<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Tue, Jan 7, 2014 at 5:11 AM, Anders Sandberg <span dir="ltr"><<a href="mailto:anders@aleph.se" target="_blank">anders@aleph.se</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><div class="im"><blockquote type="cite">So how
many super computers can this future energy grid support?
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</blockquote>
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Depends on the other law in town, Koomey's law<br>
<a href="https://en.wikipedia.org/wiki/Koomey%27s_law" target="_blank">https://en.wikipedia.org/wiki/Koomey's_law</a><br>
Up until recently energy was not much of a design criterion, so I
suspect we might even see an acceleration as we start caring more
about energy than size. </div></blockquote><div><br></div><div>My research indicates that this is the reason Intel stopped upping clock speed circa 2003, not because they COULDN'T make faster chips, but because the energy usage of such chips went up too fast for their comfort level. That is, their customers were asking for more computations per $ rather than computations per CPU per Minute.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div text="#000000" bgcolor="#FFFFFF">The limits are as always tricky to judge: <br>
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<blockquote type="cite"><span style="text-indent:0px;letter-spacing:normal;font-variant:normal;text-align:start;font-style:normal;display:inline!important;font-weight:normal;float:none;line-height:26px;color:rgb(51,51,51);text-transform:none;font-size:small;white-space:normal;font-family:palatino,georgia,verdana,arial,sans-serif;word-spacing:0px">The current IBM roadrunner does 376
million calculations per watts. If we take my mid-range
estimates of computing needs, 10^22 to 10^25 FLOPS, then a
single emulation would need 10^13 to 10^16 watts. The total
insolation of Earth is about 10^17 watts, so this won't do -
there would be space for just a few minds on the entire planet.
But current research on zettaflops computing suggest we can do
much better. A DARPA exascale study suggests we can do 10^12
flops per watt, which means "just" a dozen Hoover dams per mind.<span> </span></span><a href="http://netalive.startlogic.com/debenedictis.org/erik/Publications-2005/Reversible-logic-for-supercomputing-p391-debenedictis.pdf" style="text-indent:0px;letter-spacing:normal;font-variant:normal;text-align:start;font-style:normal;font-weight:normal;line-height:26px;color:rgb(0,51,102);text-transform:none;font-size:small;white-space:normal;text-decoration:underline;font-family:palatino,georgia,verdana,arial,sans-serif;word-spacing:0px" target="_blank">Quantum dot cellular
automata could give 10^19 flops per watt</a><span style="text-indent:0px;letter-spacing:normal;font-variant:normal;text-align:start;font-style:normal;display:inline!important;font-weight:normal;float:none;line-height:26px;color:rgb(51,51,51);text-transform:none;font-size:small;white-space:normal;font-family:palatino,georgia,verdana,arial,sans-serif;word-spacing:0px">, putting the energy needs at 200-2000
watts.</span></blockquote>
<a href="http://www.aleph.se/andart/archives/2009/03/a_really_green_and_sustainable_humanity.html" target="_blank">http://www.aleph.se/andart/archives/2009/03/a_really_green_and_sustainable_humanity.html</a><br>
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And reversible computations are way better, of course. <br></div></blockquote><div><br></div><div>This doesn't sound reasonable to me. The human brain does what it does for about 100 watts. Why couldn't one create a similar efficiency in another substrate? I won't buy the above without further data.</div>
<div><br></div><div>-Kelly</div><div><br></div></div></div></div>