In article <53953616$0$29988$c3e8da3$>,
 Steven D'Aprano <> wrote:

> Moore's Law observes that processing power has doubled about every two 
> years. Over the last decade, processing power has increased by a factor 
> of 32. If *efficiency* had increased at the same rate, that 500W power 
> supply in your PC would now be a 15W power supply.

I think you're using a strange definition of efficiency.  I would define 
it as electric_power_in / processing_power_out.  If processing power has 
gone up by a factor of 32, and electric power used has stayed more or 
less the same (which it has), then efficiency has gone up.

> Your mobile phone would last a month between recharges, not a day. 
> Your laptop could use a battery half the size and still last two 
> weeks on a full charge.

One of the real industrial problems facing today's society is storage of 
electrical energy in batteries.  The lead-acid batteries in our cars are 
not terribly different from the ones in our grandparents' cars (or even 
our great-grandparents', if they had cars).  The storage capacity has 
gone up a little, mostly because the plastic shells we use now are 
thinner than the bakelite shells they used to use, so there's more 
internal volume for the same external size container.

And, yes, we now have other chemistries (lithium ion, metal hydride, 
etc) which are better in various ways, but the energy density (joules / 
kg) really hasn't changed much in 100 years.

> No. I'm arguing that they shouldn't convert 90% of their energy input 
> into heat.

Actually, they convert 100% of their energy input into heat.  The trick 
is having them do something useful along the way.

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