What are the potential challenges of achieving zetascale computing?

[a_potato]

So exascale is going to be predominantly a power issue. What about the zeta scale platform? What kind of new and unique issues are we going to come across
At that point?

 

[mfb]

Conventional silicon will certainly get problems - it might be possible to go to 5 nanometers, that allows at most 10 times more transistors per area compared to commercial 14nm. Not enough. Using 100 times the silicon area doesn't look like a good solution. Also, power requirements become even more problematic. No one wants to have a supercomputer that needs its own nuclear power plant nearby.

Other technologies: depends on the technology?