1、最近得知，加州理工学院的Andrew Lange自杀身亡。

Lange是物理学家、宇宙学家，BOOMERang实验的领导人之一，出生于1957年，是加州理工数学天文物理部主任。

台湾大学黄伟彦教授领导的COSPA小组从1999年开始定期举办研讨会，我在2000年得知BOOMERang的实验结果，那时还有MAXIMA等实验。是这些关于CMB各向异性的重要实验让我下决心进入宇宙学领域。我私下曾感谢黄伟彦教授，他的小组直接对我施加了影响，当然，去世的Lange则间接地对我施加了影响。

加州理工校长Jean-Lou Chameau说：

It is with great sadness and regret that I must report to you the death of Professor Andrew Lange, a valued member of the Caltech faculty. Andrew was found this morning off campus, and it appears that he took his own life. Among the most difficult things that people have to deal with in life are tragedies of this sort, especially when they affect people that we know and care for; and Andrew was such a well-known, well-respected, and well-liked member of our community that many of us will be deeply affected.

Andrew came to Caltech in 1993 and was most recently the chair of the Division of Physics, Mathematics and Astronomy. He was a truly great physicist and astronomer who had made seminal discoveries in observational cosmology.

Andrew was a valued colleague and a close friend to many of us. His death is a source of great sadness to us all and our deepest sympathy goes out to his family, friends, and colleagues, all of whom mourn his loss.

We know this tragic news will come as a shock to everyone — faculty, staff, and students alike, even those of you who knew that Andrew had been struggling with personal issues. Many of us feel the need in times like these to reach out and seek help in dealing with the shock, and I urge anyone who wants help to seek it from family members, friends, faculty, and/or professional counselors. This is not only a reasonable thing to do, it is an important thing to do. I want to emphasize in particular that counselors are always available, 24-hours a day. Students should call the Counseling Center at 626-395-8331, while faculty, staff, and postdocs, should call the Staff and Faculty Consultation Center at 626-395-8360. In addition, the Counseling Center will be open on Saturday and Sunday from 10-3pm.

The only way I can think to honor Lange is to tell you a bit more about his most famous work. BOOMERang stands for Balloon Observations Of Millimetric Extragalactic Radiation and Geophysics, and it’s essentially a balloon-borne telescope designed to make measurements of the cosmic microwave background radiation — the “afterglow” of the Big Bang that still pervades our universe. The first flight, in 1997, concentrated on North America, while two subsequent flights in 1998 and 2003 circled the South Pole. Maps

Based on this data, the BOOMERang team made the most detailed map of temperature fluctuations in the CMB — at least as of April 2000, when the first results were announced.

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BOOMERang’s exciting results were the first “to resolve the structures in the CMB, allowing us to ’see’ structures that predate even the first star or galaxy in the universe,” Lange said in an interview with the European Space Agency in 2001. But he was always looking forward to the next experiment — in this case, the Planck satellite that launched last spring. Planck’s instruments have even better resolution than BOOMERang, capable of measuring many more frequencies in the CMB, and it will cover the entire night sky, instead of just select regions. “Planck will be revolutionary!” Lange declared in that 2001 ESA interview. It’s a tragedy that he didn’t live to see the revolution in action.

Lee Smolin最近写了一篇文章，声称可以从loop gravity推导出牛顿引力。对此，Erik Verlinde评论道：“Lee Smolin paper to appear getting emergent gravity from loop quantum gravity. I don’t understand the logic: explain gravity from gravity??”

我在理论所的报告中就说过，会有很多研究Verlinde的想法的人，而且一开始估计有60%的文章是错的，Smolin可能是错的之一，至少是trivial的。我没有看他的文章，但我有这种感觉。

毫无疑问，Verlinde的想法将刺激人们去获得更多的有意思的结果，而且我个人感到这个想法本身或延伸会导致一些令人意料不到的结果。目前，似乎还没有任何意料不到的结果被发表。我们只需要一点点耐心。

New Scientist对Verlinde的工作做了报道，The entropy force: a new direction for gravity，其中说：

Verlinde’s paper has prompted praise from some physicists. Robbert Dijkgraaf, a prominent mathematical physicist also at the University of Amsterdam, says he admires the elegance of Verlinde’s concepts. “It is amazing no one has come up with this earlier, it looks just so simple and yet convincing,” he says.

The jury is still out for many others. Some believe that Verlinde is using circular reasoning in his equations, by “starting out” with gravity. Others have expressed concern about the almost trivial mathematics involved, leaving most of the theory based on very general concepts of space, time and information.

Stanley Deser of Brandeis University in Waltham, Massachusetts, whose work has expanded the scope of general relativity, says Verlinde’s work appears to be a promising avenue but adds that it is “a bombshell that will take a lot of digesting, challenging all our dogmas from Newton and Hooke to Einstein.”