He defended his thesis on Friday and it was the best day. At one point during his defense, I was so proud of Mark that my heart felt like it was about to jump right out of my chest. There he was, talking knowledgeably about restricted isometry property, sub-Gaussian random variables and oracle bounds ... and I couldn't keep the big, goofy grin off my face.
We ended the afternoon with friends and cheap champagne at Valhalla (a tradition for newly minted Rice Ph.D.'s). Mark's parents treated us to a fantastic dinner, where we toasted Mark and the culmination of 6 years of hard work. 6 years of grad school! End of an era.