On 7/1/2012 12:57 AM, Evgenii Rudnyi wrote:
On 01.07.2012 09:38 meekerdb said the following:
On 7/1/2012 12:25 AM, Evgenii Rudnyi wrote:
On 30.06.2012 22:31 meekerdb said the following:
On 6/30/2012 12:20 PM, Bruno Marchal wrote:


On 30 Jun 2012, at 18:44, Evgenii Rudnyi wrote:


I think that you have mentioned that mechanism is
incompatible with materialism. How this follows then?

Because concerning computation and emulation (exact simulation)
all universal system are equivalent.

Turing machine and Fortran programs are completely equivalent,
you can emulate any Turing machine by a fortran program, and
you can emulate any fortran program by a Turing machine.

More, you can write a fortran program emulating a universal
Turing machine, and you can find a Turing machine running a
Fortran universal interpreter (or compiler). This means that
not only those system compute the same functions from N to N,
but also that they can compute those function in the same
manner of the other machine.

But the question is whether they 'compute' anything outside the
context of a physical realization?

Personally I am not sure if they compute anything even in a
physical realization. To make my point, let us consider some device
that implements a PID controller, the equation is in Wikipedia

http://en.wikipedia.org/wiki/PID_controller#PID_controller_theory

Now let us start with the M-theory (or any other) and consider the
 functioning device in this framework. There is dynamics and
evolution of superstrings, however it is unclear to me what happens
with the equation for the PID controller in this context. Does it
mean that the M-theory computes the equation of the PID
controller?

I think that's mixing up models with the thing modeled. If there is a
 device which is PID controller and it is running and controlling
something, then we have a set of equations that describes and
predicts what will happen, to a good approximation. We might program
a computer to compute what that model predicts.

M-theory is a speculative theory about matter that, if it's correct,
 would be the basis of a predictive model of the behavior of the
matter making up the device which is a PID controller at a very low
level of detail (e.g. elmentary particles and fields).


Then what is the relationship between the M-theory and the matter? How matter that must obey to the M-theory knows about it?

That's what I mean by taking it backwards; it's like asking how events must obey the description in the newspaper.


If physicists would say that the M-theory is just a model, then I could understand. However Hawking in Grand Design says that a physical theory is more than the model. If I have understood his 'model dependent realism' correctly, then according to him the M-theory is the reality.

I haven't read it, but from reviews I gather that Hawking and Mlodinow just hold that what 'exists' is model dependent.

Brent

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