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 BĂ©rut,  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 by over 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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