I have read this question:
And the answer by WetSavannaAnimal aka Rod Vance:
"Incidentally, if we confine massless particles, e.g. put light into a perfectly reflecting box, the box's inertia increases by E/c2E/c2, where EE is the energy content. This is the mechanism for most of your body's mass: massless gluons are confined and are accelerating backwards and forwards all the time, so they have inertia just as the confined light in a box did. Likewise, an electron can be thought of as comprising two massless particles, tethered together by a coupling term that is the mass of the electron. The Dirac and Maxwell equations can be written in the same form: the left and right hand circularly polarized components of light are uncoupled and therefore travel at cc, but the massless left and right hand circular components of the electron are tethered together. This begets the phenomenon of the Zitterbewegung - whereby an electron can be construed as observable at any instant in time as traveling at cc, but it swiftly oscillates back and forth between left and right hand states and is thus confined in one place. Therefore it takes on mass, just as the "tethered" light in the box does."
So is this the reason why anything with mass, like our body, that has "massless gluons are confined and are accelerating backwards and forwards all the time, so they have inertia just as the confined light in a box did", so the gluons are confined, so they must travel back and forth between some kind of confining container, a "wall" or something?
- As this body would speed up, as it reaches speed c, the gluons inside it will not be able to "accelerating backwards and forwards all the time", because they are already at speed c and the "wall/container" they are confined in is already moving at speed c in a direction, so the gluons would never reach the confining wall anymore? So they cannot have inertia anymore, and so the body cannot have mass anymore? (just like in SR, the photon clock, the photons can't reach the mirrors anymore, so time seizes to exist too)
- So as anything that reaches speed c, will (or must have no rest mass in the first place) lose its rest mass?