Other researchers in the field have had pretty impressive successes with sensory data. The most common neural prosthetic in the world is one that turns audio signals into direct nerve stimulation in the brain – the cochlear implant. More than two hundred thousand people worldwide have one. If you don't have a cochlear implant, or know someone who does, it may seem like just a specialized hearing aid. But it's very different. A hearing aid picks up audio via its microphone, cleans up that audio, amplifies it, and then plays it via a tiny speaker into the wearer's ear. But that only works if the wearer still has some hearing. If all the hair cells of the inner ear are dead, no hearing at all is left in that ear. You could play 120 decibel sound into that ear and still get nothing. So the cochlear implant bypasses this. It picks up sound and turns it into nerve signals – specifically electrical signals that stimulate the auditory nerve. And it's far from perfect, but it gives people who previously had no hearing at all hearing good enough that they can take part in conversations around them.
In the mid 2000s, scientists started to do the same for vision. A scientist named William Dobelle created the first neural vision prosthesis, and with the help of a neurosurgeon, implanted it into the brain of a man named Jens Naumann who'd lost his eyes twenty years earlier. The system is pretty simple – a digital camera worn on a pair of glasses picks up images. Those images are processed by a simple computer. And then they're sent into the visual cortex – the part of the brain responsible for vision – by a set of electrodes that enter the brain through a jack in the back of the skull. Jens, the patient who received the first of those, didn't get back vision anywhere near as good as he'd had before losing his eyes, but he got back vision good enough that he could see objects and navigate around them. In a video I play for people, you can watch Jens drive a Mustang convertible around in a parking lot, using his new prosthesis to see the obstacles in his path. The direction of research has shifted a bit since then, with current work focusing more on getting the data into the brain by stimulating the optical nerve behind the retina instead of deeper in the brain, but the principle is the same – we can take sensory data and turn it into nerve impulses that the brain understands.
We can also do the opposite. In 2011, a group of scientists at UC Berkeley, led by Jack Gallant, showed that by using a functional MRI machine (a brain scanner that can see some activity going on inside the brain) they could reconstruct video of what the person was currently seeing. The video is awfully rough, but it's a start. We can not only send sensory data into the brain, we can get it out.
One striking thing about all of these efforts is the very small amount of data going in and out of the brain. The most sophisticated brain implants created to date – like the one implanted in Jens' brain to restore vision – have only 256 electrodes. By contrast, the brain has around one hundred billion neurons. The visual cortex and motor cortex each have billions of neurons on their own. It's amazing we can get anything useful in and out with such limited data. The small amount of data bandwidth we have explains why the vision we restore is grainy, why the hearing isn't good enough for music appreciation, and so on. But one thing we've learned over the years is that electronics get better fast.
Indeed, one of the pioneers of neuroscience, an elder statesman of the field named Rodolpho Llinas who chairs the NYU Department of Neuroscience, has proposed a way to get a million or more electrodes in the brain – use nanowires. Carbon nanotubes can conduct electricity, so they can be used to carry signals. And they're so small that a bundle of one million nanowires would slide easily down even the smallest blood vessels in the brain, leaving plenty of room for blood cells and nutrients and so on. Llinas imagines inserting a million-nanowire bundle, and then letting its individual wires spread through your brain like a bush, until a million neurons in different parts of the brain could all be communicated with. A system like that would revolutionize our ability to get information in and out of the brain, enabling much of what I've described in this book.
Of course, it's still fiction. The research to date has been a great proof of principle. It's shown that we can get data in and out of the brain. It's shown that we can interpret that data to make sense of what the brain is doing, or to input new data in a way that the brain can make sense of. What we're left with is an incredible challenge for engineering and for medicine – taking that proof of principle, and building on it to increase the amount of data we can transmit, decoding more and more of that data, and doing so in a way that's safe and healthy for humans. That work will be motivated by medicine – finding ways to restore sight to the blind, hearing to the deaf, motion to the paralyzed, and full mental function to those who've suffered brain damage. And that work will take decades to bring to full fruition, if not longer.
A few other tidbits: Genetic enhancements to boost strength, speed, and stamina are likely already possible. Over the last decade researchers looking for ways to cure muscular dystrophy, anemia, or other ailments have shown that single injections loaded with additional copies of select genes (delivered by a tame virus) can have a lifelong impact on the strength and fitness of animals ranging from mice to baboons. Those enhancements, by the way, are nearly impossible to detect in humans. It's possible that some athletes, for example, are using them today. And DARPA has shown quite a bit of interest in such enhancement technologies for future soldiers.
Finally, the Nexus backdoor that Kade and Rangan code on the airplane is based on a very real hack created by Ken Thompson, one of the inventors of the Unix operating system, that gave Thompson and his colleagues a back door into every copy of Unix that existed for several years. That hack went undiscovered until Thompson revealed its existence in a public lecture, after all versions containing the back door were gone, more than a decade later.
If you're interested in more, feel free to pick up my non-fiction book More Than Human: Embracing the Promise of Biological Enhancement. That book goes in depth into brain computer interfaces and also into the genetic enhancements that might make humans stronger, faster, smarter, and longer lived than ever. As a bonus, it dives into the politics, economics, and morality of human enhancement – other topics that Nexus touches on.
To understand a thing is to gain the power to change it. We're surging in our understanding of our own makeup – our genes, our bodies, and especially our minds. The next few decades will be more full of wonders than even the greatest science fiction.
Acknowledgments
Writing is thought of as a solitary craft. Yet for me, the production of this book has been an experience of tremendous support, encouragement, and constructive engagement from others. This novel was born as a purely recreational exercise in writing fiction, in a casual writing group including Kira Franz, Gabriel Williams, Leo Dirac, Corrie Watterson-Bryant, Dana Morningstar, and Scotto Moore. Those Sunday meetings and that first handful of readers gave me something to write for. Their encouragement and critique helped me tremendously.
Eventually this work transformed from a lark to an actual attempt to write a novel. Through the subsequent process of writing a book, Molly Nixon provided me with invaluable assistance, going above and beyond what an author can ask of anyone, serving as first reader and often nightly reader of raw pages, as a keen mind to bounce ideas off of, and as a bottomless well of enthusiasm.