His Unbelievable Vision of a Post-Human Future

The Age of EM: Work, Love, and Life When Robots Rule the Earth by Robin Hanson (a professor of economics at George Mason University) is a new book that speculates in the greatest detail about what kind of world will arise if a weird possibility occurs. The weird possibility that Hanson imagines is that humans become "not the main inhabitants" of the earth, being overshadowed by what he calls “ems.” Hanson defines an “em” like this: “An em results from taking a particular human brain, scanning it to record its particular cell features and connections, and then building a computer model that processes signals according to those same features and connections.”

What Hanson is imagining is essentially android robots, but not robots who are controlled by artificial intelligence programming. Hanson is rather skeptical about artificial intelligence programming, and says on page 382 it will take two to four centuries before it is capable of achieving “human level” capabilities. But Hanson thinks there's a shortcut. He thinks we can get robots as smart as people by scanning human brains and then loading that information into robots. He thinks this will be feasible within about a hundred years. Hanson thinks that before our planet sees any robots smarter than man, there will be one or more centuries in which our planet is largely inhabited by robots about as smart as humans – robots whose electronic minds are duplicates of human brains.

Hanson gives us a cold vision that is morally repulsive. After discussing a destructive form of brain scanning that is rather like a turkey slicer (page 148), he suggests using eugenics to produce a superior stock of humans to have their brains copied into robots.

The rest of the world has pretty much rejected eugenics since the fall of the Nazis, but apparently not Hanson. On page 162 he says:

It is possible that sometime in the next half-century or so we we will be able to create babies of substantially higher genetic quality by embryo selection in the context of in vitro fertilization. If so, when they reach the right age these may be very attractive candidates for scanning into ems.

Does the professor thinks we should wait until the genetically engineered super-kids are grown, and then feed their brains into his brain scanner that is like a turkey slicer?

On page 146 the professor proposes that the millions of robot “ems” that are copies of human minds should be given only “wages near subsistence levels,” even though he assures us on page 150 that these “ems” are “mentally quite human.” He offers this cold justification for this cruel proposal.

Readers of this book may find near-subsistence wages to be a strange and perhaps scary prospect. So it is worth remembering that such wages in effect applied to almost all animals who ever lived, to almost all humans before a few hundred years ago, and for a billion humans still today.

And what about all the humans who would have all their jobs lost by this great army of “ems” that would appear? Hanson seems to have little interest in the fate of the old-fashioned creatures known as humans. I looked up “humans” in the index of his 384-page book, and I see the last reference to “humans” is on page 14. Hanson does not imagine that humans will become extinct, but he imagines on page 8 that humans will live in retirement cities, with the "em" robots living in separate cities (how is he is able to make so specific a claim I don't know). 

Hanson imagines that the human race will be economically eclipsed by robots that have copies of human minds, but we may ask: what would be the point of that? Hanson tells us that it would occur because such robots will be more efficient, and work much faster. But it is very far from clear that this would be true. Give me a year 2100 human armed with all the best year 2100 gadgets (and some pills helping him think faster), and such a person should do just as well as a robot with a brain copied from a human.

Hanson creates endless speculations based on this idea of robot minds being copies of human minds, but he does nothing to show the feasibility of the idea. So Hanson is like some person building a 10-story tower before laying a concrete foundation for such a tower. There are actually very good reasons for thinking that it is impossible to ever create a robot mind that is a copy of a human mind. One such reason is that while Hanson claims that the mind is just the brain, there are very good reasons for thinking they are not the same, and that you would not at all capture someone's mind by scanning his brain.

Let me specify some preliminary requirements that we should demand of any book centered upon speculations that robot minds can be created from scanning human minds. After these preliminary requirements are met, we can think to ourselves that we are not wasting our time by reading speculations about some possibility that will never be able to occur.

The first requirement we should demand is a detailed explanation of how it is that the human brain could possibly store memories stretching back 50 years. For the reasons I give in this post, scientists don't understand how the human brain can store memories for longer than three weeks. The most common explanation for memory is that humans store memories in synapses. But synapses are subject to molecular turnover which should prevent them from storing any memories for longer than a few weeks. So how is that humans can store memories for 50 years?

It may be too much to demand that a brain emulation theorist provide the answer to how humans store memories for 50 years, but we should demand that he can at least provide some possible answer – at least some speculative scenario which, if it were true, would explain how humans can store memories for 50 years. If no such scenario can be provided, we should not believe that you will ever be able to have robot minds that are copies of human minds.

The second requirement we should demand from our brain emulation theorist is an explanation of how such a mechanism for remembering 50-year-old memories could have naturally evolved (seeing that such a “humans will be replaced” thinker is presumably not someone who thinks some higher power had a role in human origins). This is a huge challenge, for while such a theorist may be tempted to imagine some very complicated scheme by which memories might be stored in the brain for 50 years, such a scheme will not be a plausible natural explanation unless it is something that might have naturally appeared through evolution. Here there is the huge difficulty that we cannot think of any reason why natural selection would give us memories lasting longer than a year or two. Primates could survive just as well if they only remembered memories going back a year or two.

The third requirement we should demand from our brain emulation theorist is some explanation that dismisses all of the evidence for human psychic abilities such as ESP and human survival after death. If such evidence is valid, then “your mind is your brain” assumptions are dead wrong. We have no way of explaining something like ESP as a function of the human brain, although it could be a sign of something like a human soul. If experiences such as near-death experiences are real, then we presumably have some kind of soul that survives death. But the brain emulation theorist cannot admit such possibilities.

Since such a theorist wishes to maintain that your mind is stored entirely in your brain (and not at all in any type of soul separate from the brain), such a theorist must somehow clear from the table all of the great deal of evidence that has been accumulated suggesting that there is a soul as well as paranormal psychic abilities. So our brain emulation theorist would have to somehow accomplish the long, difficult task of explaining why very many things that seem to be good evidence are not really evidence. I presume that would require at least a long chapter in a book.

As if all this is not hard enough, there is still a fourth requirement that our brain emulation theorist must accomplish before we should take seriously the claim that human minds could be copied to robot minds. The theorist must give a plausible explanation for how it could be that all the information in a human mind might be copied to a robot mind without destroying most or much of the information in the human mind.

There are good reasons for believing that even if your mind was entirely stored in your brain, it would be physically impossible to read the state of a mind in a way that would allow some robot mind to copy the contents of that mind. While things such as fMRI scanners can make large-scale maps of the brain, there is no type of external scanner that would allow us to know the exact molecular and electrical state of microscopic neurons. While we can imagine some tiny molecule-sized probe that could be injected into a brain and then read the state of one neuron, such a probe could never store more than a tiny bit of information. It would not work to simply inject millions of microscopic probes into someone's brain, for such probes would have no way of figuring out the exact positional coordinates of the neurons they were analyzing.

You might think that it is possible to do a destructive scan of the brain to determine its exact contents. We can imagine some machine that is something like a turkey slicer. First it would slice off one little slice of the brain, and then analyze that like a copy machine reading a document. Then the next little slice would be done, and so forth. But that would not work, for the very act of making these thin slices would disrupt any delicate information storage in the brain that was preserving memories.

To present a plausible scenario for robots emulating human minds, our brain emulation theorist would need to explain how this brain scanning would work, as well as do the three other items I mentioned. Hanson doesn't do anything like meeting the requirements I have mentioned.

Hanson does nothing to substantiate his claim that the mind is just the brain. Hanson's failure in considering the difficulties here are shown by page 148 of his book, where he says this about brain scans that would give human minds to robots: “The very first scans might perhaps be performed on cryonics customers, that is, people who had previously had their brains frozen and stored in liquid nitrogen, in the hope of being revived when technology improved, and who had agreed to allow em scanning later.” Determining the exact state of a brain that had just died would be a nightmare enough. Add brain freezing (with all of its resulting cell damage) to the mix, and the problem becomes 100 times worse. Hanson informs us that he is one of only 2000 living people who have arranged to be cryogenically frozen upon death.

The cryogenics fantasy (represented by the slogan “freeze, wait, reanimate”) was implausible enough. Apparently Hanson believes in an even wackier notion – freeze your brain, stay in cold storage for a few decades, then wait until someone copies your brain state into a robot.  What convenience – after that fatal car crash, you wake up 40 years later with a nice steel robot body! 

 

There are countless feasibility problems in the idea of copying human minds into robots, problems that Hanson has not paid attention to. The central assumption behind the idea is wrong. Your mind is not your brain, but something more than your brain. This is indicated both by well-substantiated psychic phenomena (such as ESP and near-death experiences), and also by the spectacular inability of neuroscience to explain basic facets of our mind such as consciousness, instant memory retrieval of obscure memories, and memories lasting 50 years despite very rapid molecular turnover in the brain (see here and here for why it is hard to imagine the last two will ever be explained neurologically). So Hanson's very elaborate speculations about what would happen if the world became full of “em” robots (with minds copied from human brains) are no more relevant than some speculations of what would happen if unicorns were to take charge of the planet.

Galaxy Expert Confesses We Don't Understand How Galaxies Form

Last Friday scientists made a surprising announcement. They announced findings about a mysterious galaxy 300 million light-years away, a galaxy named Dragonfly 44. This galaxy seems to have about roughly the mass of our galaxy, but only emits 1 percent of the light our galaxy emits. Astronomers stated that this Dragonfly 44 galaxy is 99.99% dark matter. Dark matter is believed to be a mysterious form of matter that makes up about 27% of the universe. Ordinary matter is believed to make up only about 5% of the universe, with dark energy making up about 68% of the universe.

But such an announcement presents a great paradox. If ordinary matter makes up 5% of the universe, and dark matter and ordinary matter are mixed together throughout the universe, how could it possibly be that a particular galaxy would be 99.99% dark matter? This would seem to be as unlikely as that there might be some weird local change in the composition of the air, which is normally 78% nitrogen and 21% oxygen. Imagine if somehow the nitrogen in the air became so dominant that the air above a town became 99% nitrogen, causing all the people in the town to die of oxygen starvation. Such an event seems as improbable as that some galaxy would consist of 99.99% dark matter, when dark matter and ordinary matter are mixed throughout the universe.

After a result this surprising, we must take a step back and realize that there is really no firm basis for making statements such as the claim that this Dragonfly 44 galaxy is 99.99% dark matter. Dark matter has never been directly observed, and a multi-year attempt to directly observe it has failed. What we see in this Dragonfly 44 galaxy can most simply be described like this: a galaxy is behaving in a way that is inexplicable under our current understanding of gravity, inexplicable by a factor of 1000 times. Imagine if I see a bus floating up into the air. It would be rather presumptuous to make a statement such as: “The bus must consist of 99% antigravity material.” I should instead simply say that the bus is behaving in a way I don't understand. Similarly, rather than using some exact dark matter figure that makes it sound as if they understand what is going on, our scientists should be candidly confessing their lack of understanding of what is going on.

But that is not the way of the modern theoretical scientist. The modern theoretical scientist seems to be very prone to exaggerate his understanding, to make it look as if his understanding of some great mystery of nature is good, even when it is very poor. Here are some of the techniques that are typically employed as part of such a thing.

Ignore the unanswered questions. Asked to explain what we know about a particular topic, a modern scientist will probably go into a discussion that focuses entirely on what has been discovered, as well as what has been theorized, without mentioning what we are ignorant about. For example, a scientist asked to talk about the Big Bang will go into a discussion of why we think there was a Big Bang, and may also go into speculations about some details of the first second of the Big Bang. He will avoid mentioning that we don't understand the cause of this event.

Weave a blend of fact and speculation. Asked to explain a mystery such as the origin of life, the modern scientist is often like someone who needs to have a coat, but who merely has some assorted threads of fact. The scientists will then augment his threads of fact with some threads of speculation. By artfully weaving these together, and focusing only on bits and pieces here and there, the scientist may leave you with the impression that he has something like a coat, even though he may have perhaps merely a few scattered pieces, like a collar that is half fact and half speculation, and a coat elbow that is more speculation than fact.

Clutter the answer with jargon and minutiae. Asked what we know about some mystery that is not understood, the modern scientist will very often give an answer filled with jargon and a discussion of intricate fine details – the details often being details of a speculation rather than details of fact. To the average person, this may seem very impressive, and may leave him with an impression the scientist has a deep understanding of the mystery, even when the scientist has no such thing. For example, if asked to explain how humans can remember childhood memories for 50 years, a neurologist may launch into a jargon-filled discussion of some “clustering dynamics” theory attempting to explain the persistence of human memory. It may seem impressive in all its details, until you find out that it is mere speculation.

Don't mention the problems with your explanation. Very many or most theoretical explanations have some problems associated with them, reasons for doubting such explanations. When asked about some great mystery of nature, a scientist will very often confidently discuss some theoretical explanation, but fail to make any mention of problems associated with such an explanation. For example, when asked about how memory is stored, a neuroscientist may tell you that this is caused by LTP (long term potentiation) in synapses – but completely fail to mention that LTP is actually something that quickly decays, and generally doesn't last longer than a few weeks. Similarly, when asked about the origin of species, the modern biologist will confidently offer the Neo-Darwinism explanation that the cause was natural selection and random mutations. Our biologist will not mention that such an explanation does absolutely nothing to explain why any particular biological implementation would have made the large leap from a starting point to a “reward threshold” level of complexity and coordination (often very high) necessary for the implementation to first start yielding any survival value reward. Our biologist also will not mention that helpful random mutations are many times less common than harmful mutations. 
 

I have seen these techniques used hundreds of times by scientists trying to depict themselves as “lords of knowledge” about matters which mankind is really very ignorant about. So I was utterly flabbergasted to read a statement by galaxy expert Pieter van Dokkum, a statement of great candor. Talking about the mysterious Dragonfly 44 galaxy just discussed, van Dokkum says, "It means we don’t understand, kind of fundamentally, how galaxy formation works."

No doubt van Dokkum's colleagues would respond by saying, “It's just gravitation,” but I would remind them that gravitation cannot explain the persistence of spiral galaxies such as the Milky Way, nor can it even explain the appearance of galaxies with such a shape.  See here for more on why the persistence of spiral galaxies is so hard to explain.

A spiral galaxy (Credit: NASA)

I think van Dokkum deserves great applause for this rather rare case of explanatory candor by a scientist. This is what I want from a scientist – a candid statement of ignorance where knowledge is lacking, rather than some pretentious pedantic affectation in which the speaker pretends to understand some deep mystery he does not really understand. Let's hope we can start seeing more of this candor from our biologists and neuroscientists.

An Analysis of the Recent Claim the Solar System Is in a “Unique Area of the Universe Just Right for Life”

Imagine if some huge extraterrestrial spaceship were to appear in a fixed position above some US city. Suppose the extraterrestrials wanted to get started communicating with us. How could they start the conversation, if their language was so different from ours that English was utterly unintelligible to them? One way would be for them to place 1836 identical small objects in a field. Every physicist would understand the meaning of this. 1836 is the ratio between the proton mass and the electron mass, a constant throughout the universe.

Or if the extraterrestrials wanted to do something similar that wouldn't require so many objects, they could place 137 identical small objects on a field. Every physicist would recognize what this meant. 137 is the number associated with a universal constant of nature known as the fine-structure constant. Its value is normally represented as 1/137 (or more exactly, 0.007297351). The behavior of stars crucially depends on the value of the fine-structure constant.

A few days ago the Daily Galaxy web site had an article involving the rather prosaic topic of the fine-structure constant. Following the Daily Galaxy's standard rule of “spice things up to the max,” the article had this sensational title: Our Solar System “Is In a Unique Place in the Universe – Just Right for Life.”

Such a title must have excited those who like to believe the egotistical idea that man is the centerpiece of the universe. But the facts cited by the Daily Galaxy story do not warrant the article's sensational title implying something special about the position of our solar system.

The article in question refers to some research published in 2012 by John Webb and his colleagues at the University of New South Wales. The relevant scientific paper can be found here. Studying the fine-structure constant (a fundamental constant generally believed not to vary in time or space), the scientists claimed to find evidence that the fine-structure constant “increases with increasing cosmological distance from Earth.”

But the variation reported was only about 1 part in 100,000. There is probably insufficient basis for thinking that a variation of only 1 part in 100,000 in the fine-structure constant would rule out the habitability of a particular region.

There are some reasons for thinking that stars like the sun could not exist if the fine-structure constant were much larger or smaller. The fine-structure constant controls the strength of electromagnetism. On page 73 of his book The Accidental Universe, Paul Davies states the following:

If gravity were very slightly weaker, or electromagnetism very slightly stronger, (or the electron slightly less massive relative to the proton), all stars would be red dwarfs. A correspondingly tiny change the other way, and they would all be blue giants.

But we see yellow stars like the sun all over the galaxy, and in many other nearby galaxies. So a space-dependent variation of 1 part in 100,000 cannot justify any claim that our solar system is in a “unique place in the universe – just right for life,” not unless you mean “place” to mean some large fraction of the universe.  The problem with such a claim is not the "just right for life" part, but the "unique" part implying some special zone of habitability in just one part of the universe.

 Bubble around a bright star (Credit: NASA)

There has been other research on the fine-structure constant that does not agree with that of Webb and his colleagues. A more recent paper (published in June 2016) found no evidence for variation in the fine-structure constant, not even 3 parts in a million.

So the Daily Galaxy's article title seems to be unwarranted. Another interesting result on the fine-structure constant was reported in 2016 in a scientific paper by scientist McCullen Sandora. Sandora dealt with the “inverse fine structure constant,” which is the fine-structure constant divided by 1 (this has been measured to be 137.036). The iron lying around our planet (needed for technical civilizations) is believed to have arisen in the core of a distant star (stars shoot out iron when they explode in supernova explosions). Sandora found that for stars to produce iron, the inverse fine-structure constant must have a value of 145, give or take 50. 

Sandora also found a more sensitive requirement, finding that for a planet to have plate tectonics like the Earth, the inverse fine-structure constant must be 145, give or take 9. Sandora gives some complicated reasons why such plate tectonics are a requirement for the appearance of creatures such as us. 

The latter finding puts the measured value of the inverse fine-structure constant (137.036) just barely inside the range consistent with a planet like Earth (a range between 136 and 154). This finding is consistent with the claim in this scientific paper, which says that an inverse fine structure constant “close to 137 appears to be essential for the astrophysics, chemistry and biochemistry of our universe.”

The fine-structure constant is actually derived from three other fundamental constants of nature. The formula for the fine structure constant is that it is equal to e²/hc, where e is the charge of the proton, h is Planck's constant, and c is the speed of light.

According to Sandora, planets just like ours (with plate tectonics) could not exist if the fine-structure constant varied by more than 6%. If the fine structure constant must fall in a very narrow range, then think of how fine-tuned the proton charge must be, if the fine structure constant depends on the square of the proton charge.

This is only one way in which the proton charge must be exquisitely fine-tuned. There is the additional fact (involving a far-greater sensitivity) that planets will not hold together unless the proton charge and the electron charge match each other to many decimal places (the only difference being that the electron charge is negative). For if there were not so precise a match (far more unlikely than you randomly guessing correctly someone's Social Security number), the electromagnetic force (more than a trillion trillion trillion times stronger than the gravitational force) would cause repulsion exceeding the gravity holding the planet together (as mentioned here). Experiments have shown that the proton charge and the electron charge do actually differ by less than 1 part in 1,000,000,000,000,000,000. This fact is unexplained by our physicists, and is extremely surprising given that each proton has a mass 1836 times greater than each electron.

We therefore have hints some very precise fine-tuning went on here, although we have no adequate reason for thinking that it is some special blessing applying only to our local region of the universe. 

The Thousandfold Shortfall of the Neural Reductionists

My previous three posts constitute quite an astonishing thing: a kind of neurological case for something like a human soul. Each of the posts presented an argument for the claim that your brain cannot be storing all your memories. One argument was based on the apparent impossibility of the brain ever naturally developing all of the many encoding protocols it would need to store the many different things humans store as memories. The second argument was based on the apparent impossibility of explaining how the human brain could ever be able to instantly recall memories, if memories are stored in particular locations in the brain, because there would be no way for the brain to know or figure out where a memory was stored. The third argument was based on the fact that humans can remember 50-year old memories, but scientists have no plausible explanation for how the human brain can store memories for longer than a single year.

No doubt some counterarguments arose in the minds of some readers, particularly any readers prone toward neural reductionism (the idea that human mental experiences can be entirely explained by the brain). In this post I will rebut such possible counterarguments.

The most obvious counterargument that one could give would be based on the fact of strokes and Alzheimer's disease. It can be argued that such afflictions show that very long-term memories are stored in the brain. But such an objection can be easily answered.

One way of answering such an objection is to point out that the evidence on brain damage and memory problems is very mixed. The physician John Lorber documented many cases of people whose brain tissue had been largely destroyed by disease, and found many cases of people whose memory and intelligence was still good. The operation called a hemispherectomy is sometimes performed on children, and involves removal of half of their brain. An article in Scientific American tells us, “Unbelievably, the surgery has no apparent effect on personality or memory.”

An even better way of answering such a counterargument is to point out that we cannot tell whether Alzheimer's patients or strokes have actually suffered a loss of memories. For it might be that such patients merely experience a difficulty in retrieving memories.

Imagine you are used to visiting cnn.com to get the news each morning. But one day you turn on your computer and find you can no longer access any information at cnn.com. Does this prove that the information stored at cnn.com has been lost? It certainly does not. The problem could merely be an inability for you to retrieve information at cnn.com, perhaps because of a bad internet connection. Similarly, if I write the story of my life, and place it on my bookshelf, I may one day go blind and be unable to access that information. But the information is still there on my bookshelf.

In the same vein, the memories of people with Alzheimer's may be perfectly intact, but such persons may be merely experiencing some difficulty in retrieving their memories. There are, in fact, reports of incidents called terminal lucidity, in which people suffering from memory loss or dementia suddenly regained their memories shortly before dying. Such reports tend to support the idea that memory problems such as Alzheimer's involve difficulties in retrieving memories rather than the actual destruction of memories stored in the brain. 

There is actually a way in Alzheimer's may argue against the idea that your memories are all stored in your brain.  A doctor reports the following:

One of the big challenges we face with Alzheimer's is that brain cell destruction begins years or even decades before symptoms emerge. A person whose disease process starts at age 50 might have memory loss at 75, but by the time we see the signs, the patient has lost 40 to 50 percent of their brain cells.

If your brain cells were the only place your memories were stored, why would you not notice memory loss until 40% or 50% of your brain cells were gone?
 

Another way of rebutting my argument about very-long term memory (and our inability to explain it) is to do an internet search for “long term memory,” and then find some biological component I didn't mention (perhaps some kind of protein), a component that is described as “playing a role in long-term memory.” You might then argue that I failed to mention that component, and that maybe that is the secret to very long-term memory.

But such an approach would be fallacious. Very confusingly, scientists use the term “long-term memory” for any memory lasting longer than a day. So anything at all that affects memories lasting longer than a day may be described as something that “plays a role” in long-term memory. In general, such things do nothing to answer the problem of very long-term memory, the problem of how memories can last for years or decades. For example, PKM protein molecules have been described as “playing a role in long-term memory.” But having lifetimes of less than a month, such molecules cannot explain how the brain could store memories for years.

Very rarely, it is suggested that maybe epigenetics can explain long-term memory. Epigenetics involves the effect of methyl molecules that can attach themselves to a DNA molecule. To use a rough analogy, we can imagine a DNA molecule as a protein recipe book, and we can imagine these methyl molecules as being strips of black electrical tape that block out certain parts of that book. Another analogy is that they are like “off” switches for parts of DNA. As these methyl molecules are very simple molecules, they are quite unsuitable for information storage use. Also, the methyl molecules attached to a DNA molecule are not connected to each other. So the methyl molecules involved in epigenetics lack the two characteristics of synapses that caused scientist to suspect their involvement in memory: the fact that they can have different “weights,” and the fact that they are connected to each other.

Another objection that can be made is to point out that some scientists have come up with theories trying to explain how information could be maintained long-term in synapses. Such theories are sometimes called theories of “synaptic plasticity maintenance” or “synaptic plasticity persistence,” although given that they involve attempts to show how unstable synapses could preserve information indefinitely, it might be better to call them “magic maintenance” theories. Far from debunking my objection that molecular turnover should make it impossible for synapses to maintain memories, such theories actually show that such an objection is quite weighty, and one that scientists have taken very seriously.

I can characterize such theories with an analogy. Let us imagine a young boy whose mother died a year ago. He comes to a beach where his mother used to swim, and he sees written in the wet sand a message of love.

Engaging in wishful thinking, the boy decides that the letters were written by his mother who died a year ago. When his father points out that this couldn't be, because letters in wet beach sand don't last, the boy comes up with an elaborate theory. Perhaps, the boy reasons, his mother hired some people to constantly preserve the letters she wrote in the sand. Perhaps, the boy thinks, whenever the words are overwritten by the high tide, some person hired by his mother makes sure that the letters are rewritten just as his mother wrote them.

Such a theory – basically a reality denial mechanism – would be very much like the attempts that have been made to advance theories by which synapses could preserve memories even though the protein molecules in synapses are recreated every few days. Both involve complex speculations hoping to get us to believe that some information that should be very short-lived is really very long-lived. The synapse theories in question – these “magic maintenance” theories – are not any more believable than the little boy's theory about the sand.

One such theory is a very sketchy theory of “bistable synaptic weight states,” which just offers the most fragmentary suggestion of how some special and very improbable “bistable distribution” setup might help a little --not very much, and not enough to account for memories lasting for years. But as this 2015 scientific paper states, “Despite extensive investigation, empirical evidence of a bistable distribution of two distinct synaptic weight states has not, in fact, been obtained.” The theory in question relies on an assumption of unobserved biochemical positive feedback loops, but one scientific paper notes that “modeling suggests that stochastic fluctuations of macromolecule numbers within a small volume such as a spine head are likely to destabilize steady states of biochemical positive feedback loops,” making them unsuitable for anything that can explain long-term memory.

Another such theory is a “cluster dynamics” theory advanced in this paper. The author makes a totally unwarranted ad-hoc speculative assumption. Speaking of the insertion of a new protein – where a new protein would appear when a brain cell replaces a protein, as it constantly does – the paper says, “The primary effect of this implementation is that the insertion probability at a site with many neighbors (within a cluster or on its boundary) is orders of magnitude higher than for a site with a small number of neighbors.” There is no reason for thinking that there should be any difference in these probabilities. He then attempts to show that this imagined effect can work to preserve the information in synapses, by giving us a “simplest possible case” example of a square shape that is preserved on a grid, despite turnover of its parts. But such an effect would not work in cases much more complicated than this “simplest possible” case, and would not work to preserve information more complicated than a square.

I tried created a spreadsheet that would use this type of effect. After a great deal of trial and error, I was able to find an “intensity of neighbors” formula that would set things up so that the lower set of numbers in the photo below (marked Generation 2) recreates the data in the first set of numbers (marked Generation 1). The formula used to create Generation 2 used the same idea in the “cluster dynamics” theory – the value of an item in the second generation depends on how high are the nearby values in the earlier generation. When I tried using some square-shaped data in the Generation 1 area, the effect worked okay, and the Generation 2 area looked like the Generation 1 area. 

But as soon as I tried using some data in the Generation 1 area that was not square-shaped (such as X-shaped data or E-shaped data), the effect no longer worked. Here are the results when you try some E-shaped data. The resulting Generation 2 does not look like an E-shape.

Simple as this experiment was, it captures the fatal flaw of this “cluster dynamics” theory. While it might work to explain a preservation of the simplest possible data (square shapes), it will not work to preserve any data more complicated, such as E-shapes and X-shapes. Of course, our memories involve memories of things infinitely more complicated than an X shape.

All of these “synaptic plasticity maintenance” theories have one thing in common: they have already been ruled out by experiments with long-term potentiation (LTP) and synapses. Such experiments have shown that LTP very rapidly degrades, and that synapses do not magically maintain their information states over long periods.

Another objection that could be made is one along these lines: sure, scientists don't have an explanation now for very long-term memory, but they'll find out someday how the brain is storing it. My answer to this is: no, they won't, because there are good reasons for thinking there is no place where it could be stored in the brain. The only candidates for places where very long-term memory could be stored in the brain are: synapses, DNA in nerve cells, protein molecules surrounding the DNA, other nerve cell proteins, or what is called the perineuronal net. My previous post made a good case that none of these are plausible storage places for very long-term memory. If you've ruled out all the places where something could be in some unit of space, then you have to conclude it's not in that space. For example, if you're looking for your car keys and you've ruled out all the places they might be in your bedroom, you should conclude they are not in your bedroom (rather than telling yourself: I'll find them some day hidden in my bedroom).

What is very astonishing is the difference between the longest memory that can be plausibly explained by neuroscience, and the longest memory that humans can hold. As discussed in my previous post, the best “candidate explanation” for memory is LTP (long-term potentiation), but that decays in a matter of days. The protein molecules between synapses also last no longer than two weeks. Even if you were to claim that LTP is a good mechanism for memory (something quite questionable, since it doesn't correlate highly with memory), then about the longest memory that science can currently explain (without resorting to baroque speculation) is a memory lasting about two weeks. Because humans can hold memories for 50 years, they are displaying a memory capacity that is about 1000 times longer than what can be plausibly explained by neuroscience. The explanatory gap here is like the gap between Jupiter and Saturn. How long will it be until we wake up, smell the coffee, and realize that to explain our minds we must go beyond the brain?