Quentin Anciaux-2 wrote:
> 
> 2012/9/11 benjayk <benjamin.jaku...@googlemail.com>
> 
>>
>>
>> Quentin Anciaux-2 wrote:
>> >
>> > 2012/9/10 benjayk <benjamin.jaku...@googlemail.com>
>> >
>> >>
>> >>
>> >> > > No program can determine its hardware.  This is a consequence of
>> the
>> >> > > Church
>> >> > > Turing thesis.  The particular machine at the lowest level has no
>> >> > bearing
>> >> > > (from the program's perspective).
>> >> > If that is true, we can show that CT must be false, because we *can*
>> >> > define
>> >> > a "meta-program" that has access to (part of) its own hardware
>> (which
>> >> > still
>> >> > is intuitively computable - we can even implement it on a computer).
>> >> >
>> >>
>> >> It's false, the program *can't* know that the hardware it has access
>> to
>> >> is
>> >> the *real* hardware and not a simulated hardware. The program has only
>> >> access to hardware through IO, and it can't tell (as never ever) from
>> >> that
>> >> interface if what's outside is the *real* outside or simulated
>> outside.
>> >> <\quote>
>> >> Yes that is true. If anything it is true because the hardware is not
>> even
>> >> clearly determined at the base level (quantum uncertainty).
>> >> I should have expressed myself more accurately and written "
>> "hardware"
>> "
>> >> or
>> >> "relative 'hardware'". We can define a (meta-)programs that have
>> access
>> >> to
>> >> their "hardware" in the sense of knowing what they are running on
>> >> relative
>> >> to some notion of "hardware". They cannot be emulated using universal
>> >> turing
>> >> machines
>> >
>> >
>> > Then it's not a program if it can't run on a universal turing machine.
>> >
>> The funny thing is, it *can* run on a universal turing machine. Just that
>> it
>> may lose relative correctness if we do that.
> 
> 
> Then you must be wrong... I don't understand your point. If it's a program
> it has access to the "outside" through IO, hence it is impossible for a
> program to differentiate "real" outside from simulated outside... It's a
> simple fact, so either you're wrong or what you're describing is not a
> program, not an algorithm and not a computation.
OK, it depends on what you mean by "program". If you presume that a program
can't access its "hardware", then what I am describing is indeed not a
program.

But most definitions don't preclude that. Carrying out instructions
precisely and step-by-step can be done with or without access to your
hardware.

Anyway, meta-programs can be instantiated using real computer (a program
can, in principle, know and utilize part of a more basic computational layer
if programmed correctly), so we at least know that real computers are beyond
turing machines.

benjayk

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