Among the many challenges in the 21st century is one that can pose a huge threat on the political level - the rise of digital dictatorships, argues Israeli historian and author Yuval Noah Harari.
New technologies might tempt various governments across the world to build unprecedented totalitarian regimes that will monitor and control everyone all the time, he claims.
"We have seen one wave of totalitarian regimes in the mid 20th century with Hitler and Stalin and Mao, which eventually receded and most people came to live in much more free societies," he said while delivering the Penguin Annual Lecture here.
According to him, the world might now see another wave of totalitarian regimes, which will be "far worse than anything we've seen in the 20th century because the new totalitarian regimes will have a new technology, which was unavailable to Hitler and Stalin and Mao".
Harari, author of "Sapiens: A Brief History of Humankind" and "Homo Deus: A Brief History of Tomorrow", was speaking on the topic 'Challenges in the 21st Century'.
He fears that technology may be used to hack human beings.
"In order to hack a human being, you need three things, you need a good understanding of biology, especially brain science, you need a lot of data, especially personal data, and you need a lot of computing power," he says.
"To hack humans means to know you better than you know yourself and therefore be able to understand your feelings, predict your choices and manipulate your desires," he explains.
He is also of the view that this power to hack human beings can be used for good purposes.
"It can be used to provide the best healthcare in history. It can be used to advice people how to make better decisions in their career, in their personal lives, but it can also be used for bad purposes, for terrible purposes.
"It can be used to create extreme totalitarian regimes in which all the power is concentrated in the hands of the government or of a small elite, which might not care about anybody else, but which nobody can oppose because if you even start thinking about opposing it they already know it because they can tell what you're thinking," Harari says.
He cites the return of war, ecological collapse and technological disruption as the three main challenges in this century.
He also argues that technology is now upgrading humans into gods. "This is the big story of our era and I mean this in the most literal sense possible. We are now being transformed into gods in the sense that artificial intelligence and biotechnology will soon give us abilities, which ancient mythologies ascribed to the gods, especially the ability to create life."
On AI revolution, Harari says it might also result in the emergence of a massive new class, the un-working class, the useless class.
He feels AI and robotics are likely to change almost every profession.
"Many jobs if not most jobs that people do today might disappear by 2050. Of course as all jobs disappear, new jobs will emerge, but we don't know if enough new jobs will be created and an even bigger problem will be to re-train people fast enough to fill the new job."
He predicts a major revolution by 2025, an even bigger one by 2035 and even bigger one by 2045.
"All jobs will disappear, new jobs will emerge, but very quickly the new jobs will also change advantage. So, to stay in the game, to stay relevant, people will have to re-train and re-invent themselves not just once, but many, many times," he suggests.
(With inputs from agencies.)