AI Timelines: What Do Experts in Artificial Intelligence Expect for the Future?

Artificial intelligence that surpasses our own intelligence sounds like the stuff from science fiction books or films. What do experts in the field of AI research think about such scenarios? Do they dismiss these ideas as fantasy, or are they taking such prospects seriously? A human-level AI would be a machine, or a network of machines, capable of carrying out the same range of tasks that we humans are capable of. It would be a machine that is "able to learn to do anything that a human can do," as Norvig and Russell put it in their textbook on AI.1 It would be able to choose actions that allow the machine to achieve its goals and then carry out those actions.