Comment Comment by nabla9 Because that's the conformal geomety part that is hard to understand.There is conformal boundary at the infinity. Geometrically similar to these Esher paintings: http://1.bp.blogspot.com/-xHdzmQCSOdI/U7xIsVKISmI/AAAAAAABQr...See also Penrose diagram, timelike, spacelike and lightlike infinities! https://en.wikipedia.org/wiki/Penrose_diagram(Honestly he could make all this up and none of us could tell the difference) parent nabla9 6 years ago
There is conformal boundary at the infinity. Geometrically similar to these Esher paintings: http://1.bp.blogspot.com/-xHdzmQCSOdI/U7xIsVKISmI/AAAAAAABQr...
See also Penrose diagram, timelike, spacelike and lightlike infinities! https://en.wikipedia.org/wiki/Penrose_diagram
(Honestly he could make all this up and none of us could tell the difference)