# Macroscopic objects - Interference

In Mcintyre's QM book he writes:

1. What does he mean by "a macroscopic object strongly interacts with the environment" for there to be no interference?
2. Why/how does the wave function of macroscopic objects suffer from decoherence? I assumed it had to do with the de Broglie wavelength:

$\lambda_{dB}&space;=&space;\frac{\hbar}{mv}$

and hence the mass and the velocity of a macroscopic object is relatively "big" the wavelength would be very small and would not physically possible to achieve. Furthermore, the lattice constant has a similar magnitude as the wavelength and that would also be impossible to have e.g. a 10^-37m lattice constant opening. Though it seems that this is not necessarily the reason why.