Quantum computers offer great promise for cryptography and optimization problems. ZDNet explores what quantum computers will and won't be able to do, and the challenges we still face. In 1936, some 2.4 million members of the Literary Digest magazine's mailing list responded to its publisher by mail, in the broadest presidential candidates' opinion poll conducted in the United States to that time. By a margin of 57 to 43, those readers reported they favored the Republican governor of Kansas, Alf Landon, over the incumbent Democrat, Franklin D. Roosevelt. The week after the election, the magazine's cover announced in bold, black letters the message, "Is Our Face Red!" Also: Could quantum computers fix political polls? The following January, Oxford University's Public Opinion Quarterly published an essay that examined how a seemingly much smaller survey of only 50,000 participants, conducted by a fellow named George Gallup, yielded a far more accurate result than did Literary Digest. Gallup's poll was "scientific," and Oxford wanted to explain what that meant, and why opinion polling deserved that lofty moniker. For the first time, the Oxford publication explained a concept called selection bias. Specifically, if you don't ask people for enough facts about themselves, you never attain the information you need to estimate whether the people around them think and act in similar ways.