Modern Physics Seminar(6)

宇宙学


  • 第一次讲座

Theme:The very early universe & the CMB physic Standard Model:Inflation & Hot Big Bang

宇宙微波背景(cosmic microwave background,CMB)是宇宙学中“大爆炸”遗留下来的热辐射,约为2.725K。

反弹宇宙学(Bounce Cosmology)connecting fundamental thories with observation。

量子涨落被拉开,波长拉长,距离边远后退相干变为经典涨落。

Concordance Model,inflationary Lambda-CDM model,共有6个基本参数和5个导出参数。

CMB polarization,E mode 、B mode BICEF instrument of the south polar

寻找原初引力波,Primordial GWs

实验方法: 卫星有年限,不方便更新升级。

地面目前有四个地点:南极、智利高原沙漠、格陵兰岛、西藏阿里。

第一次讲座总结: Today

  1. the  past decade has witnessed the era of presision cosmology
  2. the paradigm of early universe has been greatly developed
  3. Big Bang cosmology has become the Standard Model
  4. Inflation obtained a large amount of initial achievements
  5. Bounce cosmology is ambitious on solving big bang singularty

In near future

  1. Very early universe opens a window to explore fundamental physics
  2. It becomes possiblle to observationally probe physicsnear the Big Bang CMB experiments
  3. CMB experiments in the north earth is necessary
  4. China’s Ali CMB project will be hte first CMB experiment int the north earth

  • 第二次讲座

Theme:Primordial GWs & the CMB physic 提到了今年的诺贝尔物理学奖,LIGO项目于1992年立项,1999年运行,到2009年没结果,然后停机维护升级,2015年继续开机。

寻找原初引力波的动机Motivation:

  1. produced in very early time (within 10^(-30)s)
  2. linearly decouple
  3. originated from quantum fluctunations

Harmonic Analysis for CMB Polarization 弯曲时空,引力透镜,把E mode变成B mode

CMB Perfect Blackbody

相比于第一次讲座科普性的内容,第二次讲座最大的感受,宇宙学也是扎实的理科,用数学工具精准描述的,用实验装置观测,其基础理论涉及到了电动力学、流体力学、热统等物理知识,也有量子力学的内容。而且老师很年轻,很有活力,对于自己所研究的事情很有兴趣,不断地问:“不知道你们有没有这样的感受,我是感觉很兴奋的。”

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