Usually, you will find somebody from our group relaxing in the CaféXX (Room 0.3.02). Should this not be the case not the case, there are other ways of getting in touch with us.
If you are interested in the FSI's work, you can subscribe here for the mailing list (as long as you are enrolled as a Physics student at the FU Berlin).
Freie Universität Berlin
Arnimallee 14, Room 0.3.04
14195 Berlin, Germany
In urgent cases you might take a look at the FSI channel #FUB
We also have a blackboard outside the CaféXX with the names of the students representatives and other useful information - take a look.