Brownian motion 2025: Friend and Foe

Significant increase in position sensitivity of Brownian particle in experiments was made possible by invention of optical trapping and accompanying interferometry. In order to gauge the current scientific progress, we pose three mutually connected questions:
• What kind of instrument one must develop to reach higher position sensitivity?
• What kind of physical phenomena can one discover with higher position sensitivities?
• What kind of physical phenomena remain unexplored at currently available resolution?
These questions can be asked simultaneously for high vacuum, gases, liquids, biological matter (viscoelastic media, active matter and single-molecule experiments) and quantum fluids.
There is no laboratory that performs experiments in all of them and thus the workshop would foster interaction between laboratories that don’t usually interact.
In some cases, motion of a Brownian particle is explored for its own sake, whereas in others fluctuations of the Brownian particle have to be removed, and hence Brownian motion can be a friend or a foe.