How can someone graduate to 4th in space time?

[anagogy]

Will there be appearing a stargate or maybe the Confederation/Orion Group will pick you up? Normaly the harvest, graduate or not, occurs in time space after the physical death. Are there some people in our history known who are harvested in space time?

According to Ra, the space/time physical bodies simply evolve, through the natural process of sexual reproduction into the 4th density physical vehicles required to properly appreciate the denser illusion. Each generation becomes a bit more 4th density acclimatized until eventually the fully 4th density being is born.

Is it possible for beings to raise the vibrations of their physical body and move to 4th density that way?

I believe so, but it is rare, (the path some ascetics take, as Matt pointed out). Consider that your body, at this moment, is following a certain set of agreements, or instructions, in consciousness. To assume a new pattern of agreements or instructions, the old ones have to be let go of, and gradually transform into the new set of agreements. Those foundations of instructions are built deep into your identity as a human being, and are not let go of easily. Raising vibrations means change can happen faster, so it is a matter of raising vibrations or releasing resistance to change.