thebestaquaman , 1 month ago (edited 1 month ago)

Yes, there are an infinite number of velocities you can use, but if you look at their distribution, you’ll find that it quickly goes to zero somewhere around 1-2 m/s, so the expectation value of the velocity is convergent.

If you have an object with a velocity taken from a distribution that doesn’t approach zero sufficiently fast as the velocity goes to infinity, the expectation value diverges. A simple example would be a person that would be half as likely to get up at a velocity of 2 m/s as 1 m/s, and half as likely to get up at 4 m/s as 2 m/s, etc.

The more mathematical version of the same argument is to compute the kinetic energy of a particle whose wavefunction is a delta pulse (i.e. a particle whose position is exactly defined), and you’ll find that the particle has infinite energy.