On the large side, many astronomers estimate the diameter of our universe is approximately 1028 meters.
On the small side, are the hypothesized strings of string theory. Their size is approximately that of the Planck length, 10-35 meters.
Combining these lengths together, results in 10-7 meters, or 100 nanometers (nm). This length is comparable to many subcellular organelles that provide structure and function to our neurons. Ribosomes, which read messenger RNA and create all the proteins in our bodies, are 20 nm in size. Microtubules, which provide cellular structure and movement, are 25 nm in diameter. Synaptic vesicles, which are the basis of all neuronal communication, are 40 nm in size.
Thus, between the two extremes of size in our universe, midway between the large and the small, are dimensions compatible with basic neuronal structural entities. These subcellular organelles provide the mechanisms for neuronal function, which in turn result in the emergence of our own thoughts, our own consciousness.