According to this post, computers today are only 3 orders of magnitude away from Landauer limit. So it ought to be literally impossible for the human brain to be six orders of magnitude more efficient. Also, how the hell is the brain supposed to carry out 20 Petaflops with only 100 billion neurons and a firing rate of a few dozen Hertz? The estimate seems way off to me.
I’m using the number calculated by Ray Kurzweil for his book, the Age of Spiritual Machines from 1999. To get that figure, you need 100 billion neurons firing every 5 ms, or 200 Hz. That is based on the maximum firing rate given refractory periods. In actuality, average firing rates are usually lower than that, so in all likelihood the difference isn’t actually six orders of magnitude. In particular, I should point out that six orders of magnitude is referring to the difference between this hypothetical maximum firing brain and the most powerful supercomputer, not the most energy efficient supercomputer.
The difference between the hypothetical maximum firing brain and the most energy efficient supercomputer (at 26 GigaFlops/watt) is only three orders of magnitude. For the average brain firing at the speed that you suggest, it’s probably closer to two orders of magnitude. Which would mean that the average human brain is probably one order of magnitude away from the Landauer limit.
This also assumes that its neurons and not synapses that should be the relevant multiplier.
According to this post, computers today are only 3 orders of magnitude away from Landauer limit. So it ought to be literally impossible for the human brain to be six orders of magnitude more efficient. Also, how the hell is the brain supposed to carry out 20 Petaflops with only 100 billion neurons and a firing rate of a few dozen Hertz? The estimate seems way off to me.
I’m using the number calculated by Ray Kurzweil for his book, the Age of Spiritual Machines from 1999. To get that figure, you need 100 billion neurons firing every 5 ms, or 200 Hz. That is based on the maximum firing rate given refractory periods. In actuality, average firing rates are usually lower than that, so in all likelihood the difference isn’t actually six orders of magnitude. In particular, I should point out that six orders of magnitude is referring to the difference between this hypothetical maximum firing brain and the most powerful supercomputer, not the most energy efficient supercomputer.
The difference between the hypothetical maximum firing brain and the most energy efficient supercomputer (at 26 GigaFlops/watt) is only three orders of magnitude. For the average brain firing at the speed that you suggest, it’s probably closer to two orders of magnitude. Which would mean that the average human brain is probably one order of magnitude away from the Landauer limit.
This also assumes that its neurons and not synapses that should be the relevant multiplier.