Immortality theories:

Nietzsche, immortality, singularity and eternal recurrence

https://www.tandfonline.com/doi/abs/10.4314/sajpem.v26i1.31463?journalCode=rsph20This, it is argued, may be understood as Nietzsche’s distinctive contribution to a specifically modern notion of immortality: the ability of an individual to live in such a way that his or her singular ‘place’ in society is ensured, necessarily there, even after his or her death.

Cosmic Consciousness

https://en.wikipedia.org/wiki/Cosmic_Consciousness

this consciousness shows the cosmos to consist not of dead matter governed by unconscious, rigid, and unintending law; it shows it on the contrary as entirely immaterial, entirely spiritual and entirely alive; it shows that death is an absurdity, that everyone and everything has eternal life; it shows that the universe is God and that God is the universe, and that no evil ever did or ever will enter into it; a great deal of this is, of course, from the point of view of self consciousness, absurd; it is nevertheless undoubtedly true.[3]

‘eternity’: what it is, where it lies. It is not ‘all time’, it is ‘out of time’. He draws the following diagram:

https://www.ouspenskytoday.org/wp/wp-content/uploads/Paper-07_19a-E-Group-Recurrence-and-Immortality.pdf