006 he was a postdoc at PI. This is where his affair with black holes and quantum gravity have begun. Danny joined the faculty of the Macquarie University in Sydney in 2007, and currently he is a Professor at the School of Mathematical and Physical Sciences. He was a visitng researcher in Perimeter Institu (2011, 2025), Technion (2015) and SUSTech (2019-2020). He worked on quantum information theory, quantum foundations, quantum and optical tests of relativity, loop quantum gravity. Most of his recent work is on semiclassical black holes and related topics.
报告题目：Physical black holes: geometry, matter, information
报告摘要：
A number of interesting conclusions can be reached by investigating what the necessary conditions for formulation of the information loss problem are.
From the perspective of a distant observer, gravitational collapse may follow one of three paths: it may proceed indefinitely, with the event horizon remaining an asymptotic concept; it may produce a transient or stable ultra-compact object whose surface lies outside the corresponding gravitational radius; or it may form a light-trapping region in finite time—a physical black hole. Classical solutions such as Schwarzschild or Kerr exemplify the first case and remain consistent with current observations. The second class—exotic ultra-compact objects—is, in principle, distinguishable. The information loss paradox is also framed from the distant observer’s viewpoint and requires this third scenario—formation of physical black holes—for the problem to even arise.
Assuming finite-time formation and a weak form of cosmic censorship (curvature scalars remain finite at the apparent horizon), one can extract information about the near-horizon geometry. In spherical symmetry, only two classes of dynamic solutions are possible: evaporating black holes and expanding white holes. Their properties have notable implications: near the outer horizon, the null energy condition is violated, while it holds near the inner apparent (anti-trapping) horizon. These horizons are timelike and feature occasional mild negative energy density firewalls. Similar features are present in axially symmetric cases. The standard notion of surface gravity—proportional to Hawking temperature in static spacetimes—fails to generalize consistently to dynamical, spherically symmetric black holes, and when defined, it must vanish at both formation and possible evaporation. Wormholes arise naturally in this setting but may conflict with quantum energy inequalities. These marked deviations from classical black hole behavior motivate the study of their possible observational signatures, especially in quasi-normal modes.
