Via Arnold Kling, here is a long symposium (a good time waster), from all the names you would expect to contribute to such a symposium, plus Eric Fischl and Brian Eno. Here is Anton Zeitlinger’s offering:
Some day all semiconductors will break down and therefore all
computers as, besides historic instruments no computers exist today
which are nor based on semiconductor technology. The breakdown will be
caused by a giant electromagnetic pulse (EMP) created by a nucler
explosion outside Earth’s athmosphere. It will cover large areas on
Earth up to the size of a continent. Where it will happen is
unpredictable. But it will happen since it is extremely unlikely that
we will be able to get rid of all nuclear weapons and the probability
for it to happen at any given time will never be zero.
implications of such an event will be enormous. If it happens to one of
our technology based societies literally everything will break down.
You will realize that none your phones does work. There is no way to
find out via the internet what happened. Your car will not start
anymore as it is also controlled by computer chips, unless you are
lucky to own an antique car. Your local supermarket is unable to get
new supplies.There will be no trucks operating anymore, no trains, no
elctricity, no water supplies Society will completely break down.
I worry about that too. A lot of the answers consider nuclear bombs exploding, reengineering the human body, and nanotechnology.