Metric Definition and 1000 Threads

Hello! I am a bit confused about how the metric transforms vector into one forms. If we have a 2-sphere and we take a point on its surface, we have a tangent plane there on which we define vectors at that point. A one form at that point is associated to a vector at that point through the metric...

Hello PF! I was reading https://en.wikipedia.org/wiki/Fubini–Study_metric (qm section like always :wink:) And can't figure out how to derive: \gamma (\psi , \phi) = arccos \sqrt{\frac{<\psi|\phi><\phi|\psi>}{<\psi|\psi><\phi|\phi>}} I started with \gamma (\psi , \phi) =|| |\psi> - |\phi>||=...

I was working out the components of the Riemann curvature tensor using the Schwarzschild metric a while back just as an exercise (I’m not a student, and Mathematica is expensive, so I don’t have access to any computing programs that can do it for me, and now that I’m thinking about it, does...

Homework Statement Let the line element be defined as ##ds^2 = -(1-\frac{2m}{r})dt^2+\frac{dr^2}{1-\frac{2m}{r}}+r^2 d\theta^2 + r^2 \sin^2{\theta} d\phi^2## a) Find a formula for proper distance between nearby spherical shells, assuming only the radius changes, and ## r > 2m ## b) Now look...

Hello! I was thinking about the Riemann curvature tensor(and the torsion tensor) and the way they are defined and it seems to me that they just need a connection(not Levi-Civita) to be defined. They don't need a metric. So, in reality, we can talk about the Riemann curvature tensor of smooth...

My question is regarding how spacetime looks like beyond the event horizon of a black hole, in particular how distances behave. In the Minkowski diagram of a black hole, all paths leads to the singularity. But what is the magnitude of the distances involved here? Let's say a neutron star is...

Homework Statement Consider the set of real number with the following metric: ##\frac{|x-y|}{1+|x-y|}##. Which subsets of R with this metric are open, closed, bounded or compact? Homework EquationsThe Attempt at a Solution First I calculated the neighborhood in this metric. If the radius of...

Hi, I'm getting into general relativity and am learning about tensors and coordinate transformations. My question is, how do you use the metric tensor in polar coordinates to find the distance between two points? Example I want to try is: Point A (1,1) or (sq root(2), 45) Point B (1,0) or...

Homework Statement In special relativity the metric is invariant under lorentz transformations and therefore so is the determinant of the metric. How does the metric determinant transform under a more general transformation $$x^{a\prime}=J^{a\prime}_{\quad a}x^{a}$$ where $$J^{a\prime}_{\quad...

Homework Statement I think I have managed to do the first three parts of this problem ok, but I am struggling with part 4. [/B] A 2D negatively curved surface can be described in 3D Euclidean Cartesian coordinates by the equation: ##x^2 + y^2 + z^2 = −a^2##. 1) Find the 2D line element for...

Homework Statement I am trying to derive the following relation using inner products of vectors: Homework Equations g_{\mu\nu} g^{\mu\sigma} = \delta_{\nu}^{\hspace{2mm}\sigma} The Attempt at a Solution What I have done is take two vectors and find the inner products in different ways with...

Homework Statement Given that ##ds^2 = r^2 d\theta ^2 + dr^2## find the geodesic equations. Homework Equations The Attempt at a Solution I think the ##g_{\mu\nu} = \left( \begin{array}{ccc} 1& 0 \\ 0 & r^2 \end{array} \right)## Then I tried to use the equation ##\tau = \int_{t_1}^{t_2}...

Hi, my question is related to taylor expansion of metric tensor, and I have some troubles, I would like to really know that why the RED BOX in my attachment has g_ij (t*x) instead of g_ij(x) ? I really would like to learn the logic...

In Schutz's A First Course in General Relativity (second edition, page 45, in the context of special relativity) he gives the scalar product of four basis vectors in a frame as follows: $$\vec{e}_{0}\cdot\vec{e}_{0}=-1,$$...

Although the complete quantum gravity is unknown as the exact details of black hole evaporating, is there known some symmetric non vacuum solution of E. equations which includes radiating of matter from central mass ? One can say, that Schwarzschild solution with small perturbation is good...

If the Schwarzschild metric is, by construction, valid for ##r > r_S##, where ##r_S## is the Schwarzschild radius, so it does not make sense to talk about what happens at ##r \leq r_S##, because there will be no vacuum anymore. What am I getting wrong?

I'm looking influence of pressure on the general interior Schwarzschild metric (see for example the book by Weinberg, eq. 11.1.11 and 11.1.16. The radial component of the metric (usually called A(r)) depends only on the mass included up to radius r A(r) = \left(1-\frac{ 2G M(r)}{r}\right)^{-1}...

I am having trouble finding the equation for the metric for the Lambdavacuum solution to the EFE in radial coordinates. Any suggestions?

I would like to know the difference between this two concepts, specially the difference between the geometry deformations of space-time that they descript. As far as I know the Schawrzschild metric can be represent by Flamm’s paraboloid, but this shape is not the same that the deformation of...

Good Day, Another fundamentally simple question... if I go here; http://www-hep.physics.uiowa.edu/~vincent/courses/29273/metric.pdf I see how to calculate the metric tensor. The process is totally clear to me. My question involves LANGUAGE and the ORIGIN LANGUAGE: Does one say "one...

Please help. I do understand the representation of a vector as: vi∂xi I also understand the representation of a vector as: vidxi So far, so good. I do understand that when the basis transforms covariantly, the coordinates transform contravariantly, and v.v., etc. Then, I study this thing...

Hi everyone, I am reading Sean Carroll's note on gr and he mentioned metric compatibility. When ∇g=0 we say the metric is compatible. However from another online material, the lecturer argues ∇ of a tensor is still a tensor, and given that ∇g vanish in locally flat coordinate and this is a...

Do the field equations themselves constrain the metric tensor? or do they just translate external constraints on the stress-energy tensor into constraints on the metric tensor? another way to ask the question is, if I generated an arbitrary differentiable metric tensor field, would it translate...

Somewhere I ran across a `prescription' for computing the radial locations of the 2 event horizons of a S-dS metric, in which one merely computes where the radial gradient of g00 component vanishes, i.e., dg00/dr = 0. I am wrong, & apparently it's sufficient to merely set g00 = 0 , in order to...

Homework Statement How to show that lie deriviaitve of metric vanish ##(L_v g)_{uv}=0## <=> metric is independent of this coordinate, for example if ##v=\partial_z## then ##g_{uv} ## is independent of ##z## (and vice versa) 2. Relevant equation I am wanting to show this for the levi-civita...

Homework Statement Question attached. Homework Equations 3. The Attempt at a Solution [/B] I'm not really sure how to work with what is given in the question without introducing my knowledge on lie derivatives. We have: ##(L_ug)_{uv} =...

I suspect the following reasoning is faulty, but I am not sure why. Hence I would appreciate someone pointing out the errors. That is, which, if any, of the following statements are incorrect, and why? 1) Theoretically, albeit not practically due to the large numbers involved, the laws of...

As I understand it, in the context of cosmological perturbation theory, one expands the metric tensor around a background metric (in this case Minkowski spacetime) as $$g_{\mu\nu}=\eta_{\mu\nu}+\kappa h_{\mu\nu}$$ where ##h_{\mu\nu}## is a metric tensor and ##\kappa <<1##. My question is, how...

Why one uses Schwarzschild metric instead of FLRW metric when deriving things such - deflection of light by the sun - precession of perihelia of planets Also, as our solar system is not isotropic nor static, it seems that by using the Schwarzschild metric we would get only an approximation on...

Homework Statement Conserved quantity Schwarzschild metric. Homework EquationsThe Attempt at a Solution [/B] ##\partial_u=\delta^u_i=k^u## is the KVF ##i=1,2,3## We have that along a geodesic ##K=k^uV_u## is constant , where ##V^u ## is the tangent vector to some affinely parameterised...

Hello, I am working with numerical relativity and spectral methods. Recently I finished a general elliptic PDE solver using spectral methods, so now I want to do Physics with it. I am interested in solving the lapse equation, which fits into this category of PDEs $$ \nabla^2 \alpha = \alpha...

In the second volume, Field Theory, of popular series of Theoretical Physics by Landau-Lifschitz are given following equations as in attached file from the book. Here is considered metric change under coordinate transformation. How is the new, prime metric expressed in original coordinates is...

Is there a less boring way of deriving the Schwarzschild solution? The derivation itself is easy to going with; what I don't like is computing all the Christoffel symbols and Ricci tensor components --there are so many possible combinations of indices. I know that by using some constraint...

Consider empty spacetime containing a charged capacitor. Is there a simple expression for metric for the spacetime between the capacitor plates in terms of Kaluza–Klein theory? We are told that spacetime tells matter how to move; matter tells spacetime how to curve. Is there a Kaluza–Klein...

Homework Statement Attached Homework EquationsThe Attempt at a Solution [/B] where ##\tau## and ##\sigma## are world-sheet parameters. where ##h_{ab}## is the world-sheet metric. To be honest, I am trying to do analogous to general relativity transformations, since this is new to me, so in...

I've been reading Fleisch's "A Student's Guide to Vectors and Tensors" as a self-study, and watched this helpful video also by Fleisch: Suddenly co-vectors and one-forms make more sense than they did when I tried to learn the from Schutz's GR book many years ago. Especially in the video...

In coordinates given by x^\mu = (ct,x,y,z) the line element is given (ds)^2 = g_{00} (cdt)^2 + 2g_{oi}(cdt\;dx^i) + g_{ij}dx^idx^j, where the g_{\mu\nu} are the components of the metric tensor and latin indices run from 1-3. In the first post-Newtonian approximation the space time metric is...

In Weinberg's book it is said that a Static, Isotropic metric should depend on ##x## and ##dx## only through the "rotational invariants" ##dx^2, x \cdot dx, x^2## and functions of ##r \equiv (x \cdot x)^{1/2}##. It's clear from the definition of ##r## that ##x \cdot dx## and ##x^2## don't...

Hi All I would like to know if there is a way to produce simple one dimensional kinematic exercises with space-time metric tensor different from the Euclidean metric. Examples, if possible, are welcome. Best wishes, DaTario

Homework Statement Show that the metric connection transforms like a connection Homework Equations The metric connection is Γ^{a}_{bc} = \frac{1}{2} g^{ad} ( ∂_{b} g_{dc} + ∂_{c} g_{db} - ∂_{d} g_{bc} ) And of course, in the context of Einstein's GR, we have a symmetric connection, Γ^{a}_{bc}...

I am interested in looking at the metric where time is everywhere normal to space, so gta=0 everywhere, where t is the time coordinate and 'a' is any of the space coordinates. I'm finding it hard to look up in the literature: does it have a name that I can search for? My main interest is in...

Homework Statement Homework Equations see above The Attempt at a Solution Using the conservation equation for ##p=0## I find: ##\rho =\frac{ \rho_0}{a^3}##; (I am told this is ##\geq0## , is ##a\geq0## so here I can conclude that ##\rho_0 \geq =0 ## or not?) Plugging this and ##p=0## into...

This is probably a stupid question but so as ##r \to \infty ## it is clear that ##-(1-GM/r)dt^2+(1-GM/r)^{-1}dr^2 \to -dt^2 +dr^2 ## However how do you consider ## \lim r \to \infty (r^2d\Omega^2 )##..? Schwarschild metric: ##-(1-GM/r)dt^2+(1-GM/r)^{-1}dr^2+r^2 d\Omega^2## flat metric ...

Hi everyone, I'm currently studying Griffith's Intro to Elementary Particles and in chapter 7 about QED, there's one part of an operation on tensors I don't follow in applying Feynman's rules to electron-muon scattering : ## \gamma^\mu g_{\mu\nu} \gamma^\nu = \gamma^\mu \gamma_\mu## My...

Hello, I have a question regarding the first equation above. it says dui=ai*dr=ai*aj*duj but I wonder how. (sorry I omitted vector notation because I don't know how to put them on) if dui=ai*dr=ai*aj*duj is true, then dr=aj*duj |dr|*rhat=|aj|*duj*ajhat where lim |dr|,|duj|->0 which means...

Let we have a 2D manifold. We choose a coordinate system where we can construct all geodesics through any point. Is it enough to derive a metric from geodesic equation? Or do we need to define something else for the manifold?

Homework Statement Given the Schwarzschild metric generalisation for a mass M rotating with angular momentum J ##ds^2 = -(1-\frac{2 M}{r}) \; dt^2 +(1-\frac{2 M}{r})^{-1} \;(dr^2 +r^2 \;d\theta ^2 +r^2 \sin ^2 \theta \; d\phi ^2) -\frac{4J}{r} \sin ^2 \theta \; dt d\phi ## a) Write the...

Hello there, Suppose ## \Delta = r^2 + 2GMr + a^2## and ## \rho^2 = r^2 + a^2 \cos ^2 \theta ##. The Kerr metric is $$ ds^2 = - (1 - \frac{2GMr}{\rho^2})dt^2 - \frac{4GMar\sin^2 \theta}{\rho^2} d t d \phi + \frac{\rho^2}{\Delta} dr^2 + \rho^2 d \theta^2 + \frac{\sin^2 \theta}{\rho^2} \left[...

1. Problem ##g_{uv}'=g_{uv}+\nabla_v C_u+\nabla_u C_v## If ##g_{uv}' ## is given by ##ds^2=dx^2+2\epsilon f'(y) dx dy + dy^2## And ##g_{uv}## is given by ##ds^2=dx^2+dy^2##, Show that ## C_u=2\epsilon(f(y),0)##? Homework Equations Since we are in flatspace we have ##g_{uv}'=g_{uv}+\partial_v...

Are the metrics for say the Calabi-Yau manifolds of string theory, assuming they have a metric, dynamic in the sense that a vibrating string interacts with the compact space causing the metric to change where there is a string, even if only a tiny amount? Thanks!