I was flying out of Sterling Mass. We found some wave about 5 miles south of an inbound to Boston airway. At around 13k we could see the inbound traffic to our north. I was next to another glider when I saw him do a mild wingover to the left. Thinking, gee, you don't usually see gliders do acrobatics in wave. I watched him jog to the left when and I turned my gaze back to the west, I was looking right down two engines attached to an RJ. It looked like I might be seeing a bit of the bottom of the fuselage, so I pushed over, and literally closed my eyes. I never heard them, but there could not have been much room. After i gathered my thoughts, I called Boston Center to tell them gliders were flying between 9 and 14,000 ft. The rather terse reply was "We Know"...

I went home and bought a pcas. Now I fly with a transponder and ADS-B out.