The ‘tile’ or cellular automata wire model fits both on-chip copper interconnect wire energy and brain axon wire energy very well. It is more obvious why it fits axon signal conduction as that isn’t really a traditional voltage propagation in a wire, it’s a propagation of ion cellular automata state changes. I’m working on a better writeup and I’ll look into how the wire equations could relate. If you have some relevant link to physical limits of communication over standard electrical wires, that would of course be very interesting/relevant.
My expectation is… Well, I’m a bit concerned that I’m misunderstanding ethernet specs, but it seems that there are 4 twisted pairs with 75Ω characteristic impedance, and the voltage levels go up to ±1V. That would amount to a power flow of up to 4V²/Z=0.05W.
I’m guessing this is probably the correct equation for the resistive loss, but irreversible communication requires doing something dumb like charging and discharging/dissipating 12CV2 (or equivalent) every clock cycle, which is OOM greater than the resistive loss (which would be appropriate for a steady current flow).
Do you have a link to the specs you were looking at? As I’m seeing a bunch of variation in 40G capable cables. Also 40Gb/s is only the maximum transmission rate, actual rate may fall off with distance from what I can tell.
The first reference I can find From this website is second hand but:
When the data rate required for interconnection is less than 5 Gbps, the passive copper cable is usually used for interconnection in data center. However, they can only support 40G transmission over really short distance.
Active copper cable can support 40G transmission over copper cable up to 15 meters with QSFP+ connector embedded with electronics. In the battle over transmission distance, optical active cable wins without doubt.
The connectors attached with AOC and active copper cable are the main reason why the two cables can support 40G transmission over longer distance than that of passive copper cable. AOC which can support the longest 40G transmission distance is with the highest power consumption—more than 2W. The power consumption for active copper cable is only 440mW. However, passive copper cable requires no power during the transmission.
Active copper cable at 0.5W for 40G over 15 meters is ~1e−21J/nm, assuming it actually hits 40G at the max length of 15m.
This source has specs for a passive copper wire capable of up to 40G @5m using <1W, which works out to ~5e−21J/nm, or a bit less.
Compare to 10G from here which. may use up to 5W to hit up to 10G at 100M, for ~5e−21J/nm.
One of the weird things in this discussion from my perspective is that you’re OK with photons carrying information with less than 2e-21 J/bit/nm energy dissipation but you’re not OK with wires carrying information with less than 2e-21 J/bit/nm energy dissipation.
I do think I have a good explanation in the cellular automata model, and I’ll just put my full response in there, but basically it’s the difference between using fermions vs bosons to propagate bits through the system. Photons as bosons are more immune to EM noise pertubations and in typical use have much longer free path length (distance between collisions). One could of course use electrons ballistically to get some of those benefits but they are obviously slower and ‘noisier’.
The ‘tile’ or cellular automata wire model fits both on-chip copper interconnect wire energy and brain axon wire energy very well. It is more obvious why it fits axon signal conduction as that isn’t really a traditional voltage propagation in a wire, it’s a propagation of ion cellular automata state changes. I’m working on a better writeup and I’ll look into how the wire equations could relate. If you have some relevant link to physical limits of communication over standard electrical wires, that would of course be very interesting/relevant.
I’m guessing this is probably the correct equation for the resistive loss, but irreversible communication requires doing something dumb like charging and discharging/dissipating 12CV2 (or equivalent) every clock cycle, which is OOM greater than the resistive loss (which would be appropriate for a steady current flow).
Do you have a link to the specs you were looking at? As I’m seeing a bunch of variation in 40G capable cables. Also 40Gb/s is only the maximum transmission rate, actual rate may fall off with distance from what I can tell.
The first reference I can find From this website is second hand but:
Active copper cable at 0.5W for 40G over 15 meters is ~1e−21J/nm, assuming it actually hits 40G at the max length of 15m.
This source has specs for a passive copper wire capable of up to 40G @5m using <1W, which works out to ~5e−21J/nm, or a bit less.
Compare to 10G from here which. may use up to 5W to hit up to 10G at 100M, for ~5e−21J/nm.
I do think I have a good explanation in the cellular automata model, and I’ll just put my full response in there, but basically it’s the difference between using fermions vs bosons to propagate bits through the system. Photons as bosons are more immune to EM noise pertubations and in typical use have much longer free path length (distance between collisions). One could of course use electrons ballistically to get some of those benefits but they are obviously slower and ‘noisier’.