Feynman's Thesis, 3 Principles

In summary, Feynman's three principles are 1) that an acceleration is due to the sum of the interactions of a charge with other charged particles, 2) that the force of interaction between two charges is calculated using the Lorentz force formula, and 3) that the fundamental (microscopic) phenomena in nature are symmetrical with respect to the exchange of past and future. Each of these principles has implications for the theory of quantum mechanics, and Feynman discusses them in detail in his Feynman Lectures.
  • #1
jamie.j1989
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Hi, I've just started studying Feynman's thesis and am in need of some discussion regarding the three principles he put forward on the development of his 'Principle of least action in quantum mechanics'. The three principles are

1) The acceleration of a point charge is due to the sum of its interactions with other charged particles. A charge doesn't act on itself.
2) The force of interaction which one charge exerts on another is calculated by means of the Lorentz force formula ##F=e(E+\frac{v}{c}\times H)##, where ##E## and ##H## the electric and magnetic fields respectively and ##v## and ##c## the velocity of the particle and the speed of light respectively. The fields are the fields generated by the first charge in accordance with Maxwell's equations.
3) The fundamental (microscopic) phenomena in nature are symmetrical with respect to interchange of past and future. This requires the solution of Maxwell's equations to be used in computing the interactions is to be half the retarded plus half the advanced solution of Lienard and Wiechert.

What I would like to discuss is why he has decided on these and what exactly There individual consequences are. Most of all I'm at a complete loss as to what the third one even means.

My understanding of 1)
As far as I am aware this is currently no longer correct. Electrons do interact with themselves. However Feynman was attempting to find a way to get rid of the infinite mass that arrises classically with an electron interacting with itself; of which, I also don't quite understand.

My understanding of 2)
I'm happy with the text. I'm not sure about the motivation though, he needs a way of calculating 1); there is no reason why the physics in 2) shouldn't be used in his new formulation?

My understanding of 3)
Lost.

Thanks
 
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  • #2
Feynman discusses this in some detail in the Feynman Lectures, Vol 2 Chapter 28 at this link. Perhaps this will help. I think the simple answer to the question of why he made these assumptions is that with those assumptions things work out.
 
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Likes vanhees71
  • #3
Number three is just a statement about time symmetry, as in classical mechanics.

Cheers
 

1. What is Feynman's Thesis?

Feynman's Thesis, also known as "The Principle of Least Action" or "Feynman's 3 Principles", is a theory developed by physicist Richard Feynman in his doctoral thesis in 1942. It is based on the idea that the behavior of particles and systems can be described using a single mathematical function, known as the action, which minimizes the amount of energy used by the system to achieve its final state.

2. What are the 3 principles of Feynman's Thesis?

The 3 principles of Feynman's Thesis are the Principle of Least Action, the Principle of Stationary Action, and the Principle of Virtual Work. These principles state that a physical system will always choose the path of least action, will always follow the path of stationary action, and will always take the path that minimizes virtual work, respectively.

3. How does Feynman's Thesis relate to classical mechanics?

Feynman's Thesis is a generalization of classical mechanics, which is the study of the motion and behavior of macroscopic objects. It provides a more fundamental understanding of the underlying principles that govern the behavior of particles and systems, and can be applied to both classical and quantum systems.

4. What is the significance of Feynman's Thesis in modern physics?

Feynman's Thesis has had a profound impact on modern physics, particularly in the fields of quantum mechanics, particle physics, and cosmology. It has provided a fundamental understanding of the behavior of particles and systems at the microscopic level, and has been used to develop new theories and models that have greatly advanced our understanding of the universe.

5. Can Feynman's Thesis be applied to real-world situations?

Yes, Feynman's Thesis has been successfully applied to various real-world situations, such as predicting the behavior of particles in particle accelerators, understanding the dynamics of molecular systems, and modeling the behavior of complex physical systems. It has also been used in practical applications, such as in the development of new technologies and materials.

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