First, in quantum mechanics, space is not quantized. So, you can have particles of any size. It's not like the minimum size should be a space quantum. If there's no absolute 'huge' and no absolute 'microscopic', just relative sizes, then there should be no reason to assume that we follow general relativity while electrons follow quantum mechanics. My question is: Do quantum effects arise due to the difference in relative sizes of the observer and what is being observed? Considering space is not quantized, and you can divide it as much as you want, then there can be a particle whose size is microscopic relative to an electron and there can be living creatures for which Earth is of microscopic size. So, for those creatures, will Earth show quantum effects?