How Does Space-Time Fabric Elasticity Influence Time Flow?

nouveau_riche
Messages
253
Reaction score
0
if i consider space time to b a fabric as considered by einstein then expansion of this fabric leads in two direction
1-if the fabric has high elasticity then the curvature of space caused by the a massive object will keep on increasing,thus the flow of time will be faster and faster
2-if the fabric has low elasticity then the curvature will keep on decreasing thus the flow of time will be slow

which one is correct?
 
Physics news on Phys.org
Time does not flow in a space-time representation. It is a 'static' dimension like space, and the whole space-time object is a static object. Nothing goes anywhere, and nothing changes. All the going and changing has been done and can be inspected baked into the finished loaf.

That's the way I understand it, anyway.
 
Please don't use text-speak on PF. You're on the wrong track because your question assumes an overly literal interpretation of the rubber-sheet metaphor. Gravitational time dilation in GR depends on the difference in gravitational potential, not the curvature. Example: http://en.wikipedia.org/wiki/Pound-Rebka_experiment
 
Space and time ARE variable; that is, they are not static and fixed as Newton presupposed. Only the speed of light is fixed for all inertial observers. So things are not as they superficially appear!

Two things affect the observed passage of time: relative speeds and gravitational potential.

There is a nice brief summary of gravitational time dilation here:

http://en.wikipedia.org/wiki/Gravitational_time_dilation

You can read about length contraction and time dilation here:

http://en.wikipedia.org/wiki/Special_relativity

Mass is not the only thing that has gravitational affects: energy (like radiation), pressure, momentum also affect gravitational attraction...as compiled in the Einstein stress energy momentum tensor which is the actual mathematical source of curvature.
 
Last edited:
I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...
From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
Back
Top