  The Heisenberg uncertainty principle for material objects is an essential
corner stone of quantum mechanics and clearly visualizes the wave nature of
matter. Here we report a demonstration of the Heisenberg uncertainty principle
for the most massive, complex and hottest single object so far, the fullerene
molecule C70 at a temperature of 900 K. We find a good quantitative agreement
with the theoretical expectation: dx * dp = h, where dx is the width of the
restricting slit, dp is the momentum transfer required to deflect the fullerene
to the first interference minimum and h is Planck's quantum of action.
