There are some problems that technology can't solve.

It’s unlikely that any of those natural hazards will do us in within the next 100 years if we’ve already survived 100,000. By contrast, we are introducing, through human activity, entirely new types of dangers by developing powerful new technologies. We have no record of surviving those.

How can we trace out the links between actions that people take today and really long-term outcomes for humanity - outcomes that stretch out indefinitely into the future? I call this effort macrostrategy - that is, to think about the really big strategic situation for having a positive impact on the long-term future. There's the butterfly effect: A small change in an initial condition could have arbitrarily large consequences.

For healthy adult people, the really big thing we can foresee are ways of intervening in the ageing process, either by slowing or reversing it.

Are you living in a computer simulation?

The challenge presented by the prospect of superintelligence, and how we might best respond is quite possibly the most important and most daunting challenge humanity has ever faced. And-whether we succeed or fail-it is probably the last challenge we will ever face.

The Internet is a big boon to academic research. Gone are the days spent in dusty library stacks digging for journal articles. Many articles are available free to the public in open-access journal or as preprints on the authors' website.