Trouble Understanding GRT & Space-Time Attraction

  • Thread starter Thread starter AmorLiberalitas
  • Start date Start date
AmorLiberalitas
Messages
1
Reaction score
0
How can the distortion of space-time by matter lead to the attraction of two objects in space? What I mean is on a 2D plane representing space-time, a 3D object representing a planet can cause the geometry of space-time to warp, and that a passing smaller 3D object will spiral around the larger because of the ripple it makes. However, what I do not understand is how the two-dimensional analogy can be transferred into the three-dimensional world that we inhabit. I guess what I am trying to say is how does the curvature relate to us, are we pulled down by earth, are we pushed down by warped space-time? Sorry if none of this made sense. . .
 
Physics news on Phys.org
Space-time is 4 dimensional not two dimensional: with (x,y,z and t) I think you need to see the fabric of space as 3D rather than 2D, otherwise you'll confuse yourself. It is true that GR only works if we assume a flat space in terms of acceleration and gravity, but this is not what actually happens and is one of the reasons why relativity is not compatible in certain cases with quantum mechanics.

This picture might help.

https://www.physicsforums.com/attachment.php?attachmentid=9183&stc=1&d=1171663113

Similar questions that might help.

https://www.physicsforums.com/showthread.php?t=154960

https://www.physicsforums.com/showthread.php?t=138373&
 

Attachments

  • Spacetime_curvature.JPG
    Spacetime_curvature.JPG
    31.8 KB · Views: 709
Last edited:
I started reading a National Geographic article related to the Big Bang. It starts these statements: Gazing up at the stars at night, it’s easy to imagine that space goes on forever. But cosmologists know that the universe actually has limits. First, their best models indicate that space and time had a beginning, a subatomic point called a singularity. This point of intense heat and density rapidly ballooned outward. My first reaction was that this is a layman's approximation to...
Thread 'Dirac's integral for the energy-momentum of the gravitational field'
See Dirac's brief treatment of the energy-momentum pseudo-tensor in the attached picture. Dirac is presumably integrating eq. (31.2) over the 4D "hypercylinder" defined by ##T_1 \le x^0 \le T_2## and ##\mathbf{|x|} \le R##, where ##R## is sufficiently large to include all the matter-energy fields in the system. Then \begin{align} 0 &= \int_V \left[ ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g}\, \right]_{,\nu} d^4 x = \int_{\partial V} ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g} \, dS_\nu \nonumber\\ &= \left(...
In Philippe G. Ciarlet's book 'An introduction to differential geometry', He gives the integrability conditions of the differential equations like this: $$ \partial_{i} F_{lj}=L^p_{ij} F_{lp},\,\,\,F_{ij}(x_0)=F^0_{ij}. $$ The integrability conditions for the existence of a global solution ##F_{lj}## is: $$ R^i_{jkl}\equiv\partial_k L^i_{jl}-\partial_l L^i_{jk}+L^h_{jl} L^i_{hk}-L^h_{jk} L^i_{hl}=0 $$ Then from the equation: $$\nabla_b e_a= \Gamma^c_{ab} e_c$$ Using cartesian basis ## e_I...
Back
Top