SV: Capacity of the brain

Danny Lingman lingman at
Tue Oct 26 14:30:58 EST 1999

In article <nTsJOO57h4sa7W0W=SL59bxqUI=b at>, Ian <iadmontg at> writes:

|> My AI textbook lists a factoid saying that a typical desktop computer could
|> do "10^5 neuron updates per second".  It was written in 1995, and listing
|> figures for a processor with ~100,000 gates.  So evidently, a
|> nearly-obsolete PC CPU running neural net software could update about 10^5
|> neurodes per second.
|> The number of "neuron updates per second" for the biological brain is
|> listed as 10^14.  So there is a 9 order of magnitude difference.  Based on
|> the general speed increase over the last 4-5 years, that should be about 8
|> orders of magnitude by the present day.
|> If we assumed Moore's Law would continue to hold, this gives us an estimate
|> more optimistic than the "45 years for brain power on the desktop" estimate
|> posted earlier.  By 2030, the heuristic gives a desktop PC with 10^12
|> neuron updates per second, 10^14 by 2040.
|> Note that these figures are for running some kind of (unstated) typical
|> neural net software on a typical desktop CPU.  With some kind of
|> purpose-optimized system, the job could likely be done with significantly
|> less computing complexity.

So why wait? I'd guess a decent current machine could cope with 10^7 updates
per second. Distribute this across 1,000 machines, and we're up to 10^10.
(and you have a relatively fault tolerant brain as well)

This gives a second of "awareness" every 10^4 seconds - or about every 3 hours.

Add more, or faster machines, and you get closer to real time thought.
How many machines are running crunching cycles on SETI?

I'd think a more difficult problem would be setting up the basic programming,
the original neural configuration, and providing meaningful input.

Realistically, we ought to be able to simulate a human brain in pretty close to
real time, right now...

Anyone out there read "True Names" by V. Vinge?

Dan Lingman
Nortel Networks != Me. Not even close.

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