Recent content by OB1

I have a set of elements (matrices with symbolic entries and certain special properties) which I constructed in mathematica. I would like to identify the matrices in this (finite but large) set which solve a certain linear equation. I've tried to use Solve in conjunction with Assumptions but was...

This is without a doubt the stupidest question on the forum, but I need the answer desperately: how exactly is the word holonomy (e.g. "Calabi-Yau manifolds have SU(n) holonomy") pronounced - as in, where do we put the emphasis? Thanks in advance.

For example, the canonical commutation relation in quantum mechanics: [x,p]=i hbar TOE = theory of everything.

There is much more to Lie algebras than just differential geometry and Lie groups. Sure, you can study them as the tangent space to the identity of a Lie group, but they are a very complex algebraic structure with many applications in physics, and GR is arguably the branch of physics that relies...

I stand corrected.

Let us suppose light has mass. Take the usual Lagrangian density with the Maxwell field interaction term and add a massive term: \mathcal{L} = - \frac{1}{4} F_{\mu \nu}F^{\mu \nu}- \frac{1}{2}m^{2}A_{\mu}A^{\mu} It turns out you need to add another couple of terms, otherwise the...

The wedge product is not the same as the tensor product. They do not act on the same space - the tensor product is on the tensor algebra (which is of course just the free vector space modulo a bunch of ideals), whereas the wedge product acts on the exterior algebra (which is the tensor algebra...

Well, that still leaves us with B-field corrections as a falsifiable prediction of string theory. As for post-dictions, I think I've lost the argument there... :cry:

It is also my understanding that certain types of Regge trajectories would be indicative of strings.

String theory is not my forte, but as an example of a possibly observable phenomenon predicted exclusively by string theory, consider the predicted B-field corrections to the Maxwell field. If we were able to observe the excitations of an electromagnetic field to sufficient accuracy to determine...

I am confused about the different Ricci-named objects in complex and specifically Kahler geometry: We have the Ricci curvature tensor, which we get by contracting the holomorphic indices of the Riemann tensor. We have the Ricci scalar Ric, which we get by contracting the Ricci tensor. Then there...

I would have to respectfully disagree about "missing falsifiable predictions of new phenomena". There are plenty of predictions, and they are theoretically falsifiable. At this point in time experimental physics has yet to develop a machine which would test these predictions, but that is not a...

No, it's a quantity used by physicists to calculate the MSW effect on weakly-interacting particles going through the earth. Anyways, it doesn't matter, I found it in the PDG Review.

I'm trying to find the approximate electron number density of the Earth - what physicists call n_{e} - but can't actually get the value anywhere. Does anyone know what the value of this constant is?

(Sorry about the convoluted title) I have a (very messy) function, say f(x,y), which is dependent upon two other functions, say s(x,y) and t(x,y). I'd like to do a contour plot of f(x,y)'s dependence on s(x,y) and t(x,y) - i.e. have s(x,y) and t(x,y) on the margins. I don't get an error when I...