On Wed, 11 Jun 2014 08:28:43 -0700, Rustom Mody wrote: > Steven D'Aprano wrote: > >> Not the point. There's a minimum amount of energy required to flip a >> bit. Everything beyond that is, in a sense, just wasted. You mentioned >> this yourself in your previous post. It's a *really* tiny amount of >> energy: about 17 meV at room temperature. That's 17 milli >> electron-volt, or 2.7×10^-21 joules. In comparison, Intel CMOS >> transistors have a gate charging energy of about 62500 eV (1×10^-14 J), >> around 3.7 million times greater. >> >> Broadly speaking, if the fundamental thermodynamic minimum amount of >> energy needed to flip a bit takes the equivalent of a single grain of >> white rice, then our current computing technology uses the equivalent >> of 175 Big Macs. > > Well thats in the same realm as saying that by E=mc² a one gram stone > can yield 21 billion calories energy. [...] > ie. from a a pragmatic/engineering pov we know as much how to use > Einstein's energy-mass-equivalence to generate energy as we know how to > use Landauer's principle to optimally flip bits.
You know, I think that the people of Hiroshima and Nagasaki and Chernobyl and Fukushima (to mention only a few places) might disagree. We know *much more* about generating energy from E = mc^2 than we know about optimally flipping bits: our nuclear reactions convert something of the order of 0.1% of their fuel to energy, that is, to get a certain yield, we "merely" have to supply about a thousand times more fuel than we theoretically needed. That's about a thousand times better than the efficiency of current bit-flipping technology. We build great big clanking mechanical devices out of lumps of steel that reach 25% - 50% of the theoretical maximum efficiency: https://en.wikipedia.org/wiki/Thermal_efficiency while our computational technology is something of the order of 0.00001% efficient. I'm just pointing out that our computational technology uses over a million times more energy than the theoretical minimum, and therefore there is a lot of room for efficiency gains without sacrificing computer power. I never imagined that such viewpoint would turn out to be so controversial. -- Steven D'Aprano http://import-that.dreamwidth.org/ -- https://mail.python.org/mailman/listinfo/python-list
