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Quantum Dog

Posted: Wed Oct 18, 2017 7:27 pm
by Andrea ORiordan 1L
Hello! Just a hypothetical question- if a large object (a dog, per say) slowed down to a very, very, very, very slow speed (think 10^-30 m/s), would it have observable wavelike properties? I'm aware that classical objects are made up of billions of particles and therefore you can't really calculate the wavelength of a dog, but hypothetically speaking, if momentum were to get very, very small, could we have a Quantum Dog?

Re: Quantum Dog

Posted: Wed Oct 18, 2017 11:25 pm
by ssthirkannad
I think theoretically, this is true - you could get a larger and larger wavelength as velocity decreases, but velocity would have to be so small that it would be impossible to detect.

Re: Quantum Dog  [ENDORSED]

Posted: Thu Oct 19, 2017 9:54 am
by Chem_Mod
We simplify our treatment of quantum mechanics when we apply the deBroglie equation to classical objects such as baseballs, cars, or dogs. Doing so illustrates the point that quantum mechanics is still operating at classical limits (the so-called "correspondence principle") but its effects are usually completely negligible, immeasurable, or ill-posed. It is insightful that you are thinking about the implications of all the parameters of the equation, namely, will wavelength approach infinity as velocity approaches zero.

The short answer to the question of the quantum dog is no. Explaining exactly why would require a quantum mechanics course itself (or maybe several). The rigorous explanation involves the role of the uncertainty principle, relativity, and how we define a "particle." Macroscopic (classical) objects are not particles by definition, but assemblages of such particles along with mostly empty space. The particle is a wavefunction, a concentrated packet of energy in space, and that particle needs to be moving at a certain threshold velocity before wave effects are produced.