What can be reasonably said for artificial intelligence is that within a few years computers will outperform the computational capacities of the human brain. The brain's advantage of using very small memory units is now being superseded by chip technology that is driving the component size down to dimensions of only a couple of molecules. The brain's remaining advantage of organizational efficiency may soon be approached by customized parallel processors' delegating to several computers the solution of various aspects of a problem. However, as Penrose reminds us, limits do exist. In the case of the hardware, it is impossible to make computer components any smaller than a molecule's thickness.
Signals can travel no faster than the velocity of light.
Only so much efficiency can be achieved through parallel processing. Software limits exist as well. The brilliance of a program is limited by the brilliance of the human programmer. The realistic claims of artificial intelligence apply to computational power. This simply means that one day a computer will beat the world chess champion, that computers will one day answer questions too difficult and complex for a human think tank.