Quantum immortality is the concept that essentially you cannot die. I personally mix this precept with the fact that you live until your timeline is up.That would equate to a long human life to its fullest being around 100-110 years and then you begin again.
The concept is that you cannot die is based on the idea that there are multiple worlds and universes and that no matter what you do and how many times you die in ‘this’ universe you somehow survive in a carbon copy of this universe and continue as normal.
This immortality is characterised, for example. like when when you have a near death life experience and you are left feeling shaky and somewhat dissociated from life for a few moments and who hasn’t had this feeling?
When you should have died, or even tried to die and somehow survive impossibly; it is the fact that you have died and transferred to a different universe, part of the multiverse. You died in the last one and their universe continues for them where you died, as it does for you in the new one where you survive.
This is the many worlds interpretation (MWI) with a blend of quantum immortality from the basis of quantum physics, a science theory in its own right.
What do you think of it?