I don’t think we’ll be able to take a nap and wake up at Alpha Centauri

An article asks, Reaching the stars: is human hibernation really possible? It’s not very deep — and it seems to not understand that hibernation is a physiological state of reduced metabolism, rather than a kind of freezing — and it seems to shift the goalposts a couple of times. It also seems to think that therapeutic hypothermia is a practical way to fly to Mars.

A few years ago, SpaceWorks Enterprises delivered a report to NASA on how they could use this therapeutic hypothermia for long duration spaceflight within the Solar System.

Currently, a trip to Mars takes about 6-9 months. And during that time, the human passengers are going to be using up precious air, water and food. But in this torpor state, SpaceWorks estimates that the crew will a reduction in their metabolic rate of 50 to 70%. Less metabolism, less resources needed. Less cargo that needs to be sent to Mars.

Whoa. Therapeutic hypothermia is a technique to reduce cerebral metabolic demand when the cranial circulatory system has been compromised. As the article notes, it’s been used for as long as two weeks, with intermittent arousals. Would a healthy astronaut be willing to undergo this procedure? Doesn’t sound wise to me. And do I really want to go on a trip where the bean-counters have figured out that they can pack half as much oxygen for me by rendering me unconscious in an ice bath for half a year?

A 50% reduction in metabolism also isn’t going to get anyone to even the nearest star, sorry.

But even worse — therapeutic hypothermia isn’t trivial. Here’s a review of the medical consequences of therapeutic hypothermia.

Treated patients in this trial reached target temperature to 34°C quickly but adverse events included periorbital emphysema, epistaxis, perioral bleeding, and nasal discolorations.

Not too bad, right? Air around the eyeballs, nosebleeds, small hemorrhages around the mouth, and bruised noses. I suppose that’s manageable. But then there’s this:

Adverse events associated with endovascular cooling include pneumonia, cardiac arrhythmia, thrombocytopenia, and vascular dissection.

I’d definitely want a doctor attending my awakening. Unfortunately, the doctor might have experienced this:

Uncontrolled re-warming has been associated with rebound cerebral edema, elevations in intracranial pressure, and death.

I think I’ll pass. It’s not to say it doesn’t have benefits in specific medical situations, but I wouldn’t want to risk compromising a currently healthy body.

It’s also completely different from the idea of freezing someone solid, to virtually no metabolic activity, and then thawing them out and having them survive. There’s a kind of bait-and-switch at play in these kinds of articles: squirrels can hibernate all winter long, and hey, doctors have cooled people’s body temperature to 34°C, so why not just suggest the feasibility of sub-zero freezing? The problem is that these are entirely different problems and technologies, there is no continuum here, and you can’t make this kind of blithe extrapolation.

In the next few years, we’ll probably see this technology expanded to preserving organs for transplant, and eventually entire bodies, and maybe even humans. Then this science fiction idea might actually turn into reality. We’ll finally be able to sleep our way between the stars.

I don’t think so. And it wouldn’t be anything I’d call “sleep”, either.


  1. ajbjasus says

    Ah, but that’s how the Golgafrinchams managed to get to Earth, to escape the giant mutant stargoat, and where would we be without them ?

  2. Larry says

    With my luck, I’d be frozen in suspended animation for the trip with a homicidal computer controlling the ship!

  3. AndrewD says

    There is another problem with “deep freeze” to the stars as was pointed out at Charlie Stross’s place during a discussion of slower than light star travel. The Human body contains naturally radioactive elements (eg Carbon 14), hence there will be radiation damage due to the Isotopic decay which will not be repaired in the hibernating body-when thawed there will be serious risk of immediate cancer(or worse).
    See at:-

  4. says

    Hibernation won’t counteract what we already know is a major problem with long durations in space, the effects of microgravity. In fact I’m guessing it might actually make things worse, since a hibernating person won’t be engaging in exercises intended to counter those effects.

  5. whywhywhy says

    Even if folks could be frozen and reliably thawed, there remains the problem of solar radiation and cosmic rays. This problem is not just in the travel but also once the people arrive on the planet if the planet does not have a magnetic field of sufficient strength to shield the planet.

    Here is a fun thought experiment: how much would it cost to create a magnetosphere, atmosphere, oceans, etc (ie. terraform Mars)? How much would it cost for us to substantially lower our carbon emissions and mitigate all effects of climate change?

    I am willing to bet focusing on earth will be cheaper.

  6. davidnangle says

    Annoyingly, warp speed, hyperspace, wormholes, infinite improbability drives… none of that stuff works, because the lightspeed limit is not a prohibition against velocity through space, per se, but a prohibition against being in a new place too soon after having been in a previous place.

    For reasons of causality. Whatever that means.

  7. tacitus says

    I’ve written a couple of SciFi short stories, one involving interstellar travel, that required some form of suspended animation to work. One of the issues I have with my fictional scribblings is that I tend to strive for plausibility at the expense of telling a good story.

    But in the case of suspended animation I just decide to go with the idea that “stasis” was a thing and get on with telling the story. Much easier that way!

  8. euclide says

    another solution to send humans over vast distance is :
    1) have advanced robots
    2) have an artificial womb
    3) send frozen embryos to be raised on Alpha Centauri

  9. blf says

    The TARDIS does not need “suspended animation”. So grow your own and avoid all that messiness. Easy-peasy ! The power source, the “Eye of Harmony” — the nucleus / singularity of a (artificial?) black hole — may present some minor difficulties, but enough spherical cows & reversals of the polarity of the neutron flow should suffice.

  10. cartomancer says

    Hmm… puffy eyes, weird mouth, brain damage… you don’t think Trump and Bannon were accidentally flash-frozen and brought to the modern world from the 1800s do you? It would explain a lot.

  11. says

    “Travel thousands of years. Die.” Sounds like a great recruiting poster.

    I understand that as a species we are curious and want to travel and see places, but it seems like a lot of work to go somewhere and die when there are plenty of ways to do that here.

  12. slithey tove (twas brillig (stevem)) says

    You mean ScienceFiction movies aren’t documentaries of actual technology. The Nostromo (Alien</b) staff would simply plop into their “cold sleep” pods to start, at arrival, climb out and wolf down breakfast to recharge.
    Don’t emphasize Science
    Fiction, I I know it is ScienceFiction. [fingers in ears].
    –Contrarian signing off
    thank you for smilng AT me.

  13. blf says

    [were] Trump and Bannon were accidentally flash-frozen and brought to the modern world from the 1800s […]?

    c.1800 BCE I presume…

    That would seem to require either ancient alien astronauts, Mormon wooden submarines, or the Soros / Obama time machine. Of the three, a regression to the original B-Ark cargo seems more likely, albeit one cannot quite rule out a Boys from Brazil scenario where the appearance of the clones differs from the original.

  14. slithey tove (twas brillig (stevem)) says

    re @12
    Tpyo alert
    dropped a > leaving everything after it bolded.
    Don’t tell me it is ScienceFiction, I know it is ScienceFiction

  15. katiemarshall says

    I’m a cryobiologist (I study animals that naturally survive freezing like barnacles and some species of frogs and insects). It’s…not an easy thing. Even in these species we see the involvement of hundreds of genes (see here for an example: https://www.ncbi.nlm.nih.gov/pubmed/28082102), and as PZ points out, it’s a totally different stress than just cold. The species that do this have lots of adaptations in their cell membranes to permit water and cryoprotectant flows–it’s not just a matter of pumping them full of fluid.

    Even cold exposure is complex–we have a paper where we showed that depending on the type and duration of cold exposure you actually get totally different responses (http://jeb.biologists.org/content/214/23/4021.short).

  16. a_ray_in_dilbert_space says

    No worries about waking up. The radiation from galactic cosmic rays would slice your DNA to ribbons long before you had to worry about that. It would take more than a meter of aluminum equivalent shielding even to cut it down by a factor of 10–and you aren’t going to be going anywhere in space if you are surrounded by a meter of aluminum.

  17. Rob Grigjanis says

    davidnangle @6:

    For reasons of causality. Whatever that means.

    It means that FTL implies possible scenarios in which you can return from a trip before you leave. Or receive a reply to your message before you send it. See here.

  18. davidnangle says

    Rob Grigjanis, I understand the paradox possibility. I just don’t understand why the universe prevents them. In your first example, you’d just have your timeline folded for a bit. It will straighten out in the end.

  19. Rob Grigjanis says

    davidnangle @18: So you (B) return before you (A) leave. Then you (A) decide not to leave. Not sure how this “straightens out”.

    I just don’t understand why the universe prevents them.

    Because that’s how the universe works? It seems odd (to me) to make stuff up and then wonder why it is “prevented”.

  20. says

    timgueguen #4

    Hibernation won’t counteract what we already know is a major problem with long durations in space, the effects of microgravity. In fact I’m guessing it might actually make things worse, since a hibernating person won’t be engaging in exercises intended to counter those effects.

    To be fair, it could also have the opposite effect. The deterioration of bones and muscles is not a passive process so, as metabolism lowers, these processes might well also be inhibited.

    Still, micro-gravity effects are definitely a thing. I expect we’re going to have to come up with some pharmaceutical work-around, to trick the body into staying stronger than it really needs to be.

    euclide #8

    another solution to send humans over vast distance is :
    1) have advanced robots
    2) have an artificial womb
    3) send frozen embryos to be raised on Alpha Centauri

    4) Hope that being raised by robots with no adult human contact at all is perfectly fine and won’t lead to any kind of social dysfunction in the first generation that will form the basis of this new society.

  21. davidnangle says

    Me: “I just don’t understand why the universe prevents them.”

    Rob Grigjanis: “Because that’s how the universe works? It seems odd (to me) to make stuff up and then wonder why it is “prevented”.”

    Well, I’m intimating that the universe does not. A universe that puts me in the same room as a future me does not seem impossible. And paradoxes from lightspeed violation don’t seem like they would unravel reality.

  22. a_ray_in_dilbert_space says

    A limerick from George Gamov:
    There was a young lady named Bright;
    Who could travel much faster than light;
    She took off one day;
    In an Einsteinian way;
    And returned the previous night.

    There is an idea of a “cosmic censor,” which basically says that, “The Universe makes sense, so events that would lead to the Universe not making sense must be impossible (or at least, highly improbable and inconsequential).” Thing like a naked singularity (singularity that isn’t behind an event horizon) or FTL travel don’t happen.

  23. Mark Jacobson says

    David’s thinking is flawed not because they don’t understand something which doesn’t make sense is impossible, but that just because something does make sense doesn’t make it possible. There are many things which make sense which the universe does not do. If that wasn’t the case, physics would be pure mathematics, without need for observation.

  24. KG says


    Another limerick, no idea who wrote it, similar relation to relativity, but doesn’t actually require FTL:

    There was a young fencer named Fisk.
    Whose style was exceedingly brisk.
    So fast was his action,
    Fitzgerald’s contraction
    Foreshortened his foil to a disk.

  25. Matrim says

    All we have to do is raise the speed of light, then it will be much easier because we can accelerate more. Easy peasy. /s

    Seriously, though, if we work at it I’m pretty sure we’ll eventually be able find some way to suspend biological function and resume it, but I doubt it will involve freezing.

    Out of curiosity, does anyone know how to calculate subjective time at relativistic velocities? If we can find a way to get going fast enough, stasis won’t even be required (at least not to go to Alpha Centauri or even Epsilon Eridani). Regardless it’s still nothing we’re going to be doing any time soon.

  26. Rob Grigjanis says

    Matrim @25: If v is the instantaneous speed of the ship relative to Earth,

    Δt(ship) = Δt(Earth) x (1 – v²/c²)^(1/2)

    But, see a_ray_in_dilbert_space @16.

  27. unclefrogy says

    if there are not found some work arounds for the speed of light. the vast distances and biology we will not be going to the stars in any way similar to Buck Rogers or captain Kirk. to travel that kind of distance (space/time) we would need a very large ship maybe the size of a small planet that could offer adequate shielding and be self sustaining for the trip and maybe indefinitely with proper maintenance something like the L-5 proposals maybe even larger with a population large enough that would help ensure a healthy bio-diversity with all of the species that would have to be included, It could be made out of the material in the Oort cloud and the Kuiper belt. a true ark. iff that is it’s purpose, cryogenics and warp speed?nothing suggests they are really possible.
    question are not we already on something like that traveling through space/time on an incredible journey on a with a time frame that exceeds many lifetimes?
    uncle frogy

  28. leerudolph says

    Mark Davidson @23: ” If that wasn’t the case, physics would be pure mathematics, without need for observation.” Or mathematical proofs, come to that…

  29. Matrim says

    @26, Rob Grigjanis

    Honestly, the radiation seems like one of the easier problems to solve, given we know what has to be done to solve it and mostly just need to work out practical application. Seems like building a propulsion system that is capable of accelerating to high fractions of c and a way to power it would be more difficult.

  30. says

    Nobody posted a central reason why freezing humans can’t work. Water expands when it freezes. Some animals have cells that have cell walls that can expand. Humans for the most part do not. (Overwhelmingly)

    Thus, when humans, like hamburger, have their cells frozen, those cells explode. Thus, after thawing, a human body, just like hamburger on the counter, would have a puddle of intracellular fluid dripping everywhere. And that body would be VERY dead.

  31. Ichthyic says

    Honestly, the radiation seems like one of the easier problems to solve,

    no, it isn’t at all easy to solve, given that:

    cosmic radiation can literally pas through an entire planet.
    if you freeze something, it no longer has the ability to repair damage from cosmic radiation
    add long timescales for travel.

    it doesn’t matter if you use frozen humans or frozen eggs. at the moment, this is an intractable problem, full stop.

  32. Ichthyic says

    …and apparently the code here can’t even understand a simple numbered list.

    oh well.