Recent content by Frost_Xue

That was great answer. Thank you so much for the help and time. Sorry to bother you with such trivial question. have a good weekend.

I was reading Dirac's "The principle of QM" and bit of confused. In equation (21) does the number 1 in the sum or outside of the sum? If out side how come the sum over r is 1? X function is the quotient when the factors diveded by single one factor. for example if a*b*c*d then X_b is a*c*d i

Yea, please let me know that would be very helpful thanks a lot!

What is the good reason then?

As I was replying mass is energy so you can get rid of the concept of mass and think just Chuck of energy "flying off".

The real question is what is mass. You can think mass is invariant energy under transformation. Photon mass is zero it only has "moving" energy instead of "rest energy" plus "moving energy" like mass particles

oh I didn't pay attention on the order of the commutator on the right hand side. Thank you so much for the help and time. And sorry for bothering you again.

ok if I replace F(B) = e^At then should it be [A,B](e^At)' ? how does the t come from? and what do you mean by A=B? also the order of commutator seems reversed shouldn't it be negative then? Sorry I am stupid.

Hi, I don't understand how to use 51 get 66. Can you help me with that?