[FRIAM] What is the most important selection principle in evolution?

[_ Bruno W]

Not sure about the natural selection, but here are 2 small (possibly
important) corrections.
1.  The lifeguard is still to the left of the swimmer when the lifeguard
hits the water.  But by a much smaller distance than if
he had ran straight at the swimmer.
2.  The most widely accepted explanation for the origin of the least action
principle has to do with waves or paths, and doesn't
require the photon to know in advance where it should go.
In one version, the wave function of the photon goes out in all directions
with a phase at any point given by exp(iS/hbar) where
S is the action.  Because hbar is small, the waves oscillate rapidly and
generally cancel out everywhere, except of course
when the derivative of the action is zero and the wave stops oscillating
completely.  This will happen at the path of least (or in some
cases greatest) action.
Feynman did this one better by saying you don't need waves, you integrate
over all paths, and you get to include all kinds
of crazy paths, even ones that go in crazy loops and backwards in time and
whatever.  Once again the extreme action paths
are the only ones that survive in the classical limit (hbar -> 0).
Hope this helps?

On Sun, Feb 16, 2020 at 10:05 PM <thompnickson2 at gmail.com> wrote:

> Hi, Everybody, and Steve, and Miles
>
>
>
> Please everybody forgive me for what I am about to garble.
>
>
>
> Steve Guerin and I have a long standing argument concerning the above
> question.  He thinks my answer to the above question will be “natural
> selection.”  His answer to that question is, is that as energy flows from
> high to low concentrations, it seeks, and finds the most efficient route.
> Today, steve presented to me a most astounding example, which I am sure
> most of you are familiar with, but which I had never quite grasped.  It is
> illuminated by a metaphor.  Imagine a beach and a lifeguard standing on the
> beach when a drowning swimmer calls out to the lifeguard’s right.  Should
> the lifeguard run directly toward the drowning swimmer.  No, because he can
> make a lot faster progress toward the swimmer while running on the beach
> than he can while swimming.  So he should chose a path that minimizes his
> time to the swimmer, not the path directly toward the swimmer.  That path,
> the path of least action, will carry him to the right of the swimmer until
> he reaches he water’s edge and starts to swim.   Lifeguards have to be
> trained to do this, and lifeguards argue about which direction to head off
> under  under which conditions.
>
>
>
> Well, light approaching boundary between air and water faces the same
> situation.  And the stunning fact is that light finds the least action
> path.  As I understand it, the light leaves the source in a direction that
> takes into account the boundary that it is approaching.  PLEASE correct me
> if I have this wrong. Yet, of course, in this situation there is no trial
> and error.  Photons of light just “know” how to do this.  If this is true,
> I promise NEVER to yawn again when one of you is going on about quantum
> physics.
>
>
>
> Now, Steve, èIFç I understood you, you also went on to describe ants
> behavior and lightening behavior as analogous processes that also find
> Least Action Pathways.  And, I think you are also going to perhaps assert
> that a tornado is a structure that facilitates a least action pathway.
> Etc.  But these are plainly “historical” processes. I.e, in all cases the
> process tries out options, and settles on  the LAP.  But with light, here
> is no history.  Photons are like lifeguards who know instinctively what
> path to set out on to reach the swimmer with the least action
>
>
>
> Could I possibly have this right?  Once we get this first bit straightened
> out, I have a question about its relation to natural selection.
>
>
>
> Nick
>
>
>
> Nicholas Thompson
>
> Emeritus Professor of Ethology and Psychology
>
> Clark University
>
> ThompNickSon2 at gmail.com
>
> https://wordpress.clarku.edu/nthompson/
>
>
>
>
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