Physical scale, tiny robots, and life

Sabine Hossenfelder has an interest post (and video) about small, smaller, and vanishingly small robots, These tiny robots could work inside your body:

Here's a passage:

No, the problem with tiny robots is a different one. It’s that, regardless of whether the prefix is nano, micro, or xeno, at such small scales, different laws of physics become relevant. You can’t just take a human sized robot and scale it down, that makes no sense.

For tiny robots, forces like friction and surface tension become vastly more important than they are for us. That’s why insects can move in ways that humans can’t, like walking on water, or walking upside-down on the ceiling, or like, flying. Tiny robots can indeed fly entirely without wings. They just float on air like dust grains. Tiny robots need different ways of moving around, depending on their size and the medium they’re supposed to work in, or on.

Scale played an important role in a paper David Hays and I published some years ago:

William Benzon and David G. Hays, A Note on Why Natural Selection Leads to Complexity, Journal of Social and Biological Structures 13: 33-40, 1990, https://www.academia.edu/8488872/A_Note_on_Why_Natural_Selection_Leads_to_Complexity https://ssrn.com/abstract=1591788

Here’s the relevant passage:

We live in a world in which “evolutionary processes leading to diversification and increasing complexity” are intrinsic to the inanimate as well as the animate world (Nicolis and Prigogine 1977: 1; see also Prigogine and Stengers 1984: 297-298). That this complexity is a complexity inherent in the fabric of the universe is indicated in a passage where Prigogine (1980: xv) asserts “that living systems are far-from-equilibrium objects separated by instabilities from the world of equilibrium and that living organisms are necessarily ‘large,’ macroscopic objects requiring a coherent state of matter in order to produce the complex biomolecules that make the perpetuation of life possible.” Here Prigogine asserts that organisms are macroscopic objects, implicitly contrasting them with microscopic objects.

Prigogine has noted that the twentieth century introduction of physical constants such as the speed of light and Planck's constant has given an absolute magnitude to physical events (Prigogine and Stengers 1984: 217-218). If the world were entirely Newtonian, then a velocity of 400,000 meters per second would be essentially the same as a velocity of 200,000 meters per second. That is not the universe in which we live. Similarly, a Newtonian atom would be a miniature solar system; but a real atom is quite different from a miniature solar system.

Physical scale makes a difference. The physical laws which apply at the atomic scale, and smaller, are not the same as those which apply to relatively large objects. That the pattern of physical law should change with scale, that is a complexity inherent in the fabric of the universe, that is a complexity which does not exist in a Newtonian universe. At the molecular level life is subject to the quantum mechanical laws of the micro-universe. But multi-celled organisms are large enough that, considered as homogeneous physical bodies, they exist in the macroscopic world of Newtonian mechanics. Life thus straddles a complexity which inheres in the very structure of the universe.