A walking person has a de Broglie wavelength too; it is merely around 10⁻³⁵ m, far below anything measurable. Since λ = h/p runs inversely with momentum, the lighter and slower an object is, the more its wave nature shows. An accelerated electron lands near 0.17 nm, about the spacing between atoms in a crystal, so it genuinely diffracts — exactly what Davisson and Germer measured off nickel in 1927. A tennis ball works out to some 10⁻³⁴ m, which is why it behaves as a pure particle.
A walking person has a de Broglie wavelength too; it is merely around 10⁻³⁵ m, far below anything measurable. Since λ = h/p runs inversely with momentum, the lighter and slower an object is, the more its wave nature shows. An accelerated electron lands near 0.17 nm, about the spacing between atoms in a crystal, so it genuinely diffracts — exactly what Davisson and Germer measured off nickel in 1927. A tennis ball works out to some 10⁻³⁴ m, which is why it behaves as a pure particle.
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