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Imagine a future where nobody dies—
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instead, our minds are uploaded to a digital world.
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They might live on in a realistic, simulated environment with avatar bodies,
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and could still call in and contribute to the biological world.
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Mind uploading has powerful appeal—
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but what would it actually take to scan a person's brain and upload their mind?
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The main challenges are scanning a brain in enough detail to capture the mind
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and perfectly recreating that detail artificially.
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But first, we have to know what to scan.
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The human brain contains about 86 billion neurons,
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connected by at least a hundred trillion synapses.
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The pattern of connectivity among the brain's neurons,
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that is, all of the neurons and all their connections to each other,
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is called the connectome.
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We haven't yet mapped the connectome,
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and there's also a lot more to neural signaling.
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There are hundreds, possibly thousands of different kinds of connections,
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or synapses.
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Each functions in a slightly different way.
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Some work faster, some slower.
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Some grow or shrink rapidly in the process of learning;
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some are more stable over time.
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And beyond the trillions of precise, 1-to-1 connections between neurons,
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some neurons also spray out neurotransmitters
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that affect many other neurons at once.
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All of these different kinds of interactions
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would need to be mapped in order to copy a person's mind.
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There are also a lot of influences on neural signaling
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that are poorly understood or undiscovered.
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To name just one example,
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patterns of activity between neurons
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are likely influenced by a type of cell called glia.
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Glia surround neurons and, according to some scientists,
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may even outnumber them by as many as ten to one.
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Glia were once thought to be purely for structural support,
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and their functions are still poorly understood,
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but at least some of them can generate their own signals
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that influence information processing.
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Our understanding of the brain isn't good enough to determine
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what we'd need to scan in order to replicate the mind,
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but assuming our knowledge does advance to that point,
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how would we scan it?
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Currently, we can accurately scan a living human brain
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with resolutions of about half a millimeter
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using our best non-invasive scanning method, MRI.
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To detect a synapse, we'll need to scan at a resolution of about a micron—
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a thousandth of a millimeter.
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To distinguish the kind of synapse and precisely how strong each synapse is,
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we'll need even better resolution.
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MRI depends on powerful magnetic fields.
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Scanning at the resolution required
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to determine the details of individual synapses
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would requires a field strength high enough to cook a person's tissues.
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So this kind of leap in resolution
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would require fundamentally new scanning technology.
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It would be more feasible to scan a dead brain using an electron microscope,
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but even that technology is nowhere near good enough–
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and requires killing the subject first.
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Assuming we eventually understand the brain well enough to know what to scan
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and develop the technology to safely scan at that resolution,
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the next challenge would be to recreate that information digitally.
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The main obstacles to doing so are computing power and storage space,
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both of which are improving every year.
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We're actually much closer to attaining this technological capacity
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than we are to understanding or scanning our own minds.
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Artificial neural networks already run our internet search engines,
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digital assistants, self-driving cars, Wall Street trading algorithms,
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and smart phones.
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Nobody has yet built an artificial network with 86 billion neurons,
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but as computing technology improves,
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it may be possible to keep track of such massive data sets.
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At every step in the scanning and uploading process,
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we'd have to be certain we were capturing all the necessary information accurately—
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or there's no telling what ruined version of a mind might emerge.
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While mind uploading is theoretically possible,
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we're likely hundreds of years away
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from the technology and scientific understanding
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that would make it a reality.
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And that reality would come with ethical and philosophical considerations:
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who would have access to mind uploading?
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What rights would be accorded to uploaded minds?
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How could this technology be abused?
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Even if we can eventually upload our minds,
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whether we should remains an open question.