Today I learned about optogenetics. As this TED talk describes, neurons can be selectively activated or deactivated by injecting genes that code for light-sensitive proteins into living brain cells and then manipulating light. This is done with millisecond-scale temporal precision and points to many exciting applications.
Today I meditated for 20 minutes.
Today I acted kindly by hiding anonymous, friendly notes (similar to Day 12) inside notebooks and greeting cards at a stationary shop for people to find unexpectedly.