报告题目：The not so quiet night sky

报 告 人：Prof. Ralph A.M.J. Wijers, University of Amsterdam

报告时间：Friday, November 10, 2017, 07:00pm

报告地点：金沙总站6165地址大礼堂

报告摘要：Traditionally humans have looked up to the sky as a majestic, unchanging place, much more dignified than our imperfect, ever changing world. However, the sky is not always so quiet. Even with our naked eye, we can sometimes see changes, and early humans thought these might be bad omens. Chinese astronomers were among the first to record "new stars" appearing in the sky. Nowadays we know that these new stars often signify very violent events in the universe, such as explosions of massive stars, when exotic objects are formed such as black holes and neutron stars. Also, in other wavelgnths of radiation, such as X rays and radio waves, the sky is much less quiet than in visible light. We can often learn very extreme physics from these events, because the conditions in them are very different from what we can observe in laboratories on Earth. In this talk, I will show some of the things we have learnt from observing these so-called transient sources, and some of the questions we are still trying to answer.