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1. ### Symmetric, antisymmetric and parity

Let me see if I can make it clearer. Problem 5.5 In David Griffiths “Introduction to Quantum Mechanics” says: Imagine two non interacting particles, each of mass m, in the infinite square well. If one is in the state psin and the other in state psim orthogonal to psin, calculate < (x1 -...
2. ### Symmetric, antisymmetric and parity

Problem 5.5 In David Griffiths “Introduction to Quantum Mechanics” says: Imagine two non interacting particles, each of mass m, in the infinite square well. If one is in the state psin and the other in state psim orthogonal to psin, calculate < (x1 - x2) 2 >, assuming that (a) they are...
3. ### Differential forms. Why?

I was reading lethe's thread on differential forms and suddenly it dawned on me that I had no idea what differential forms were for, or why the process was developed. Do they replace vector calculus, or are they a more powerful form of linear algebra or what? For me it is much easier to study...
4. ### Infinite wave train for an electron?

The normalization of the free (say, electron) in quantum mechanics is achieved by a trick with the dirac delta function. Typically we write the orthogonality conditions for u1=c*exp(i*k1*x) and u2=c*exp(i*k2*x) as: int(u1*u2)=delta(k1-k2) and then out pops the nomalization constant...
5. ### Tunneling and transmission coefficient

If an ensemble of quantum partcles, with energy E, traveling in x direction encounter a very wide potential barrier V0 > E, the ensemble wavefunction will exponentially decay within the barrier. I thought that meant that there was a small probability of detecting an electron within the...
6. ### Energy and postion in QM

In the hydrogen atom the 1s orbital has a clearly defined energy of 13.6 eV, but the probability density and radial probability density says you are liable to find the 1s electron anywhere from the nucleus on out. How does this exact energy value jive with this variable position?