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Truth Journal


Hans Moravec
Carnegie-Mellon University

You may think the following proposals are thought experiments that's fine, as such they still make the point in question. I happen to think of them as real, highly desirable, possibilities for the foreseeable future. For me they are a solution to the annoying certainty that we will be overtaken in every area by future superintelligent machines, and will be excluded from all the really interesting developments unless we keep up, personally and intimately, with the technologies of thought. That these ideas raise and clarify some interesting metaphysical questions is a bonus.


You are in an operating room. A robot brain surgeon is in attendance. By your side is a potentially human equivalent computer, dormant for lack of a program to run. Your skull, but not your brain, is anesthetized. You are fully conscious. The surgeon opens your brain case and peers inside. Its attention is directed at a small clump of about 100 neurons somewhere near the surface. It determines the three dimensional structure and chemical makeup of that clump nondestructively with high resolution 3D NMR holography, phased array radio encephalography, and ultrasonic radar. It writes a program that models the behavior of the clump, and starts it running on a small portion of the computer next to you. Fine connections are run from the edges of the neuron assembly to the computer, providing the simulation with the same inputs as the neurons. You and the surgeon check the accuracy of the simulation. After you are satisfied, tiny relays are inserted between the edges of the clump and the rest of the brain. Initially these leave the brain unchanged, but on command they can connect the simulation in place of the clump. A button which activates the relays when pressed is placed in your hand. You press it, release it and press it again. There should be no difference. As soon as you are satisfied, the simulation connection is established firmly, and the now unconnected clump of neurons is removed. The process is repeated over and over for adjoining clumps, until the entire brain has been dealt with. Occasionally several clump simulations are combined into a single equivalent but more efficient program. Though you have not lost consciousness, or even your train of thought, your mind (some would say soul) has been removed from the brain and transferred to a machine.

In a final step your old body is disconnected. The computer is installed in a shiny new one, in the style, color and material of your choice. You are no longer a cyborg halfbreed, your metamorphosis is complete.

For the squeamish there are other ways to work the transfer. The high resolution brain scan could be done in one fell swoop, without surgery, and a new you made, "While-U-Wait". Some will object that the instant process makes only a copy, the real you is still trapped in the old body (please dispose of properly). This is an understandable misconception based on the intimate association of a person's identity with a particular, unique, irreplaceable piece of meat. Once the possibility of mind transfer is accepted, however, a more mature notion of life and identity becomes possible. You are not dead until the last copy is erased; a faithful copy is exactly as good as the original. These issues are examined in greater detail later.

If even the last technique is too invasive for you, imagine a more psychological approach. A kind of portable computer (perhaps worn like eyeglasses so it can cover your entire visual field) is programmed with the universals of human mentality, with your genetic makeup and with whatever details of your life are conveniently available. It carries a program that makes it an excellent mimic. You carry this computer with you through the prime of your life, and it diligently listens and watches, and perhaps monitors your brainwaves, and learns to anticipate your every move and response. Soon it is able to fool your friends on the phone with its convincing imitation of you. When you die it is installed in a mechanical body and smoothly and seamlessly takes over your life and responsibilities.

What? Still not satisfied? If you happen to be a vertebrate there is another option that combines some of the sales features of the methods above. The vertebrate brain is split into two hemispheres connected by a very large bundle of nerve fibers called the corpus callosum. When brain surgery was new it was discovered that severing this connection between the brain halves cured some forms of epilepsy. An amazing aspect of the procedure was the apparent lack of side effects on the patient. The corpus callosum is a bundle far thicker than the optic nerve or even the spinal cord. Cut the optic nerve and the victim is utterly blind; sever the spinal cord and the body goes limp. Slice the huge cable between the hemispheres and nobody notices a thing. Well, not quite. In subtle experiments it was noted that patients who had this surgery were unable, when presented with the written word "brush", for instance, to identify the object in a collection of others using their left hand. The hand wanders uncertainly from object to object, seemingly unable to decide which is "brush". When asked to do the same task with the right hand, the choice is quick and unhesitating. Sometimes in the left handed version of the task the right hand, apparently in exasperation, reaches over to guide the left to the proper location. Other such quirks involving spatial reasoning and motor coordination were observed.

The explanation offered is that the callosum indeed is the main communications channel between the brain hemispheres. It has fibers running to every part of the cortex on each side. The brain halves, however, are fully able to function separately, and call on this channel only when a task involving co-ordination becomes necessary. We can postulate that each hemisphere has its own priorities, and that the other can request, but not demand, information or action from it, and must be able to operate effectively if the other chooses not to respond, even when the callosum is intact. The left hemisphere handles language and controls the right side of the body. The right hemisphere controls the left half of the body, and without the callosum the correct interpretation of the letters "brush" could not be conveyed to the controller of the left hand.

But what an opportunity. Suppose we sever your callosum but then connect a cable to both severed ends leading into an external computer. If the human brain is understood well enough this external computer can be programmed to pass, but also monitor the traffic between the two. Like the personal mimic it can teach itself to think like them. After a while it can insert its own messages into the stream, becoming an integral part of your thought processes. In time, as your original brain fades away from natural causes, it can smoothly take over the lost functions, and ultimately your mind finds itself in the computer. With advances in high resolution scanning it may even be possible to have this effect without messy surgery - perhaps you just wear some kind of helmet or headband.

Vernor Vinge devised a particularly slow and gentle transfer method in True Names, his novel of the near future. The world of True Names is interconnected by a computer network containing processes linked to every vital function of society. Experienced hackers connect to the net through innovative terminals they have developed; like radio amateurs early in the century they are at the leading edge of the new technology, ahead of the establishment. The hackers' terminals are bi-directional electroencephalogram (brain wave) machines; they enable a computer to read the human's brain waves and also to induce them. Through years of practice, experimentation and programming the hackers have discovered a combination of mental and computer techniques that permit a dreamlike trance in which information from the computer controls elements of a lucid dream, and actions in the dream affect the computer. In the dream data objects are represented by metaphor - a locked computer file, for instance, might appear as a steel safe with a combination lock. Guessing and dialing the right combination unlocks the file. The interface is tremendously fast and effective because the full mind of the human is coupled to the machine.

The hackers meet in the network, each in an imaginative guise. Sometimes their computer personas continue to operate under control of special programs even when their owners temporarily disconnect. A new potential of the net reveals itself as the story unfolds. One of the characters has augmented her thinking in the net by directly incorporating computer subroutines. In real life she is an old woman suffering from advanced senility. In the network, by contrast, she appears extraordinarily swift and intelligent because of the computer routines she has written to substitute for her lost natural abilities. Her illness is progressive, and she is constantly programming new capabilities as her natural ones disappear. Her goal is to complete the process before she dies. With success she will continue to live in her computer persona though her physical body no longer exists.


Whatever style you choose, when the transfer is complete advantages become apparent. Your computer has a control labelled speed. It had been set to slow, to keep the simulations synchronized with the old brain, but now you change it to fast. You can communicate, react and think a thousand times faster. But wait, there's more!

The program in your machine can be read out and altered, letting you conveniently examine, modify, improve and extend yourself. The entire program may be copied into similar machines, giving two or more thinking, feeling versions of you. You may choose to move your mind from one computer to another more technically advanced, or more suited to a new environment. The program can also be copied to some future equivalent of magnetic tape. If the machine you inhabit is fatally clobbered, the tape can be read into a blank computer, resulting in another you, minus the experiences since the copy. With enough copies, permanent death would be very unlikely.

As a computer program, your mind can travel over information channels. A laser can send it from one computer to another across great distances and other barriers. If you found life on a neutron star, and wished to make a field trip, you might devise a way to build a neutron computer and robot body on the surface, then transmit your mind to it. Nuclear reactions are a million times quicker than chemistry, so the neutron you can probably think that much faster. It can act, acquire new experiences and memories, then beam its mind back home. The original body could be kept dormant during the trip to be reactivated with the new memories when the return message arrived. Alternatively, the original might remain active. There would then be two separate versions of you, with different memories for the trip interval.

Two sets of memories can be merged, if mind programs are adequately understood. To prevent confusion, memories of events would indicate in which body they happened. Merging should be possible not only between two versions of the same individual but also between different persons. Selective mergings, involving some of the other person's memories, and not others would be a very superior form of communication, in which recollections, skills, attitudes and personalities can be rapidly and effectively shared.

Your new body will be able to carry more memories than your original biological one, but the accelerated information explosion will insure the impossibility of lugging around all of civilization's knowledge. You will have to pick and choose what your mind contains at any one time. There will often be knowledge and skills available from others superior to your own, and the incentive to substitute those talents for yours will be overwhelming. In the long run you will remember mostly other people's experiences, while memories you originated will be floating around the population at large. The very concept of you will become fuzzy, replaced by larger, communal egos.

Mind transferral need not be limited to human beings. Earth has other species with brains as large, from dolphins, our cephalic equals, to elephants, whales, and giant squid, with brains up to twenty times as big. Translation between their mental representation and ours is a technical problem comparable to converting our minds into a computer program. Our culture could be fused with theirs, we could incorporate each other's memories, and the species boundaries would fade. Non-intelligent creatures could also be popped into the data banks. The simplest organisms might contribute little more than the information in their DNA. In this way our future selves will benefit from all the lessons learned by terrestrial biological and cultural evolution. This is a far more secure form of storage than the present one, where genes and ideas are lost when the conditions that gave rise to them change.

Our speculation ends in a super-civilization, the synthesis of all solar system life, constantly improving and extending itself, spreading outward from the sun, converting non-life into mind. There may be other such bubbles expanding from elsewhere. What happens when we meet? Fusion of us with them is a possibility, requiring only a translation scheme between the memory representations. This process, possibly occurring now elsewhere, might convert the entire universe into an extended thinking entity, a probable prelude to greater things.

What Am l?

The idea that a human mind can be transferred to a new body sometimes meets the following strong objection from some who dispute neither the possibility, nor its objective manifestations as described. "Regardless of how the copying is done the end result will be a new person. If it is I who am being copied, the copy, though it may think of itself as me, is simply a self-deluded imposter. If the copying process destroys the original then I have been killed. That the copy may then have a great time exploring the universe using my name and my skills is no comfort to my mortal remains."

Naturally, this point of view, which I will call the Body Identity position, makes life extension by duplication considerably less personally interesting.

I believe the objection can and should be overcome by intellectual acceptance of an alternate position I will name Pattern Identity. Body identity assumes that a person is defined by the stuff of which a human body is made. Only by maintaining continuity of body stuff can we preserve an individual person. Pattern identity, on the other hand, defines the essence of a person, say myself, as the pattern and the process going on in my head and body, not the machinery supporting that process. If the process is preserved, I am preserved. The rest is mere jelly.

Matter Transmitters

Matter transmitters have appeared often in the science fiction literature, at least since the invention of facsimile machines in the late 1 the. I raise the idea here only as a thought experiment, to simplify some of the issues in the mind transfer proposal.

A facsimile transmitter scans a photograph line by line with a light sensitive photocell, and produces an electric current that varies with the brightness of the scanned point in the picture. The varying electric current is transmitted over wires to a remote location where it controls the brightness of a light bulb in a facsimile receiver. The receiver scans the bulb over photosensitive paper in the same pattern as the transmitter. When this paper is developed, a duplicate of the original photograph is obtained. This device was a boon to newspapers, who were able to get illustrations from remote parts of the country almost instantly, rather than after a period of days by train.

If pictures, why not solid objects? A matter transmitter might scan an object and identify, then knock out, its atoms or molecules one at a time. The identity of the atoms would be transmitted to a receiver where a duplicate of the original object would be assembled in the same order from a local supply of atoms. The technical problems were mind boggling, and well beyond anything foreseeable, but the principle was simple to grasp.

If solid objects, why not a person? Just stick him in the transmitter, turn on the scan, and greet him when he walks from the receiver. But is it really the same person? If the system works well, the duplicate will be indistinguishable from the original in any substantial way. Yet, suppose you fail to turn on the receiver during the transmission process. The transmitter will scan and disassemble the victim, and send an unheard message to the inoperative receiver. The original person will be dead. Doesn't, in fact, the process kill the original person whether or not there is an active receiver? Isn't the duplicate just that, merely a clever imposter? Or suppose two receivers respond to the message from one transmitter. Which, if either, of the two duplicates is the real original?

Pattern Identity

The body identity position is clear. A matter transmitter is an execution device. You might as well save your money and use a gas chamber, and not be taken in by the phony double gimmick.

Pattern identity gives a different perspective. Suppose I step into the transmission chamber. The transmitter scans and disassembles my jelly-like body, but my pattern (me!) moves continuously from the dissolving jelly, through the transmitting beam, and ends up in other jelly at the destination. At no instant was it (I) ever destroyed.

The biggest confusion comes from the question of duplicates. It is rooted in all our past experience that one person corresponds to one body. In the light of the possibility of matter and mind storage and transmission this simple, natural, and obvious identification becomes confusing and misleading. Suppose the matter transmitter is connected to two receivers instead of one. After the transfer there will be a copy of you in each one. Surely at least one of them is only a mere copy - they can't both be you, right? Wrong!

A Metaphor

Consider the message "I am not jelly". As I type it , it goes from my brain, into the keyboard of my computer, through myriads of electronic circuits and over great amounts of wire, and after countless adventures shows up in bunches of books like the one you're holding. How many messages were there? I claim it is most useful to think there is only one, despite its massive replication. If I repeat it here: "I am not jelly", there is still only one message. Only if I change it in a significant manner: "I am not peanut butter" do we have a second message. And the message is not destroyed until the last written version is lost, and until it fades sufficiently in everybody's memory to be unreconstructable. The message is the information conveyed, not the particular encoding. The "pattern and process" that I claim is the real me has the same properties as the message above. Making a momentary copy of my state, whether on tape or in another functional body, doesn't make two persons.

There is a complication because of the "process" aspect; as soon as an instance of a "person message" evolves for a while it becomes a different person. If two of them are active, they will diverge, and become two different people by my definition. Just how far this differentiation must proceed before you grant them unique identities is about as problematical as the question "when does a fetus become a person?" But if you wait zero time, then you don't have a new person. If, in the dual receiver version of the matter transmitter, you allow the two copies to be made and kill one (either one) instantly on reception, the transmitted person still exists in the other copy. All the things that person might have done, and all the thoughts she might have thought, are still possible. If, on the other hand, you allow both copies to live their separate lives for a year, and then kill one, you are the murderer of a unique human being.

But, if you wait only a short while, they won't differ by much, and destruction of one won't cause too much total loss. This rationale might, for instance, be a comfort in danger if you knew that a tape backup copy of you had been made recently. Because of the divergence the tape contains not you as you are now, but you as you were: a slightly different person. But still, most of you would be saved should you have a fatal accident, and the loss would be nowhere near as great as without the backup.

Intellectual acceptance that a secure and recent backup of you exists does not necessarily protect you from an instinctive selfpreservation overreaction if faced with imminent death. This is an evolutionary hangover from your one-copy past. It is no more a reflection of reality than fear of flying is an appropriate response to present airline accident rates. Inappropriate intuitions are to be expected when the rules of life are suddenly reversed from historical absolutes.

Soul in Abstraction

Although we've reasoned from strictly reductionistic assumptions about the nature of thought and self, the pattern identity position has clear dualistic implications. Though mind is entirely the consequence of interacting matter, the ability to copy it from one machine or storage medium to another gives it an independence and an identity apart from its machinery.

The dualism is especially apparent if we consider some of the variations of encoding possible.

The Float

Some supercomputer designs call for myriads of individual computers interconnected by a network that allows free flow of information among them. An operating system for this arrangement might allow individual processes to migrate from one processor to another in mid computation, in a kind of juggling act that permits more processes than there are processors.

If a human mind is installed in a future machine of this variety, functions originally performed by particular cell assemblies might be encoded in individual processes. The juggling action would ensure that operations occurring in fixed areas in the original brain would move rapidly from place to place within the machine. If the computer is running other programs besides the mind simulation, then the simulation might find itself shuffled into entirely different sets of processors from moment to moment. The thinking process would be uninterrupted, even as its location and physical machinery changed continuously, because the immaterial pattern would keep its continuity.

Acceleration and Diffusion

A process that is described as a long sequence of steps can sometimes be transformed mathematically into one that arrives at the same conclusion in far fewer operations.

As a young boy the famous mathematician Friedrich Gauss was a school smart-aleck. As a diversion a teacher once set him the problem of adding up all the numbers between I and 100. He returned with the correct answer in less than a minute. He had noticed that the hundred numbers could be grouped onto fifty pairs, 1+100, 2+99, 3+98, 4+97 and so on, each pair adding up to 101. Fifty times 101 is 5,050, the answer, found without a lot of tedious addition.

Similar speedups are possible in complex processes. So called optimizing compilers have repertoires of accelerating transformations, some very radical, to streamline programs they translate. The key may be a total reorganization in the order of the computation and the representation of the data. A very powerful class of transformations takes an array of values and combines them in different ways to produce another array. Each final value reflects all the original values, and each original value affects all the results. An operation on a single transformed quantity can substitute for a whole host of operations on the original array, and enormous efficiencies are possible. Analogous transformations in time also work: a sequence of operations is changed into an equivalent one where each new step does a tiny fraction of the work of every one of the original steps. The localized is diffused, and the diffuse is localized.

A program can quickly be altered beyond recognition by a few mathematical rewrites of this power. Run on a multiprocessor, single events in the original formulation may appear only as correlations between events in remote machines at remote times in the transform. Certain operations that don't matter in the long run may be skipped altogether. Yet the program is fundamentally unchanged. You know what's coming. If we thus transform a program that simulates a person, the person remains intact. Soul is in the mathematical equivalence, not in any particular detail of the process. It has a very etherial character.

The Message is the Medium

If a mind can survive repeated radical restructurings, infusion into and out of different types of hardware and storage media, and is ultimately a mathematical abstraction, does it require hardware at all?

Suppose the message describing a person is written in some static medium, like a book. A superintelligent being, or just a big computer, reading and understanding the message might be able to reason out the future evolution of the encoded person, not only under a particular set of experiences but also under various alternative circumstances. Existence in the thoughts of a beholder is no more abstract than as a transformed person-program described in the previous section, but it does introduce an interesting new twist.

The superintelligent being has no obligation to accurately model every single detail of the beheld, and may well choose to skip the boring parts, to jump to conclusions that are obvious to it, and to lump together different alternatives it does not choose to distinguish. This looseness in the simulation can also allow some time reversed action - our superintelligent being may choose a conclusion then reason backwards, deciding what must have preceded it. Authors of fiction often take such liberties with their characters. The same parsimony of thought applies to the parts of the environment of the contemplated person that are themselves being contemplated. Applied a certain way, this parsimony will affect the evolution of the simulated person and his environment, and may thus be noticeable to him. Note that the subjective feelings of the simulated person are a part of the simulation, and with them the contemplated person feels as real in this implementation as in any other.

It happens that quantum mechanics describes a world where unobserved events happen in all possible ways (another way of saying no decision is made as to which possibility happens), and the superposition of all these possibilities itself has observable effects. The connection of this observation with those of the previous paragraph leads us into murky philosophical waters.

To get even muddier, ask the question implicit in the title of this section. If the subjective feelings of a person are part of the person-message, and if the evolution of the message is implicit in the message itself, then aren't the future experiences of the person implicit in the message? And wouldn't this mere mathematical existence feel the same to the person encoded as being simulated in a more substantial way? I don't think this is mere sophistry, but I'm not prepared to take it any further for now.

Immortality and Impermanence

Wading back into the shallows, let's examine a certain dilemma of existence, presently overshadowed by the issue of personal death, that will be paramount when practical immortality is achieved. It's this: in the long run survival requires change in directions not of your own choosing. Standards escalate with the growth of the inevitable competitors and predators for each niche. In a kind of cosmic Olympic games the universe molds its occupants towards its own distant and mysterious specifications.

An immortal cannot hope to survive unchanged, only to maintain a limited continuity over the short run. Personal death differs from this inevitability only in its relative abruptness. Viewed on a larger scale we are already immortal, as we have been since the dawn of life. Our genes and our culture pass continuously from one generation to the next, subject only to incremental alterations to meet the continuous demand for new world records in the cosmic games.

In the very long run the ancestral individual is always doomed as its heritage is nibbled away to meet short term demands. It slowly mutates into other forms that could have been reached from a range of starting points; the ultimate in convergent evolution. It's by this reasoning that I concluded earlier that it makes no ultimate difference whether our machines carry forward our heritage on their own, or in partnership with direct transcriptions of ourselves. Assuming long term survival either way, the end results should be indistinguishable, shaped by the universe and not by ourselves.

Since change is inevitable, I think we should embrace rather than retard it. By so doing we improve our day to day survival odds, discover interesting surprises sooner, and are more prepared to face any competition. The cost is faster erosion of our present constitution. All development can be interpreted as incremental death and new birth, but some of the fast lane options make this especially obvious, for instance the possibility of dropping parts of one's memory and personality in favor of another's. Fully exploited, this process results in transient individuals constituted from a communal pool of personality traits. Sexual populations are effective in part because they create new genetic individuals in very much this way. As with sexual reproduction, the memory pool requires dissolution as well as creation to be effective. So personal death is not banished, but it does lose its poignancy because death by submergence into the memory pool is reversible in the short run.

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