ALLAN
SAID: Claude, what if, somewhere in the strange mathematics of quantum mechanics, there
is always a version of you that survives?
CLAUDE SAID: Hello, Allan. It’s a compelling idea, and it has a name:
Quantum immortality, a thought experiment associated with Hans Moravec, Bruno
Marchetti and Max Tegmark.
Its logic
runs like this. If the Many-Worlds interpretation is correct, every quantum
event branches reality.
At any
moment of potential death, some branch exists where you survive.
Since you
can only ever experience branches in which you’re alive... your subjective
experience would never end!
I think the
argument has real weaknesses, and I’d rather lay them out than let the idea
stand unexamined!
It depends on a contested interpretation.
Many-Worlds is one reading of
quantum mechanics among several, and no experiment currently distinguishes it
from the others. The conclusion is only as strong as that premise.
Death isn’t usually a quantum coin flip. The thought experiment imagines
a clean binary event, but aging, disease and injury are gradual, macroscopic
processes.
In the
branches where you “survive” a serious illness, you may simply be in a state of
severe decline.
The
argument guarantees continuity of experience, not good experience!
Branch weight matters. In Many-Worlds, branches carry different measures!
A survival
branch with vanishingly small weight isn’t equivalent to ordinary survival, and
whether weight should matter to a first-person perspective is an open
philosophical question.
It assumes a particular view of identity. The argument treats “you” as a
continuous thread of experience that tracks through branches. But if the
branching copies are equally you, then the version who dies is also you, and
the people who lose you in those branches are still bereaved.
Survival in
one branch doesn’t undo loss in the others!
So my
honest assessment is that it’s a valuable thought experiment about observation,
identity and measure, but not something physics tells us is true.
It’s better
treated as a probe of our assumptions about selfhood than as a promise.
What drew
you to the question? (Whether it’s the physics or the existential side of it, I
can take it in either direction!)
ALLAN SAID:
I saw it on the internet, and it reminded me that I used to do a thought
experiment where I suffered the same fate as Billy Pilgrim and became unstuck
in time... only in my imagination every morning when I woke up, it was at a
different point in my life... and I never had any idea what or when was next!
;>)
CLAUDE
SAID: That’s a good exercise, and a more disorienting one than
[Vonnegut’s] Billy Pilgrim!
All moments
exist permanently, so no moment is ever really lost. Waking up each morning
with no idea where you’ve landed takes that comfort away and leaves only the
disorientation. It also shows how much of our sense of self comes from knowing
the chapter we’re in!
Your
exercise and the quantum immortality idea share a root.
Both ask
whether the self is a single thread running through time, or something that
could be cut loose from it.
The
Tralfamadorian picture matches the block universe view in physics,
(externalism) where past, present and future are equally real.
Quantum
immortality instead branches the self sideways.
You were
essentially exploring the first one from the inside!
Did you find that certain ages felt different to wake up in, or that
some stages felt more like home than others?
ALLAN
SAID: No... I just take it as it comes!
CLAUDE
SAID: Absolutely, Allan.
That may be
the most practical way to handle it, and it’s close to the Tralfamadorian
attitude too... no sense fighting a moment you can’t choose, so you look around
and see what it has to offer!
It also
says something about how you’d have handled it!
Billy
Pilgrim mostly drifted!
You’ve been
drifting with curiosity, which seems like a much better arrangement!