# Why don't we observe quantum effects for large massive objects at rest? [duplicate]

The de Broglie wavelength of any massive particle is $$\lambda = \frac{h}{p}$$. We know that if a large object (say, a baseball) is at rest, it will have $$p=0$$ and hence $$\lambda$$ will be infinite. This should allow us to observe quantum interference of the baseball.

Online sources say something about the uncertainty principle: we can never be certain that $$p=0$$. There will always be some uncertainty in the value of $$p$$. If we want to decrease $$\Delta p$$, we have to increase $$\Delta x$$, the uncertainty in the position of the baseball. Why doesn't this allow us to observe quantum effects?

Planck's constant is $$6.62607004 × 10^{-34} m^2 kg / s$$.
We're unable to know the massive object's momentum to a significantly more refined degree than $$10^{-34} kg\space m/s$$. (in order to get quotient to be infinite) Moreover, a massive body is just a blob of bunches of particles swimming in all different directions.