Archive for June, 2006

The uncertainty principle

Monday, June 26th, 2006

the more precisely the position is determined, the less precisely the momentum is kown in this instant, and vice versa.

In the most extreme case, absolute precision of one variable would entail absolute imprecision regarding the other.

SWNT

Saturday, June 24th, 2006

single-wall nanotubes (SWNT) are quasi-one dimensional nanowires and exhibit either metallic and semiconducting properties depending on their chirality and radius. one of the grand challenges of research on carbon nanotubes has been the realization of nanometer optoelectronic device. Recently, the modification of electronic properties of carbon nanotubes by the adsorption of foreign atoms or molecules has been actively studied.

de Sitter狭义相对论

Sunday, June 11th, 2006

 

格致上看到中科大的闫沫霖教授在演讲中提到了de Sitter狭义相对论,是爱因斯坦狭义相对论的一种推广。问题的解决是从Lagrange量开始的。分为三部分:牛顿力学、爱因斯坦狭义相对论、de Sitter不变狭义相对论。通过对比三种理论在同样的原理要求下后者是前者的推广形式。有趣的是,他提出了三个理论中分别有0、1、2个普适常数,其中de Sitter不变狭义相对论的普适常数是光速和宇宙常数

de Sitter不变狭义相对论是有陆启铿教授在70年代提出的,由于其实验上难以实施证明,所以这方面似乎没有多大的发展。不知这里是否有人从事这方面的研究的,或者知道这方面内容的。

闫教授推荐了一篇关于这方面的论文

世界杯狂热

Saturday, June 10th, 2006

最近忙于看世界杯

很少有时间写blog了,明天转一贴!

标准

Friday, June 9th, 2006
  • 弗兰克林:校长,您有没有想过您的标准或许有点过时了吗?
  • 校长:当然,它们过时了。标准总是过时的。这就是它们能成为标准的理由。

——艾伦.贝纳特

electronics structure

Friday, June 9th, 2006
As a result of recent successes in describing and perdicting properties of materials, atomistic simulations in general and electronic stucture calculations in particularly have become increasingly important in the fields of physics and chemistry over the past decade, especially with the advance of present-day, high-performance computer. Assuming a knowledge of the types of atoms comprising any given material, a computational approach enables us to answer two basic question:
  • what is the atomic structure of the material?
  • what are its electronic properties?

有时候

Friday, June 9th, 2006
有时候我像孩子一样惶恐地看着这个世界
却不知道自己犯了什么错误

Friday, June 9th, 2006

wedding

今天一个朋友婚礼,八卦一下。

measurement of the conductance of single cojugated molecules

Friday, June 9th, 2006
electronical conduction trought molecules depends critically on the delocalization of the molecular orbitals and there connection to the metallic contacts.

man and woman

Friday, June 9th, 2006
男人伪装坚强,只是害怕被女人发现他软弱。女人伪装幸福,只是害怕被男人发现她伤心