Expectation of Momentum in a Classical (Infinite) Potential Well

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The discussion centers on calculating the expectation of momentum for a classical particle in an infinite potential well, emphasizing the wavefunction's normalization and boundary conditions. The expectation value of momentum is derived, leading to a conclusion that aligns with quantum mechanics, where the wavefunction must vanish at the boundaries. Participants debate the implications of using complex exponentials versus sine and cosine functions, noting that uniform velocity is maintained with complex exponentials. The conversation also touches on the nature of classical particles in quantum contexts, suggesting that classical behavior emerges at high energies. Ultimately, the calculation for momentum remains consistent regardless of whether the particle is treated classically or quantum mechanically.
  • #31
To elaborate on @jtbell #24. The expectation value, as you know, is an average.

Suppose you performed ##N## measurements of the momentum at random intervals and you got ##N_1## values at ##+p## and ##N_2## at ##-p##, where ##N=N_1+N_2##. What is the average value of the momentum?

Suppose you flip a fair coin ##N## times and you get ##N_1## tails and ##N_2## heads. You assign +1 point to tails and -1 point to heads. How would you express the average of the flips as a number? What do you think the a priori average could be before you do any measurements?
 

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