Recent content by Harel

If we have 2 particles A and B with entangled spins like in the EPR case. we know by the pauli matrices that there is an uncertainty relation between the x and z spin direction for example so what happens if we Alice measures the spin in the x direction while simultaneously Bob measures the spin...

Hey, in sean carroll's book about GR he said something about transverse vector, can someone explain me what a transverse vector is? Also he said:"Remember that the vectors are defiend only in the two transverse dimensions" what is the meaning of transverse dimension

Because by the defenition of sean, let's take a type (1,0) tensor which is a vector and another (1,0) tensor which is also a vector and the product will be a (2,0) tensor, which is a metrix.

Hey it might be a stupid question but I saw that the tensor product of 2 vectors with dim m and n gives another vector with dimension mn and in another context I saw that the tensor product of vector gives a metrix. For example from sean carroll's book: "If T is a (k,l) tensor and S is a (m, n)...

But how can you know that r increasing means time decreasing and not increasing?

Thanks for the answers! I know the kruskal diagrams and why a photon that originated at region 2 must end up in the singularity in those coordinates yet I try to understand how one can know that the same thing will happen using only the Schwarzschild coordinates. I had a problem with Peter's...

Hey first thankes for your help, I ment for the sign of dt/dr and as I understood negative dt/dr means ingoing geodesic anywhere, I didn't understand why dt/dr change his meaning in the r<2GM region, so if you could explain to me why I will be gratefull. And yet even with that logic, if we...

Schutz states in his book in the black hole section that: At r<2GM, r is a timelike coordnate, while t has become spacelike: even more evidence for the funniness of t and r! Since the infalling particle must follow a timelike world line, it must constantly change r, and of course this means...

Hey, I know that one doesn't work with polar coordinates (t,r,θ,φ) because they don't behave well in the event horizon. But my problem is with raidal null curves, if we take ds2=0 and dφ, dθ = 0 so we have When, if I'm correct, the + sign determine that it's outgoing and the - infalling, so...