In this note I try to outline my current thoughts on quantum physics,
for your comments. I am sending this to a few mailing lists with
overlapping memberships, so you may have received this twice or more.
I apologise if this is the case and also for the very imprecise
language and gross simplifications and analogies that I am using to
make my point. While this is really a sketch of a sketch, I wish to
discuss the core idea with people who understands these things better
than I do, so please let me have your comments (even "go back to your
first year textbook and stop wasting my time").
I think that, while Everett's Relative State formulation of quantum
mechanics makes a lot of sense, its popular interpretation as "Many
Worlds"(MWI) should be taken only as a simple pictorial device useful
for a first understanding of the theory.
As a more accurate interpretation, I propose thinking of perceived
realities as shadows of a more complex reality. I suspect this is what
some authors, perhaps including Everett himself, were trying to say,
and that others may have said it explicitly (perhaps Lockwood), so I
would appreciate any pointer to relevant works.
I will use poor Schroedinger's cat as an example. Following Everett,
the cat is in a superposition of [cat dead] and [cat alive] states
before an observer opens the box and looks inside, and stays so after
(there is no collapse). After opening the box and looking inside, the
observer is in a superposition of [observer who remembers having seen
the cat dead] and [observer who remembers having seen the cat alive].
The MWI says that after the act of observation (measurement) the
universe is split in two branches where the first has [cat dead] and
[observer who remembers having seen the cat dead], and the second has
[cat alive] and [observer who remembers having seen the cat alive].
The difficulty that I have is: on the one hand we are saying that
fundamental reality contains no such things as cats dead or alive, but
on the other hand we are describing the world(s) with cats dead and
cats alive.
To clarify the first part of the statement: as we can choose any two
directions to form a basis to use for the description of a particle's
spin, all
choices generating equally valid descriptions, besides [cat dead] and
[cat alive] we should be free to use another basis to describe the
cat. While any pair of independent linear superpositions of [cat dead]
and [cat alive] will do, of course I have no idea of what such a
superposition would "look like".
Since I cannot remember having ever seen one, I do not know what a
superposition of [cat dead] and [cat alive] would look like, so
probably I would not recognise one if I saw it. Perhaps this is the
reason why I cannot remember having ever seen one.
In other words, perhaps since reality is One Big World too complex for
our minds to process efficiently, we use a simplified representation
as Many (small) Worlds for our processing. This is not so surprising
when we remember that our best computer programs use data compression
and segmentation techniques, throwing most of the information away, to
perform complex tasks such as face recognition efficiently. Perhaps
reducing a complex reality to parallel worlds is a successful trick
that sentient beings have developed to process reality more
I believe thinking of shadows may be a better mental device than
thinking of parallel worlds. Using this model the realities that I,
and my doubles in other branches of the MWI model, perceive can be
thought of as shadows of a more complex reality. Observing a shadow
permits saying certain things about its source, like size and overall
shape, but not other things like colour and smell. The shadow does not
contain such information. Also, much of what we can say about shadows
has more to do with illumination and the surface where the shadow is
cast than with the actual source.
Thinking of multiple worlds as shadows brings us back to Plato's cave,
but there are two important differences: First, each of us observes
shadows of the *real* world in a very large number of caves in
parallel. Second, we are shadows ourselves, our mental computational
processes being shadows of other, possibly much more complex,
computational processes.
In my view of the world, saying "my mental computational processes" is
just another way to say "I". So what am I a shadow of? I don't know,
but perhaps by observing the shadow I can develop some plausible
assumptions on the source.
I know that I am a conscious being: though I am not able to put my
finger precisely on what consciousness *is*, I know that it is a
property that I posses. I also think that consciousness must have
something to do with complexity: if a computational process is complex
enough, it may become a conscious process.
So, since it seems reasonable to think that a source must have a
degree of complexity not lower than its shadow, we should consider the
possibility that we are shadows cast by conscious sources.
Following Greg Egan who outlined something similar in his novel
"Quarantine", we can use the term "smeared self" to indicate such a
source. Your smeared self is simultaneosly conscious of a very large
number of Everett branches, and you, who can only perceive one, are
the shadow that your smeared self is casting on this specific branch.
The mental activity of your smeared self may well be much more complex
than yours, and perhaps the interaction between I who wrote this very
speculative and imprecise note, and you who are reading it, is the
shadow of a much more complex interaction between our smeared selves.

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