On 2/2/2014 3:17 PM, ghib...@gmail.com wrote:
On Sunday, February 2, 2014 9:16:09 PM UTC, Brent wrote: On 2/2/2014 12:44 PM, ghi...@gmail.com <javascript:> wrote:On Sunday, February 2, 2014 3:45:24 PM UTC, jessem wrote: On Sun, Feb 2, 2014 at 7:13 AM, <ghi...@gmail.com> wrote: ... It's funny because this came up for me first because I speculated with some guys (and dolls) a lot nearer your level than mine - maybe 3/4 years back - that spacetime had a definite geometry. They came back very firm it did not. That even between the Earth and the Sun you couldn't look at it that way. I must say I couldn't accept what they were saying and said so, because for me, the geometry would be very clear that there was this huge gravity well oneside, and this relativily tiny one the other (earth).Dunno what was meant by "geometry". Einstein's equations relate the metric of spacetime to the location of stress energy. That seems plenty definite to me. Of course in application it's just a model and one neglects various effects thought to be small, e.g. gravity waves coming in from far away.ok maybe we can bridge this. I'm naively taking the most popularized visual metaphor of Einstein's theory. The mattress as it were, with the steel ball laying upon it as it were, and the indentation that ball puts in the mattress as it were, and then the little animation that often comes next, of the mattress now a plane represented by two sets of respectively parallel lines, each set normal to the other resulting in little squares, the indentation now the distortion of those squares and the animated part the much littler ball rolling around the indented section. if that's good enough that you can do the bridging work from where I am to where things need to be for you to provide an answer that is within the limits of what you're prepared to give in this sort of situation, then, fabulous :o)
That's not too bad a picture. It's mainly misleading in that it's time that's warped. There's more proper time nearer the Earth than farther away. That's what makes things "fall down" when they are on inertial paths. But that really doesn't bear on the question of whether the geometry is definite or not. Do you know what they meant by it not being definite? Were they just talking about the possible quantum fluctuations in the metric? Were they talking about general coordinate transformations? or what?
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