The term 'etheric body' is usually used to rifer to a body inhabiting 'etheric world', which, perhaps can be seen as, or also called, 'ashtral world'. When we visit the ashtral worlds, we don't go with our visible body. We go with an unseen body and leave the seen one behind. Such unseen body can, at least in some circles, be termed as 'etheric body'. But apart from being 'unseen', what else can such a body perform that the seen body cannot do? I guess we desire a body that either cannot get sick, die, is not limited to 'speed of light', and perform other such 'miracles'. So can what I will term it as a 'quantum body' perform all such acrobatics? Let us see.

There are several things that a quantum particle can perform which would be seen as 'miracles' if they were done by the usual, macroscopic object. To list just a few of them:

1.)A quantum particle can be altered by a mere observation.

2.)A quantum particle can tunnel through walls

3.) Two quantum particles can instantly communicate with each other even if one of them is in Andromeda and the other one is here on earth!

4.)A quantum particle can disappear off a place and reappear from another place!

5.)There is likely hood that quantum particles inhabits over 12 dimensional worlds!

Sure, all these are 'miracles' that we thought only 'spirits' can perform, plus there are other things that these particles can do that we did not even imagine that a 'spirit' could do! For example, if an entire macroscopic object was to 'quantum tunnel' through a wall, that would be like what Jesus did after resurrection. So given this modern knowledge of physics, it makes sense to wonder if, for instance, Jesus, after resurrection, simply had a body composed of particles that maintained their quantum characteristics despite being macroscopic. In such a way, by forming a theory that admit some quantum nature even in macroscopic, we can scientifically explain things that are as bizarre as those that people term them as 'miracles', or even those that are more bizarre than many people can even imagine!

But how does the 'quantumness' get lost in the macroscopic world? Actually, it doesn't 'get lost'. It gets suverely reduced in a world that is thought to be 'accidental'. The probability of a large number of things all of them performing a given task simultaneously is extremely low, if you think that each of those task are done randomly. The probability of everyone in a stadium sneezing at the same time is seen as to be next to zero since we think there is no cause outside the individual that compels him to sneeze. Therefore when two people sneezes simultaneously, we don't think that this is a result of a common cause that is driving both of them to sneeze at that time. We think that it is all a 'coincidence'. Similarly, if we think that quantum states are driven by something far bigger than the particles themselves, then it becomes easer to appreciate that the manifestation  of a quantum transition in macroscopic world is possible.

So we understand that an individual particle can 'quantum tunnel' through a wall. Since a macroscopic object is made up of the very same particles, nothing, in principle, prevents the entire macroscopic object from 'quantum tunneling'.What 'prevents' the entire object from 'quantum tunneling' is the same thing that 'prevents' everyone in the stadium from sneezing all at once! In other words, for the macroscopic object to tunnel in it's entirety, everyone of it's particles must tunnel simultaneously, which is seen as extremely hard because quantum processes are seen as 'random'. What quantum's wave amplitude indicates is the probability of a given particle being at that state. So in our case, the wave amplitude of a particle at 'the other side' of the wall indicates the probability of finding the particle there, hence the probability of the particle 'tunnelling' there. In an ensemble of quantum particles that forms the macroscopic world, the waves of the particles generaly decohers, leading to the cancellation of the wave amplitude at the 'other side' of the wall. This cancellation does not completely destroy the wave. It only reduces it surverely, making it undetectable in the usual macroscopic way.

Now in quantum mechanics, the same wave amplitude can describe any number of particles. When observing a single particle described by a single wave, we will see one particle every time we make the observation. The amplitude of the wave at a given place gives the probability of finding the particle at that place. When observing a wave that describes two particles, we will always see two particles at generaly two different places. So when observing an extremely large number of particles, we will see all these particles all at once. Since the wave amplitude at a given place indicates the probability of finding the particle there, a large number of particles described by a single wave will appear in areas of higher wave amplitude.This is because if the probability of finding a particle at a given place is largest, then it is there most of the time. So if a large number of particles are there at a given place most of the time, then every time we see the place, then we find a large number of particles there.In other words, the probability of finding a particle at a given place translates into the 'density of particles at that place' in the macroscopic world. Since the 'cancellation' of waves in classic world never leads to a complete disappearance of the wave, but only to an extreme reduction of it's amplitude, there will always be an extremely less dense body that maintains 'quantumness'. This is what I am suggesting as 'etheric body'.

So the understanding of the quantum in macroscopic world is elucidated as follows: In a large ensemble of particles forming the macroscopic object, the extremely low probabily of a particle moving across the wall translates to 'extreemly few particles crossing there' at any given time. This translates to a less dense body managing to cross the wall at every time. It is this extremely low density of the bodies that makes the quantum world un-detected in the macroscopic world. So it is not that there are no macroscopic bodies that behaves like quantum particles. They are there, but are only of extremely less density. As candidates for etheric bodies, you can see that such 'quantum bodies' are ideal.