Does this paragraph contain any grammatical errors?

Do these two paragraphs make grammatical sense? How could they be improved?

What fills the 'medium' between myself and my wall? There must be 'something' other than 'nothing' for the structure of reality to manifest as we see it. If it were 'nothing' then I would not be able to see my wall, would I? Place an imaginary cube in front of your eyes and open one of its surfaces. What do you see inside of this cube? Do you see darkness; much like a void of 'nothingness'; though that is still 'something' or do you see the matter inconceivable to our senses. Matter that which under the 'laws of physics' allows for the fabrication of reality in which we exist. What is this reality I and everything exists in? Why does it manifest in this particular way to allow for life and the differentiation of other matter?

I have two congruent pens on my desk, the designs of which are identical and indistinguishable to our eyes. However, on an atomic level, the atoms that constitute to the fabrication of the first pen are different to the atoms that constitute to the fabrication of the second pen in our reality. One pen might be slightly damaged on an atomic level and so have a different number of atoms to the other pen. Therefore, despite appearing identical to you and I, these two pens are in fact different. In fact, one could argue that there exists only one of everything for the manifestation of congruent matter in the particular scale of reality in which we live is atomically different; yielding every conglomerate of matter we discern as unique.