[CutterJohn]

Any more than the concept of healing at all? If we assume its just nanites rebuilding you, well, then, these are just nanites sprayed onto you, healing you at the direction of a remote scanner the medic is carrying.

Every time you respawn nanites are placing quadrillions of atoms in a precise alignment. Even fiddling with the quantum states of many of these atoms. And they are doing this in a matter of moments. Thats so far into the realm of sci fi its absurd.