Wei Dai wrote:
On Sat, Jan 24, 2004 at 11:49:09PM -0500, Jesse Mazer wrote:
But measures aren't just about making decisions about what to *do*, the main
argument for a single objective measure is that such a measure could make
predictions about what we *see*, like why we see regular laws of physics and
never see any "white rabbits". Although Bob can decide that only universes
where gravity is repulsive matter to him in terms of his decision-making (so
that he'd be happy to bet his life's savings that a dropped ball would fall
up), he'll have to agree with Alice on what is actually observed to happen
when a particular ball is dropped.
Well, when the ball is dropped, in one universe it falls down, and Bob has
to agree with Alice, and in another universe it up, and Alice has to agree
with Bob. Alice thinks the second universe is less important than the
first, but Bob thinks it's more important. How do you break this symmetry?
Well, each of us only experiences a single universe (and further, all
of the other humans that we observe
are also observing the same universe we are observing.) Even if one
believes a strong version of MWI in
which there are untold numbers of other us's experiencing other
universes, it's still true that each of those
duplicates only gets to experience a single universe. That's something
about the nature of observation and
observable universes themselves.
So if Alice and Bob are IN the same universe, where balls fall down,
they'd both be well-advised to
"believe in" the facts of their own universe, and not some speculative,
or at the very least completely
inaccessible, alternate universe. From the perspective of an observer
(within a universe), the universe
they inhabit is more important.
PRINCIPLES:
---------------
1. A UNIVERSE IS WHERE ONLY ONE OF THE POSSIBILITIES FOR ANYTHING
HAPPENS.
2. EACH OBSERVER ONLY EXPERIENCES ONE UNIVERSE
3. COUNTERPART OBSERVERS SHOULD BE CONSIDERED DIFFERENT OBSERVERS,
BECAUSE
THERE IS NO SUCH THING AS CROSS-UNIVERSE ACCESSIBILITY OR EXPERIENCE.
I simply do not believe that the notion of an observer being able to
access or meaningfully experience the life
of the observer's other-universe counterparts, even if counterpart is a
well-formed notion.
I'm familiar with all of the various logic variations of the notion
of trans-world identity, and I find them to be model-level concepts
(matters of representative opinion) more than
object-level concepts. What I've learned about identity is that there
is a mixture of objectivity and subjectivity
(affected by focus of concern) to it as a concept. What trans-world
identity means (or is useful for) if a premise of
total inter-world inaccessibility is accepted, is questionable.
Eric
Without an objective measure, I don't
think there's any way to explain why we consistently see outcomes that obey
the known laws of physics (like why we always see dropped balls fall towards
the earth).
What good are the explanations provided by an objective measure, if I
choose to use a different subjective measure for making decisions? How do
these explanations help me in any way?
Choosing a measure from some other universe that you speculate exists
(with, necessarily, no evidence) is
risky and counterproductive to your survival in your universe. I'd
advise you to get out of the path of
the falling ball. Even if "counterparts" makes sense (not granted), if
all counterparts made decisions
based on their speculations about other-world likely happenings, then
all counterparts of that particular
observer would quickly die off for sure. Observers like that would not
evolve. Only home-body observers
(with local-universe concerns) would.
Received on Sun Jan 25 2004 - 13:32:16 PST