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visits | member for | 2 years, 8 months |
seen | 19 hours ago | |
stats | profile views | 295 |
Apr 1 |
comment |
A.C. spectrum of the non additive perturbation BAB of a self-adjoint operator A where B is strictly positive
Is this related to anderson localisation ? |
Mar 6 |
answered | Does positivity preserve compactness? |
Dec 3 |
comment |
Fixed point theorems and equiangular lines
@Peter: Can you formulate the conjecture as a fixed point problem ? |
Nov 1 |
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What is entropy, really?
@Marek : The entropy of a black holes is not zero. Instead it is much greater than the entropy of the star that collapsed to the black hole. |
Nov 1 |
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What is entropy, really?
Entropy measures our ignorance : It is the logarithm of the phase space volume of macroscopically indistinguishable states. See Roger Penrose, The road to reality, chapter 27.3 . |
Oct 16 |
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Set of physical states of FQHE on closed Riemann surface = ?
to "set of possible states of that physical system" : That's just the Hilbert space of the quantum system. Furthermore there is no phase transition in FQHE / IQHE (in contrast to superconductivity). |
Oct 8 |
comment |
Bunimovich stadium bouncing ball
to "probabality distribution of the particles" : There is only 1 particle (the ball). |
Oct 1 |
awarded | Caucus |
Aug 23 |
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Self-adjointness of a perturbed quantum mechanical Hamiltonian specified in an infinite matrix form
to (2) : you should make this more precise : For instance, there is a divergent series of eigenfunctions of $H_N$ with eigenvalue zero. |
Aug 22 |
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Ergodic Mean for Schrodinger flow
Your operator acts on the fourier transform $\hat{f}(k)$ as a multiplication by $(e^{-i k^{2}T}-1)/(-i T k^{2})$ |
Aug 19 |
awarded | Yearling |
Aug 19 |
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Ergodic Mean for Schrodinger flow
For a proof use fourier transform or resolution of identity of normal operators. However, I don't know if this is useful for the nonlinear case. |
Aug 16 |
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C*-algebras and quantum fields
to "Quantum fields have infinitely many degrees of freedom, okay (but only countably many, sorry)" : How do you count them ? |
Jul 11 |
awarded | Nice Answer |
Jul 10 |
answered | What is a good method to find random points on the n-sphere when n is large? |
Jul 3 |
comment |
Why is this operator compact?
I think this is a Hilbert-Schmid-Operator : It's an integral operator with kernel f(x)g(x-y) where g is the fourier transform of $\langle D\rangle^{-n}$ . Hope g is good enough such that this argument works. |
Jun 30 |
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Quantum mechanics formalism and C*-algebras
If you know the expectation values of all projection operators then you can also calculate the expectation values of the unbounded operators. |
Jun 25 |
awarded | Revival |
Jun 1 |
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Is the Poincare action on the Klein-Gordon quantum field strongly continuous?
Your argument only shows that the action is not norm continous, and this means that the generators of the group action are unbounded operators. |
May 23 |
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Is there anyway to rewrite a partial differential equation using language of differential forms, tensors, etc?
An example are maxwells equations, see en.wikipedia.org/wiki/Maxwell%27s_equations. |