Re: trends in brain imaging

From: John Clark (
Date: Sat Jan 20 2001 - 22:40:04 MST

mez <> Wrote:

> I find the man's [Kurzweil] math to be incredibly sloppy (and
> often downright wrong) so I'm not too optimistic. For example, his
> estimate of the amount of power necessary to simulate the brain was
> around 10^12 operations per second, if I recall correctly. Even quick
> back of the envelope math shows that to be around 6 orders of
> magnitude too low.

10^12 doesn't sound too far off to me, there are 10^11 neurons in the human brain and
10^14 synapses connected to them. Neurons are very very slow so even at the best a neuron
can only fire a few times a second and in any given second lots of them won't be firing at all.
It's true this is a pretty crude analysis but as envelopes go it's not too bad, I don't know where
you got those 6 orders of magnitude.

By the way, Drexler once calculated the amount of computer power needed to simulate ALL the
brains that have ever existed before humanity, that is, all the brains since brains were invented in
the Cambrian Explosion 570 million years ago. He concluded that about 10^38 machine instructions
would do the trick. A Nanotechnology computer the size of a large present day factory and using
no more power, could perform 10^38 machine instructions in about 2 years.

       John K Clark

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