The e-coli calculations make no sense to me. They posit huge orders of magnitude differences between an “optimal” silicon based machine and a carbon one (e-coli cell). I attribute this to bogus calculations
The one part I scrutinized: they use equation 7 to estimate the information content of an E-coli bacterium is ~1/2 TB. Now that just sounds absurd to me. That sounds like the amount you’d need to specify the full state of an E-coli at a given point in time (and indeed, that is what equation seven seems to be doing). They then say that E-coli performs the task of forming an atomically precise machine out of a max entropy state, instead of the actual task of “make a functioning e-coli cell, nevermind the exact atomic conditions”, and see how long it would take some kind of gimped silicon computer because “surely silicon machines can’t function in kilo kelvin temperatures?” to do that task. Then they say “oh look, silicon machines are 3 OOM slower than biological cells”.
They then say that E-coli performs the task of forming an atomically precise machine out of a max entropy state, instead of the actual task of “make a functioning e-coli cell, nevermind the exact atomic conditions”, and see how long it would take some kind of gimped silicon computer because “surely silicon machines can’t function in kilo kelvin temperatures?” to do that task. Then they say “oh look, silicon machines are 3 OOM slower than biological cells”.
The methodology they are using to estimate the bit info content of the bio cell is sound, but the values they plug in result in conservative overestimate. A functioning e-coli cell does require atomically precise assembly of at least some components (notably DNA) - but naturally there is some leeway in the exact positioning and dynamic deformation of other components (like the cell wall), etc. But a bio cell is an atomically precise machine, more or less.
They assume 32 bits of xyz spatial position for each component and they assume atoms as the building blocks and they don’t consider alternate configurations, but that seems to be a difference of one or a few OOM, not many.
And indeed from my calc their estimate is 1 OOM from the maximum info content as implied by the cell’s energy dissipation and time for replication (which worked out to 1e11 bits I think). There was another paper linked earlier which used a more detailed methodology and got an estimate of a net energy use of only 6x the lower unreliable landauer bound, which also constrains the true bit content to be in the range of 1e10 to 1e11 bits.
Then they say “oh look, silicon machines are 3 OOM slower than biological cells”.
Not quite, they say “a minimalist serial von neumman silicon machine is 2 OOM slower:
For this, the total time needed to emulate the bio-cell task (i.e., equivalent of 1e11 output bits) will be 510 000 s, which is more than 200 larger than time needed for the bio-cell.��
Their silicon cell is OOM inefficient because: 1.) it is serial rather than parallel, and 2.) it uses digital circuits rather than analog computations
The e-coli calculations make no sense to me. They posit huge orders of magnitude differences between an “optimal” silicon based machine and a carbon one (e-coli cell). I attribute this to bogus calculations
The one part I scrutinized: they use equation 7 to estimate the information content of an E-coli bacterium is ~1/2 TB. Now that just sounds absurd to me. That sounds like the amount you’d need to specify the full state of an E-coli at a given point in time (and indeed, that is what equation seven seems to be doing). They then say that E-coli performs the task of forming an atomically precise machine out of a max entropy state, instead of the actual task of “make a functioning e-coli cell, nevermind the exact atomic conditions”, and see how long it would take some kind of gimped silicon computer because “surely silicon machines can’t function in kilo kelvin temperatures?” to do that task. Then they say “oh look, silicon machines are 3 OOM slower than biological cells”.
The methodology they are using to estimate the bit info content of the bio cell is sound, but the values they plug in result in conservative overestimate. A functioning e-coli cell does require atomically precise assembly of at least some components (notably DNA) - but naturally there is some leeway in the exact positioning and dynamic deformation of other components (like the cell wall), etc. But a bio cell is an atomically precise machine, more or less.
They assume 32 bits of xyz spatial position for each component and they assume atoms as the building blocks and they don’t consider alternate configurations, but that seems to be a difference of one or a few OOM, not many.
And indeed from my calc their estimate is 1 OOM from the maximum info content as implied by the cell’s energy dissipation and time for replication (which worked out to 1e11 bits I think). There was another paper linked earlier which used a more detailed methodology and got an estimate of a net energy use of only 6x the lower unreliable landauer bound, which also constrains the true bit content to be in the range of 1e10 to 1e11 bits.
Not quite, they say “a minimalist serial von neumman silicon machine is 2 OOM slower:
Their silicon cell is OOM inefficient because: 1.) it is serial rather than parallel, and 2.) it uses digital circuits rather than analog computations