TG: Do you feel that in 50 years, we’ll be closer to having some kind of unified theory that incorporates all the forces?

DG: Currently, I spend part of my time trying to tell people … that the chances of you living 50 [more] years are very small.
Due to the danger of nuclear war, you have about 35 years.

TG: Why do you think that we’ll blow ourselves up, essentially, within 35 years, give or take?

DG: So it’s a crude estimate. Even after the Cold War ended, [when] we had strategic arms control treaties, all of which have disappeared, there were estimates there was a 1% chance of nuclear war [every year]. Things have gotten so much worse in the last 30 years, as you can see every time you read the newspaper. I feel it’s not a rigorous estimate, that the chances are more likely 2%. So that’s a 1-in-50 chance every year. The expected lifetime, in the case of 2% [per year], is about 35 years. [The expected lifetime is the average time it would take to have had a nuclear war by then. It is calculated using similar equations as those used to determine the “half-life” of a radioactive material.]

TG: So what do you suggest as remedies to lower that risk?

DG: We had something called the Nobel Laureate Assembly for reducing the risk of nuclear war in Chicago last year.
There are steps, which are easy to take — for nations, I mean. For example, talk to each other.
In the last 10 years, there are no treaties anymore. We’re entering an incredible arms race. We have three super nuclear powers.
People are talking about using nuclear weapons; there’s a major war going on in the middle of Europe; we’re bombing Iran; India and Pakistan almost went to war.
OK, so that’s increased the chance [of nuclear war]. I would really like to have a solid estimate — it might be more, and I think I’m being conservative — but a 2% estimate [of nuclear war] in today’s crazy world.

TG: Do you think we’ll ever get to a place where we get rid of nuclear weapons?

DG: We’re not recommending that. That’s idealistic, but yes, I hope so. Because if you don’t, there’s always some risk an AI 100 years from now [could launch nuclear weapons], but chances of [humanity] living, with this estimate, 100 years, is very small, and living 200 years is infinitesimal.
So [the answer to] Fermi’s question of “Where are the civilizations, all the intelligent organisms around the galaxy, and why don’t they talk to us?” is that they’ve killed themselves.
You asked me to think about the future, and I am obsessed the last few years, thinking about that ‪—‬ not the future of ideas and understanding nature, but of the survival of humanity.

TG: I think in some ways, during the Cold War, it was easier for people to conceptualize because we had one major enemy. Now there’s chaotic interactions between countries.

DG: There are now nine nuclear powers. Even three is infinitely more complicated than two. The agreements, the norms between countries, are all falling apart. Weapons are getting crazier. Automation, and perhaps even AI, will be in control of those instruments pretty soon.

TG: That scares me too ‪—‬ that a lot of weapons are using AI systems to make decisions on some level.

DG: It’s going to be very hard to resist making AI make decisions because it acts so fast. If you have 20 minutes to decide whether to send a few hundred nuclear armed missiles to both China and Russia for “our dear president,” the military might feel that it’s wiser to make AI make that decision. But if you play with AI, you know that it sometimes hallucinates.

TG: The problem feels too big for ordinary people to do anything about, which is the same thing with climate change, right?

DG: People have done something about climate. So that’s something scientists began to warn people about 40 years ago. And they convinced people that’s a real danger.
It’s a much harder argument to make than about nuclear weapons.
We made them; we can stop them.