What is reality? What is existence? I take the postition that these
are "emergent" phenomenon. It seems to me to be a clear trend in
physics that our common sense notions do not apply at a fundamental
level, and that things like space and time emerge for us, in our
frog perspective, out of our particular place embedded within our
mathematical structure.
Why shouldn't the very concept of "reality" be among these? Try
to define reality, and I think you might agree that it is illusive.
Our whole concept of reality comes from our common sense, and is
therefore particularly suspect. As we developed as children, we
learned that particular objects persisted even when we weren't
looking at them, and were therefore "real". I ask you this: have
philosophers *ever* had much success at adapting this concept to
more abstract things, other than the concrete objects around us?
I've been finishing up an old book (1973) called "Are Quanta Real?",
and I've been enjoying it very much. It is dated, and doesn't even
mention MWI, but it does illustrate the old hidden variables /
Copenhagen Interpretation argument quite nicely. The book is
written in dialogue form, and the foible character, Simplicio,
tries to maintain a position that there is indeed some such thing
as objective reality out there. He is thus a proponent of the
hidden variables concept: that QM is incomplete, and that there
must be something about these particles that we just don't know.
But the bottom line is that if we can get the math to work out
right, and we discover that beings like ourselves are embedded
in some sort of mathematical or computational structure, then we
can dispense with all other philosophical concepts, such as
reality, as unnecessary in our description.
I like this quote from a post of Hans':
By the same reasoning, beings in the many universes may not
really exist, but they think they do.
If I write down the equations for a toy universe, and discover
that this universe actually has SAS's embedded within it, well,
so what? That toy universe is no more real to me than it was
before I wrote the equations. But it sure is real to the SAS's
who live there! And it's real to them, whether or not I write
down the equation -- it certainly doesn't matter to *them* that
*I* exist!
So in a sense, reality *does* depend on consciousness. But in
another sense, it doesn't. Tegmark makes this explicit, by
stating that "mathematical existence" IS EXACTLY EQUIVALENT TO
"physical existence". One might be inclined to say that
this lends more ontological significance to
mathematical equations. On the other hand, one might think
instead that it detracts from the concept of physical existence.
Physical existence is only really "real" to those SAS's
embedded within the structure.
I think that there is a great reluctance to let go of these
concepts of an absolute objective reality, and that a conscious
entity must be somehow "instantiated". When, if the Principle
of Plenitude is correct, everything just plain is. All self-
consistent instantiations of conscious entities do exist --
but in what sense? They exist to themselves, and to the other
SAS's within there structure. To everyone else they are just
mathematical formalisms.
SLP wrote:
>
> HM:
> This makes our own self-awareness a circular object: its causes
> only exist when we already admit to its existence.
>
> SLP:
> No. Logically, for any A, the cause of A must PRECEDE A's existence.
> Here, I use the word "precede' to describe a logical and not necessarily
> a temporal relation. But a human's self-awareness is generated by a
> physical system, a brain, which is a macroscopic object inhabiting a
> quasi-classical physical domain where there is a well-defined time
> direction. So in this particular case, "precede' ALSO has a
> well-defined temporal sense.
>
> HM:
> But isn't a tenet of the larger discussion that existence itself
> a similarly circular business: universes exist because beings
> within them perceive them. But those beings exist only if
> you admit the existence of the universes that contain them.
>
> SLP:
> This is Wheeler's "self-excited circuit" nonsense. Universes exist
> because of physical laws that have nothing whatever to do with
> self-aware systems. Self-aware systems are particular CONSEQUENCES of
> physical law, not vice-versa. One great virtue of Everett's original
> relative state formulation was that it was able to assert this in a very
> clean way and give an explicit understanding of why "measurements" on
> quantum systems show the particular patterns they do to physical
> recording devices necessarily embedded within the universal wave
> function. Your claims would (a) effectively return us to Bohr's
> Copenhagen nuttiness and (b) imply some type of primacy of consciousness
> metaphysics. How, for example, would you reconcile the origin of our
> local, observable universe some 13 billion years ago with the fact that
> consciousness did not evolve until a much later time?
>
> HM:
> Works for me.
>
> SLP:
> I'm puzzled. Please explain how.
>
> Steve Price, MD
--
Chris Maloney
http://www.chrismaloney.com
"Knowledge is good"
-- Emil Faber
Received on Sun Jul 11 1999 - 20:17:35 PDT