Class 3, 1/13/03 Highlights

*  The universe has been expanding since its birth 1.4x10^10 yr ago.
    ** Hubble's law
    ** Hublle's constant, and its value (related to the age of the universe) and dimension
*  Age of the universe, age of the Sun, and the age of the humans
    ** On scientific scale (i.e., log_10) in age
    **  On scientific scale (i.e., log_10) in time ago
* Highlighting c and ly on p. A-2, Useful Numbers, and we all should understand and memorize the numbers.
* Reordering numbers given in Table 1.2 so that the numbers are in descending order
* Advice: Mark numbers in Scientific notation to the second significant figure at the book margin when reading.
* Discussions on HW2, SA2.1, SA2.2.
* Thanks to the excellent special effort by Mr. Greer, the TA, Graded HW1 (handed in just a couple days ago) was given back to students, and copies of solution were distributed
    ** Students are advised to follow the example of presenting HW as given in the solution:
        *** Write neatly the solutions in the front HW page.
        *** Organize and write the key equations on the back page, for future referencing and getting credit if the results are wrong simply due to an arithmetic error.
        *** Document references for every problem, for future reviewing.
* Statistics of HW1 score were shown. Chau hopes that the low end will disappear in future HW scores
* New Policy: Every student can have one HW score not counted. (Those who missed HW1, or did poorly, have already used up this opportunity. So please do good work from now on.)

Bonus point project: Find good web sites that give the history and a simple description about the scientific scale (or Log), useful for the class. One bonus point for the student whose finds the site suitable for the class link. Half bonus point for students who find other useful sites. Please send to Chau only those you have read and found useful. The deadline for acceptance is midnight, Saturday, 1/15/05.

 


* We finished discussing material of the following reading assignments and HW2.

Related reading assignment (Please finish reading them before class 3.):
  · TB1:  Chpt 1,  p.2-25 , "Our Place in the Universe"
  · TB2:   Starting page to p.xv and p.3-p.20, Prefaces and Chpt 1, "Tie Up with String".