Recent content by dontknow

can you elaborate a little more? What if the ket alpha is like [1 , i ], a basis state, would the complex conjugate operator act on such a state?

sorry, I was not clear. we usually interpret propagators as particle popping out in space at some spacetime, let's suppose x and then it gets annihilated at spacetime point y. so if we follow the same interpretation here the particle which pops out at some point x can go back in time gets...

Eq 4.44 in Peskin and Schroeder. My question is: Does causality imply that time coordinates of z (internal vertex over which we doing the integration) should lie between the time coordinates of field phi(x) and phi(y)?

I was reading zee's group theory in a nutshell. I understand that we can decompose a 2 index tensor for rotation group into an antisymmetric vector(3), symmetric traceless tensor(5) and a scalar(trace of the tensor). Because "trace is invariant" it put a condition on the transformation of...

"Sure you can map higher rank tensors to scalars using tensors of the same rank, but not to map vectors to scalars." Thanks. Trace is a linear mapping. So is it going to be in the cotangent space?

"The dual space is the space of all linear maps from the original vector space to the real numbers." Spacetime and Geometry by Carroll. Dual space can be anything that maps a vector space (including matrix and all other vector spaces) to real numbers. So why do we picked only a vector as a...

I was reading mehran kardar (books and lectures) it says the concept of irreversibility comes from an assumption (in which we increase the length scale by interaction disctance between two particles). So My question is the concept of irreversibility is still valid in the case of 1 particle...

In Rigid body rotation, we need only 3 parameters to make a body rotate in any orientation. So to define a rotation matrix in 3d space we only need 3 parameters and we must have 6 constraint equation (6+3=9 no of elements in rotation matrix) My doubt is if orthogonality conditions...

I am a master student from India with specialization in quantum physics. I think the discussion is the best way to teach ourself any subject.