How viable would an analog computing revolution be?
I am trying to write a sci-fi setting in a not so distant future in which analog signal (brainwaves, in this case) processing is one of the main points of the plot and pretty much required to explain some of the mechanics going on in the universe.
Thing is, analog to digital conversion is expensive, and it may compress data into a easier to handle finite set of values that would, in exchange, make it drop some information in the process. This is something I don't want, since some of the mechanics required to develop the plot require subtle differences in a person's brainwaves (in this case, used as some sort of biometric key). This last part can be avoidable by just throwing more resources at a regular digital computer, but that's lazy and something I don't want, as an analog computer could allow for more interesting details and implications.
Just how viable would it be for the world to go back to analog? In the past we had analog computers, but we changed to digital because apparently they weren't designed with programmability in mind (as in, they were like ASICs) and soon digital became better than analog so there was no reason to try to improve a deprecated technology. Likewise, most of our telecommunication devices operate on waves and analog signals, but they are translated to digital at some point of the process (ie. the modem) and lose all the properties an analog signal has.
DARPA tried to build an analog "cellular neuronal network" CPU (project UPSIDE) for computer vision back in 2012, but there is not much information about it. Apparently, it allows for much faster speeds at a lower energy cost, at the expense of some errors from time to time and what has been described as requiring a much different way of tackling problems. Problem is, it says nothing about how programmable it is (which it apparently is, but it doesn't mention if it's Turing complete by itself or not). In addition, it seems to be a hybrid analog-digital computer, which is the concept I initially thought about including in my story.
In the future, could we see the following things? How superior would they be to their digital counterparts? Would they have any limitations?
* Purely analog CPU (could they run the programs we run today? As in, would they still be usable as a PC?)
* Hybrid analog-digital CPU, where they complement each other depending on the problem at hand
* Analog RAM/storage. 634
May be digital-analog or purely analog. Could it be made persistent, like with memristors? How would this work, anyway?
* Truly analog telecommunications. I know they are impractical due to possible signal noise, but let's assume we have a reliable solution to compensate that, such as algorithms capable of discerning the real signal
* Holographic CPU? Both digital and analog. I know a digital optical CPU is viable in theory, but I have no idea about analog; I assume it could operate on light frequency/color or something.
* Analog-oriented programming languages. How different would they be from the programming languages we use today, if any? Could a uniform analog-digital language exist, where a smart compiler decides whether to use the analog CPU or the digital CPU in a fashion similar to what hUMA compiler optimizations already do?
Mind you that while this setting isn't supposed to be hard sci-fi at all, it isn't fantasy science either. Whatever the answers are, they should be at least remotely viable in reality, and more specifically, doable within the following 70 years or less, although computer science could always do some breakthroughs. No suspension of disbelief should be required to enjoy the setting, even if you were somewhat knowledgeable about the field.
Note: I guess you could draw some parallels from analog computing to quantum computing, since both seem to work best (or only) on probabilistic algorithms instead of deterministic, but this is not about quantum. Quantum technology exists in this setting, but it's extremely rare and only used in some specific contexts, not to mention most of it is extremely experimental and the general public is oblivious about the existence of the somewhat viable prototypes.
Edit: to be more specific, the context and usecase of this technology is that user input is now handled through some sort of a matrix of electrodes implanted into the brain, capable of reading the user's brain activity/thoughts. The software handling the output of this matrix already tries to transform brain activity to some sort of "universal brain language" that covers up the differences between human brains, but still requires an analog/real numbers/wave signal for fine precision (not as in error-free, but as in descriptive) and high throughput. 634