One source of concern is that a sudden and unexpected "intelligence explosion" might take an unprepared human race by surprise. In one scenario, the first computer program found able to broadly match the effectiveness of an AI researcher is able to rewrite its algorithms and double its speed or capabilities in six months of massively parallel processing time. The second-generation program is expected to take three months to perform a similar chunk of work, on average; in practice, doubling its own capabilities may take longer if it experiences a mini-"AI winter", or may be quicker if it undergoes a miniature "AI Spring" where ideas from the previous generation are especially easy to mutate into the next generation.