Bandwidth of your brain

How much bandwidth does it take to run a completely convincing virtual environment for one person? The answer is surprisingly small. In Consciousness Explained, Dennett claims that an "interactive smello-feelo television would have an astronomical bandwidth" (6); he didn't bother to estimate how astronomical. If you've ever studied physics, you'd be familiar with this kind of estimation: a Fermi problem. Let's play:

A Blu-ray disk outputs a maximum of 40 Mbit/s; it's the best quality video for the general consumer, and it's just about as good as our eyes can see. Blu-ray has surround-sound audio too, so the 40 Mbit/s covers two of our senses: sight and hearing.

Smell and taste are both slower and less sensitive than hearing, and way less than vision. We can distinguish something that's flashing once per second from something that's flashing once per half second. We can easily tell when a musician switches from one time signature to another. But have you ever smelled something that pulsates every second? 10 Mbit/s should cover both smell and taste, and that's being generous.

Proprioception is even simpler. The body has 200ish bones and a similar number of joints. At each moment we are aware of the angle of each of those joints. We are also aware of how tense each of  those skeletal muscles are. A virtuoso piano player can hit about 20 notes per second, and she must know exactly where her fingers are; that gives 20*200*16 = 64 kbit/s, with the 16 bits encoding the angle.

That just leaves touch: pressure, pain, and heat. Skin is the biggest sensory organ in the body, but is it more sensitive than sight? We can feel tiny vibrations and locate pressure with pin-prick precision, especially near our hands and lips. I think 50 Mbit/s would suffice for the entire body (including those extra sensitive parts :)

What about output? The only interesting way of sending information is through our muscles. Yes, I'm going to exclude any excretion of bodily fluids. We have 600ish skeletal muscles which can be moved at about 20 times per second, with varying levels of contraction. That's only about 1 Mbit/s. It's not surprising that our sensory input is 100 times greater than output. You'll probably find the same ratio if you look at your computer's network usage.

So that adds up to about 100 Mbit/s, give or take a factor of 10. In comparison, the current wireless LAN protocol (802.11n) has a max data rate of 600 Mbit/s: more than enough to saturate every one of our senses. All we need is a modem to convert digital signal to the right impulses, and splice it into our nerves.

 Yes, you can kick ass in the Matrix through an 802.11n wireless network.

What about Dennett's other objection, that interactive simulations will take more bandwidth? That is actually a mistake; I have already covered all the input and output channels of a human brain, and analyzed the total bandwidth. Interactivity with the environment is a result of the laws of physics: gravity, thermodynamics, light, solids and liquids, etc. Calculating the result of you throwing a rock into a pond will not demand any more bandwidth; this simulation only requires processing power. Today, we have graphics chips (from nVidia and ATI)  that can produce real-time, nearly realistic rendering of scenes; these chips use specialized circuits to compute the way light interacts with matter. Those same companies are also making specialized physics chips that can simulate how pieces of matter interact with each other.

What's the hold-up then? Why aren't we hooking our brains up to virtual worlds yet?

Oh, right.

More than human

In the olden days, people use to think that the Earth was at the center of the Universe. They thought that their particular city or country was at the center of the world. All of their maps were drawn this way, but this isn't just a matter of convenience - it was an outlook, a philosophy. People are by nature self-centered and narcissistic beings.

Today, some people believe that human beings are the end-product, the apex of billions of years of evolution.  Again, it's not a matter of convenience, but an actual perception of biological history. The cartoon above (parody of the iconic illustration by Rudolph Zallinger) shows a progression from ape to modern man. It presents evolution as an inevitable ascension toward the top: us. This view is false. Though we can trace our own lineage back to proto-apes, and though there are no surviving semi-human species, evolution is not directed, and it does not have an end-goal. We are merely an extremely successful species among millions of others.

There's no reason to believe that the homo sapiens is the final step. The optimist tells me that we are not a dead end species either. No, there will be a next step; we will become more than human. Once we embrace that idea, only one question remains:

How long?

Epic Showdown: American power armor vs Japanese cyborg exoskeleton

We need to make this fight happen.

On the right: the XOS combat chassis, developed by Raytheon Sarcos to augment the American soldier of the future; can bench 200 lb weights till he gets bored; flexible enough to go up and down steep inclines, and strong enough to punch your head clean off. May come with bulletproof armor plating and sharp stabbing hooks. Available exclusively to the military. (video)

On the left: HAL exoskeleton, developed by Cyberdine and Japanese roboticist Dr. Sankai; can lift a paralyzed man to the summit of the Swiss Alps; carries your grandmother down the stairs; controlled by nerve impulses; helps paralyzed or weakened people to walk again. Comes with a 5 hour battery. Anyone can rent this for $2000 a month! (video, video)

Who do you think would win in this fight? Obviously, the killer military machine, right? Don't be so sure. Doesn't the HAL suit remind you of something? Maybe a story that we all know and love:

A gawky and oppressed teen finds shiny robotic suit. It transforms nerd into superhero. He stops criminals and saves babies and rescues stranded commuters. At the end, he faces down the nasty bully who has been slapping him around for years, and somehow the bully had gotten hold of the battlesuit that looks like a Terminator. It's David vs. Goliath. I think we all know how that fight should turn out.

This scenario brings up the issue of image and narrative. We have learned so many associations and stories that we can't help but draw connections when we contact something new. A piece of technology is not just a collection of functions; it speaks to us, to our subconscious. Apple, for example, is a master of this technique: merging function with personality.

If we hope to make smooth strides in living with any new forms of technology, we should pay attention to the public perception of it.

Article: Cyborg Exoskeletons May Soon Become as Common as Bicycles