Feynman lectures and electron path

In summary, the conversation discusses the principle that keeps electrons from falling into the nucleus and the concept of a ground state for electrons. Feynman explains that if the electrons were in the nucleus, the uncertainty principle would require them to have a very large momentum, causing them to break away from the nucleus. Thus, electrons compromise by allowing for some uncertainty and maintaining a minimum amount of motion. This principle is crucial in understanding the Heisenberg Uncertainty Principle and the concept of escape velocity for the positive nucleus.
  • #1
forcefield
141
3
I read the Quantum Physics section of the online version of Feynman lectures http://feynmanlectures.caltech.edu/I_02.html#Ch2-S3 and I don't understand the problem with the electrons "breaking away from the nucleus". So why can't the electrons just keep going in and out of the nucleus ?
 
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  • #2
Feynman says:
"What keeps the electrons from simply falling in? This principle: If they were in the nucleus, we would know their position precisely, and the uncertainty principle would then require that they have a very large (but uncertain) momentum, i.e., a very large kinetic energy. With this energy they would break away from the nucleus. They make a compromise: they leave themselves a little room for this uncertainty and then jiggle with a certain amount of minimum motion in accordance with this rule."

This is an informal analysis of why elecrons have a ground state that is outside of the nucleus.

If this was violated you can compute the momentum of the electron required to satisfy the Heisenberg Uncertainty Principle for position vs momentum ... and the momentum calculated this way is more than the "escape velocity" for the positive nucleus.
 

1. What are the "Feynman lectures" and what do they cover?

The "Feynman lectures" refer to a series of three physics lectures given by Nobel Prize-winning physicist Richard Feynman at the California Institute of Technology in the 1960s. These lectures cover a broad range of topics in physics, from classical mechanics to quantum mechanics and beyond.

2. How do electrons move and what determines their path?

Electrons move in a wavelike manner, described by quantum mechanics. This means that their exact position and velocity cannot be known simultaneously. The probability of finding an electron at a given point is determined by its wave function, which is influenced by the electric and magnetic fields in its environment.

3. Can electrons travel in a straight line?

No, electrons do not travel in a straight line. Due to their wavelike behavior, electrons can exhibit interference patterns and can be found in multiple locations at once. In addition, their paths can be affected by the presence of other particles and fields.

4. How does the electron path affect the behavior of atoms and molecules?

The path of electrons plays a crucial role in determining the properties and behavior of atoms and molecules. The arrangement of electrons around an atom's nucleus determines its chemical and physical properties, and the interactions between electrons in different atoms can result in the formation of molecules with unique properties.

5. Are Feynman lectures still relevant in modern physics?

Yes, Feynman lectures are still relevant in modern physics. While they were originally given in the 1960s, the concepts and principles covered are still applicable and important in understanding current theories and advancements in physics. Many universities still use these lectures as a foundation for teaching introductory physics courses.

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