A man came up to me looking for a solution to live forever. Arguably, that should be totally doable. Since humanity in the 21st century believes that human nature is but the result of brain activity, all it takes to live forever is keeping a brain alive forever--a challenging technological feat to be sure, but nothing prohibited by the laws of physics. As a prototypical man of the Information Technology era, his understanding was that we, humans, are no different than computers: we have a brain, which is equivalent to a computer's hardware, and we are the software that tells the hardware what to do. Therefore, in his view, what makes us us is the code, the software that runs the brain. The information processing that goes on in the brain supposedly (and magically?) generates consciousness. He also understood that the cerebral program, differently from computers, was coded into the brain through neuronal plasticity, meaning, the software was encoded via physical modifications of the actual hardware's internal interconnections and not as high-level instructions executed by an immutable structure.
As a neuroscientist, I was kind of used to keeping brain slices artificially alive. The technique of Brain Slices, invented in the 20th century, was quite useful for drug development and intraneuronal studies. Also, having worked with brain mapping of candidate patients to epilepsy and brain tumor surgery, I had a general understanding of the different areas of the brain and their functions. Better yet, I was aware of a "new technology", which would allow me to keep this man's brain alive artificially and indefinitely. I would monitor the activity of all of his neurons and, as they started malfunctioning, I'd simply replace the original neurons with synthetic ones, which were based on this new technology.
And here starts our thought experiment.
For decades, I followed that man, continuously mapping his brain activity and the health of every neuron. Every time a neuron got sick, I'd just replace it with a new, artificial one, which was rated for at least a thousand years. Meanwhile, other doctors and scientists would make sure his other organs were functioning properly as well, so that the brain would never run out of a body for it to play with.
By his 200th anniversary, my client's artificial brain was performing wonderfully and this man was quite happy, feeling at the top of his mental and cerebral game. Fortunately, his body was equally flawless and he was living a very accomplished life. (In order to care for him for such a long time, I found another scientist that applied the same technique on my own brain as well).
A few decades later, the man started feeling a little bored. He had lived all the experiences available to man and the technology wasn't keeping up to provide him with new and more exciting experiences. He asked me if I would put him to sleep for a few decades, so that the world would have the time to develop some more interesting stuff for him to do. "No problem," I said. We agreed that I would take good care of his brain while he was away. Sweet dreams.
When he returned, though, a few decades later, he thought he needed a new body, more in line with the other bodies of the time. Perhaps a body that could fly or submerge and breathe under water. Given body-science developments, I proposed to simply transfer his brain into a brand new body. He agreed. Since all he was was his brain, a physical and replicable machine, we also reasoned he wouldn't really need to keep using his old, outdated brain. It'd make more sense to simply transfer the old brain into a new one that would be based on newer technologies. Also, the new brain would allow for some added enhancements, which would include a universal translator and other knowledge that he would know without ever having to study.
As the computers that our brains are, we knew that, to transfer someone or someone's brain (which actually are the same thing, right?) into a new brain, it's not enough to simply replicate the hardware. Most importantly, we need the installed software to be the same and, particularly, the system state to remain the same in the new brain. That way, I would guarantee my client would continue to be exactly him. To capture the exact state, we would need to "hibernate" the man, which, in biology, is accomplished by freezing. And so we did.
We froze the man and his brain and started the process of transferring his old brain into a new brain. At this point in our technological evolution, the process is quite simple. It basically consists of 3D-scanning the old brain and 3D-printing an exact copy of it to nano-scale detail. (Unfortunately, there still was no way for us to make a brain copy to the quantum-scale level, because of all those fuzzy and ever fluctuating states, which are not readily copyable. Nevertheless, our technology was a marvel of science and, since what makes us us are the neural networks in the brain, there's no need to worry about that quantum mess.)
The process goes on flawlessly and, after a few hours, we have our client back, in his new, unfrozen superbody and his new brain. He woke up after unfreezing just as he usually does after a good night of sleep, which was expected. As previously agreed, we would exhaustively test the new brain in the new body to make sure the process concluded flawlessly and would not need to be repeated.
The final result was perfect! He was soon eager to see his friends and family members, who were unaware of the update just to allow for a blind validation that the man continued to be exactly him. That night, there was a dinner party to gather many of his more direct acquaintances. Our team followed him up close while discretely observing and measuring every interaction, every behavior and every human interaction during the party. By the end of the night, there was no doubt: the software and state transfer to the new brain was a real success. The client was very happy and nobody noticed a thing. He continued to be fully him. We did not attempt to try the new brain enhancements, like the translator, because there were no foreign guests at the party to practice with. Just noticing he was able to speak other languages was already very exciting for him at that point (let alone the new ability to fly and breathe under water!).
Next day, he came up to me to ask about the rest of the plan. Gosh, I wished that part of the memory transfer had failed, but he remembered... In any case, per contract, I was legally bound to unfreeze the original body, since the original client wanted to be sure it was really him in the new body. That was way out of protocol, which should have precluded me from waking up the old body, but he managed to push it on me anyway considering he was such a great sponsor of my research... The man in the new body was happy enough and wasn't really interested in waking up the old body, but he also remembered the agreement and the contract. And I had given my word, damn it...
We proceeded as originally agreed and unfroze the man in his original body with his original brain (as a matter of fact, at that point, his brain was anything but original, since I had already replaced most of the neurons with synthetic replacements). The man in the new body couldn't care less and went flying.
"Welcome back!", I greeted him in his old body. "I have great news! Your brain transfer was a huge success!".
"Oh, good morning doc. I had the most amazing dreams while I was away. How long has it been?"
Me, being a "great" doctor and fully ignoring his talk about dreams: "It's been just about 48 hours. We were able to verify that you in your new body and brain are just the same good ol' you. You're good to go for at least 2,000 more years!"
"That's interesting. Can I see him?"
"Well, that'd be totally against protocol. You should just trust me you're doing great out there."
"I'm sorry, but I can't trust that. If he's there and I'm here, that means I'm not there and I'm not him."
"Well, you're kinda right and wrong here. We do have two instances of the same program running in two different brains (they're actually equal, but distinct brains), but both instances are indeed you. Who else could that other instance be if not you, right?"
"I don't know, doc. All I know is that that one isn't me. As soon as you shut me down, I'll be gone for good and that was definitely not part of the plan."
"Listen, I can assure you: you are living, you are well and you are having a great time! You're just no longer using this old body and brain."
"Can he really fly?"
"Man, I wish I could that"
"But you can!"
"But it doesn't feel like it."
"Don't worry. As soon as we shut down this body, you'll be totally fine. Unfortunately, you won't be able to feel it while you continue to run in this body. That's why we need to shut you down."
"I'm sorry, doc, but I'm having second thoughts now. I don't trust that man to really be me."
"Well, he surely is you. His brain is a perfect copy of yours, sharing exactly the same state. Whatever consciousness that brain is generating, it is you! That brain is only capable of generating the very same consciousness that your old brain does, the one that I'm talking to right now."
"Well, if you're talking to me now and not to him, we are definitely not sharing the same consciousness. We're just two equal, but independent consciousness. I really don't think this is going to work. I want my own brain transferred to the flying body."
"But that's what we did! It is your brain that's there."
"It's not! That one is a copy!"
"Well, if you think this through, you'll realize that your current brain is no longer original either. I've already replaced almost all of its original neurons with new ones. Your current brain in this body is essentially a copy of your old brain, just like the brain in the new body is just a copy of this brain.
"I'm confused, this is the first time you make a copy of my brain."
"Actually, this was the first time I made a separate copy of your brain, but your brain is no longer your original brain either. It is also a copy. And that has been the case for a long time now."
"That's it! That separate copy is not me. The incremental improvements you made were still me, but that separate thing is someone else. I want this brain to continue to be upgraded, instead of getting a new one."
"You realize there's no real difference, right? Every time I did an upgrade in the past, I hibernated you. While you were hibernating, your brain was literally dead. There was no neural activity at all! It remained a dead brain while I was doing the improvements, which is a requirement to preserve the "state." As you can see, upgrading brains using our current technology requires me to deactivate the brain to preserve its state to then reactivate it in the same state as before. That's how you continue to be exactly the same as before after the procedure."
"You mean you killed me every time before bringing me back?"
"Not quite. If I had killed you, you wouldn't be here, right?"
"What you are is your brain activity, your brain state. As long as your brain is working, you are alive and you are you. The only difference now is that you insisted to be brought back in your old body and brain instead of just moving on with your new body and brain. If you continue to be using the old brain, we'll have a big problem. Your two brains will continue to develop independently and this you and your other you will start to diverge and will no longer be the same. Also, your wife has made it very clear that she loves you, but she can't handle two of you."
"Typical... Doc, let's move this brain to the new body."
"But it's the same thing! This brain will hibernate and will wake up in another body. The brain that is already there is structurally, connectively and logically the same as yours now, but it has better materials and will last much longer. While the brains are hibernating, they're just resting matter. They're scientifically indistinguishable from one another. If I didn't label them, I wouldn't even know which one is which, no matter how much I tested them. They were built to be equal!"
"OK, doc, enough arguing. You will put this brain in the new body and that's it."
"Well, then what do I tell the other you?"
"You figure it out. It's your grant at stake."
About 48 hours later...
"Welcome to your new body! You now have flying and submerging powers!"
"Hey doc, good to see you again! I had the most amazing dreams while I was gone!"
"Glad to hear! I want to hear all about it, one day..."
There certainly are many ways to interpret what's going on in the tale. Below is how I, particularly, see it.
1. Either you die and are born every moment or you can't die
We feel pretty comfortable with the idea of going to sleep, but we are terrified of the idea of dying. But what is the difference exactly?
If you believe that you are your brain state and you can accept that your brain is always changing and you can accept going to bed with one brain state and waking up the next morning with a different state that is no longer the same you as yesterday, then you should accept that the other person in the experiment really is you and you should accept to be shut down. Because that's effectively what's going on all the time with us in our lives. We're continuously shutting down one state (one copy) and creating a new state (a new copy) of our brains every single moment. That new copy is always going to be something slightly different than you, because you are changing (dying and being born) every single moment. From a strict physical perspective, you are your brain state. Your brain state is continuously changing, so you are continuously changing. If you're not the same as before, that kind of means that your prior you has died and the current you is something new (assuming we only are our brain states). Of course, those states are quite similar, in such a way that others continue to recognize you as you. But given enough time apart, people might stop recognizing you as you (which actually happens a lot in real life). As our brain state evolves, we continuously die and are born again. Whether that change of state happens in the "same brain" or in a "copied brain" is physically irrelevant. The brain state encodes our ego, that part of us that is deeply associated with the brain state. If all we are is the ego, then we die and are born every moment until we are not born again. Then again, what difference does it make to be born again if whatever will be born is no longer us?
But consciousness, differently from ego, could be non-local... There's a serious lack of evidence for consciousness being local. The only reason making us assume consciousness to be local is that we also assume non-physical realities to not exist, for which there's also a great lack of evidence. On the other hand, evidence for the existence of consciousness is plenty, even though each one of us is only capable of experiencing the first-person evidence of our own consciousness' existence. As a collective, though, we have billions of data-point evidence (i.e., conscious individuals) for the existence of consciousness. Yet, no physical process has ever been found to require the existence of consciousness at all. We only discuss consciousness, because we experience it, not because experiments have shown it to exist. If consciousness is non-local (perhaps even non-physical), then it might be the case it can't die just because a physical process has been terminated. For consciousness to die, it would have to be locally generated in the brain.
But, if consciousness is indeed local, whatever the Physics is that causes the brain to generate consciousness is completely unknown to current Science. Of course, that doesn't mean consciousness can't be locally generated by the brain, but that'd probably require new Physics. If new Physics is required, then it could well be the case that it might end up revealing a non-local sort of consciousness. What kind of crazy properties could a non-local consciousness have? Would it have to die at all? Think about it, we're already marveled at the whole new world perspective provided by non-local quantum entanglement, let alone a non-local consciousness...
It's worth noting that it took a 100-year revolution in Physics to make a physical machine able to generate a mere true random number (which was only recently achieved by quantum computers). What kind of revolution in Physics will we need to understand how to generate consciousness? What sorts of wonderful new realities could that new Physics entail?
2. If you can exist in more than one instance (more than one brain), where is your consciousness located?
Every time the doctor made a procedure to upgrade the brain along the years, it resulted in a new brain (a copy of the previous brain that replaced the original brain). The only difference in the experiment is that there had never been another copy of the brain existing at the same time to cause discomfort. Think of sleeping as a brain-upgrading procedure. Every time you go to bed and wake up, you feel comfortable that you continue to be you, that you continue to exist. You're not afraid of shutting down at night, because you know you'll be back tomorrow. But tomorrow's you is no longer you (because if you are just a brain state, tomorrow's state will be something or someone else). But you don't care, because your old you no longer is able to care and the new you is happy to exist. Whatever it is that exists doesn't bother about non-existing. When you see from an old body that you continue to exist in a new body, you should be more than happy to allow the doctor to shut you, the old body and brain, down. You don't need to be afraid of dying, because you continue to exist, just as you continue to exist every morning. But it's always another you, not the same you as before. In a sense, you die every night. The only difference now is that you are seeing yourself waking up next morning from the perspective of the you that hasn't gone to bed yet, the you that now realizes it's going to die. Because whatever wakes up the next morning is not really you, since you are there talking to the doctor while that other you isn't! It's uncomfortable. Yet, we go through that process every night (every moment, actually). So, if consciousness is local, you've already died multiple times. You're always dying. You're actually more like a simulation than a living thing. You shouldn't be afraid of dying, because you're not really alive in the first place. You're just a state machine.
If consciousness is non-local, however, it can't really die just because the brain died or was shut down. It's non-local and non-physical. And that would be e the difference between ego and consciousness. Because ego (behavior, social identity, etc.) is quite clearly related to brain state while consciousness isn't.
3. Every equal instance is nevertheless unique
The tale deals with the subject of identity, of what makes us us. Does our consciousness emerge from brain states and is thus physical and local by nature (even if understanding that would probably require some new Physics), or is it a non-local something that only makes use of our physical brain?
If we really are just our brains and consciousness is locally emerging from brain activity, then it should be possible to make physical copies of our consciousness. But if you do make a copy of your consciousness, then both copies are conscious versions of you, claiming the other one to be not you. Yet, the other you consciously experiences itself to be you too! The second copy will (rightfully) claim to be conscious and to be you and it won't accept being shut down (i.e., dying). We could probably have two equal egos in two different bodies, but could we also have two equal consciousness in two different bodies? If consciousness is local, then yes. If consciousness is non-local, however, then it could be the same, non-local consciousness experiencing two realities (two perspectives) from two different bodies. And if that is the case, couldn't we all be manifestations of a single consciousness? Could that all-permeating, non-local consciousness be what we call God? And if consciousness is able to non-locally experience two different bodies at the same time, could it be also able to experience the entire physical timeline at once? This could be seen as empty speculation, but "speculation" only applies to whatever is eventually factual and provable. Is our non-provable, non-factual, but every-day, first-hand conscious experience of life speculation as well? Certain realities can only be consciously accessed, not physically accessed. That's not a speculation. That's simply the most fundamental fact of life: that we are conscious and alive, even though that can't be (or at least hasn't been) scientifically proven.
If you believe that, when you wake up every morning, you continue to be the same person as yesterday, then you should have accepted that the copied brain in the tale with the new, superbody is indeed the same person as the one in the old body. If you reject that idea, you're actually putting consciousness outside the physical brain. In that case, consciousness would be defined by whatever makes one copy different than the other. But that difference can only be non-physical, for the physical brains are exactly the same.
In other words, your "consciousness identity" is not established in the brain or in the brain state. Since two brains with the exact same state will claim to be independently conscious and the same, then the brain states alone can not tell the two consciousness identities apart. There shouldn't be a reason for them to feel separate.
Identity (and, most fundamentally, we), as provided only by physical brain state, would be just that, just a physical state. In a sense, the existence of an exact copy of you would be proof that you do not actually exist. Because if the other copy is you and there's no way to tell you both apart, when only one of the copies is deleted, you both live and die, which is sort of a paradox. You either exist or you don't. If you don't exist, you can't live. If you exist, you can't die.
4. The choice is yours to make
It is important to note that, given the level of evidence we have today, assuming consciousness is local or non-local is an individual choice. It is your choice to live a life believing your consciousness is ephemeral, locally produced in your brain; or eternal, non-locally existing somewhere else (if you can make that choice, by the way, it means you have free will; and since no physical law has been discovered to empower a brain or machine of any sort with free will, that'd probably mean your free will comes from a non-physical counterpart).
We don't have the scientific evidence to show that the brain generates conscious experiences or that consciousness exists. Yet, we do have direct evidence that we are conscious beings. It is a choice between Science, a highly successful human-invented method for understanding non-human and non-living matters (like engineering, physics, chemistry, etc.) and a not-so-successful method for understanding human and living matters (economics, politics, psychology, etc.); and the Direct, First-Person Evidence that you are a living, conscious being. One assumes physicality is all there is. The other is non-constrained and unbound. Pick the one that makes you happier (or, if you're already happy, the one that gives you more degrees of freedom).
5. And what about the dreams??
There is a good deal of anecdotal evidence, with great consistency across the stories, of people who have gone through near-death experiences. It is interesting to notice that it seems to be the case that the more affected (knocked-out) the brain is in the near-death experience, the richer and more vivid the near-death experience is. That has led me to conjecture that the physical brain might actually work as a filter to a much broader consciousness field, so to speak. If consciousness is non-local, it could pertain to a realm with less constraints than our 4D, spacetime reality. The brain being physical, however, allows consciousness to narrow down its experience focus to just those stimuli allowed by the physical senses. Rather than generating consciousness, the human brain's job would actually be to constraint consciousness into a human life experience. Likewise, other types of brains would allow consciousness to experience reality from different perspectives. Only consciousness would know, for example, how it feels like to be a bat. Do bats experience ultrasound echolocation as an image, as a sound or as something else? That is a type of knowledge that can only be inferred from a third-person, scientific perspective (based on neural correlates and similarities to the human brain, for example), but only a conscious bat would have access to knowing what it feels like to be a bat that perceives ultrasound to produce echolocation.
To whoever may feel anxiety with the concept of death, I hope this will bring some comfort. Keep dreaming!