Class 2 and Discussion 1, 1/11/03

Lecture Highlights:

* The three basic units -- m, s, kg --- are sufficient to specify all quantities in our universe, by using a composition of the three basic units.
* Light year, ly, defined and discussed.
* The universe is the totality of mass, energy, and the spacetime.
* From Einstein's E = M c^2, mass and energy are different manisfastation of the same thing.
* The dimensions of our spacetime, as far as established by experiments, are (3+1).
* Photon (the particle of light) has zero rest mass, however it always moves at speed c and is never at rest.
* Our universe is huge, massive, and dynamical. We showed pictures and demos from TB1.
* Our Earth spins, in addition to rotating around the Sun.
* In order to plot quantities for the whole universe on a piece of paper, we need to use the scientific scale (log_10 scale).
* We discussed how to make plots on the scientific scale, and demonstrated in Attachment to HW2 (which shows the plot from the size of a person to the observable universe).
* We discussed a simpler way to do unit conversion.
* We discussed HW2, SA2.2.

Discussion 1 Highlights:
* Students who found reports "Bees use vector analysis to find home" gave search engine used: msn.com, google.com, and wikipedia.com.
* Finer points about the scientific scale. (2 is approximately at one third of a step of 10, and 5 is approximately at two third of a step of 10.)
* More about unit conversion, and HW2, SA2.1.
* We discussed Chapter 1 of TB2:
    **  Table 1.1: three families of fundamental particles
    **  Table 1.2: four forces of nature
* Students are advised to use the pyramid scheme to study and prepare exam, as given in the link of "Guidelines for Study and Exam Preparation."


Related reading assignment (Please try to read as much as you can before class 2.):
  · 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".