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Is the brain Quantum or Classical

While Max Tegmark opposes the idea that the brain could be a quantum computer, Sir Roger Penrose and others would say otherwise. I will not go into the details of their individual reasons for making their assertion but I would like to explain why Sir Roger Penrose alongside Stuart Hameroff might have a good point.


Max Tegmark in his view that the brain is not quantum points to the fact that it's wet, warm, and noisy nature may prevent any kind of quantum effect from taking place. This idea almost borrows from the fact that Quantum Computing takes place most favourably in highly controlled environments that are sealed as much as possible from the environment. These systems also operate at extremely low temperatures akin to the kind you could find in deep space. So from this understanding, Tegmark argues that it is not possible for the brain to be a quantum computer.

Penrose and Hameroff go on the opposite trajectory by insisting that the brain at the level of microtubules is actually performing quantum computing via a mechanism called Quantum Orch-Or. While the details a much more involved, what I intend to do here is to make a proposition which I think from my own intuition could be correct.

If you read my previous blogpost on quantum computing you would remember that I described the difference between classical and quantum computing being that while in classical computing adding an extra bit only increases the computing capacity of the system linearly in quantum computing every extra qubit increases the computing power available exponentially.

I also talked about a theoretical scenario where we would be searching for the solution of a problem which is represented as a sequence of bits and that in classical computing would have to go through each set of bits sequentially but in a quantum computer one could search all possible configurations simultaneously. If this is too vague just read that blog post again.

Both parties on either side of the conflict are very knowledgeable and have very solid points backing thier arguments. I wonder what are Tegmark's views concerning the recent discovery of quantum effects observed during photosynthesis? As we all know, the plant is also a wet and messy medium so it would be interesting to see what his views are.

Personally, I am inclined to follow the Penrose/Hameroff path because I think at some level, even if it's not via microtubules, the brain is doing some kind of quantum computation.

Our current understanding of learning and intelligence is focused solely on the connectivity of the neurons in the brain. These are the roots behind deep learning, etc. Not many people in the mainstream artificial intelligence community think beyond the connections of neurons in the brains as the source of intelligence but if we consider how simple brain functions like memory recall work we would see that our simple connectionist view cannot account for the sheer speed with which information is recalled which makes me suspect that the brain might indeed be quantum and memory recall could simply be a process or measuring the results of some quantum search operation.

Without going into much about how the brain actually recognizes patterns or does computations lets just focus on one aspect of the brain which is memory and recall. How could you go mentally from thinking about something that happened yesterday and something that happened when you were 10 years old in such a very short period of time? Considering the enormous amount of information you would have to sort through and the tiny amount of computing power it took and compare it to how much power is actually used to service a single Google request.

If one thinks of all the sophisticated computing that must take place to service a single Google request and what is required to just jump around in your mind then one must realize that the brain is really amazing.

But without get caught up let us ask how the brain is doing this with very little power and within so short a timeframe? The answer I think lies in quantum computing, rather than go through a search sequentially as a classical computer would do, although with some sophisticated algorithm the search is far from sequential, generally the search doesn't happen all at once like would be the case on a quantum computer.

I think that the way the human brain is able to access all its memory at once and find what it's looking for may be because the brain is fundamentally quantum and somewhat able to search its whole database instantly.

One could say that why is it hard to remember sometimes if the brain is able to search its own memory at once, it would say it is because of physical imperfections and the natural variations from one brain to another. Why the regular everyday person could notice major lags in trying to recall some memory, someone like rain man would not have any such lag and would recollect anything instantly. So the lag is not an inherent aspect of the human mind rather it is the case with brains that are not biologically sophisticated enough to be photographic.

With the neural learning paradigm, we are seeing that some information could be learned and stored in a model and then when we want to search for something we could query the model with some new information and the model would return some meaningful result about the query.

We could say that our brains do not store information but rather models that are capable of generating whatever information the brain has stored and while we are all in the buzz with Neural Networks etc. One would think this is sufficient to explain all brain function but one must realize that a model compresses information as it attempts to generalize if not the model size would grow at the same rate as the amount of information it stores.

Generalization is a kind of lossy compression because not every aspect of the source information would be generated if queried but enough features of the source information are encoded in the model to enable us to match the model and some new unseen source information and produce a reasonably confident prediction about what the source information is.

Generalization holds a key role in the nature of our intelligence but it is not everything. The brain not only has a model of the information it has perceived but also the full data that was input.

Personally, I would say that the brain could be quantum at some level just because of the way it searches its database. Either way, time will tell finally



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