I’m a bit suspicious of the model for interconnect energy.10Gb Ethernet over copper wire can extend 100 meters, and uses 2-5 watts at each end for full duplex. This works out to 5⋅10−21J/(bitnm), a bit lower than your 10−20 number for “complex error correction” at 0.1V and much lower than the 2.5∗10−19 that would be implied by the voltage of 2.5 V. What’s going on here? Is this in a regime where capacitive losses are much lower per bit-meter than they must be in the brain, as mentioned in the other comment thread?
Also, the image is of blood vessels, not interconnects in the brain.
If you follow that comment thread the tile model ends up being equivalent to or deriving small wire capacitance models. However it leaves open the possibility of having an interaction distance larger than the natural minimal unit of one electron radius, if you had a much larger wire structure. Coax cable uses exactly that, and the capacitance for thicker insulated wires gets a further small gain proportional to log of wire thickness. The brain also uses that a bit for long range interconnect (myelination) - which also provides speed.
But that logarithmic gain in energy efficiency vs wire thickness just isn’t a useful tradeoff for interconnect in general due to the volume cost.
The link is for cat6e cable, not coax. Also, the capacitance goes down to zero as r → R in the coaxial cable model, and the capacitance appears to increase logarithmically with wire radius for single wire or two parallel wires, with the logarithmic decrease being in distance between wires.
I’m a bit suspicious of the model for interconnect energy.10Gb Ethernet over copper wire can extend 100 meters, and uses 2-5 watts at each end for full duplex. This works out to 5⋅10−21J/(bit nm), a bit lower than your 10−20 number for “complex error correction” at 0.1V and much lower than the 2.5∗10−19 that would be implied by the voltage of 2.5 V. What’s going on here? Is this in a regime where capacitive losses are much lower per bit-meter than they must be in the brain, as mentioned in the other comment thread?
Also, the image is of blood vessels, not interconnects in the brain.
If you follow that comment thread the tile model ends up being equivalent to or deriving small wire capacitance models. However it leaves open the possibility of having an interaction distance larger than the natural minimal unit of one electron radius, if you had a much larger wire structure. Coax cable uses exactly that, and the capacitance for thicker insulated wires gets a further small gain proportional to log of wire thickness. The brain also uses that a bit for long range interconnect (myelination) - which also provides speed.
But that logarithmic gain in energy efficiency vs wire thickness just isn’t a useful tradeoff for interconnect in general due to the volume cost.
The link is for cat6e cable, not coax. Also, the capacitance goes down to zero as r → R in the coaxial cable model, and the capacitance appears to increase logarithmically with wire radius for single wire or two parallel wires, with the logarithmic decrease being in distance between wires.