Most people find it more intuitive than QM. But OK, consider people who experience
Aristotelian physics.
Brent
On 5/24/2015 11:12 PM, Jason Resch wrote:
I don't think Newtonian physics is intuitive. Most people's intuition and experiences
would not lead them to the idea that once set in motion an object continues to move
forever, nor that the the total direction of matter is conserved. Even Descartes missed
this.
Jason
On Sun, May 24, 2015 at 8:27 PM, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 5/24/2015 5:05 AM, Pierz wrote:
On Sunday, May 24, 2015 at 4:02:42 PM UTC+10, Brent wrote:
On 5/23/2015 9:58 PM, Pierz wrote:
On Saturday, May 23, 2015 at 8:36:40 PM UTC+10, Liz R wrote:
I'm not sure why comp would predict that physical laws are
invariant for
all observers. I can see that it would lead to a sort of
super-anthropic-selection effect, but surely all possible observers
should
exist somewhere in arithmetic, including ones who observe different
physics (that is compatible with their existence) ?
I really must dig up the old thread! But I'm not saying comp does entail
invariant physics for all observers, just that if there are different
physics,
the substitution level must be very low indeed. Think of the original
scenario
in the UDA: a person in Washington is suddenly annihilated, and then
duplicated in Helsinki and Moscow (or whatever). That operation creates
a 50%
probability of finding oneself in Helsinki or Moscow. But the ultimate
point
of the UDA is that one's actual probability of finding oneself in
Helsinki or
Washington depends on the total measure of /all/ virtual environments
within
which that observer is instantiated in an environment that looks like
one of
those cities. One can't isolate a particular virtual system from the
trace of
the UD. So you can't create an arbitrary physics in an environment that
looks
like either city (or anywhere). Well you can, but any observer will
always
find their own physics to be the measure of *all* their continuations in
arithmetic. So there can't be an environment that is like Helsinki or
Moscow
at some point but that has different physical laws. Carry this logic
over to
the scenario of a person standing in an empty room - the physics the
person
experiences will be the measure of all such identical persons standing
in
empty rooms.
"Experiencing physics" I think needs some explication. If experiencing
only
refers to consciously thinking propositions, then one may not be
experiencing
much physics: the world seems 3D with colors, there's a mild
temperature, air
smells OK,... One doesn't directly, consciously experience the 2nd
law, or the
Born rule. The "laws of physics" are human inventions to describe and
predict
events. They're not out there in Nature; which is why we have to revise
them
from time to time as we find more comprehensive, more accurate "laws".
OK, but it doesn't seem relevant to the argument. We experience a world
predictable
and stable in certain ways that, now we're so sophisticated, we formalise
into the
science of physics. Bruno's claim is that these regularities are not
intrinsic
properties of some primary stuff, but emergent from the computational
properties of
observers - namely how often various continuations of those observers crop
up
relatively to one another in the abstract space of all possible
continuations. I'm
trying to make an admittedly difficult point about whether or not observers
in
different places can experience different physics within this paradigm, and
if so,
how that relates to "substitution level". If you're worried about people
"experiencing physics" let's just concentrate on observers who go to the
trouble of
doing physics experiments. It really doesn't matter.
My point was that most people's conscious experience most of the time could
be
accommodated within a large range of physics. For example Newtonian
physics seems
intuitive while quantum mechanics isn't; but we think QM is the better
theory. But
Bruno claims that his theory implies QM and not Newtonian mechanics. So if
people
consciously experienced a Newtonian universe (which they once thought they
did)
would that falsify comp or would it just imply that the UD can instantiate
Newtonian
universes.
Brent
The question here is what constitutes the observer? How detailed would a
simulation of me have to be before it became a subjective /duplicate/
of me,
its continuations my continuations? If there is a person A somewhere in
the UD
who is experiencing an empty room with physics A, and another
identically
configured person B somewhere else experiencing physics B, what is
stopping
the continuations of A mixing with the continuations of B, so that the
measures combine into a merged physics? There has to be something in
both
observers' computational states that distinguishes them sufficiently
that
their experiences cannot interfere with one another - the comp
equivalent of
decoherence. (In fact if QM effects are the manifestation of UD observer
measures, the threshold at which these effects start to kick in should
probably give us a strong clue about how low the substitution level is!)
Observers and their experiences, including physical laws, can't be kept
apart
by physical or temporal space, but only by differences in the
computational
states that define them. Physics is emergent from the computational
properties
of observers, and therefore any difference in physics experienced by
different
observers is a function of their mathematical configuration. If we find
that
there are observers in other universes who experience different
physics, then
it must be the case that the substitution level for those observers
includes
their entire universe.
That said, if I recall our previous discussion correctly, Bruno
disfavoured
the idea of different physics for different observers. He seems to
believe it
should indeed be invariant.
That position appears to me to be at odds with the direction of modern
cosmology.
That would seem to depend on how different. Modern cosmology naturally
builds
on quantum field theory, so it starts with the hypothesis the QFT
applies, but
possibly with different values of those parameters we attribute to
symmetry
breaking (i.e. random).
Yeah. I mean the ultimate underlying unity and coherence of reality is
surely a
given, so go deep enough and of course there is only one law that applies
to all
observers. But at issue is whether quite different apparent physics (say,
the
elements and their properties, or the masses of particles) is possible
without the
substitution level being super-duper low. It seems to me not, and I believe
Bruno
agreed, though I may have misunderstood. No-one seems to be addressing that
question.
Brent
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