2,265 reputation
419
bio website azimuthproject.org/azimuth/…
location Munich, Germany
age 39
visits member for 3 years, 8 months
seen Jun 20 '13 at 19:28

I'm a physics graduate working as an IT-developer and -consultant.


Jan
27
comment What is a maximal analytic extension?
The last sentence seems to indicate that you are just confused by the wording "analytic extension", choosing a different chart that does not exhibit coordinate singularities where another one does, does not have a direct relationship to "extending" a complex function, although both topics are about removing "artificial singularities" coming from an inadequate chosen representation (a chart or a representation of a complex function).
Jan
27
comment Newton's Bucket
Sorry, I don't understand your question. In GR we have a spacetime, it is a solution to the Einstein field equations. Any mass distribution influences this solution, therefore any mass will influence the local gravitational field and therefore will influence what the local reference frame is (unless, of course, it does not because the mass and the point we are looking at are for ever spacelike separated, for example).
Jan
27
answered Haag's theorem and practical QFT computations
Jan
27
answered Newton's Bucket
Jan
27
awarded  Supporter
Jan
27
comment Is a normal-ordered product of free fields at a point a Wightman field?
Hi there, this software is unfit to host ongoing discussions, so I'll be brief: Making sense of $\phi(x) \phi(x)$ as a Wightman field would, that's my educated guess, result in the very first construction of an interacting Wightman theory. I doubt that it can be done. Products of distributions can be defined, however, under certain circumstances. Note that in the two point function for a Wightman field the product is actually a tensor product (you feed every factor one test function separately).
Jan
26
awarded  Editor
Jan
26
revised Is a normal-ordered product of free fields at a point a Wightman field?
added 771 characters in body
Jan
26
answered Is a normal-ordered product of free fields at a point a Wightman field?
Jan
26
comment Is causality a formalised concept in physics?
@Nigel: No, as far as I know there is no deeper formalization of causality in physics, as Lubos already said. Maybe one could add that the time evolution of physical systems is described by hyperbolic evolution equations and that the causal relationship of events is preserved via the appropriate representations of the Poincare group, and that's it.
Jan
25
answered Is causality a formalised concept in physics?
Jan
24
awarded  Teacher
Jan
24
answered Why are von Neumann Algebras important in quantum physics?