It’s all about the connections
This CNN story is a bit off the wall (the title is “Brain downloads ‘possible by 2050′”); it is mostly about how the new PlayStation 3 and other modern supercomputers are approaching the computational power of the brain. From the article:
“The new PlayStation is one percent as powerful as the human brain,” Pearson told the Observer. “It is into supercomputer status compared to 10 years ago. PlayStation 5 will probably be as powerful as the human brain.” [Pearson is "head of British Telecom's futurology unit".]
But is this really an accurate estimate?
We were discussing this story in lab and my advisor came up with this analysis:
PlayStation 3 has 0.3 x 10^9 transistors and runs at 3 x 10^9 Hz.
That works out to 10^18 switching operations per second.
Your brain has 10^15 synapses running at 10^3 Hz.
That also works out to 10^18 elementary operations per second.
So it’s arguable that PlayStation 3 is just as powerful as your brain,
in terms of raw computational power. We just don’t know how to organize
that power properly.
June 2nd, 2005 at 11:41 pm
neat… so why is this off from Kurzeil’s estimate of 2020? I assume it’s that you are counting transistors in the machine, and he is counting how many operations the software actually gets to use?
Btw, Daniel Hillis made an interesting point in “The connection machine” called “the von Neumann bottleneck”, which he credits to J Backus.
In the old days, “processors were made out of relatively fast and expensive switching components, such as vaccum tubes, whereas the memories were made of relatively slow and inexpensive components, such as delay lines or storage tubes. The result was a two-part design that kept the expensive vacuum tubes as busy as possible.”
But today, this is inefficient: in a modern components, most of the transistors (/most of the silicon/most of the wire length) are in memory, which is mostly idle at any given moment (~97%): the “von Neumann bottleneck”. This gets worse the bigger we build machines.
June 2nd, 2005 at 11:43 pm
I should add that, as implied by the title of his book, Hillis agreed that “It’s all about the connections”. His solution to the von Neumann bottleneck was to creat computing architectures with lots of CPUs, each with a little memory, and with extreme connectivity.
June 3rd, 2005 at 12:17 pm
This measurement ignores that every switching operation performed on a playstation is stimulated by one of two possible values. Equivelent “switches” in the brain may respond differently to an infinite number of values. I think we may need to add a few more variables than just transister count and clock speed before a worthy comparison is made.