Author Topic: Some Thoughts on Space and Time  (Read 70 times)

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Richard Mellor

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Some Thoughts on Space and Time
« on: April 23, 2018, 06:02:33 PM »
Some Thoughts on Space and Time

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I read these brief comments written by a comrade in response to a person who claimed proof of "god". I found it sort of interesting although I have to admit, I don't really understand it, but I know some will.  I'm also aware that with subjects such as these there will be some controversy and different opinions. I am not referring to controversy between religious doctrine (idealism) and science but within the scientific community itself. Anyway, read away.

On the matter of "God" and "creation" (I just posted elsewhere):

Dave Parks, Exeter UK

The Friedmann solution to the Einstein equations of General Relativity  is something I studied in my 2nd year at University. For simplicity here  I will describe the closed model solution - this is where there is  enough matter in the universe for it to eventually collapse under it's  own gravity. A bit like a rocket shot directly upwards but without  enough speed to escape the effects of Earth's gravity - eventually it decelerates and falls back to Earth.

First thing this is a 4-D model. There are two assumptions the universe  is homogeneous and isotropic. Basically made of the same stuff  throughout and in a symmetric or equal way in all directions. Any  localised clumping or asymmetry evens out on a grander scale. Evidence  from microwave background radiation suggests this is a highly reasonable  if not accurate assumption for the early universe.

It is almost  impossible for us humans to visualise 4-D - so we use analogies. For the  closed Friedmann model that analogy is the surface a 3D sphere  representing the whole history and expanse of 4D space-time. The North  pole of this sphere represents T=0 (the Big bang). Time (1D) is  represented by longitude, 3D space is represented by latitude. At this  point the radius of the universe is the extent of the latitude of the  sphere at that point which is also zero. As longitude increases as you  move away from the north pole the size of the universe increase until it  reaches a maximum at the equator. From then on the universe stops  expanding and starts contracting back down to zero size - a "big  crunch".

All points in space and time throughout the entire  history and expanse of the universe are represented on the surface of  this 3D model. This is a finite and bounded model. There is no "edge" -  if you could travel around it you would not fall off the edge. If you  could somehow approach the north pole you would find the region "smooth"   no edges or boundaries. To speak of a minus time here is meaningless.  There is no minus time or time "before". This is to abstract "time " as a  concept separate from relativistic space-time. It is hard to understand  for those who have not studied the maths and physics of Riemann  geometry - non-Euclidean geometry is the reality of the Universe we live  in. Talk of creation and "gods" have to be understood in that context.

Source: Some Thoughts on Space and Time