Even in my most religious moments, I have never been able to take the idea of hell seriously. Prevailing Christian theology asks us to believe that an all-powerful, all-knowing being would do what no human parent could ever do: create tens of billions of flawed and fragile creatures, pluck out a few favourites to shower in transcendent love, and send the rest to an eternity of unrelenting torment. That story has always seemed like an intellectual relic to me, a holdover from barbarism, or worse, a myth meant to coerce belief. But stripped of the religious particulars, I can see the appeal of hell as an instrument of justice, a way of righting wrongs beyond the grave. Especially in unusual circumstances.

Take the case of Adolf Hitler. On the afternoon of 29 April 1945, Hitler was stashed deep in his Berlin bunker, watching his Third Reich collapse, when he received word that Benito Mussolini was dead. Hitler was aghast at the news, not because he’d lost yet another ally, but because of the way Mussolini had died. The Italian dictator had been trying to slink into Switzerland when he was caught, shot, and dragged to a public square in Milan, where a furious mob kicked and spat on his body, before hanging it upside down on a meat hook.

Worried that he might meet a similar fate, Hitler decided to test the strength of his cyanide capsules by feeding a few of them to his dog, Blondie. By midafternoon on the following day, 30 April, the Red Army was rampaging through Berlin, and the Fuhrer’s empire had shrunk to a small island of land in the city centre. Rather than fight to the end and risk capture, Hitler bit into one of his cyanide pills, and fired a bullet into his head for good measure. When the Soviets reached the bunker two days later, his body had been burned and his ashes buried, in a shallow bomb crater just above ground.

It is hard to avoid the conclusion that Hitler got off easy, given the scope and viciousness of his crimes. We might have moved beyond the Code of Hammurabi and ‘an eye for an eye’, but most of us still feel that a killer of millions deserves something sterner than a quick and painless suicide. But does anyone ever deserve hell?

That used to be a question for theologians, but in the age of human enhancement, a new set of thinkers is taking it up. As biotech companies pour billions into life extension technologies, some have suggested that our cruelest criminals could be kept alive indefinitely, to serve sentences spanning millennia or longer. Even without life extension, private prison firms could one day develop drugs that make time pass more slowly, so that an inmate’s 10-year sentence feels like an eternity. One way or another, humans could soon be in a position to create an artificial hell.

At the University of Oxford, a team of scholars led by the philosopher Rebecca Roache has begun thinking about the ways futuristic technologies might transform punishment. In January, I spoke with Roache and her colleagues Anders Sandberg and Hannah Maslen about emotional enhancement, ‘supercrimes’, and the ethics of eternal damnation. What follows is a condensed and edited transcript of our conversation.

Suppose we develop the ability to radically expand the human lifespan, so that people are regularly living for more than 500 years. Would that allow judges to fit punishments to crimes more precisely?

Roache: When I began researching this topic, I was thinking a lot about Daniel Pelka, a four-year-old boy who was starved and beaten to death [in 2012] by his mother and stepfather here in the UK. I had wondered whether the best way to achieve justice in cases like that was to prolong death as long as possible. Some crimes are so bad they require a really long period of punishment, and a lot of people seem to get out of that punishment by dying. And so I thought, why not make prison sentences for particularly odious criminals worse by extending their lives?

But I soon realised it’s not that simple. In the US, for instance, the vast majority of people on death row appeal to have their sentences reduced to life imprisonment. That suggests that a quick stint in prison followed by death is seen as a worse fate than a long prison sentence. And so, if you extend the life of a prisoner to give them a longer sentence, you might end up giving them a more lenient punishment.

The life-extension scenario may sound futuristic, but if you look closely you can already see it in action, as people begin to live longer lives than before. If you look at the enormous prison population in the US, you find an astronomical number of elderly prisoners, including quite a few with pacemakers. When I went digging around in medical journals, I found all these interesting papers about the treatment of pacemaker patients in prison.

Suppose prisons become more humane in the future, so that they resemble Norwegian prisons instead of those you see in America or North Korea. Is it possible that correctional facilities could become truly correctional in the age of long lifespans, by taking a more sustained approach to rehabilitation?

Roache: If people could live for centuries or millennia, you would obviously have more time to reform them, but you would also run into a tricky philosophical issue having to do with personal identity. A lot of philosophers who have written about personal identity wonder whether identity can be sustained over an extremely long lifespan. Even if your body makes it to 1,000 years, the thinking goes, that body is actually inhabited by a succession of persons over time rather than a single continuous person. And so, if you put someone in prison for a crime they committed at 40, they might, strictly speaking, be an entirely different person at 940. And that means you are effectively punishing one person for a crime committed by someone else. Most of us would think that unjust.

Let’s say that life expansion therapies become a normal part of the human condition, so that it’s not just elites who have access to them, it’s everyone. At what point would it become unethical to withhold these therapies from prisoners?

Roache: In that situation it would probably be inappropriate to view them as an enhancement, or something extra. If these therapies were truly universal, it’s more likely that people would come to think of them as life-saving technologies. And if you withheld them from prisoners in that scenario, you would effectively be denying them medical treatment, and today we consider that inhumane. My personal suspicion is that once life extension becomes more or less universal, people will begin to see it as a positive right, like health care in most industrialised nations today. Indeed, it’s interesting to note that in the US, prisoners sometimes receive better health care than uninsured people. You have to wonder about the incentives a system like that creates.

Where is that threshold of universality, where access to something becomes a positive right? Do we have an empirical example of it?

Roache: One interesting case might be internet access. In Finland, for instance, access to communication technology is considered a human right and handwritten letters are not sufficient to satisfy it. Finnish prisons are required to give inmates access to computers, although their internet activity is closely monitored. This is an interesting development because, for years, limiting access to computers was a common condition of probation in hacking cases – and that meant all kinds of computers, including ATMs [cash points]. In the 1980s, that lifestyle might have been possible, and you could also see pulling it off in the ’90s, though it would have been very difficult. But today computers are ubiquitous, and a normal life seems impossible without them; you can’t even access the subway without interacting with a computer of some sort.

In the late 1990s, an American hacker named Kevin Mitnick was denied all access to communication technology after law enforcement officials [in California] claimed he could ‘start a nuclear war by whistling into a pay phone’. But in the end, he got the ruling overturned by arguing that it prevented him from living a normal life.

What about life expansion that meddles with a person’s perception of time? Take someone convicted of a heinous crime, like the torture and murder of a child. Would it be unethical to tinker with the brain so that this person experiences a 1,000-year jail sentence in his or her mind?

Roache: There are a number of psychoactive drugs that distort people’s sense of time, so you could imagine developing a pill or a liquid that made someone feel like they were serving a 1,000-year sentence. Of course, there is a widely held view that any amount of tinkering with a person’s brain is unacceptably invasive. But you might not need to interfere with the brain directly. There is a long history of using the prison environment itself to affect prisoners’ subjective experience. During the Spanish Civil War [in the 1930s] there was actually a prison where modern art was used to make the environment aesthetically unpleasant. Also, prison cells themselves have been designed to make them more claustrophobic, and some prison beds are specifically made to be uncomfortable.

I haven’t found any specific cases of time dilation being used in prisons, but time distortion is a technique that is sometimes used in interrogation, where people are exposed to constant light, or unusual light fluctuations, so that they can’t tell what time of day it is. But in that case it’s not being used as a punishment, per se, it’s being used to break people’s sense of reality so that they become more dependent on the interrogator, and more pliable as a result. In that sense, a time-slowing pill would be a pretty radical innovation in the history of penal technology.

I want to ask you a question that has some crossover with theological debates about hell. Suppose we eventually learn to put off death indefinitely, and that we extend this treatment to prisoners. Is there any crime that would justify eternal imprisonment? Take Hitler as a test case. Say the Soviets had gotten to the bunker before he killed himself, and say capital punishment was out of the question – would we have put him behind bars forever?

Roache: It’s tough to say. If you start out with the premise that a punishment should be proportional to the crime, it’s difficult to think of a crime that could justify eternal imprisonment. You could imagine giving Hitler one term of life imprisonment for every person killed in the Second World War. That would make for quite a long sentence, but it would still be finite. The endangerment of mankind as a whole might qualify as a sufficiently serious crime to warrant it. As you know, a great deal of the research we do here at the Oxford Martin School concerns existential risk. Suppose there was some physics experiment that stood a decent chance of generating a black hole that could destroy the planet and all future generations. If someone deliberately set up an experiment like that, I could see that being the kind of supercrime that would justify an eternal sentence.

In your forthcoming paper on this subject, you mention the possibility that convicts with a neurologically stunted capacity for empathy might one day be ‘emotionally enhanced’, and that the remorse felt by these newly empathetic criminals could be the toughest form of punishment around. Do you think a full moral reckoning with an awful crime the most potent form of suffering an individual can endure?

Roache: I’m not sure. Obviously, it’s an empirical question as to which feels worse, genuine remorse or time in prison. There is certainly reason to take the claim seriously. For instance, in literature and folk wisdom, you often hear people saying things like, ‘The worst thing is I’ll have to live with myself.’ My own intuition is that for very serious crimes, genuine remorse could be subjectively worse than a prison sentence. But I doubt that’s the case for less serious crimes, where remorse isn’t even necessarily appropriate – like if you are wailing and beating yourself up for stealing a candy bar or something like that.

I remember watching a movie in school, about a teen that killed another teen in a drunk-driving accident. As one of the conditions of his probation, the judge in the case required him to mail a daily cheque for 25 cents to the parents of the teen he’d killed for a period of 10 years. Two years in, the teen was begging the judge to throw him in jail, just to avoid the daily reminder.

Roache: That’s an interesting case where prison is actually an escape from remorse, which is strange because one of the justifications for prison is that it’s supposed to focus your mind on what you have done wrong. Presumably, every day you wake up in prison, you ask yourself why you are there, right?

What if these emotional enhancements proved too effective? Suppose they are so powerful, they turn psychopaths into Zen masters who live in a constant state of deep, reflective contentment. Should that trouble us? Is mental suffering a necessary component of imprisonment?

Roache: There is a long-standing philosophical question as to how bad the prison experience should be. Retributivists, those who think the point of prisons is to punish, tend to think that it should be quite unpleasant, whereas consequentialists tend to be more concerned with a prison’s reformative effects, and its larger social costs. There are a number of prisons that offer prisoners constructive activities to participate in, including sports leagues, art classes, and even yoga. That practice seems to reflect the view that confinement, or the deprivation of liberty, is itself enough of a punishment. Of course, even for consequentialists, there has to be some level of suffering involved in punishment, because consequentialists are very concerned about deterrence.

I wanted to close by moving beyond imprisonment, to ask you about the future of punishment more broadly. Are there any alternative punishments that technology might enable, and that you can see on the horizon now? What surprising things might we see down the line?

Roache: We have been thinking a lot about surveillance and punishment lately. Already, we see governments using ankle bracelets to track people in various ways, and many of them are fairly elaborate. For instance, some of these devices allow you to commute to work, but they also give you a curfew and keep a close eye on your location. You can imagine this being refined further, so that your ankle bracelet bans you from entering establishments that sell alcohol. This could be used to punish people who happen to like going to pubs, or it could be used to reform severe alcoholics. Either way, technologies of this sort seem to be edging up to a level of behaviour control that makes some people uneasy, due to questions about personal autonomy.

It’s one thing to lose your personal liberty as a result of being confined in a prison, but you are still allowed to believe whatever you want while you are in there. In the UK, for instance, you cannot withhold religious manuscripts from a prisoner unless you have a very good reason. These concerns about autonomy become particularly potent when you start talking about brain implants that could potentially control behaviour directly. The classic example is Robert G Heath [a psychiatrist at Tulane University in New Orleans], who did this famously creepy experiment [in the 1950s] using electrodes in the brain in an attempt to modify behaviour in people who were prone to violent psychosis. The electrodes were ostensibly being used to treat the patients, but he was also, rather gleefully, trying to move them in a socially approved direction. You can really see that in his infamous [1972] paper on ‘curing’ homosexuals. I think most Western societies would say ‘no thanks’ to that kind of punishment.

To me, these questions about technology are interesting because they force us to rethink the truisms we currently hold about punishment. When we ask ourselves whether it’s inhumane to inflict a certain technology on someone, we have to make sure it’s not just the unfamiliarity that spooks us. And more importantly, we have to ask ourselves whether punishments like imprisonment are only considered humane because they are familiar, because we’ve all grown up in a world where imprisonment is what happens to people who commit crimes. Is it really OK to lock someone up for the best part of the only life they will ever have, or might it be more humane to tinker with their brains and set them free? When we ask that question, the goal isn’t simply to imagine a bunch of futuristic punishments – the goal is to look at today’s punishments through the lens of the future.