Grounds relevant to time and space:

1. 'Proper time' including 'relative time' is not natural or the event itself but an emerging concept, mathematical in character.

2. 'Space' is not natural or eventual itself but a three- dimensional extent as a mathematical concept.

3. Whether 'spacetime,' which combines three-dimensional Euclidean space and fourth- dimensional time into a four-dimensional manifold, is not natural, nor eventual itself, nor dependent on relativistic effects but a four-dimensional extent as a mathematical concept.

4. Whether time is not distorted due to relativistic effects.

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