Originally posted by sonhouse
You have a problem with some of your conclusions. You think it impossible to repair a brain cell without touching it, but you are forgetting about the possiblities of nanoengineering...
I was coming to the problem of nano-engineering but the post would not let me send any more words of the article I have made about it so that I could not explain my reasoning. I have sent the next part of my article below from the paragraph where the first part I sent ended but it is still very incomplete:
...firstly, I think it is unlikely that a non-toxic antifreeze mix that it fully soluble in water can be made to have a freezing point as low as liquid nitrogen temperature (although I would really like to be proven completely wrong!). That would mean that the brain couldn’t be cooled to as low a temperature as with conventional cryogenic preservation and that would mean that there may be slow chemical degradation of the cryogenically preserved brain though centuries of storage. Still, if the temperature can be made cold enough, perhaps this slow chemical degradation can be made so slow that, even after several centuries, the damage done would not be too significant.
The second reason why there may be slow chemical degradation is that, because the brain would not be frozen solid, the brain cells would be constantly exposed to a liquid media. Because the soluble organic molecules in the brain cells would be immersed in a liquid and not a frozen solid, even though the temperature would be vary low, they would still inevitably move and drift by diffusion. After a century, a soluble molecule could have slowly moved quite a distance from its original position. I would guess that all the soluble molecules in a brain cell would eventually end up on the outside of that cell after a century and probably much less time than that. Perhaps it is possible to design an antifreeze mix that is so viscose at that low temperature as to make such movement of molecules insignificant but I seriously doubt it. What could be just as bad is that this movement of molecules would make them regularly meet with each other and one of the minimal requirements for a chemical reaction to take place is for molecules to meet. This could mean that they could sometimes chemically react when they meet and that would inevitably mean slow chemical degradation. But one thing chemical reactions also need is sufficient temperature and if the temperature can be made to be cold enough then perhaps this could stop all significant chemical reaction -but I doubt it.
My conclusion here is that what I call ‘soft preservation’ of the human brain would be less than ideal and, again I conclude that we desperately need to find a way of freezing the brain solid without producing micro fractures.
The ‘nanobot delusion’:
Some people have the wildly optimistic delusional idea that technology will eventually solve all these problems because they assume that eventually technology will somehow eventually create so-called ‘nanobots’ (robots that are only a few nanometers across) that are so small that they can squeeze between the brain cells and brain cell connections and be programmed to repair the microscopic damage. Unfortunately there are several reasons why this will always be pure science fiction:
Firstly, and most importantly, I believe that it not possible for any ‘useful’ ‘nanobots’ to physical exist without subtlety and implicitly braking the laws of physics. Don’t misunderstand me here; I am not simply saying that nanobots could not physical exist per se. I just believe that, despite the tremendous hype surrounding nanobots, no ‘useful’ or ‘practical’ nanobots could physically exist and certainly not useful enough to perform the extremely complex task of repairing some microscopic damage in a human brain.
There are a number of reasons for this but first we must clearly understand the distinction between a ‘nanomachine’ and a ‘nanobot’. Obviously, all robots are machines but not all machines are robots. Strictly speaking, what distinguishes a ‘true robot’ from a mere machine is that all true robots have three extra things:
1, they all have ‘sensors’ that can measure some aspect/aspects of their external environment.
2, they all have what are called ‘activators’ which are devices that allow the robot to perform physical movement by exerting a force that pulls or pushes or rotates something such as a leg or arm or wheel etc.
3, they all have some kind of ‘brain’, that may merely consist of a tiny circuit, that can take in signals from the sensors, analyse them, and then, depending on that analysis, send some appropriate signals to the robot’s activators to make the robot perform the appropriate movements.
There is no doubt that nanomachines can physically exist. After all, nanomachine already exist throughout nature! For example, the structure called a flagella on sperm that wipes around and propels sperm forward can be considered to be one of natures nanomachine. There are many other examples: structures called ‘microtubules’ that exist in all living cells including our own human cells pump around chemicals around the cell and can be considered to be another one of natures nanomachine as they are just a few nanometers across. So, obviously, as nanomachine already exist in nature, it must be possible for them to be artificially created.
However, the problem here is that all these ‘nanomachine’ are essentially ‘dumb’ and each type of nanomachine blindly and crudely performs only one repetitive task. But what would be required to repair the microscopic damage in a conventionally cryogenically frozen human brain would be something with intelligence for it would somehow would have to work out and ‘know’, for example, which broken end of a nerve connection belongs to which other broken end of the corresponding nerve connection along a micro fracture. No ‘dumb’ machine could do this, hence, if nanomachines are to do the job, what would be presumably required here is that they must be ‘nanobots’.
But for a robot to be nano-size, it would have to have nano-sized sensors, nano-sized activators and a nano-sized brain. It would be possible to make nano-sized activators without too much problem and we can be sure of this because such activators already exist in nature (e.g. flagella on sperm). The problem is creating nano-sized sensors and a nano-sized brain; especially a nano-sized brain. That is because anything that is nano-size can only consist of a very few molecules at most and this severely limits the sophistication of what it can do.
It must be possible to make nano-sized sensors because such a thing already exists in nature. But each kind of nano-sized sensor that exists in nature can only detect only one narrow kind of simple stimulus such as the presence or absence of a particular bandwidth of light or the presence or absence of a particular kind of molecule or class of molecules. One thing that is physically impossible for a nano-sized sensor to do is to act as a complete camera that can take a visual picture of its environment. That is because, implicitly, according to the laws of quantum physics, no lens can effectively focus an image to the back of a camera film (or, indeed, a retina) if the lens has a diameter that is less than half of the wavelength of light it is supposed to focus. But, in practice, it is generally agreed that the lens would have to be at least several times wider than that to be practical because otherwise the image produced would be blurred anyway. Visible light has a wavelength between about 390 to 740 nm so any robot with a practical camera lens would, at the very least, because of the size of that lens, have to be more than just a ‘few’ nanometers across but then it would be too large to be described as a ‘nanobot’. Even if a ’nanobot’ can somehow be built with super-intelligence, how is it supposed to repair the microscopic damage in a cryogenically frozen brain if it has no camera to give it a clear picture of exactly were the microscopic damage is and how to fix it? For similar reasons (related to wavelengths), you can rule out the possibility of a nanobot using ultrasound-sonar as well as radar to give it a clear picture of exactly were the microscopic damage is and how to fix it.
I suppose it could use a sense of touch so that it would be like a blind-man feeling about with a walking stick. But, on that scale, you could not even make a robot use a walking stick with nearly the same skill and sophistication as a blind man can. There are a number of reasons for this; a blind man has a sense of touch vastly more sophisticated than what can be achieved by a bunch of touch sensors consisting of just a few molecules. And, even a blind man has a sense of direction and orientation because he has such sophisticated things as the movement of fluid within a balance-organ in his middle ear. But on a nano-scale virtually all liquids and even pure water behaves as if they are thicker than treacle so how can a nanobot have such a sense of direction? I had thought of equipping each nanomachine with a molecular-sized magnet and placing the whole of the brain in a powerful magnetic field but this would, at best, give it a crude sense of direction; it may tell it which way is ‘north’ but how would it be able to distinguish ‘east’ from ‘west’? And, more importantly, how would a ‘nanobot’ be able to ‘sense’ exactly where it currently is in the human brain? I don’t see how it is physically possible for something that consists of just a few molecules to have such an amazingly sophisticated senses that it can ‘sense’ exactly where it is in something as complex human brain or were it is in relation to some molecule just a few micrometers away from it. So how would a ‘nanobot’ be able to intelligently navigate through a human brain? The answer is it couldn’t.
You can rule out the possibility of making nano-sized sensors that can see in X-rays and can be used to see the microscopic damage in the human brain because, although they have shorter wavelengths than visible light, X-rays ionise orga...