The Voice of CCNU On the night of October 9th, the activity ‘Face to Face with Professors’ was held successfully in room 9201 of the 9th building. Professor Yu Yunwei gave a lecture on black holes and other knowledge that students are interested in. Except some normal majors interested in astronomy, most of the audiences were freshmen, sophomores and juniors from non-teaching majors of College of Physical Science and Technology.
10月9日晚，俞云伟主讲的“教授面对面”学术报告专场在9号楼9201教室顺利展开，俞云伟针对黑洞及大家感兴趣的内容做了重点讲解。本次活动主要面对物理学院2018至2020级非师范专业的同学，当然也有对天体感兴趣的师范专业的同学参与活动。
Professor Yu started with the introduction to the foreground of astrophysics, and then led students to the question ‘what is a black hole?’ He talked about Newton’s universal law of gravity, escape velocity and general relativity, and finally gave out the definition of black hole, ‘a black hole is something which has the event horizon that nothing can escape within.’ And an object being attracted to another object is essentially falling into the space-time trap created by that object. The professor also elaborated the relationship between gravity and the curved space-time, as well as the forming progress of black holes----star contraction, with vivid language.
俞云伟以天体物理的前景为切入点，谈到“什么是黑洞？”这一问题，他讲到牛顿的万有引力定律、逃逸速度以及广义相对论这些物理知识，最后告诉同学们“事件视界内的任何物质都不能逃逸，即为黑洞”而一个物体被另一个物体所吸引本质上是掉进了那个物体所造成的时空陷阱里面。他还生动地阐述了万有引力与时空弯曲的联系以及黑洞的形成过程——恒星收缩产生黑洞。
So can we see black holes? Professor Yu mentioned that ‘Riccardo Giacconi deduced the existence of the X-1 Scorpio black hole by looking for X-rays.’ And he continually talked about black holes and AGN in the age of gravitational waves, and then emphasized the possible existence of a black hole four million times the mass of the sun at the center of the Milky Way.
那我们能看到黑洞吗？俞云伟说道：“里卡尔多·贾科多通过找寻X射线而推断出“天蝎座X-1”黑洞的存在。”接着他讲到引力波时代的黑洞和活动星系核两个问题，并对银河系中心可能存在的400万倍太阳质量的黑洞做了重点讲解。
And what on earth do black holes look like? Knowing the answer to the question requires efforts from all over the world, and the best proves would be photos. So the professor introduced the application of EHF, radio telescope and VLBI, and told students that black holes should be observed by the whole world, and the photos of M87 are the best proof of the existence of black holes.
那黑洞究竟长什么模样呢？照片是最好的证据，这一问题的解决全球各地的努力。俞云伟向同学们介绍了事件视界望远镜（EHF）以及射电望远镜和甚长基线干涉技术的运用。他告诉同学们黑洞需要全世界一起看，而M87的黑洞照片是黑洞存在的最好的证据。
Professor Yu’s lecture had made students bring up many questions. One student asked about the time lag in the film Interstellar, and Yu gave detailed explanation to this. Freshman Chen Xuancheng said, ‘the most impressive part was the explanation of the black hole photos, because of the existence of black hole, the space time nearby was distorted, and the image of a black hole isn’t like a black dot in the center of a halo, in fact, there’s a glowing line in the middle of a black hole. Professor Yu had explained profound theories in simple, vivid languages, and aroused my interest in astrophysics. I hope there would be more lectures like this.’ The activity of ‘Face to Face with Professors’ stimulated students' interest in physics and broadened their knowledge.
聆听了俞云伟生动地讲解，同学们产生了许多问题。有人问到“星际穿越”这一影片中时间差异的问题，俞云伟针对同学的问题，展开了丰富细致的讲解。2020级学生陈宣丞在采访中说道：“最让我印象深刻的应该是俞教授对黑洞照片的讲解，因为黑洞的存在，附近时空扭曲，黑洞的照片不是一个光环中间一个黑点，而是在黑洞中间还会有一段发光的线！俞教授简单、直观、生动的讲述激起了我对天体物理方面的兴趣，我很希望以后有更多的机会来接触这样的讲座。”“教授面对面”活动激发了同学们对物理的学习兴趣，开阔了同学们的知识面。
Source: The Voice of CCNU
Author: Yang Liu
Translator: Qin Hailan
Date: October 14, 2020
Words: 430
