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The is no absolute rest frame as far as we know (and we know quite a bit about it). So there is no such thing as completely still in spacetime. However, that's boring and I'm in the mood for a debate, so I'm going to phrase this answer in the form of a debate where I will be arguing on your behalf. Me: The is no absolute rest frame, so this question makes ...

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I guess you are talking about the Planck lebgth, not the planck-constant. But this is no minimum distance either. Its just the minimum space in which action can be defined. Its the distance, which is traveled trough by light in one planck second. But that does not mean it is the smallest distance to exist.

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As sted by John, the ratio of width d over distance l $\frac d l$ is a function of the angle. Intercept Theorem tells you that if the angle stays the same (i.e. your thumb just covers the object) $\frac{d_1}{l_1} = \frac{d_2}{l_2}$. If we take your thumb to be 2 cm at a distance of 1m, then the object at 2000m has a width of $d_2 = \frac{2\, \rm cm}{1\, \... 2 The way we do this is to consider the angle subtended by your thumb: The angle subtended is the angle between the dashed lines. Obviously this depends on how big your thumb is and how long your arm is, but in general this angle is taken to be about$2\$º. Someone actually did a study to verify this, proving mainly that some scientists have too much free ...

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