Beneath rolling storm clouds and a spattering of spring rain, about two dozen people holding blue and white signs march in front of Harvard University’s Science Center. Circling around a young woman holding a megaphone, their chants ricochet off stately brick buildings dotting the campus. The woman in the middle shouts: “What’s outrageous?”  “Harvard’s wages!” the crowd replies. Why We Wrote This Harvard University’s graduate student union went on strike this week to demand higher wages for all graduate student workers and more protections for immigrant student workers. The university has countered with an offer to raise salaries more modestly. These protesters are among more than 4,000 graduate student workers at Harvard who began a strike this week, walking off campus jobs where they teach classes, grade papers, and conduct research that has long placed the school among the world’s top universities.…