Re: [FRIAM] Watch "The Most Important Idea in Physics: The Principle of Least Action - Ask a Spaceman!" on YouTube

2023-07-10 Thread Barry MacKichan
This is late since another ISP cut my fiber connection a week ago. 
Living with only cell service plus $15 per gigabyte is not pleasant.


Some comments.
1. I believe that the fact that photons travel on geodesics (least 
distance betwee2 points on a surface (manifold)) gives a fingerhold on 
trying to grasp least action.
2. I read the wikipedia artice, and it hints that the application to 
electromagnetism and quantum physics requires some tweaks, so it is not 
as straightforward as the video implied.
3. Granted that Newton’s laws are simpler, my understanding is that 
problems involving constraints are easier to set up than integrating the 
constraints into the setup of the equations.


Just sayin’

—Barry

On 3 Jul 2023, at 2:51, Pieter Steenekamp wrote:


Hi Nick,

Exercise caution when attempting to grasp the principle of least 
action,

particularly if you desire an intuitive comprehension of it.

It is essential to recognize the significance of the principle of 
least
action, as it applies to various areas of physics and could 
potentially
hold a closer answer to the "why" question than Newtonian physics 
regarding

the laws of motion.

However, based on our current knowledge, the best explanation for why 
the

principle of least action holds true is that it aligns with the
observations and experiments conducted in the real world. Although a
breakthrough might be on the horizon, a consensus has not yet been 
reached

regarding the "why" question.

Therefore, at present, the following points can be made:
a) When applied to the laws of motion, the principle of least action 
and

Newton's laws of motion are equivalent.
b) The reason for their acceptance lies in their agreement with 
empirical

evidence and experimental results.
c) The principle of least action carries more depth as it applies 
across

several other fields of physics, such as electromagnetism and quantum
physics.
d) The fundamental formulation of the principle of least action is 
also

simpler than that of Newtonian physics.

However, if you are aiming to develop an intuitive understanding of 
the
motion of objects in the real world, it is advisable to adhere to 
Newtonian
physics. The principle of least action lacks inherent intuitiveness. 
Let me
rephrase that: I have personally constructed an intuitive 
understanding

that I find useful, but I cannot present it as the definitive answer.
Perhaps someone else has a compelling intuitive explanation? I am open 
to

hearing different perspectives.

Moreover, for practical mechanical engineering calculations involving
forces and motion in the real world, Newtonian physics surpasses the
principle of least action.


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[FRIAM] McCarthy v Peirce

2023-07-10 Thread Nicholas Thompson
Dear Colleagues,

Jon Z and Frank have me reading Cormac McCarthy.  I have started with his
last book, Stella Maris  (?Star of the Sea?).  It is the dialogue that each
of us has always wished we had with our psychiatrist . It is witty, often
funny, makes lots of references to Los Alamos, is always engaging, and
sometimes deep.  I am enjoying it and may have to read it a second time.

In the following lines, the patient character expresses an opinion on the
central issue of Pragmat[ic]ism.

 *Patient:] …The world you live in is shored some up by a collection of
agreements.  Is that something you think about?  The hope is that the truth
of the world somehow lies in the common experience of it.  Of course the
history of science and mathematics and even philosophy is a good bit at
odds with this notion.  Innovation and discovery by definition war against
the common understanding.  One should be wary.  What do you think? [pp
91-2]*

I am not going to comment.  I just thought you might like to have the quote
to mull over.

Nick
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