Berkeley is one of the cradles of modern theoretical computer science. Over the last thirty years, our graduate students and, sometimes, their advisors have done foundational work on NP-completeness, cryptography, derandomization, probabilistically checkable proofs, quantum computing, and algorithmic game theory. The mild weather, celebrated eateries (see here and here), and collaborative atmosphere are known to be conducive to great theory-building and problem-solving.
In addition, Berkeley's Simons Institute for the Theory of Computing regularly brings together theory-oriented researchers from all over the world to collaboratively work on hard problems. The institute organizes a sequence of programs based on topics (see current & future programs and past ones), supported by workshops (see current & future workshops and past ones) and other events.
On Wednesdays, our group comes together for Theory Lunch, an event featuring an informal lunch followed by a whiteboard presentation; this allows for much mingling, including with our friends from Statistics and Math (and, occasionally, Physics and Chemistry). On Fridays, TGIF, the informal student seminar that is off-limits to faculty, provides a comfortable space for students to learn about each other's work.
Some of our current focus is on using computation as a lens to the sciences. Like probabilistic thinking in the last century, computational thinking will give mathematics and, more generally, science a new language to use and the ability to formulate new fundamental questions. We are studying the applications of theoretical computer science in many sciences, including economics (with our work on computational game theory and mechanism design), physics (with our work on random structures and quantum computing), biology, and pure mathematics (especially geometry, functional analysis, and additive number theory). The core problems in algorithms, compexity theory, and cryptography remain, of course, dear to our hearts.