QM: Potential Energy & Particle Free Fall

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SUMMARY

The discussion centers on the differences and similarities between classical mechanics and quantum mechanics (QM) regarding potential and kinetic energy. In classical mechanics, potential energy is defined as ##mgh## and kinetic energy as ##\frac{m\upsilon^2}{2}## for a particle in free fall. In contrast, QM describes potential as a function of space rather than for individual particles, allowing particles to exist in regions where their total energy is less than the potential energy. This highlights a fundamental difference where quantum particles can occupy forbidden locations that classical particles cannot.

PREREQUISITES
  • Understanding of classical mechanics principles, specifically potential and kinetic energy.
  • Familiarity with quantum mechanics concepts, particularly the behavior of particles in potential fields.
  • Knowledge of matrix elements and their non-relativistic forms in quantum mechanics.
  • Basic grasp of Fourier transforms and their application in deriving potentials.
NEXT STEPS
  • Study the implications of potential energy in quantum mechanics compared to classical mechanics.
  • Explore the concept of forbidden regions in quantum mechanics and their significance.
  • Learn about matrix elements in quantum mechanics and how they relate to potential energy.
  • Investigate Fourier transforms and their role in quantum mechanics, particularly in deriving potentials.
USEFUL FOR

Students and professionals in physics, particularly those studying classical mechanics and quantum mechanics, as well as researchers interested in the foundational differences between these two fields of study.

LagrangeEuler
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In classical mechanics is defined potential and kinetical energy for particular particle. For example, in case of free fall potential energy of the particle is ##mgh## and kinetic energy is ##\frac{m\upsilon^2}{2}##. In QM there isn't potential of the particle, but potential of part of the space. For example particle could be in the space part where whole energy of the particle is less then potential. Could you explain me this? I'm really confused with this.
 
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There is no such difference between classical mechanics and QM. The potential for a specific particle is a function of space both in quantum mechanics and classical mechanics. The total energy is a property of the particle both in quantum mechanics and classical mechanics.
or example particle could be in the space part where whole energy of the particle is less then potential.
That is a difference, right. In quantum mechanics, the particle can be at locations forbidden for a classical particle (as it does not have enough energy).
 
In case one can get a matrix element and take it's non relativistic form,fourier transform of it gives a potential.
 

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