If gravity is a warping of space-time, why is it that we see no distortions in our visual field? - by Steve Baker - Quora Question review

This document contains a review of the answer by Steve Baker on the question in Quora: "If gravity is a warping of space-time, why is it that we see no distortions in our visual field?"
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• The text in italics is copied from the article.
  
• Immediate followed by some comments
  

Contents

• 1. Answer Review by Laslo Petruska
• 2. Answer Review by Viktor T. Toth

Reflection

• Reflection 1 - Question Review

1. Answer Review by Laslo Petruska

Gravity cannot warp spacetime because spacetime is a purely mathematical abstract concept on paper. The “fabric of spacetime” is not a physical entity.

What’s is real is the gravitational field. Einstein created a conceptual three-dimensional lattice of tiny clocks at every point in space. This is spacetime.

In the absence of mass/gravity (special relativity) the lattice structure of clocks is flat, meaning the clocks are in a cubical arrangement and tick at the same rate.

In the presence of mass/gravity (general relativity) the lattice structure of clocks is curved, meaning the clocks are in a warped arrangement arrangement and the clocks closer to the center of mass tick slower.

2. Answer Review by Viktor T. Toth

Well, the main reason is that Newtonian gravity is primarily about distortions of time, that is to say, the rate at which clocks tick. The stronger the gravitational field, the slower clocks tick in it compared to other clocks situated elsewhere. Compared to this temporal distortion, spatial distortion is exceedingly tiny. As a matter of fact, the temporal distortion is tiny, too. Here on the surface of the Earth, terrestrial gravity alters the rate of clocks by roughly one part in a billion compared to clocks in deep space. It would take several decades before the difference between two such clocks reaches one second. Yet the distortions are visible, just not with the naked eye. In 1919, an expedition lead by Arthur Eddington was measuring just that: the visual distortion due to the Sun’s gravity during a total solar eclipse. As expected, some stars that appeared near the solar disk (its light blocked by the Moon) were displaced by a tiny amount. How tiny? About 1.75 arc seconds. For comparison, that would be like looking at an object that is a mile away, and noticing that it is displaced by about half an inch. Curiously though , in the case of light both spatial and temporal distortions play an equal role. That is to say, half of that 1.75 arc seconds was due to temporal distortion but the other half was due to spatial distortion. As a result, this value is double the value one would predict using Newtonian gravity. This was therefore seen as a much celebrated confirmation that Einstein’s theory of gravitation is the correct one. If you find my posts useful, please consider supporting my efforts.

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