Tim Urban at Wait But Why (highly recommended blog) recently published a 2-parts article series on Artificial Intelligence and its possible consequences for humankind:
This pattern—human progress moving quicker and quicker as time goes on—is what futurist Ray Kurzweil calls human history’s Law of Accelerating Returns. This happens because more advanced societies have the ability to progress at a faster rate than less advanced societies—because they’re more advanced. [...] So—advances are getting bigger and bigger and happening more and more quickly. This suggests some pretty intense things about our future, right?
The second article takes things further still:
To absorb how big a deal a superintelligent machine would be, imagine one on the dark green step two steps above humans on that staircase. This machine would be only slightly superintelligent, but its increased cognitive ability over us would be as vast as the chimp-human gap we just described. And like the chimp’s incapacity to ever absorb that skyscrapers can be built, we will never be able to even comprehend the things a machine on the dark green step can do, even if the machine tried to explain it to us—let alone do it ourselves. [...] But the kind of superintelligence we’re talking about today is something far beyond anything on this staircase. In an intelligence explosion—where the smarter a machine gets, the quicker it’s able to increase its own intelligence, until it begins to soar upwards.
If you don't trust my advice, maybe you'll trust Elon Musk's?