Robert, left, and Michael Rosenberg in June 1953. Fifty years ago Thursday, Julius and Ethel Rosenberg were executed in the electric chair at Sing Sing. Their execution, originally set for 11 p.m. on Friday, June 19, 1953, was rescheduled for 8 p.m. to avoid conflict with the Jewish sabbath. "They were to be killed more quickly than planned," the playwright Arthur Miller wrote, "to avoid any shadow of bad taste." A shadow lingers. "I grew up believing Ethel and Julius were completely innocent," Robert Meeropol, who was 6 years old in 1953, says of the Rosenbergs, his parents. "By the...