Harold Grinspoon worries Jewish culture in the US is fighting a losing battle against assimilation. So, the former real estate titan and philanthropist gathers Jewish thinkers and other donors in Aspen every year to envision… as he calls it… “the Jewish future.” But they don’t meet in a hotel or events center. They hike and bike and talk outdoors. The annual gathering’s happening in Aspen this week. Ryan Warner talks with Harold Grinspoon.