(Cross posted from my blog)

Epistemic Status: Unfounded speculation about a far future technology

Would time travel by any other name smell just as sweet? Apparently not, since few people are interested in developing cryonics technology (funny enough, antifreeze does smell sweet). Fundamentally, successful cryonics would offer the ability to travel forward in time, a fact which is often overlooked.

It’s a fascinating idea which would open up a lot of new opportunities. Though there is plenty of debate about whether or not it makes sense to sign up for cryonics, virtually nobody (even the cryonics companies!) discusses the benefits to society if it became viable.

For the purposes of this post, I will define “cryosleep” as both the successful preservation and resurrection of a person. Cryonics today focuses mostly on preservation, and further work is needed to successfully resurrect people.

Imagine if being successfully preserved and resurrected was as safe as driving a car. It would change everything.

Cryosleep would allow people to travel into the future with ease. This is already an amazing benefit, and it is fun to consider how far into the future you might choose to travel.

The other benefits of cryosleep follow from freeing people of the constraint that they must live within a particular time. For example, cryosleep opens up the possibility of interstellar travel without requiring extreme speeds. A person can simply set a course for a distant world, preserve themselves, and wake up when they arrive.

Even on earth, there would be several huge benefits. For one, individuals with terminal illnesses can wait for a life saving therapy to be developed. Anyone can await the development of life extension technologies postponing their death until immortality is invented [1].

People can also wait for better living conditions. Individuals with particular skills can sleep until those skills are in high demand. They can also wait for exciting opportunities to work. One might imagine a great artist waiting to wake up until they are commissioned for a large project. This has the effect of reducing the relative the cost of living, as preservation is cheap and individuals only work when their wages are high [2].

This self-selection has interesting effects on culture. The option to leave your current time period would concentrate productive, happy, and altruistic people in the present [3].

Cryosleep also increases longtermism as many of your loved ones might be under preservation at any given moment and those that are preserved have a direct stake in future success. Ensuring continuous progress becomes more important to everyone. This increases investment in research, far-future technologies, long-term growth, institution-building, x-risk reduction, and space exploration.

Going in hand with the increased investment in progress, cryosleep creates new opportunities for problem solving. We can “save” important minds and set them to tasks they are well suited for. Imagine resurrecting Ramanujan every time we had an interesting math problem to solve. In general, one could imagine arranging different minds through time, coordinating groups of thinkers in different periods. This has the effect of increasing the diversity and number of minds that are part of our civilization.

Cryosleep also offers an alternative to suicide. People who are unhappy with their lives could instead choose cryosleep and jump to a time which better suits them. This would be significantly less damaging than actually committing suicide since loved ones would still have the option of seeing the person who chose cryosleep on occasion.

Another benefit of cryosleep is that it creates the possibility of temporal exit rights since individuals or groups can leave an entire time period they disagree with. This creates new incentives for society as a whole to be accountable to the happiness of its individuals. Imagine if massive numbers of people left society in response to poor management of atmospheric pollution. This would create strong, global incentives to clean up the atmosphere in order to get them to return.

These strange dynamics are just the beginning of what is possible. Cryosleep opens up the possibility of temporally organized societies. For example, one can construct an Archipelago through time where groups rent the same space for different governmental systems at scheduled times, joining or leaving depending on which governments they like. Alternatively, societies might be organized around a single great task, resurrecting people with the relevant skills for each stage.

Though we are far from developing this technology, I find that thinking about how to best organize people through time offers a new lens on policy today. Many policies can be thought of as getting the right people and ideas to the right place (e.g. YIMBY, Open Borders). But what about getting people to the right place at the right time? Not only is it important to allow people to move to the places they will be productive, they also need to concentrate their efforts at a time when it is valuable. This is closely related to economic catalysis, where users, inventors, and managers need to coordinate in time to make a new product. Byrne Hobart argued recently that some tech bubbles have this beneficial coordinating property. But rather than rely on chance, it is worth thinking explicitly on how to solve what I think of as a “time coordination problem”.

Because of this time coordination problem, cryosleep has a dark side. Simply put, it creates opportunities for freeriding on other peoples innovations. Highly selfish or highly optimistic individuals might wait for future breakthroughs, at the cost of slowing current progress. Rather than build a better world, why not wait for one?

Once some people started to leave, others might follow, seeing less opportunity to innovate today. This negative selection process could create problems if left unchecked [4]. Fortunately, I think there are straightforward solutions including Pigouvian taxes on cryosleep and retroactive rewards for inventors.

Another criticism of cryosleep is the possibility that it will be made obsolete by the creation of Em’s which can easily preserve a mind for long periods. Perhaps brain emulations will progress faster than cryosleep research, but it makes little sense to avoid research in one speculative direction in hopes that another speculative direction pans out. Additionally, the fields are complimentary to each other since both study brain structures essential to consciousness. Brain emulations benefit from better brain preservation and from the imaging techniques developed for cryosleep, while people using cryonics today benefit from the creation of Em’s as this is a potential route to resurrection.

Before we spend too much time on the benefits and costs of cryosleep technology, it is important to remember that there are several key barriers to development.

First, we have very little understanding of the brain, which structures are essential to preserve, and how best to preserve them. This will require a lot of fundamental research (though this research will be beneficial for other fields as well).

Second, there are currently no financial structures to incentivize a guardian to make decisions on behalf a preserved person. How should a guardian choose when to reanimate someone? What financial structures need to be designed so that they act in the preserved person’s best interest? Even worse, governments will make decisions that are highly consequential to citizens under preservation, how should they legislate without being able to elicit feedback? I think the counterfactual contracts framework becomes crucial to both problems.

Third and most importantly, there needs to be an ethical way to do trials of resurrection technology as it poses significant risks to subjects. Those that are tested on first have the lowest chance of success, and even a successful reanimation may cause significant amounts of suffering.

Despite these hurdles, I am optimistic that these problems can be solved. If developed, cryosleep opens up fascinating and strange opportunities to travel in space and time and would change the organization of society as we know it.


  1. Beyond medicine, people can simply wait for the result of a scientific advancement. Say that someone wanted to know the 10^16th digit of pi, they could start a computation and wake up once the 10^16th digit has been computed.

  2. This also means that civilization can better handle the congestion effects of having a high population as people can simply cryosleep and wait for a less crowded time period. One might imagine having congestion pricing for being awake during a popular time period.

  3. The existence of long-preserved individuals also makes it harder to censor people or warp historical records since there are literal witnesses to the past who can be called upon when needed.

  4. Might cryosleep be a society-slowing innovation which accounts for the lack of advanced alien civilizations?

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Neat ideas though fundamentally it requires the assumption that organic human minds will continue to offer value into the future. This assumption is almost certainly false, artificial circuitry already vastly outperforms brain tissue in almost every meaningful dimension but scale and power efficiency. (The brain is still significantly larger in scale than the biggest ANNs and needs much less power).

At discrete tasks of course AI software can trivially outperform humans albeit only on a limited subset of tasks so far. But the trend seems pretty clear.

With artificial brains everything you describe above is obviously trivial since a "mind" can just be archived to a VCS until you need it. Or for interstellar journeys you just lower clock speed such that perceptually the journey is a few minutes even if it requires centuries.

I generally agree. It seems unlikely to me that Cryosleep will be developed or in use for very long before brain emulations or AI become dominant. But like you point out, a lot of the benefits listed here would apply to brain emulations too.

Even if it won't be useful for long, cryonics research seems like an important precursor to Em's. Developing tools to preserve/image the brain, determining which brain structures are important to preserve, and finding ways to upload organic minds will all be important.


I think the current tech curves suggest it will never be developed before it isn't needed. The human brain is extremely fragile, complex, and not designed to tolerate freezing. There may simply not be a way to freeze it without installing so much support nanotechnology that the brain is essentially artificial.

While making AI better than humans at task n is mostly an engineering problem, assuming a good definition of what it means to do well at task n is available.