I do worry about whether we will get through this century without severe setbacks.  I think there are two different classes of risk we need to worry about.  The first is the category which we are imposing collectively because there are more of us on this planet, a growing population, and each of us is more demanding of energy and resources.  There are now nearly seven-and-a-half billion people on the planet; there will be nine billion by mid-century.  We’re not sure what will happen after that; it could go up even more.  But also, we’ll all be more demanding in terms of energy and resources. And of course, we hope that the developing world will close the gap with more fortunate countries like ours, and that will, of course, increase the pressure on energy and resources.  So there’s a risk that this is going to lead to despoliation of the environment —  climate change; it could have severe long-term effects — and to disruption of ecologies, leading to mass extinctions.  And of course, those will be irreversible degradations of our environment.  So we will not be leaving an environment for future generations as good as the one we inherited.  So that’s a serious concern, our collective effects.

There’s a different kind of concern which also worries me, which is that because of powerful technologies, in particular biotech and cybertech and AI, individuals are much more empowered than they were in the past.  That, therefore, means that an individual or a small group can, by error or by design, have a consequence, a damaging consequence, that could cascade globally.  I like to say that the global village will have its village idiots, but they will now have a global range.  And this is something which worries me very much.  The new technologies are very exciting, and of course, we depend on new technology in order to feed nine billion people and to provide a good life for them all.  So we don’t want to slow down technology. But we do want to redirect it and control it if we can, so as to minimize these serious risks because we are in an interconnected world where a disaster in one region will cascade around the world.  No part of the world is isolated from what happens elsewhere now.  So we need to be very concerned, and that is why I do worry about how we will get through this century without severe setbacks.

Martin Rees:  I think climate change raises special problems because, first of all, the science is still rather uncertain.  Everyone agrees that the temperature on average is going up and that, more importantly, that rise in temperature is going to trigger a big global change in weather patterns, The regions where you have the monsoons, where you have droughts, et cetera, will change.  And this will be a disruptive effect on the climate, far more rapid than any natural changes in climate that have happened in the past.  But, of course, these timescales, although very short in an astronomical context, are long in a political context, and we’re talking about what will happen in the next few decades and what might make the lives of people now just born — who will be alive in the 22nd century — worse than they are now.

And it’s very hard to persuade politicians to do something now which will not benefit the here and now — between now and the next election — but will have an effect on the lives of children now born who will be alive at the end of the century, and also on the lives of people in the low parts of the world, who will be more affected than we are in Europe and North America.

So that’s why it’s difficult to deal with because, obviously, the focus of most action is the urgent and the parochial rather than the long-term.  And for that reason, I think it’s very hard to keep dealing with climate change high on the agenda.  I personally think we should be prepared to pay an insurance premium now, as it were, to remove a potentially serious risk from the lives of future generations.  But it’s hard to make that point.  We’ve got to think of ways in which we can keep that on the agenda.

One policy which I think we can realistically adopt and get countries to accept is to pursue accelerated research and development into all forms of carbon-free energy because those involve exciting new technology and give a boost to the nation that develops them first.  And the faster the development proceeds, the sooner will the cost come down.  So, for instance, India — which clearly needs to have new sources of power to replace stoves burning wood and dung, which is hugely damaging environmentally — they’ll be able to afford clean energy and not build coal-fired power stations.  So we’ve got to accelerate the R&D so that clean energy is as cheap as coal-fired power stations.  And then, without any further incentive, India and other countries will go directly to clean energy, leapfrogging the phase when they have huge fossil-fuel power stations.  So developing clean energy as quickly as possible is a sort of win-win situation for the world.  So that should be our priority.  And the amount of R&D in those areas is very small compared to defense R&D, for instance, and medical R&D. And why shouldn’t it be comparable?  Indeed, I would say that one of the most inspirational goals for young engineers should be to provide clean and affordable energy for the developing, as well as the developed, world.  That would be a very exciting development.

The other thing we can do is really to persuade politicians that they should think about long-term questions.  And they will only do this if the public persuades them it’s important.  And here, I think the great religions of the world are important.  And I would cite as an example the papal encyclical in the summer of 2015, which was a very clear statement about the risks to the natural environment caused by climate change.  The Pope declared far more clearly than his predecessors that humans have an obligation to the nonhuman world and the rest of God’s creation, as it were. And this, I think, had a big effect in forging a consensus at the climate change conference in Paris in December 2015.  And the reason for that was that, whatever one thinks of the Catholic Church, no one can doubt its long-term vision, its global reach, and its concern with the world’s poor.  Therefore, that had a big effect.  Politicians don’t listen just to experts.  In fact, I know many people who have been political advisers and have been frustrated that the politicians don’t pay much attention to them because they have more urgent issues.  But they do pay attention to what’s in the press and what’s in their inbox.  So if one can ensure that these issues, like climate change, are more prominent in the public consciousness — and therefore in the press and their inboxes — then they will pay regard to them.  And the intervention of the Pope did have such an effect.  It had a global effect.  He got a standing ovation at the UN.  It really had a big effect on opinion in Latin America, both among the public and political leaders, and in Africa and in East Asia — sadly, not much in the American Republican Party, but certainly around the rest of the world.

Martin Rees:  So let’s suppose astronomers had found evidence that there was an asteroid heading for the earth and that we calculated it might hit the earth in 2100. That’s 83 years from now.  And suppose we could say that with ten percent confidence, not with certainty.  What would the reaction of the public be?  Would we say, “Well, in 50 years’ time, we’ll have better technology to deal with it.  It may miss us anyway, so let’s do nothing now.”  I don’t think we would.  I think if that were the case, we would do our damnedest, starting now, to see what we could do to make sure that we could somehow deflect it or minimize its impact.   And here’s the analogy with climate change because in the context of our knowledge of climate change now, we can say that there is a ten percent chance that by the year 2100, climate change will have triggered irreversible tipping points, rather like the melting of Greenland’s ice, which would eventually raise sea level by about seven or eight meters and also cause huge global changes in climate.  We can’t be sure, but that’s likely.  My view is that we should already be prepared to pay the insurance premium to reduce that risk now.  We shouldn’t say, “Well, 50 years from now, people will be richer and they will have better technology. Let’s leave it to them.”  We should start now.  And I think the analogue of the asteroid indicates that it is worth paying an insurance premium now to eliminate a risk, even if it’s an uncertain risk.  We shouldn’t just say it may not happen.  We shouldn’t say that they can deal with it better in 50 years than we can now.  We should already start to see what we can do about it.

Martin Rees: Cyber attacks are becoming very, very serious, and they’re an example of how just one person can produce a really major disruption by disrupting electric power grids and things like that.  This is a new kind of warfare if nations engage in it, but even an individual could cause pretty serious damage.

And similarly with biothreats — the new techniques, for instance, to make the influenza virus more virulent and more transmissible.  These have been developed in a few years — a few years ago — and in 2014, the American federal government stopped funding research into these because it was thought to be dangerous knowledge and the risk of the virus escaping, et cetera.  So that’s an example where there’s a new technique.  And of course, we’ve got the wonderful new gene-editing technique, CRISPR/Cas9, which has huge benefits but also could have unintended consequences if so-called “gene drive” is used to make species extinct, and that has runaway consequences.  So there’s a big risk with these things.

Now, quite rightly, there are lots of discussions within scientific academies and elsewhere about how to regulate these new technologies — particularly bio — modeled on a famous conference in Asilomar 40 years ago, in the early days of recombinant DNA, when the researchers agreed to a moratorium and to follow certain guidelines.  And in that spirit, there have been, in the last two or three years, similar gatherings of academicians and experts.  But things are different this time. They’re different because far more nations are involved.  It’s far more widespread.  And also, there’s much stronger commercial pressure, which there wasn’t 40 years ago; there was no biotech industry.

And for that reason, I think whatever guidelines we have — and feel should be adopted on prudential or ethical grounds — enforcing them is going to be very hard.  I would say it’s going to be as hopeless to enforce them globally as it is to enforce the drug laws or the tax laws.  We’ve had precious little success in enforcing either of those.  And this I find very scary.

The point is that the equipment that is needed is very modest. Cyber attacks, you just need access to the Internet, and the techniques needed for some of these gene modification techniques are available in university labs and industry, et cetera.  It’s not like nuclear, where you can’t build a nuclear weapon in your garage, but it’s going to be conspicuous, and therefore, it’s feasible to have inspection and monitoring of nuclear developments.  We can’t do that in these cases, and so my worry is whatever can be done in the bio and cyber area will be done somewhere by someone, and I don’t know what we can do to eliminate that risk.

We can certainly try and reduce it, and I think we should focus very hard on ways to reduce it, to have surveillance, et cetera.  Although, there again, there’s going to be tension between security, freedom, and privacy if we want to try and guard against individual lone wolves, as it were, misusing this technology.  But I think it’s something we do need to worry about, and that’s — even on time scales of ten or twenty years — what worries me most.

As to what will happen in the future, we don’t know.  Will it be more organic creatures or not?  I would argue that it will be — not natural selection, Darwinian selection — but it will be a new kind of intelligent design where we humans design future organisms.  Or more likely, in my opinion, where we develop electronic intelligences which may, within a century or so, surpass what humans do.  So it could be that humans are the culmination of organic evolution, but we will jump-start the transition to a new phase of evolution, which will be electronic and entities which have more intelligence, but of course, aren’t biological at all.  As to how this will happen, I actually think it’s going to happen on Mars, not here on the earth.  And the reason I say that is that if we think about space exploration and space travel, then the case for sending people into space is now getting weaker because robots can do all the things that humans did in the past.

These people trying to live on Mars, they’re very ill-adapted.  Humans are very ill-adapted to living in space, especially on Mars.  Gravity is different; there’s no atmosphere, et cetera.  So they’d have every incentive to use all the techniques of cyber and bio to adapt to that alien environment.  And that may involve trying to change and generate intelligent electronic species.  And once you’ve got them, then of course, they don’t want an atmosphere at all.  They may prefer zero-G, and they’ll go off into space, and this will be the start of a post-human era. And of course, if these entities are near immortal, then a long voyage to the stars won’t deter them.  So I think, if you think of the future, then it may be that it’ll be a future of inorganic electronic entities which will spread from our solar system and far beyond in the billions of years that lie ahead.  So I think that’s a potential future.  But we are well-adapted to being on Earth, so we have less incentive to do it.  That’s why I think it’s the crazy adventurers who will be the pioneers of triggering the transition to a new species, as it were.  So that’s why I would cheer them on even if I may not want to join them.

Martin Rees:  Well, of course, the world could end with a bang all too soon, and if that happened, then this would foreclose the billion-year future of post-human evolution.  But of course, what I think is a more plausible scenario is that here on Earth, we will continue as humans, with some setbacks, and with some evolution, but that life will spread beyond the earth.  And that that life spreading beyond the earth will have a future of maybe billions of years, evolving in ways we can’t predict.  And evolving in ways that are not Darwinian selection but intelligent design by the creatures themselves, which will have human intelligence.  So that’s one scenario.  Of course, the other thing which will affect the long-term future is whether there’s life out there already.  Because it’s gratifying, in a way, that even if life was unique to this earth — making our pale blue dot in the cosmos important, not just to us but on a cosmic scale — then that doesn’t mean that life will forever be a sort of minor feature of the galaxy.  It could spread, in its far future, elsewhere.

But of course, one of the fascinating issues for us as astronomers, and indeed for biologists, is to ask, “Is there life out there already?” One of the things we are doing now is understanding the likelihood of life.  And also, can we detect it?

There are some projects now to actually look for any evidence for something artificial out there.  Some artifacts, or some kind of transmission in radio or optical light, which is not natural, which is either something beeping away or some very narrow band signal which can’t be explained naturally.  Because if we could find any evidence for something which was artificial like that, that would be a huge discovery because it would show that concepts of logic and physics weren’t limited to the hardware in human skulls but had emerged somewhere else.  Of course, what is out there, it may not be anything like us. It could be some machine made by some long-dead civilization, which is beeping away or malfunctioning in some way.

I think, even if we detect something which is artificial, it’s most unlikely it’s a message and aimed for us, et cetera, as some science-fiction stories say.  But nonetheless, if we could find anything manifestly artificial out in the cosmos, that would tell us that the cosmos is even more interesting than we think it is because complex evolution would have happened somewhere else.  So that’s why I’m extremely in favor of using all the techniques we now have to look for evidence for something artificial out there, as well as, of course, trying to understand the natural environments, not just on Earth but in the cosmos.