Brain Emulation for Manned Interstellar Flight: Feasibility and Design Considerations

posted by Andreas Hein on June 27, 2012

 written by Aaron Cardon

brain space

Close your eyes and picture that first moment of direct extraterrestrial contact, but add a less familiar twist: imagine that we are the arriving extraterrestrials.  Far (or, perhaps, nearer than we think) into our future, with ever-advancing astronomy, unmanned extrasolar probes, and perhaps manned missions to nearby planetary systems, the depths of the vast interstellar ocean finally yield that Holy Grail of astrobiology: dozens of light years away, we spot another planet stamped with an unmistakable signature of intelligent life.  After our species-long history of wondering, and with the technology available, are we not compelled to go to them?

            If your answer is yes, read on…but prepare yourself for another imaginative leap.  I’ve told you that we have the technology, and asked you to vaguely imagine us, arriving in their solar system, to present ourselves to them in that incredible moment of first contact.  But I didn’t describe what we would look like descending from the skies; I left your brain to fill in what this interstellar technology looks like.  My mind normally goes to a habitation-module lander (think Apollo), cruising to the softest landing possible under intensive thrusters, with the deck then slowly unfolding to reveal a biped silhouette.  Others, perhaps, think first of Kirk and crew appearing suddenly, transported from their orbiting ship directly in front of an alien welcoming committee.  Did you imagine, however, that when we arrive, perhaps we fall directly to their planet’s surface, with no gear except our “selves.”  We may walk on two legs, or perhaps four, or eight; we might not walk at all.  Most noticeably, however, we are a fraction of our current size and weight, almost certainly don’t look very hominid at all, and are composed entirely (or at least mostly) of circuit boards, memory sticks and processor chips.

            When discussing deep-space exploration, brain emulation – the use of advanced computers to digitally recreate a complete (or essentially complete) human neural network – comes up with increasing frequency.  As our computers become progressively faster, more intricate, and compact, it becomes easier and easier to envision such a “digital crew” and the benefits it might offer to mission design.  I will introduce here, to stimulate discussion, what is known about the feasibility of whole-brain emulation technology, the advantages it may offer in its application to manned interstellar exploration, and the mission designs implied by those advantages.  We may then proceed to discuss the state of the evidence and develop each of these sections in further detail.


Technology-readiness and Feasibility

            If emulation turns out to be feasible, it is important to remain clear in distinguishing its many independent research goals and purposes.  Most basically, we can conceptualize whole brain emulation as taking three forms: whole brain emulation (WBE) can be defined as a successful digital representation of the general components of a whole brain, operating in real-time (or close to it) in such sufficient detail as to reliably reproduce its most important outputs (i.e. behaviors).  The more specific use of brain emulation to model the “standard” output of a human brain (most generally validated as successful by some sort of Turing test), can be labeled mind emulation..  It is at this level, where its use becomes comparable to that of other AI models, that I think most of us begin to envision practical brain emulation and the fantastic uses it could provide.  Person emulation, finally, is the digital reproduction of specific minds (i.e. individuals).  It is difficult, at our current level of knowledge, to predict the relative difficulty in achieving each of these forms of emulation, although it seems likely that they require increasing levels of technological sophistication.  Person emulation, for example, would appear to require the ability to specifically image and capture (either destructively or not) all relevant parameters of a particular brain, while mind emulation could be demonstrated by merely gathering sufficient data, from as many sources as necessary, to construct a model of each of the relevant systems to whole brain function.

            Although the feasibility of even basic WBE has yet to be demonstrated, there are good reasons to expect that it may be possible, even in the relative near-term future.  Only a few unproven assumptions must be true to accept its theoretical plausibility – most notably, scale separation. Other assumptions or speculations depend on the particular form of emulation being discussed.

Ghost in the shell

Ghost in the shell: Brain emulation is a common topic in science-fiction

            The feasibility of any sort of whole brain emulation is dependent on scale separation – the principle that at some sufficiently high level of system function, brain activity can be described, accurately predicted, and reproduced.  Brains, as most modern students will remember, are made up of neurons (usually estimated at 100 billion of them), connected to one another by, on average, 1000 synapses (100 trillion synapses, for those keeping count).  Neurons communicate with one another across these synapses by chemical stimulation: an action potential is “fired” in a neuron, stimulating the release of neurotransmitters, which float across the synapse and modify the properties of the receiving neuron (usually by increasing or decreasing the receiving neuron’s probability of firing).  Neurons, like all cells, are incredibly complex individual units whose function relies on tightly-regulated protein interactions.  Protein interactions are governed by quantum and classical chemical behaviors which we have yet to completely model.  So at which level of this complex system is the information contained? 

            It has been suggested, though never widely accepted, that information contained either at the quantum molecular level, or within the continuous variables of the analog signals, may be used by the brain to enable “hypercomputation” which will not be amenable to emulation.  These two scenarios would essentially compel us to accept that the physical structure of a brain is necessary to produce a mind, or at least make it unlikely that the necessary computation is a tractable problem.  These both remain valid hypotheses (they will be best tested by progressively improvements in the neural network models discussed below); fortunately for our future emulators, however, they both contain significant problems to reconcile to current neuroscience.

            So returning to our levels of scale, the action potential (the “all-or-none” activations of individual neurons) – or, perhaps, the repeated action potentials in a spike trains – is the fundamental unit of information in contemporary neuroscience. Neurons are, after all, binary on/off units, just like bits.  Their information-processing capacity lies in their extensive interconnectedness.  Wait, you say, but the connections of neurons are not random or average at all; rather, there are different specialized neuron types which have specific unique functions and connections; in other words, even if we had complete, functional electronic models of 100 billion “typical” neurons with their thousand connections each, we obviously could not simply connect them to each other randomly and expect a mind to emerge (more to the point, we should probably expect an epileptic meltdown).  Thus, to emulate the brain, we may “merely” have to digitize the relevant properties of two things: the thresholds and excitability of individual neurons (compartment model) and the map of their connections (the connectome) in the human brain.

            Indeed, that combination is very close to the form of most modern neural network models.  Individual nodes, representing neurons, act to process their input according to their compartment model, and based on their result, either propagate a signal to the next node or not.  Usually, depending upon the application, most models simplify either the compartment model or the connectome, even while focusing on a small population of neurons (often, though not always, modeled off of part of the brain).  Even such limited models, however, have been successful in replicating some functions and outputs of neural networks.  For example, auto-associative networks modeled from the hippocampus (one of the most extensively  studied regions of the brain, known to be important to memory) have been shown to be capable of pattern recognition akin to prompted memory recall: input of a small portion of a previously “learned” pattern will reliably reproduce the pattern.  Another group, working on prosthetic replacement of the hippocampus, has developed an integrated circuit that, when used to replace parts of the hippocampus circuit, can reliably replicate the spike timing and output of the network.

            Although our models remain limited in size and scope, advanced simulations running on standard computers may still take hours to produce mere seconds worth of real-time output.  There are, however, good reasons to believe such limitations are temporary and that whole brain, real-time emulation can still develop from extrapolations of the models above.  These reasons are closely related to those which would offer reduced payloads, so we will discuss them together later.

             Successes such as those mentioned above indicate that a faithful emulation could emerge from models containing some sufficient detail of compartments and connectedness.  At the groundbreaking conference on whole brain emulation, held by Oxford’s Future of Humanity Institute in 2008, an informal poll of attendees produced this consensus of an expected range of complexity for mature emulation technology (Sandberg and Bostrom, 14).  It is possible (and suggested by a few at that conference), that non-reducible information may be contained at the level of neurotransmitter concentrations, quaternary protein structures, or ephaptic (local electrical fluctuation) effects.  While the evidence for such information-processing capacity is preliminary at best, addition of this information could increase the computational and imaging requirements by a few orders of magnitude, but should not generally be considered a major impediment to its development.

            So while it is certainly possible that some of the unanswered questions described above could, when answered, demonstrate that digital technology cannot emulate biological brains to a sufficient degree to replace (or equivalently complement) human crew members, the future of whole brain emulation overall looks quite bright.  Introducing their summary of the Oxford conference, Sandberg and Bostrom summarize the expert consensus that although “WBE [whole brain emulation] represents a formidable engineering and research problem…[it] could, it would seem, be achieved by extrapolations of current technology.” (5).  Research is being funded across the globe with the explicit intent of further defining and completing the reverse engineering challenges.  When we return to discuss next the advantages of WBE to crew design, we will review the successes of the Blue Brain Project and their goals with the Human Brain Project, as well as HHMI’s Janelia Farms projects making strides toward maturing the necessary technologies, to extrapolate from current success to predict the usefulness to future missions.


Design Advantages of Digital Crews

            Whereas traditional biological crews require extensive life-support systems, a digital crew would theoretically allow massively reduced payloads; after all, the digital crew can be reduced to simply computer hardware powered directly by electricity, thus achieving the same ends while eliminating those pesky biological nuisances like food, oxygen, and waste disposal?  Once we get our minds out of these weary cranial vaults and into their sturdy emulation modules, we may be better pilots without biological fatigue, or require a smaller crew without the need for shifts for sleep, right?

            Indeed, I framed my scenario above to contain a pair of essential design challenges which would support such a crew choice: a large distance (at the very edge of our foreseeable feasibility based on other mission design considerations) with a consequently long mission, along with a mission objective requiring a crew (establishing first contact). In comparison, my favorite description of brain emulation in science fiction happens to be from Stephen Baxter’s Manifold: Space.  In that case, a journey for two human astronauts (and their alien and Neandertal companions) to the center of the Milky Way is enabled by  reduction of the entire payload, into a “ship,” presumably consisting of a very miniaturized (not to mention durable) supercomputer the weight and size of a relay baton, allowing an exotic propulsion system to accelerate this small payload to near the speed of light. I will avoid any further spoilers to Baxter’s plot, but the common elements across most proposals to use digital crews appear to be: reduced payload, stability and self-sufficiency extending beyond the human lifespan, and.  So it is reasonable to consider, by doing our best to envision what such a far-off digital crew would look like, what kind of payload reduction we may achieve.

            No matter the propulsion system, payload is a costly consideration in discussing mission design.  Although we must assume that early brain emulation would occur in very large distributed computing networks, relatively conservative applications of Moore’s Law and the relative energy cost of silicon versus carbon-based information-processing predicts that, once demonstrated feasible, brain emulation, particularly with the type of design appropriate for use as crew members, should be reducible to a point of being more cost-effective in payload considerations.

            Self-sufficiency and stability of such crew members, unfortunately, remains entirely uncertain.  While I am loathe to invoke any “mad-at-the-edge-of-space” stereotypes, one of the first research goals of mind emulation is massive improvements, through availability of model systems for hypothesis testing, in the standard models of psychology, neurology, and particularly cognitive neuroscience.  There are few clinical evidences to support speculating that a mature mind emulation may be amenable to “saving and storing,” by turning on and off at will.  However, even in this simple design question, we do not, and cannot, know that until we find it possible (and, perhaps more importantly, ethical) to do just that.  As we move progressively through the steps of “building a mind” with a brain emulator, the questions mount further and faster regarding psychological stability, and by extension, what support structures must be put in place to achieve such stability.

            Though certainly still one of the most fanciful propositions for use in deep-space mission design, the promise of  digital crews offered by possibilities for brain emulation and brain-like computers remain exciting and alluring.  Brain emulation remains, at best, technology-readiness level 1, with active investigation of basic principles and ever-increasing hopes of near-term proof-of-concept experiments.  Brain emulation is an exciting possible technology which could offer such significant benefits to a deep-space mission as to become indispensable, even though replacement of biological crews may not turn out to be its primary function.  Should it prove feasible, it may well serve better as an adjunct to traditional crews, as an intermediary between a human crew and ship control systems – an integral crew member with particular mission duties, but not a self-sufficient crew entirely separate from its human counterparts.


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10 Responses to Brain Emulation for Manned Interstellar Flight: Feasibility and Design Considerations

  1. Mithril says:

    Digital uploaded brains come with a few philosophical drawbacks.
    the biggest one is what the webcomic Schlock Mercenary calls “the continuity flaw” ( )

    is a digital copy, even a supposedly perect digital copy, of me actually me? if i volunteer for to upload into a starprobe, i personally, the fleshy me, will either be dead or stuck here on earth, while the digital me goes to the stars. the copy is not me, it is ultimately a copy. either way, i personally do not get to go to the stars. and my digital copy will understand that, which would likely lead to psychological issue later on down the road.

    this continuity flaw is the main problem with such digital immortality concepts. anyone who has an Id strong enough to actually desire immortality or the ability to make long starflights, is going to have a personality that won’t accept the idea that they as a digital copy are the same person they were as a flesh and blood person.
    especially if the flesh and blood person is still around after the upload.

    and if the upload process results in the death of the person being uploaded, you now have a major moral problem on your hands, since you are effectively committing murder. (murder doesn’t distinguish between the body and mind.. and you’d have a major political issue regarding whether the uploaded person’s mind counts as a person or just software, property..)

  2. JohnHunt says:

    Without the context of existential risks, scenarios such as the above might seem like a viable option. But honestly, does whole brain emulation pose no immediate existential threat. When technology reaches that level, could we copy the brains of the smartest people in the planet? Could the very intelligent minds be copied in copious quantities. If they were to collaborate, might they be able to figure out how to improve the intelligence of their brains which would then be able to create yet more intelligent brains in an accelerating manner? If so, would such a singularity pose an existential risk to humanity?

    You’ve got to take these issues into account when thinking about interstellar missions. Reality doesn’t have to follow our wishes for the future. To be prudent, we need to take into consideration that the future may close down some of our scenarios against our wishes.

    Silicon minds pose a far greater threat to our future than biological brains. We are really not far from being able to produce humans from frozen single cells. Since the 1970s we have been able to do this using mothers. Stem-cell derived artificial uteruses are being researched with considerable success in the rat model.

    Now, it is true that life-support for a biological colonist is harder than for a silicon one. But since silicon mind technology poses such a greater threat than biological minds, I figure we don’t have a choice. We have to go with the biological model and get it launched before whole brain emulation or more likely IMO seed AI or any other existential threat is developed.

  3. Emulating a human brain means creating a human, albeit in a different body, with all the good and bad things that we have. This also means that we cannot conceive to “enslave” humans into long missions without their consent – even if they are physically speaking, “machines” – and we should also make sure that when they arrive at their destination, they behave better than a Hitler-in-a-can. In such far-reaching developments, ethics, philosophy and morals play a role as great as science and technology. We should pay attention to that.

  4. Andy Allen says:

    With a view to the article and comments made above, I would like to propose a short, perhaps possible, evolutionary path and see what questions are raised by the exercise.

    I would like to start by raising the point that we do not have to fully understand the brain in order to interface technology with it. For example, by mapping particular though patterns it is possible to control electric wheelchairs with no other human intervention. This is achieved by attaching sensors to a cap worn by the driver (what I will refer to as non-invasive).

    It is also possible to control an external robotic arm by sensors implanted into the brain (what I will refer to as invasive).

    It would appear that the initial stimulus for developing this technology would be for medical and possibly military applications (i.e. UAVs controlled by thought rather than joysticks, as a crude example).

    It would seem likely that some of the non-invasive technology would start to find its way into commercial and leisure activities. i.e. in such areas as information access, computer gaming, general interaction with electronic devices, controlling certain instruments and vehicles. Note at this stage options would be interpreted by our own sensors (i.e. a console presents you with certain options, but the choice is made by mapping thought patterns).

    A possible next stage of development would be the introduction of additional electronic sensors. To some extent this is likely to overlap with development stated in the previous paragraph at the basic level. Initially the sensor data is likely to be relayed in a form our own sensors can interpret. However, it may be possible to train the brain to interpret these external sensors directly by stimulating key areas. [***] (To what level we would have to understand the brain in order to achieve this last point is an open question. It may turn out that we may only have to understand the functions of key areas)

    I feel, if possible, this stage may represent a turning point between the non-invasive and invasive technologies. How well our brains can interpret these additional sensors will be the key point. It may turn out that it is advantageous to further develop the brain for this purpose (either through circuits implanted into key areas, or perhaps via biological manipulation). (however, it is likely that a sound knowledge of the brain or at least key areas would be required before the above would be possible.)

    My key points are:
    1)1) It is likely that understanding the brain will be driven by commercial applications in the future.
    2)2) If the above is possible before Brain Emulation, or at least certain levels thereof, will the ethical and moral dilemmas alluded to appear quite so large? (we are viewing this issue from our own technological time)
    3)3) If the last noted stage of development does occur before Brain Emulation to what extent will our brains differ from those today?
    4)4) If it appears advantageous to increase the circuit proportion of the brain of the “biological/circuit hybrid”, is turning “machine” just the next stage of evolution.
    5)5) The above is just a train of thoughts and has no justification, but I would enjoy feedback. It may be that point [***] cannot be advanced upon without an almost complete brain model. I would also like to apologize for my grammar.

  5. JohnHunt says:

    If I understand what you’re saying you’re basically describing a practical way to achieve the Chinese room argument. Is that correct?

    Andy, your suggestion is most interesting. I don’t know of it would work but I think it might. I think the question at that point would be if that deciding machine was up to the task at hand. If the required task would be to analyze different planets and choose a destination I think the deciding machine might be adequate. If the task required was to raise children in which there is a lot of subtle interaction I think that would be more difficult to achieve the required goal.

  6. Sakramentos says:

    The brain emulation is useless as far as true interstellar manned flight is considered. I cannot fathom why nobody realizes that this propsition equals sending a software program that is in no way different from regular one as far as human existence is considered. Yes, it is much more complicated and appears (appears being key word) to be intelligent, but that’s it. It is an equiqualent of sending unmanned probe. There is no true existence or counciousness that experiences interstellar flight and is part of it. And while I think that idea is very good and should be conisdered, it is obvious that this method does not allow to truly travel between stars. Maybe when a real human could be re-created from stored data, then this would somewhat solved this problem, but still this is an equiqualent os sending signal to receiver with inforamtion how to make clone of somebody. It kind of does the trick, but not really.

    • Sakramentos, I can tell you one thing as an aviator: Flight simulators achieve today such a level of realism that “flying” them is exactly the same as flying a real aircraft. They do not “appear” to be aircraft; they “are”. Even legally, they are considered as aircraft in which you can log flight hours, inspectors can write your license off and you can tune them to work exactly as the real thing, down to flight and engineering manual specs. Simulators are used to solve problems or gain training in procedures that are too dangerous to try in “real” aircraft. With this in mind, there is really no reason to assume that emulation of a human being cannot attain full humanity one day. Nothing is impossible.

  7. Astronist says:

    Interesting article, but needs to be considered in conjunction with an article such as this:
    by Athena Andreadis.

    Stephen, Oxford, UK

  8. Astronist says:

    By the way, is this blog article written by Andreas Hein or Aaron Cardon? Both attributions appear under the title.

  9. JohnW says:

    The simulations will be of parts of the brain for specific purposes or rather tasks not an actual person, more likely from a collection of unknown cadavers ( thankfully the use of criminals for cadavers is no longer common ). There would be Just enough simulation to perform a function difficult for known algorithms to do such as visual perception, walking, etc. These components may be controlled by a traditional program but the neural nets will only be used where they work best.

    There will be exceptions to this, I can see someone having their brain digitized after their natural death and leaving a foundation behind to repair the damage from death, perhaps redressing memories with videos, photos and journals and creating a virtual recreation of themselves. Continuity would not be a problem as this is after their natural deaths, they would simply be the best available version of themselves and hence there would be a willingness to accept themselves as they are.

    Such more complete emulations of individuals may eventually perform functions perhaps as jobs which brings a serious issue about rights as such simulations could easily be only rewarded virtually or reset into a co-operative state with only promises of compensation.

    These more complete emulations and eventually more thorough use of partial emulations may begin to obviate organic humans particularly if they could be simulated at a higher speed than organic humans but only to the cost and operation of the equipment needed. Total obsolescence will depend on how trivial the equipment costs and energy may become and it only needs to undercut the living costs of organic humans to obsolete them. Personal fabricators and liquid fluoride thorium reactors could make the equipment costs and energy costs truly trivial.

    The obsolescence of organic humans would occur economically, through the lost of jobs till their support falls to the social system where they may likely be “zooed” in self supporting agrarian communities and encouraged perhaps forcibly to reduce reproduction.

    Both the simulated crew and any organic crew that might accompany them on an interstellar trip may, by the single purpose of the trip, be the only versions of our descendants not on such a dystopic path, at least not till they colonize or lose sense of a combined mission.

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