Recent content by shchr

meteor: I have that book. According to my understanding, that Hilbert space is infinite dimensional means that a function f(x) can be considered as infinite dimensional vector.

I don't understand the meaning of the above sentence. Usually potentials are real functions.

If I could help you somehow. I think when a photon hits an electron around a nucleus the distribution of an electron cloud is polarized. As is in classical theory, this polarization causes new electromagnetic field which probably means new photon is emitted. According to a book of optical...

"as if there was a different physics at work in the two cases" O.K. I understand. Thank you, everyone!

Another idea came to my mind. I hope this example inspires all of you futher. If the number of electrons with same quantum number is only one, same two scattering process don't occur in the universe. Because electrons in the universe have different quantum numbers, in state of scattering...

Let's turn to the case of hydrogen atoms. Supose that there are two hydrogen atoms here. The electrons in 1S orbit in each atom have same quantum numbers. Yes, each electron is in different system. For different sysytem, there is different Hilbert space. But what is the effect of being...

Thank you for your response. If the number of electrons with same quantum state in the universe is only one, they make a sort of Fermi sea in vacuum which should, I think, be called Dirac sea. But according to my memory, Dirac sea is denied by QFT. Does Dirac sea truly exist?

I am confused! Fermi particles cannot occupy the same quantum state simultaneously. When considering quantum states in solid material, I was taught that in solid material, an electron occupies one quantum state and then many electrons occupy lower states making Fermi sea. Then, is this...

Let's take the case of harmonic oscillator. x is an observable and p is also an observable. But they cannot be measured simultaneously because they don't commute. As we know, a=C x + i D p (C and D are proper constants) is annihilation operator. But a does not have diagonal elements which should...

Hello! My favorite QM book is Messiah's book which is also sold from Dover. Although this book has a large volume and is an old book, you may get many important idea about QM.

Hello, tavi_boada. I'm interested in your assertion. But I think an observable corresponding to a physical value must be a one which can be observed by direct mesurement. But, although A and B are directly observed, A+iB cannot be observed directly. Could you give us an example of an observable...

Hi, sharpstones. I have not taken a course of QED. I just studied QED by reading some book. So I'm not confident about my reply. But I hope it is helpful for you. You seem to be thinking repel of same charge is caused by repel when virtual photon is emitted or absorbed by electrons. But I think...

I am not 100% confident of my answer. If there is any mistake please correct someone. I remenber that I read one popular science book which said: Planck was investigating his equation which was discovered by optimal fitting to data of the experiment and happened to realize that the equation...

For everyone who are interested in quantum tunneling. Check this book! Quantum theory of tunneling written by Mohsen Razavy, World Scientific Pub This book describes how tunneling time may be defined and possibly speed of quantum tunneling is superluminal.

I don't know the answer to the question 1. But we need to think particle-wave duality seriously. We don't have a clear view about this based on language we use in a usual life. The second question is clear. The arrow indicates the phase for path integral. Feynman refers to a formulation of QED...