Some year’s ago Chris Chatham posted a look at the differences between a brain and a computer (Chatham post) and recently Steven Donne re-visited the idea in a post (Donne post) These are both interesting reading.
I part company with Donne on several points. The first has to due with the definition of computer. Some people define ‘computer’ so widely that it includes anything that computes anything. In that case the brain is a computer and there is no metaphor to examine. On the other hand it is reasonable to include more than the stock home or business computer. Super-computers, robotic computers and those that are just around the corner are metaphor material. Donne brings up computers that are built precisely to mimic and explore the brain - simulations of the brain. As a metaphor this is lame. If I build a replica of something, there is nothing to be gained in understanding by a metaphor between the original and the replica. So we are left with brain simulations in fairly conventional but advanced computers or some more faithful replica of the brain.
Second, Donne feels that there will not be a problem with size and appeals to the idea that computing power increases exponentially so it cannot be all that long before a computer could be built that would handle a brain simulation in real time. He points to a 1 second of brain activity having been simulated. Well, that should be ‘sort-of-simulated’. The 1 second took 40 minutes to compute. (factor of 2400) Then the brain activity for the simulation was a simple network exercise – not really brain activity, missing the complications of real brain physiology. (factor of ?) The amount of brain simulated was small – 1.73 billion neurons simulated with about 83000 processors. (factor of 50) 10.4 trillion synapses were modeled. (factor 100+). I assume that the glia calcium ion communication, magnetic and chemical fields and so on were not part of the simulation. (factor ?) So I am assuming that something like 5 million times the size of this simulation would be needed for a realistic one and that would be 40-50 years of Moore’s Law type exponential growth at a bare minimum. But this would not give a brain-receiving computer that could accept the upload of a real human brain. That is a much bigger problem than a standard simulation. There would have to be an understanding of how and where all information was held in that human brain, a way to ‘read it out’ and place it in the simulation so that it has the same usefulness. Are we going to understand the brain at that level within 50 years – maybe but I doubt it.
Thirdly, Donne says that if it is possible, it will happen. I think that is possible - once. But the idea that anyone who wants to be immortal could just have their brain up-loaded on death is plainly silly. It would be too expensive to do more than a few times even if it were possible. I can imagine what would happen the first time there was not enough ‘power’ for both the living people and the simulated brains. The power would be switched off of some simulations. It seems the height of arrogance for someone to assume that they have the right to be immortal and to have future generations honour that right. The people at a time more than 50 years into the future will have more pressing problems, given current predictions of climate change, population growth, resource depletion, pollution, more destructive wars and whatever else is in store. Immortal brains in simulations seem to me part of the optimistic myopic vision of the science fiction lovers – futures of space travel, infinite resources, even time travel. Humans will be lucky to live through the century without being reduced to a rough and hard dark age.