Recent content by koolmodee

Could you put that clearer? Do you find it difficult that - quanta of gravity must have spin 2 and be massless and - can't construct a quantum field theory which is Lorentz-invariant and renormalizable If so, why do you find it difficult?

thanks! I remember I read something like that in Barbara Ryden cosmology book, but forgot it all. many thanks

Alright, when I think of it, converting only a tenth of the baryonic mass into electromagnetic radiation, that would add incredible many more photons to the universe, so I guess they are negligible.

Thanks for the answers! But I'm not quite satisfied yet. Was their contribution non-negligible only in the early universe? Is it present universe negligible?

So they say the universe is made of baryonic matter, dark matter and dark energy. What about photons?

As far as money being destroyed and burned at the financial market, picture a situation with say ten people siting on a table and passing around a card. The first one sells it to the second one for 10 dollars, the second one to the third one for 20 dollars and so on. The last one buys the card...

We have f(E)q(-E) + f(-E)q(E) now change to x(E)=q(E) + f(E)/ (term) and get -(f(E)f(-E))/(term) I plugged the changed variable in, but didn't get the result, any hints how to proceed? I got that from page 63, 64 equations 7.6, 7.7, 7.8 from this text...

I know, this is what I did in post 1. But why and how makes that su(n) and sl(n,c) isomorphic?

Thanks for answering! Right, complexifaction is it also called by others. But why and how are su(n) and sl(n,C) isomorphic?

Shorter version of my question above: What does ' tensoring su(n) with the complex numbers we get sl(n,C), which shows that su(n) and sl(n,C) are isomorphic' mean? thank you

Thanks D H!

su(n) is isomorphic to sl(n,C), when we tensor su(n) with the complex numbers we get sl(n,C). Say we have su(2) with E_1= 1/2 [i, 0;0, -i], E_2=1/2[0,1;-1,0], E_3=1/2[0, i; i,0] sl(2,C) with F_1=[1, 0; 0, -1], F_2=[0, 1; 0, 0], F_3=[0, 0; 1, 0] so that...

The vector product in C³ is a three dimensional Lie algebra. Taking the standard basis (e_1,e_2,e_3) of C³, the brackets can be defined by the relations: [e_1,e_2]=e_3 [e_1,e_3]=-e_2 [e_2,e_3]=e_1 That what my book says, but I don't get. But what does the author mean here with the...

3 reflections and 3 rotations, right? But what does |D3| mean? And what is |A5 x Z2|? Where can I look up the symmetries for other geometric objects, like for example the other platonic solids? And what about the number of elements, how do i find out about those?

How many symmetries (and what symmetries) and how many elements do the transformation groups of the equilateral triangle and the icosahedron have? thanks