I don't have a big problem with the idea of the Earth moving towards (or away from) the stone. What does give me pause for thought is the insistence that gravity is not a force. If gravity is a distortion of spacetime, I find it difficult to visualise the tiny distortion round a stone, or a grain of sand, being able to influence the movement of the Earth.
Another thought that comes to mind is that if space, at the quantum level, is grainy, and if the Planck length defines the size of the grains, would we have a situation, similar to the photoelectric effect, in which the Earth would move only if the influence of the smaller object was sufficient to move it a distance equal to, or greater than, the Planck length?
I had thought of this possible limit immediately, even while I was making the declaration. I have an engineering background and I have learned to look for possible interferences as soon as possible.
I have never looked over Planck’s work in an attempt to size up all the assumptions and final accuracy. I have no doubt that the basic idea is correct. Indeed, the universe has an underlying discrete nature to it. I know that personally, I would not be enthusiastic if I was charged with the job of attempting to derive Planck’s Limits. In my opinion; I think that it is most likely that the final published resulting values are in error. I’m sure that there is probably an erroneous assumption somewhere but, I still stand by the concept and I still believe that there are a lot of truths about it.
One thing that you can immediately notice about Planck’s Length is how much smaller it is than the width of a neutrino (10 -35 vs. 10 -24). Obviously, the premise for Planck’s Length is not an over-simplification. In effect, Planck is compensating for situations like this problem as well as all other contingencies.
I think of the concept of PL as --- The smallest possible happening in the shortest amount of time. I take it on faith that in “Planck’s world”, the stone is looking more like a heavenly body and that all actions at this scale easily fit within the limits.
I’m glad that you mentioned it.
I think that if we were to somehow come across a situation where PL is violated that; it just means Planck made a “mistake” and came up with an erroneous value…but he still wouldn’t be “wrong”. I think that the idea (intention) of it is rock solid.
