[sjastro]

Originally Posted by xelasnave

I guess what I suggest is that the grid can only bend toward an object.. such that the squares of the grid become "smaller" and I associate smaller squares with increased gravity...and in an effort to bend we get out arcs.. that is obvious I guess...I dont know what smaller squares suggest other than time must be the thing that does it... I dont know if I am the right track but I imagine that space is compacted the closer it is to matter.

You're partly right Alex. The more convergent the grid lines the higher the gravitational potential or the strength of the field at that point.

Space time diagrams are much more complicated than that. The angle of the grid lines to the X or spatial axis as they dip into the depression determines if a particle can follow this trajectory. For example if the angle is less than 45 degrees no particle can follow this trajectory as causality is violated and the particle travels faster than light.

This is difficult to explain in a few sentences. You might want to look at these.

http://en.wikipedia.org/wiki/Schwarz...27s_paraboloid
http://en.wikipedia.org/wiki/Minkowski_diagram

Sorry I am so bewildered by all this I have difficulty in accepting anything I can not explain to myself with absolute confidence...and with all this I am not confident that I understand it...as I said all I see is geometry ..I read someplace that one could think of it as a pythagorean therom with an addition of a negative time line...now just because I read it takes me little further than visualising a grid that has curves which represent variations in gravity.

I simply hope the concepts are not so abstract that I am unable to visualise for the purpose of my limited understanding but maybe if I keep at it I will achieve a better understanding.

Unfortunately the physical sciences have gone well past the visualization stage for understanding and a command of mathematics is essential.

But so far I see general relativity as a geometry to describe space time...and I at this point think that space time has been derived from the principle of equivelence..(I know there is more to it and there are many contributions of others before Dr A but it seems to me that acceleration has been related to the effect of gravity... I guess that is where T got involved ...however I feel there is something fundamentally wrong about the approach as we use a human experience to describe something more complex than such approach admits... but not being absolutely at ease with the subject I can only speculate and grasp at thread I see bear...

Quantum mechanics is a much more esoteric subject than GR (and mathematically much more challenging). It is contary to human experience by bringing into question the concept of reality. Yet it has contributed to major technological changes in the 20th century.

Regards

Steven