Regarding 5, my understanding is that mechanosynthesis involves precise placement of individual atoms according to blueprints, thus making catalysts that selectively bind to particular molecules unnecessary.
No, that does not follow.
The shell could be made of diamond panels with airtight joints. The daughter cell’s internal components and membrane are manufactured inside the parent cell, then the membrane is added to the parent cell’s membrane, it unfolds in an origami fashion into two membranes of original size, then the daughter cell separates.
...for one thing, that’s not airtight.
It seems to me that the “step” for molecular linear motors could be an arbitrarily long distance.
No, the steps happen by diffusion so they become slower. That’s why slower muscles are more efficient.
The “floppy enzymes” has the same solution as section 8. In chapter 13 of Nanosystems Drexler also gives three different ways this problem is solved, two of which involve molecular manipulators:
I don’t know how to engage with the first two comments. As for diffusion being slow, you need to argue that it’s so slow as to be uncompetitive with replication times of biological life, and that no other mechanism for placing individual atoms / small molecules could achieve better speed and energy efficiency, e.g. this one.
I don’t have the expertise to evaluate the comment by Muireall, so I made a Manifold market.
Such actuator design specifics aren’t relevant to my point. If you want to move a large distance, powered by energy from a chemical reaction, you have to diffuse to the target point, then use the chemical energy to ratchet the position. That’s how kinesin works. A chemical reaction doesn’t smoothly provide force along a range of movement. Thus, larger movements per reaction take longer.
Biological life uses an ATP system. This is an energy currency, but it’s discrete. Like having batteries that can only be empty or full. It doesn’t give a good way to apply smaller amounts of energy than 1 atp molecule carries, even if less energy is needed.
Nanobots could have a continuous energy system, or smaller units of energy.
No, that does not follow.
...for one thing, that’s not airtight.
No, the steps happen by diffusion so they become slower. That’s why slower muscles are more efficient.
see this reply
I don’t know how to engage with the first two comments. As for diffusion being slow, you need to argue that it’s so slow as to be uncompetitive with replication times of biological life, and that no other mechanism for placing individual atoms / small molecules could achieve better speed and energy efficiency, e.g. this one.
I don’t have the expertise to evaluate the comment by Muireall, so I made a Manifold market.
Such actuator design specifics aren’t relevant to my point. If you want to move a large distance, powered by energy from a chemical reaction, you have to diffuse to the target point, then use the chemical energy to ratchet the position. That’s how kinesin works. A chemical reaction doesn’t smoothly provide force along a range of movement. Thus, larger movements per reaction take longer.
Biological life uses an ATP system. This is an energy currency, but it’s discrete. Like having batteries that can only be empty or full. It doesn’t give a good way to apply smaller amounts of energy than 1 atp molecule carries, even if less energy is needed.
Nanobots could have a continuous energy system, or smaller units of energy.