We shall now see that quantum and thermal noise breaks any upwardly causal deterministic chains between the physics of the atomic and molecular level and the biophysics of the organic world. It also breaks any upward deterministic chains between the neurobiological brain and the mind, replacing them with a statistical causality that provides us with what William James called “some looseness in the joints.” []
We present two processes that exhibit randomness in the component atoms and molecules, thus blocking any organized upward influences. The first is present in every biological cell. The other is critically important in the operation of neurons. The first separates the living from the simply material. The latter is at the mind/brain boundary.
Ribosomes Build Hemoglobin from Randomly Moving Amino Acids (Life from Matter)
The twenty amino acids move about randomly in a cell, the consequence of thermal and quantum noise. Attached to them are tiny bits of transfer RNA, each with three letters of the genetic code that identify them. They bump randomly into the ribosome, which may be moving along a sequence of the genetic code written in messenger RNA sent from the cell nucleus, which has noticed that more of a specific protein or enzyme is needed. This random motion shows us that no organized or coherent information is present in the unattached tRNAs that could cause something from the bottom up to emerge at a higher level.
[Look at the animation of mRNA translation] Notice the absurdity of the idea that the random motions of the transfer RNA molecules (green in the video at right), each holding a single amino acid (red), are carrying pre-determined information of where they belong in the protein.
It is the information processing of the higher-level ribosome that is in control. As the ribosome moves along the string of mRNA, it reads the next three-letter codon and waits for a tRNA with the matching anti-codon to collide randomly. With over 60 codons for the 20 amino acids, it might be some time before the desired amino acid shows up. Note that it is the high speed of random motions that allows this process to proceed rapidly. Consider the case of hemoglobin.
When a ribosome assembles 330 amino acids in four symmetric polypeptide chains (globins), each globin traps an iron atom in a heme group at the center to form the hemoglobin protein. This is downward causal control of the amino acids, the heme groups, and the iron atoms by the ribosome. The ribosome is an example of Erwin Schrödinger's emergent "order out of order," life "feeding on the negative entropy" of digested food.
When 200 million of the 25 trillion red blood cells in the human body die each second, 100 million new hemoglobins must be assembled in each of 200 million new blood cells . With the order of a few thousand bytes of information in each hemoglobin, this is 10 thousand x 100 million x 200 million = 2 x 1020 bits of information per second, a million times more information processing than today's fastest computer CPU.
The ribosome is an information-processing biological system that has emerged from the lower level of chemistry and physics to exert downward causation on the atomic and molecular components needed to manufacture hemoglobin.
Ion Transporter Pumps in Neurons Organize Randomly Moving Individual Atoms (Mind from Life)
When a single neuron fires, the active potential rapidly changes the concentration of sodium (Na+) ions inside the cell and potassium (K+) ions outside the cell. Within milliseconds, thousands of sodium-potassium ion transporters in the thin lipid bilayer of the cell wall must move billions of those ions, two or three at a time between inside and outside the cell wall, to restore the reduced chemical potential.
All the individual ions, atoms, and molecules in the cell are moving rapidly in random directions. The indeterministic motions of the ions randomly move some near the pump opening, where quantum collaborative forces can capture them in a lock-and-key structure. The idea that the physical/chemical base level contains enough information in the motion of its atoms and molecules to cause and completely explain the operations of the higher levels of life and mind is simply absurd.
The emergent biological machinery of an ion channel exerts downward causation on the ions, powered by ATP energy carriers (feeding on negative entropy).
The sodium-potassium pump in our neurons is as close to a
Maxwell's Demon as anything we are ever likely to see.
When many motor neurons fire, innnervating excitatory post-synaptic potentials (EPSPs) that travel down through the thalamus and the spinal cord where they cause muscles to contract, that is as literal as downward causation gets between the mind and the body. When the emergent mind decides to move the body, mental causation is realized as downward causation.
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