Lizwi

Hi I have learnt that notepad is HTML editor, then what is HTML itself, is HTML a software? Can I edit directly on HTML? For example, if I do programming in python I write a code in python itself not in any editor. Is HTML a software like python? Thanks

Yes, I am doing QM. Thanks a lot. How do I write the hermitian conjugate of operator A. Please see the attachment.

Yeah, is Kronecker delta reaulting because of diagonal matrix?

Why is i =j in the steps highlighted in green?

What type of mathematics must I do to understand this mathematics in the picture below?

What type of mathematica is this on the picture. When I start to study relativity, it appears and I don't understand it.

Everything that exists