A cat runs through a door. Assuming h = 1 J s, mass of the cat is 1 kg, and the velocity of the cat is 1 m/s. Assume the cat is a quantum particle. How wide does this door have to be for the cat to interfere with itself?
I think what I am struggling with most here is the assumption one needs to make. My instinct is telling me to use de Broglie's wavelength:
$\lambda = \frac{h}{p} = \frac{h}{mv} = \frac{1\,J\,s}{1\,kg\;1\,m/s} = 1\,\mbox{m}$
But how does one know that this is the width of the door?