Welcome & thanks.
Yes it must be recognizable, logically or scientifically and directly or indirectly.
Yes, that may not be immortal but long terms unless some godlike work can be anticipated. What about clones & dead body remains? I think we got these intact even after many million years.
I don't see why one would anticipate "godlike work." Clones are physical copies but do not possess the experience of the individual. I have a sheet of stamps. Every stamp is like every other, but this stamp is not that stamp. A thing is what it is, not what it is like. And no, we do not get dead body remains intact after many million years. There are fossils, but we cannot depend on them, and they are usually not the remains of an individual but the deposited minerals which have replaced them. And in any case, though that preservation is long indeed, it is not guaranteed that it will be forever.
Yes quite logical. True basis of all these will be needed to know in science. Logically, our prime energy form should be immortal/eternal. But how it can hold information of our individuality, will be a question mark. Soul/ghosts-- can it be some form of emitted or reflected spectrum of EMRs at the time of death? Reincarnation: can it be, emitted or reflective spectrum(say soul), merged in any other form of body and make energy basis to that? I think, such spectrum remain present in environment/universe eternally. ?
Think what you will, but there's no evidence for it, and even if there were there's no evidence that either the preservation of energy or the recycling of souls through reincarnation preserves any aspect of individuality in a way that can be identified or that can have any useful meaning.
Imagine that a body rots and turns to dust, and other chemicals, scattered to the wind. Imagine that a super-duper-unreal but
imaginable scientist sifts through the dust and using some super-duper-unknown but
imaginable technical gee-whiz science identifes the particles, and correlates his findings to some super-duper-never was and never will be but
imaginable database. Ah yes, this atom came from Kumar. This molecule was part of Kumar. And over here, look, this mote of dust came from Kumar. After a crazily extended, uselessly long, but
imaginable period he has found all or most of Kumar. He has a pile of dust and atoms and bits extracted from trees and rutabagas and the gullets of fish that ate the worms that ate the microbes that ate the remains of Kumar, and there it is, the pile. Has he, in any useful, identifiable or meaningful way, found who and what Kumar was? Has he made Kumar immortal? Or just gathered up a bunch of the world.