xialigang的个人博客分享 http://blog.sciencenet.cn/u/xialigang


Saturn\'s moon (土星的卫星)
2023-10-11 09:34
Last night, I observed Saturn with my telescope. However, it is cloudy and I had to quit the photography soon. Here are a couple of photos. Cassini's division is hardly visible. Interestingly, a moon is visible after increasing the exposure! It is right above Saturn. Can you ...
个人分类: 物理妙趣|437 次阅读|没有评论
My first observation of Cassini division in Saturn rings
2023-10-9 08:58
Saturn is a beautiful planet. The history of its discovery can be found here . Saturn is a special planet because of its rings. It is my favourite object to observe with a telescope. The figure below shows its ring struction and its moons. Saturn rotates and its ring evolves with time (see ...
个人分类: Life|367 次阅读|没有评论
2023-9-4 14:47
In the first place, let me share two plots. This is Saturn. It is just beautiful. I used my cellphone to take a vedio and stacked hundred of frames to make this plot. A vedio is available on bilibili (see 土星手机实拍 ). This is Sun and you can see the sunspots. I took it ...
个人分类: 物理妙趣|716 次阅读|没有评论
Nature cannot pee while sneezing?
2021-11-12 17:36
At around 5pm, while going to release myself, I sneezed and the pee stopped immediately. This reminds me of momentum conservation. You know both sneeze and pee will make you lose some momentum in the same direction because our nose and urinary system work in the same direction. Th ...
个人分类: 物理妙趣|1492 次阅读|没有评论
Why do I keep writing single-author papers(为什么我坚持写唯一作者文章)?
热度 1 2021-7-19 17:10
Because thousands of authors would appaer on a research paper in our field. For example, the famous paper from ATLAS reporting the observation of the Higgs boson has around 3000 authors. This is not unique. Because every paper from the ATLAS collaboration would have around 3000 authors. ...
个人分类: Life|2281 次阅读|2 个评论 热度 1
Can Higgs explain Leption Universality Violation in B->Kll ?
2021-3-25 10:11
A few days ago, the LHCb collaboration reported an evidence for Lepton Universality Violation (LUV) in the beauty-quark decays B - K l + l - where l represents muon or electron. They measured the ratio of muon to electron to be (more details see their paper ) This ratio i ...
个人分类: 物理妙趣|1563 次阅读|没有评论
A problem about the AM-GM inequality (一道关于均值不等式的题目)
2021-2-1 11:29
Recently, Kai-Liang brought to my attention an extension form of the classic inequality of the arithmetic and geometric means. It is easy to see C2=1. It is not easy to calculate C3. I spent a couple of days on this problem and found the solution. My method is very sta ...
个人分类: FUN MATH|2972 次阅读|没有评论
My experience of using Fourier transformation (我使用傅利叶变换的经历)
2021-1-19 10:42
I was shocked the first time when I knew Fourier transformtion. It is amazing that nearly any function could be expanded as a sum of simple sine and cosine functions. It is very different from another famous expansion, Taylor expansion. Taylor expansion focuses on one point while Fourier ...
个人分类: 数据分析|1784 次阅读|没有评论
First observation of Mercury 第一次看到水星
热度 1 2020-11-13 10:42
11th Nov. is said to be the last and best day in 2020 to observe Mercury. Because the angular distance between Sun and Mercury is the greatest on this day. I set a reminder at 5:00 am and got up on time. It was very cold in early morning. What's worse. The school gate was lock ...
个人分类: 物理妙趣|2488 次阅读|2 个评论 热度 1
热度 1 2020-10-16 17:57
素数基本定理 是描述素数分布的一个非常重要的定理。它表明素数的密度大约是1/log(x),即 不大于x内的素数个数大约为x/log(x) 。 Jacques Solomon Hadamard和Charles-Jean de la Vallée Poussin于1896年按照B. Riemann的思想首次证明。 简单地说,素数基本定理等价于 黎曼zeta函数zeta(s)在实部为1的 ...
个人分类: FUN MATH|2779 次阅读|1 个评论 热度 1

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