On 6/11/2016 10:14 AM, John Clark wrote:
On Fri, Jun 10, 2016 at 6:11 PM, Brent Meeker <[email protected]
<mailto:[email protected]>>wrote:
>>
It makes no difference if the physics is simulated or not; a
simulated calculation produces real arithmetic not simulated
arithmetic and a simulated brain will produce real
consciousness not simulated consciousness. Bruno's brain
works according to the laws of simulated physics and
simulated cyanide with stop that simulated brain from working
and thus the consciousness it produces.
>
Exactly - provided you identify "Bruno" as the person we know in
this branch of the multiverse,
But why does cyanide have any effect on any Bruno in any branch of
the multiverse if physics is unrelated to consciousness?
>
Bruno just notes that it is commonly assumed that consciousness is
realized by certain computations
And I agree with that, but for computations to exist physics is
required.
That's where you (and I) disagree with Bruno. He takes mathematical
existence, as in, "There exist infinitely many prime integers." or
"There exists a successor to every integer.", as the most fundamental
kind of "exist" and consciousness as derivative, emerging from all
possible computations (which "exist" in arithmetic and similar axiomatic
systems). From conscious thoughts, physics emerges - not just the
physics we observe, but all possible physics because physics is nothing
more than a certain pattern and consistency of conscious thoughts
(perceptions) from which we infer a physical reality as the best
explanation.
I don't think this works because it implies the Boltzmann brain
problem. Bruno admits there is a "white rabbit" problem, but he thinks
he can prove that "white rabbits" and miracles are of measure zero. I
don't think he can, which would make his project not very interesting
since it's easy to explain things by saying everything happens so THIS
is just one of them. A good theory must predict THIS and NOT THAT.
>
So if all possible computations exist (and they do in the
mathematical sense)
All correct calculations exist, but all incorrect calculations exist
too, to sort one from the other physics is required.
There are no "incorrect calculations". It's just a universal Turing
machine that runs all one step programs, all two step programs, etc.
Some programs stop. Some programs fall into infinite loops. Some just
keep computing. These are all abstract processes that "exist" in the
mathematical sense. There is no sense in which they can be correct or
incorrect. Among all those infinitely many computations will be some
that instantiate your consciousness and a physical world of which it is
conscious - including other people.
In mathematics you assume some axioms are true and then use them to
build something out of them, but with physics it doesn't matter what
your opinion of the conservation of energy is, if it violates that
principle your perpetual motion machine will let you know mighty damn
quick by not working.
That's in*/our/* physics - not in all possible physics. Consider
computer games. They generally implement some internally consistent
physics.
And even if your mathematical axioms are true,
You mean their interpretation applied to something non-mathematical?
Within mathematics axioms are "true" by definition - although it's just
a marker "t" that is conserved by logical transformations. It's quite
different from the correspondence meaning of "true". This is why
Bruno's ideal machine, that he interviews, which "believes" everything
provable in airthmetic can have false beliefs about the physical world.
The first "believes" in just mathematical provability. The second
"beliefs" is a relation between thoughts and perceptions and actions.
when you use them to derive something there is no way to definitive
know if you made a mistake in doing so.
You mean in your applied interpretation.
But if the physical machine I built doesn't work I know for a fact I
made a mistake in my use of physical principles.
Unless there's a miracle. Right. We use "physical principles" to mean
rules that apply to all times and places (that's why energy and momentum
are conserved, as proved by Emmy Noether). So whenever some application
of principle doesn't work, we just say, "Well, we must be mistaken about
what the physics is." and we modify our theories. Remember the
neutrino. Sometimes we just exclude stuff from physics because of
this. At one time Kepler thought that there was a mathematical rule
that determined the number and orbital spacing of planets. Now we leave
that to chance.
Brent
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