I've usually tended to go with "deep jhana" explanations, for example as taught by monks like Ajahn Brahm. This is the theory that "vivicceva kamehi" in the first jhana formula means "secluded from the senses" and therefore there is no perception of the physical body at all. This is in contrast to monks like Ven. Thanissaro for example who take the jhana similes (as found in DN2 for example) which mention bliss and rapture pervading and suffusing the body in first jhana.
Well, I've just come across a passage in MN43, the Mahavedalla sutta which throws new light on the issue.
Here its quite clear that when the five senses shut down, the immaterial realm is experienced, otherwise the four jhanas would've been mention too.Friend, what can be known with the purified intellect-consciousness divorced from the five [sense] faculties?"
"Friend, with the purified intellect-consciousness divorced from the five faculties the dimension of the infinitude of space can be known [as] 'infinite space.' The dimension of the infinitude of consciousness can be known [as] 'infinite consciousness.' The dimension of nothingness can be known [as] 'There is nothing.'
My explanation and contribution to the (endless) jhana debate is as follows:
Basic jhana is attained based upon the physical body where consciousness pervades the body with bliss and rapture in the first jhana and a pure bright mind in the fourth for example, just as is stated in the jhana similes. But the concentration can and should be made stronger by spatially expanding the pervasion of mind gradually all around oneself until it reaches "mahaggata" status, something that can reach about the size of the planet (from MN 127 Anuruddha Sutta):
So it is seen above that the first level of mahaggata concentration the meditator is pervading with mind an area the size of a root of a tree. Whether this corresponds to the basic attainment where they are pervading his own body or the next step where they have began to expand outward I cannot decide. But ultimately the concentration increases to the size of the planet and you can imagine the size of the body compared to this would be so negligible as to be non-perceptible. And the higher level of concentration than this are the immeasurable states such as the Brahmaviharas, possibly the kasinas too. From the same sutta:Householder, what is the release of mind grown great? The bhikkhu indulges
pervading the extent of the root of one tree and abides. This is the release of mind
grown great. The bhikkhu indulges pervading the extent of the roots of two or three
trees and abides. This is the release of mind grown great. The bhikkhu indulges
pervading the extent of one village and its fields and abides. This too is the
release of mind grown great. The bhikkhu indulges pervading the extent of one large
kingdom and abides. This too is the release of mind grown great. The bhikkhu
indulges pervading the extent of two or three large kingdoms and abides. This too
is the release of mind grown great. The bhikkhu indulges pervading the
earth limited by the great ocean and abides. This too is the release of mind grown
great.
So my theory is that some meditators with paramis jump straight to the mahaggata or immeasurable concentration and there they cannot perceive the body since its a tiny speck in their massive field of awareness. Actually I recall reading an account somewhere of a kasina meditator feeling that they were just a small point in the middle of their experience. What this also means that trying to jump straight to expanded perception may be counterproductive for most meditators and the gradual expansion method may be more useful after attaining the first jhana based on the body. Indeed, the visuddhimagga tradition has you concentrate on an even smaller area, coin sized, under your nostrils. The meditators who expound the body only theory may not have gradually expanded their awareness and so see only this as the truth. Maybe they have all the concentration they need to practice insight and a strong wisdom faculty and have no interest in developing the jhana further.Householder, what is the limitless release of mind? Here, the bhikkhu pervades
one direction with thoughts of loving kindness. Also the second, the third, the
fourth, above, below and across, in all circumstances, for all purposes, pervades
the whole world with thoughts of loving kindness, extensive, grown great and
measureless without ill will and anger. The bhikkhu pervades one direction with
thoughts of compassion,...re....intrinsic joy,...re.... equanimity. Also the second, the
third, the fourth, above, below and across, in all circumstances, for all purposes,
pervades the whole world with equanimity, extensive, grown great and
measureless without ill will and anger. Householder, this is the limitless release of
mind.