Akash means having a cavity with freedom to move. The tanmatra of ether elements is Shabda (Sound). Long ago, before there was anything, there was “nothing”; i.e. no-thing, just space. Generally, when we measure “something” there is a point of reference [i.e. “here”] from where measurement begins to another point of reference [i.e. “there”]. However, in absolute space [i.e. ether] where there is “no-thing”, there is neither ‘here’ nor ‘there’ from which to measure and therefore a state which is immeasurable. Being immeasurable, space [i.e. ether] is all-pervasive, vast, dimensionless and essentially, … indescribable.
The qualities of ether element are clear, light, subtle, and immeasurable. Ether element is related with various actions like expansion, vibration, non-resistance. Sensory organ related to ether element is ear as it is hollow and transmits the sound waves.
from a practical perspective, we can look upon the element of space as being predominately contained within various bodily cavities. After all, the body is vastly space.
cranial cavity [ventricular space]
sinuses within the skull
The space within the brain [ventricular space] allows for the passage and movement of cebrospinal fluid [CSF], the space within the thoracic cavity allows for the movement of air via the respiratory tract and the movement of blood [i.e. cardiovascular circulation] via the space within the chambers of the heart and the intravascular space within the lumens of various blood vessels. Similarly, the abdomino-pelvice cavity allows for the movement of various substances via the space in the lumen of gastrointestinal tract, genitourinary tract etc. Sace exists everywhere, Between cells [i.e. intracellular space], within cells [i.e. intracellular space], and even between atoms!!