I'm 62, so I'll have to limit my projections to what I expect to happen in the next two to three decades. I believe these will be the most interesting times in human history (Remember the old Chinese curse about "interesting times?") Humanity will see, before I die, the "Singularity," the day when we finally create a human level artificial intelligence. This involves considering the physics advances that will be required to create the computer that is capable of running a strong AI program.
Although by both my calculations and those of Ray Kurzweil (originator of the "Singularity" idea), the 10 teraflop speed of today's supercomputers have more than enough computing power to run a minimum AI program, we are missing some crucial idea in this program. Conway's Game of Life has been proven to be a universal program, capable of expressing a strong AI program, and it should therefore be capable, if allowed to run long enough, of bootstrapping itself into the complexity of human level intelligence. But Game of Life programs do no do so. They increase their complexity just so far, and then stop. Why, we don't know. As I said, we are missing something, and what we are missing is the key to human creativity.
But an AI program can be generated by brute force. We can map an entire human personality, together with a simulated environment into a program, and run this. Such a program would be roughly equivalent to the program being run in the movie The Matrix, and it would require enormous computing power, power far beyond today's supercomputers. The power required can only be provided by a quantum computer.
A quantum computer works by parallel processing across the multiverse. That is, part of the computation is done in this universe by you and your part of the quantum computer, and the other parts of the computation are done by your analogues with their parts of the computer in the other universes of the multiverse. The full potential of the quantum computer has not been realized because the existence of the multiverse has not yet been accepted, even by workers in the field of quantum computation, in spite of the fact that the multiverse's existence is required by quantum mechanics, and by classical mechanics in its most powerful form, Hamilton-Jacobi theory.
Other new technologies become possible via action across the multiverse. For example, the Standard Model of particle physics, the theory of all forces and particles except gravity, a theory confirmed by many experiments done over the past forty years, tells us that it is possible to transcend the laws of conservation of baryon number (number of protons plus neutrons) and conservation of lepton number (number of electrons plus neutrinos) and thereby convert matter into energy in a process far more efficient that nuclear fission or fusion. According to the Standard Model, the proton and electron making up a hydrogen atom can be combined to yield pure energy in the form of photons, or neutrino-anti-neutrino pairs. If the former, then we would have a mechanism that would allow us to convert garbage into energy, a device Doc in the movie Back to the Future obtained from his trip to the future. If the latter, then the directed neutrino-anti-neutrino beam would provide the ultimate rocket: the exhaust would be completely invisible to those nearby, just as the propulsion mechanism that Doc also obtained from the future. The movie writers got it right, Doc's future devices are indeed in our future.
Quantum computer running an AI program, direct conversion of matter into energy, the ultimate rocket that would allow the AI's and the human downloads to begin interstellar travel at near light speed, depend on the same physics, and should appear at the same time in the future.
Provided we have the courage to develop the technology allowed by the known laws of physics. I have grave doubts that we will.
In order to have advances in physics and engineering, one must first have physicists and engineers. The number of students majoring in these subjects has dropped enormously in the quarter century that I have been a professor. Worse, the quality of the few students we do have has dropped precipitously. The next decade will see the retirement of Stephen Hawking, and others less well-known but of similar ability, but I know of no one of remotely equal creativity to replace them. Small wonder, given that the starting salary of a Wall Street lawyer fresh out of school is currently three times my own physicist's salary. As a result, most American engineers and physicists are now foreign born.
But can foreign countries continue to supply engineers and physicists? That is, will engineers and physicists be available in any country? The birth rate of the vast majority of the developed nations has been far below replacement level for a decade and more. This birth dearth also holds for China, due to their one-child policy, and remarkably is developing even in the Muslim and southern nations. We may not have enough people in the next twenty years to sustain the technology we already have, to say nothing of developing the technology allowed by the known laws of physics that I describe above.
The great Galileo scholar Giorgio de Santillana, who taught me history of science when I was an undergraduate at MIT in the late 1960's, wrote that Greek scientific development ended in the century or so before the Christian era because of a birth dearth and a simultaneous bureaucratization of intellectual inquiry. I fear we are seeing a repeat of this historical catastrophe today.
However, I remain cautiously optimistic that we will develop the ultimate technology described above, and transfer it with faltering hands to our ultimate successors, the AI's and the human downloads, who will be thus enabled to expand outward into interstellar space, engulf the universe, and live forever.