Lily Tomlin canceled the opening night of her show, “The Search for Signs of Intelligent Life in the Universe,” in Chicago on Tuesday, 50 minutes after she began. Tomlin broke out of character and apologized to the crowd, saying her throat problem probably stemmed from a Labor Day sail on Lake Michigan. “It was a big mistake but you have such a beautiful lake here,” she said. “If I hadn’t thought I could get through it, I wouldn’t have started. But the problem is: How do I get you all back here? Maybe I could come to all your homes.” Before going off, Tomlin lamented, “Oh, this will probably be the end of my career,” but the crowd gave a warm ovation anyway. Wednesday night’s show also was canceled.