Interesting. Do you know what assumptions went into their analysis?
 
I would think that this is a medium dependent value; i.e. what underlying 
medium is the relying on to hold its logical state. Did the researchers attempt 
to figure out the minimum scale system (say an electron spin for example in a 
spintronics device -- which have not yet been built, but which is very much one 
of the future paths to the ever more small scale and which is sucking down big 
R&D money to try to find an economic means of building the single electron type 
gates that would rely on the electron's spin.
 
What if some hypothetical future technology is able to access more fundamental 
sub-atomic systems and a logic state is able to be contained in something far 
smaller than an electron. I am speculating here of course because such 
technology does not exist (as far as I know), but what if a state could 
reliably be inferred -- even if not directly measured -- in something that 
begins to approach the Planck scale -- say some property of a vibrating string. 
Wouldn't the minimum energy to flip a bit, in this new hypothetical and vastly 
smaller scale circuit be considerably less (by many orders of magnitude) than 
the energy required to flip a macro gate  (which by comparison even the most 
miniaturized transistor would be)?
 
My point in replying is that the medium and the scale in which the logic is 
etched (or some equivalent process for non-lithography based production) are 
other drivers that need to be considered, and that lower energy does not 
necessarily equate to slower performance. The twenty watt human computer can 
solve (especially subtle pattern recognition) problems that bring a 
super-computer to its knees; admittedly this is changing as computer 
hardware/software improves and better pattern recognition algorithms are 
developed, but our energy frugal computing machines cannot be said to be slow 
-- yes I know nerve impulses travel at a vastly reduced speed as compared to 
electrons flipping logic circuits, but the brain is a massively parallel 
architecture and is performing thousands maybe millions of tasks each and every 
second.
 
-Chris
 

________________________________
 From: L.W. Sterritt <lannysterr...@comcast.net>
To: everything-list@googlegroups.com 
Cc: L.W. Sterritt <lannysterr...@comcast.net> 
Sent: Friday, September 20, 2013 1:50 PM
Subject: Re: What gives philosophers a bad name?
  



Chris,
An article in Nature last year presents a calculation of the theoretical 
minimum energy required to erase a bit - independent of the computer:  
        * Antoine Bérut,        * Artak Arakelyan,      * Artyom Petrosyan,     
* Sergio Ciliberto,     * Raoul Dillenschneider&        * + et al.
>Nature 483, 187-189 doi:10.1038/nature10872
L.W.Sterritt
On Sep 20, 2013, at 1:22 PM, Chris de Morsella <cdemorse...@yahoo.com> wrote:

>> A computation always takes a nonzero amount of energy to perform, 
>> theoretically you can make the energy used be as close to zero as you like, 
>> but the less energy you use the slower the calculation.
>
>How does that square with the increased (well measured) energy efficiency per 
>fundamental unit of logic (single machine operation) -- it takes far less 
>energy to perform an elementary logic operation on a modern CPU than it did on 
>say a CPU from ten years ago (even if the modern CPU may suck down more total 
>power -- it is performing far more work)
>
>Modern CPUs clearly are also operating at much higher speeds. I think you are 
>not factoring in the dimension of scale or the physical size of the logic 
>container/state-machine. As the size of a logic gate is scaled down it takes 
>less energy and can operate at a higher clock speed. 
>
>http://en.wikipedia.org/wiki/Performance_per_watt
>"For example, the early UNIVAC I computer performed approximately 0.015 
>operations per watt-second (performing 1,905 operations per second (OPS), 
>while consuming 125 kW). The Fujitsu FR-V VLIW/vector processor system on a 
>chip in the 4 FR550 core variant released 2005 performs 51 Giga-OPS with 3 
>watts of power consumption resulting in 17 billion operations per 
>watt-second.[1][2] This is an improvement byover a trillion times in 54 years."
>
>Size (or rather the lack of it) matters in this equation.
>-Chris
>
>
>________________________________
> From: John Clark <johnkcl...@gmail.com>
>To: everything-list@googlegroups.com 
>Sent: Friday, September 20, 2013 10:38 AM
>Subject: Re: What gives philosophers a bad name?
>  
>
>
>On Thu, Sep 19, 2013 at 6:10 PM, LizR <lizj...@gmail.com> wrote:
>
>
>
>>> As Rolf Landauer said "Computation is physical", all computations must use 
>>> energy and generate heat. And what's the difference between a physical 
>>> process and a non-physical process anyway? 
>>>
>>>
>>>
>>> I thought it was only erasing the results of computations that had to use 
>>> energy and increase entropy? - if so - quibbling, I know, but sometimes 
>>> quibbles have important consequences.  
>
>
>A computation always takes a nonzero amount of energy to perform, 
>theoretically you can make the energy used be as close to zero as you like, 
>but the less energy you use the slower the calculation.
>
>
>  John K Clark
>
>
>
>
>
>
> 
>
>>
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