I would have included the Causal Set programme by R.Sorkin.
But as a string theorist myself I'm really interested in the review by Coleman's student, thank you Marcus.
ok great, so why is the outer product on minkowski x^y^z^t=1? And is (x,x) always =1 ?
Also, so in this formalism is the magnetic field the Hodge dual to the electric field in Minkowski space?
thanks.
I'm having problems understanding Hodge duality in its most basic form. It relates exterior p forms to exterior n-p forms where n is the dimensionality of the manifold. I can't seem to follow the discussion on the hodge dual operator on this lecture course (page 19)...
At all times the centrifugal acceleration pushes the pilot onto the seat. The difference is the direction of the weight of the pilot, which is always the directed towards the centre of the earth. So at the bottom force = centrifugal + weight, at top its centrifugal - weight.
just think about what d/dx is from your first chain rule equation (factor out the u on which the differential acts on). then use this to find the second derivative and u'll get the mixed terms.
Just so you know what I did is calculate the general form of T(L):
T(L) = t_0 ln(L/a) + T_0
Then find the force on an infinitesimal stretch of the string then finally equate this to the acceleration via Newton's second law. The method is consistent for tangential waves but I have problems...
Hi guys, this is Barton Zwiebach's Introduction to String theory question 4.2 on the longitudinal wave on a taut string. The problem is purely classical and I seem to obtain a solution which seems far too complicated for me. If anyone has the answers it would be great, if not just your help...
One method is via extra dimensions. These quantum gravity theory work in extra compactified dimensionalities. Some of the high energy experiments can probe the results of the extra compactified dimensions and hint at a possible Qgravity theory.
What physicists need is a high-energy quantum gravity theory which reduces to GR at low energies (i.e. planets). This is basically what the whole of string theory is trying to do (in fact pretty successfully atm). Other approaches have been tried involving twistor theory, quantum loop gravity...
Hum ok, firstly applying QM to the "heaviest objects" such as planets is amost pointless as the QM effects are negligible. Secondly there is an intrinsic incompatibilty regarding particle number conservation, this is solved by the most basic Quantum field theory. For particle motion in SR there...
Just so you know what I did is calculate the general form of T(L):
T(L) = t_0 ln(L/a) + T_0
Then find the force on an infinitesimal stretch of the string then finally equate this to the acceleration via Newton's second law. The method is consistent for tangential waves but I have problems...
Hi guys, this is Barton Zwiebach's Introduction to String theory question 4.2 on the longitudinal wave on a taut string. The problem is purely classical and I seem to obtain a solution which seems far too complicated for me. If anyone has the answers it would be great, if not just your help...
The basics of the incompatibilty lie in the extremely small (Planck length) scenario. Basically GR predicts a "smooth" (C-infinite manifold) underlying space-time at the very small scale whilst QM, due to its intrinsic probabilistic nature, predicts this to be "rough" with pairs of particles...