Stephen Perrenod holds Ph.D. and Master's degrees in Astronomy from Harvard University and a Bachelor's in Physics from M.I.T. His primary research focus was on the cosmological evolution of X-ray emitting clusters of galaxies. After several years as a postdoctoral researcher in astrophysics he moved into the High Performance Computing field, where he has worked for over a quarter century. He has been a frequent public speaker on HPC, Grid and Cloud computing topics. When he was active in astrophysics in the 1970s, the cosmological constant - which now is of such great significance - was usually dismissed as unlikely to have a non-zero value.