This talk deals with measurements of small forces at sub-micron separations. It tries to address an innocent enough question: Is Newtonian gravity valid at all distances? I will try to convey the deep sense of ignorance we still have in this topic, and describe the efforts undertaken to advance our knowledge. In particular, our experiments are sensitive to Yukawa-like corrections (i.e. interactions mediated by massive bosons) in the 0.1 to 1 micron range.
It will be shown that when trying to measure the gravitational interaction at short separations (on the order of 100 nm), other forces have to be taken into account. Among them, vacuum fluctuations are the more ubiquitous ones.
A brief description of how macroscopic bodies (classical objects) interact with vacuum fluctuations (a purely quantum effect) will be presented… towards developing approaches that are insensitive to them! These approaches use an engineered sample which allows to establish better constraints in Yukawa-like interactions. This is accomplished by measuring the difference in forces in configurations where vacuum fluctuations are the same, but the corrections to Newtonian gravity (if any) are not.