Sand in the Brain: A Fundamental Theory To Model the Mind 105
An anonymous reader writes "In 1999, the Danish physicist Per Bak proclaimed to a group of neuroscientists that it had taken him only 10 minutes to determine where the field had gone wrong. Perhaps the brain was less complicated than they thought, he said. Perhaps, he said, the brain worked on the same fundamental principles as a simple sand pile, in which avalanches of various sizes help keep the entire system stable overall — a process he dubbed 'self-organized criticality.'"
As a physicist: (Score:4, Insightful)
Dear fellow scientists, admire us for the 1% of the cases when things like "oh i have a very simple theory about this" are brilliant and dont hate us for the 99% of the cases where this is just idiotic and arrogant.
As an observer (Score:4, Insightful)
The objective reality is that this process has been observed to happen in the brain. Repeatedly; consensually; experientially.
The open question, at least for me, is, is there any reason to think that this is the only, or even the primary, mode of neural operation?
Sand will indeed avalanche following the power law when it's poured on top of itself. But it does something completely different when it is suspended in turbulent water, or melted into glass, or just sitting there on the beach (seems to have an affinity for the inside of bathing suits as I recall, though it's been a while.)
Perhaps avalanche at criticality is "the" answer. But I think we're quite some distance from declaring that particular win. I'm all for the exploration, though.
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Just because i observe something simple, it does not need to the the complete explanation.
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Didn't Slashdot have another story recently about how pop-science was in love with trying to find power laws in everything? (And producing nothing of value along the way.)
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Re:As an observer (Score:5, Interesting)
Except we are seeing many cases where it is counterintuitive even to working scientists in their own fields, just which explanation is simpler.
For example, Guth's inflationary hypothesis in Cosmology has resulted in a prediction that certain constants must be random (because otherwise, there's the implication of something we might as well call God behind the non-random values). A hypothesis that invokes God is probably not the most simple - anything that might merit the name of God is likely to be more complex than the very universe it 'explains'. Fair enough, but random values seem to imply an infinity of parallel universes, which however will never be detected by real science, only in science fiction. An infinity of untestable phenomina as the outcome of a model hardly makes that the preferred model by Occam either. Last I looked, neither one of these interpretations of the inflationary hypothesis* has been mathematically shown to be the more simple of the two. If people who have had some real impact on the specific field (i.e. Hawking), can't really agree on what they mean by simple, Occam's Razor isn't working very well.
This has shown up in several other areas of science, for example recent math proofs by computer that are so complex there's a real chance the computer made errors during the months it was crunching numbers for the millions of steps required. Once a proof is too complex for humans to even check, how can we possibly tell whether it is more complex than another proof or not? (Counting lines of code is not a very good measure there). And while I'm hardly up on all the issues in the "universe as a giant computer" debate, I've seen arguments from some of the pros in that field that seem to show there's problem with determining which explanations are the most simple there too, and I've heard at least one working scientist in the field of sexual selection pressure complain about the same thing.
* The recent Antarctic discovery might argualbly elevate Cosmic Inflation from hypothisis to full fledged theory if it wasn't there yet. For those who think it was a theory already, these observations would seem to place it on even more solid ground, in much the same way as Crick and Watson's work helped strengthen the claim of Evolution to be a well tested and heavily supported theory. But, not being able to predict whether the initial universal constants were random or non-random is a real problem when it comes to proclaiming Cosmic Inflation has the status of a solidly tested theory, no matter how much other evidence scientists gather.
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Or does the simplest explanation in this Universe require
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This gets tiresome to explain. Occam's Razor "excludes" absolutely nothing. It does not say what is possible, it does not say what is more probable. It resolves in no way what the facts of the situation are.
Occam's Razor says, and only says, that if you have two models that vary in no way whatsoever in terms of evidentiary or inferential support, direct or indirect, stipulate using the simpler one, because, and -only- because, it is simpler and therefore has more conceptual economy.
In the general case, E
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Hear, hear.
I just hate it when biologists, social scientists, etc. confuse probability with intuition.
Just because something seems improbable, that proves nothing about how probable it acutally is.
If anything the study of probability has taught us, is just how wrong our intuition and gut feelings can be.
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I think it should be noted that the human brain also has an affinity for the inside of bathing suits. . .
Re:As an observer (Score:5, Informative)
There was an idea in computing several decades ago about "asynchronous computing". The idea was that you could get rid of the need to have all the different regions of your silicon chip clocked at exactly the same speed. Instead, data would move between different units at different speeds according to demand. If a particular circuit wasn't used, you could put it in a low power state, if something was being filled up with data, you boosted the clock speed. You end up with data "flowing" through the system or data-flow- computing.
So it's much similar to the brain where different regions light up under fMRI analysis as oxygen flow increases as they are used. And scientists have a good idea what different regions of the brain do - usually a high-level function like generate-muscle-motion-to-say-phrase or recognise-name-of-object-from-picture. From other methods of MRI scans, they have identified the pathways where different parts of the brain communicate along, and are able to visualize these as "connectograms", Phineas Gage is the best example.
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Except for standard computers it doesn't work so well since the CPU is almost always faster than everything else so the other parts of the system almost never have a chance to kick back and relax - its usually the CPU waiting for them to do something. Also a serial computer is pretty much like a road - everything moves at the speed of the slowest vehicle/component. Slow one thing down and you slow everything down. Parallel systems improves things a bit - you now have a multi lane highway - but even so , the
Serial computer like a road (Score:1)
The limitation on serial computation is not really in the architecture, it's in the code. If the compiler were to generate multi-threaded code where serial dependencies were minimized, (and if coders learned to use this feature), then it would be fairly easy to uncouple the various cars on the computer train and let them each follow their own tracks until some intermediate output was exchanged.
A lot of new VLSI architecture is capable of this kind of uncoupling. Even with the same clock rates.
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The objective reality is that intoxication, aneurisms, drug trips, and brain tumors also have been observed in the brain; that doesn't mean they have anything to do with thinking or the mind.
Re:As a physicist: (Score:5, Interesting)
"I have a simple theory" is the result of multidisciplinary collaboration, in which new connections get made by someone who understands the patterns and foundations of apparently, but not really, unrelated subjects.
"Your field is fundamentally wrong" could be idiotic and arrogant. Or it could be something so intrinsically obvious as two plus two does not equal four, or God exists (or doesn't). Democrats are evil, Republicans are evil, and the focus of neuroscience should be about how the system maintains criticality.
I hardly consider this arrogant. Arrogance is an inflated sense of superiority, and usually the arrogant person knows, on some level, that it is just a front. Just stating something gives them a feeling of superiority, triggering pleasure centers. Being proven right, in public, is quite possibly the best thing ever because it presents a factual basis for what is, at least occasionally, a fantasy.
People who know, or believe, something truly and completely, do not do this. Believers seem to rebel against any contrary information, actively rejecting it. Knowers present clarity of fact. They may be completely wrong, and may cross over into being believers, or they may disbelieve when proven wrong.
Because science is fundamentally about trying to prove others wrong (and either failing or succeeding), it is important to distinguish among a deep-rooted belief, transference of knowledge (even if it is mistaken), arrogance, idiocy, and the scientific method.
As far as physicists specifically, I would expect that biological and chemical functions would have some level of physics at their core. Whether it is a true correlation or just similar in appearance will have to be decided. But I would prefer to have an asshole physicist say everything is wrong and be right 1% of the time, and the rest just be brushed off like the guy from marketing at the Christmas party.
Nitpick the oversimplified psychobabble if you like, but the point is that words mean things. And attributing intent to people based on their ideas, and even their words especially if they are not a native speaker, is a great way to completely miss the point. Not debating that it's an issue - but it is far too easy to dismiss an interloper from another discipline as arrogant - all the easier if you believe in your field of study, as opposed to knowing it.
I ahve seen (Score:2)
physicist, many, many times make statements about other disciplines and been wrong every time.
Why? becasue they don't hold themselves to the same level of rigor in other fields as they would in there own..
Sure, maybe he is correct, but not likely. So.. write a scientific paper held to a high level of rigor.
If you can do that, then I don't care what you expertise is in. Hell, you could be a ditch digger, but if you write a paper that stands up to peer review, then you history should not matter.
Unless you his
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Science is a process with the end goal of leading us to fact.
One of the parts of the process, is if you are faces with many different models that work, the simplest one is probably the correct one.
However the simplest model isn't obvious all the time, as you are trying to make a pattern out of complex results. Because we are trying to figure out a pattern from a complex result, we will need to try out many different models, and these models can get complicated. But in the process of finding the complicate
oblig xkcd (Score:5, Insightful)
The really interesting thing will be when Randall does a comic about how you can get easy upvotes for "oblig xkcd" posts.
Re:oblig xkcd (Score:4, Insightful)
This comes from the fact physicists are used to working with differential equations that they can't prove existence or uniqueness of a solution for.
So they simplify, i.e. 'assume a spherical cow' as a way of living.
Of course that almost never works for a real system so they go off and try to understand the universe one particle at a time.
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From a topological standpoint, a cow and most lifeforms are not spheres at all. We are all donuts. The only true hole that goes through the entire animal, is the intestinal track. The rest are just pockets (lungs, etc).
So, cows and people are donuts, not spheres.
If you want spheres, you have to loop at starfish.
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three ends - two in your nose and 1 in your mouth to which the other two come down to so result is a donut with 4 wholes alltogether. I am also not so sure about the ears of people that got ear shuttering explosion near their heads or some doctors doing experiments on them but I guess for population at large that is not a valid configuration. So here we go
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Intestinal TRACT.
depends on there (Score:2)
discipline. It's not like there is a physicist factory where everyone just pound out physics. So disciplines are less abstract the others.
Re:oblig xkcd (Score:5, Interesting)
But over time, in fits and starts, Bak’s radical argument has grown into a legitimate scientific discipline. Now, about 150 scientists worldwide investigate so-called “critical” phenomena in the brain, the topic of at least three focused workshops in 2013 alone.
Just goes to show that xkcd is not the answer to everything.
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That is what I thought of too, but in this case neuroscientists agree with him. If you read the article:
But over time, in fits and starts, Bak’s radical argument has grown into a legitimate scientific discipline. Now, about 150 scientists worldwide investigate so-called “critical” phenomena in the brain, the topic of at least three focused workshops in 2013 alone.
Just goes to show that xkcd is not the answer to everything.
Except notice how the field is gaining complexity? So it's clearly not that simple. It might end up being right, but the final product is not going to end up adding a lot of complexity back in.
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Early mornings and working on a few things at once :)
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a) neurons while not necessarily geniuses are actually not that stupid, and that the real problem a brain solved was not "thinking" but that a single thinking neuron can't be used to control a multicellular body because of connectivity and redundancy reasons (can't have a whole body wasted just because one neuron died).
b) The brain is like a bunch of Bingo halls each filled with neurons that yell Bingo when something they recognize is "read out". The fancy trick is
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That is what I thought of too, but in this case neuroscientists agree with him...
There's a huge difference between identifying a principe behind some low-level aspect of neural activity, and explaining how the brain works. This sort of article (and other pronouncements of Dr. Bak, apparently) gives reductionism a bad name. Only if he could show how consciousness arises directly from neural self-organized criticality would the absurd hyperbole of the first paragraph be justified.
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150 scientists worldwide, three "focused workshops" and "trying to start a journal" is pretty fringe. I think time cube guy has them beat on that one.
This is more like what's going on. (Score:3, Insightful)
http://www.smbc-comics.com/?id=2556
Re:oblig xkcd (Score:4, Insightful)
I think this SMBC comic is very appropriate as well: http://www.smbc-comics.com/?id... [smbc-comics.com]
Re:oblig xkcd. TFA itself points this out (Score:2)
Sand in our Brain (Score:2)
alright just kidding, but seriously...if our brains really are just jumbled masses of impulses...
Then jumbled masses of impulses must be pretty darn good.
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I don't understand how it helps us understand intelligence. I mean, I'm sure things happen in the brain in waves, you could say the same thing about a computer as well, when I start JAVA there is a mass of RAM allocations, that suddenly get released in varying sizes when the GC happens. But I'm not sure that's a helpful way of looking at things......
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Some kind of convergent FPGA timing solution during the key moments when a correct timing is required might be a good analogy. To me the article seems to trying try explain why the brain works at all, and why the result of this process of working actually converges to discreet thoughts such as language elements and concepts, and life preserving processes such as hearing, seeing and corrected heart beat. Occasionally. In other words, this would be the clock tree of the brain.
Re:Sand in our Brain (Score:5, Informative)
Ok, well... my understanding of it is that nature is made up by random events. If those events were all there were, you'd get white noise. A perfectly even randomness. However, nature also has laws. With regard to sand, there's gravity, and slope, friction, etc... and that means these randomly falling grains of sand, on the macro scale, end up forming patterns. These patterns end up being very complex but predictable with statistics. Understanding a dune from the point of view of a grain of sand is nearly impossible. You just need to know the rules the system is following and then you can make accurate macro-scale predictions without having to compute every grain of sand in the dune.
The arguments made its way into nearly every branch of science now. Our attempts at brute forcing nature, and trying to connect the sub-atomic scale with the macro scale have mostly failed. But it now seems that maybe nature doesn't work that way. Nature seems more to work based on sets of probabilities, and particles seem to work more like "attributes" than matter. So perhaps the brain works like this to. It's a collection of chaos, bound by rules. Those rules cause the microscopic chaos to form patterns on the macro scale.
Re:Sand in our Brain (Score:5, Interesting)
The pendulum regarding self-organized criticality is beginning to swing back in the other direction: many researchers now believe it's being over-applied, and the "power law" distributions that people see for natural phenomenon that are "evidence" of S.O.C. have been shown to not actually obey power laws (it's really easy to make these kinds of mistakes when you make your graphs on log-log scales). Sorry if that was a bit dense, but the long and short of it is that not everything that is being touted as an example of self-organized criticality likely is. For instance, the Bak–Tang–Wiesenfeld sandpile (Bak being the one from TFA)? Turns out it's a HORRIBLE model for how real sandpiles behave.
A lot of the above really needs citations, but I'm too tired and lazy, sorry. To "back this up," let me just say that I have a Ph.D in physics, specializing in nonlinear dynamics, and the above comes from a graduate-level course I took from a professor who knows her shit.
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I'm reminded of the dinosaur flocking animations of Jurrassic Park. The dino herds flock about here and there, respond to events such as predator attacks, and it all looks very realistic, but the computer models there can't be what nature really uses, because they work by having some parts of the herd respond to others faster than the individual elements could really sense what the others are doing. Yet it looks realistic, and if you use the same formulae to animate model birds or sheep or such things, even
Re:Sand in our Brain (Score:4, Informative)
Look up "boids". Each critter has a field of view and a current direction. It only responds to what it sees in that field-of-view. If other critters start running, it starts running too. If they stop, it stops. With fish, the minute one turns, there is a flash of light. That instructs all the others to turn as well, providing the flash is bright enough. Maybe it takes two or more.
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It's like you just told an economics professor to look up "double entry accounting".
hhh (Score:2)
" nature is made up by random events"
no. It's made up of complex events interacting and may seem random only because we don't understand everything. The more properties you understand, then the less random it becomes.
I am talking about the macro world, natch.
"So perhaps the brain works like this to. It's a collection of chaos, bound by rules. Those rules cause the microscopic chaos to form patterns on the macro scale.
You might as well of said the brain works like things in nature work. well. no duh.
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The theory is an overarching idea of how the brain works and best makes sense when compared to other theories. One (not this theory) way to think of the brain is that it is like a computer, with specialized areas which each calculate for specific functions and having a whole mess of complicated parts that evaluate against each other and somehow all work together. This theory instead sees the areas not as having logically complicated interlocking parts, but as each part having a sort of pile where if enough
Re:Sand in our Brain (Score:5, Informative)
The linked article was horribly written. I'll give a shot at trying to explain it (or rather, a really, really simplified version).
Two of the fundamental problems that neural circuits must solve are the noise-saturation dilemma and the stability-plasticity dilemma. The first is best explained in the context of vision. Our visual system is capable of detecting contrast (ie. edges) over a massive range of brightness, spanning a space of about 10^10. Given that neurons have limited firing rates (typically between 0 and 200hz), there needs to be some normalization criteria that allows useful contrast processing over massive variations in absolute input (more on this later). The stability-plasticity dilemma is that the brain needs to be sufficiently flexible to learn based on a single event (let's say, touching a hot stove is a bad idea), but once learned memories have to be sufficiently stable to last the rest of a creatures' life span.
The stability-plasticity dilemma implies that neural circuits must operate in at least two (as I said, very simplified) distinct states, a "resting" or "maintenance" state, and a "learning" state, and that there is a phase-transition point in between them. Furthermore, these states need to have the following properties regarding stability:
1) the learning state must collapse into the maintenance state in the absence of input (otherwise you get epilepsy).
2) reasonable stimulation (input) during the resting state must be able to trigger a phase change into the learning state (or you become catatonic).
Many circuits/mechanisms have been proposed to explain how the brain solves these dilemmas. Most of them involve the definition of a recurrent neural network [scholarpedia.org] using some combination of gated-diffusion and oscillatory dynamics to fit well known oscillatory and wave-based dynamics that have been recorded in neural circuits. Some of these models employ intrinsic learning using a learning-rule (ie. self-organized maps) while others are fit by the researcher. One key point about this class of models (as opposed to the TFA approach) is that they have a macro-circuit architecture specified by the modeler. Typically these models are at least somewhat sensitive to parametric perturbation.
TFA describes another approach, which comes out of research on cellular automata done by Ulam, von Neumann, Conway and Wolfram. This approach posits that parametric stability and macro-circuit organization is only loosely important so long as the system obeys a certain set of rules regarding local interaction (could also be through of as micro-circuit) because it will self-organize to a point of 'critical stability'. In the the two-state model described above, this approach predicts that neural circuits are always at a state of 'critical stability' where maintenance occurs through frequent small perturbations or avalanches, and any new input will trigger a large avalanche, causing learning. Bak has proposed this as a general model of neural circuit organization. One trademark of these type of models is that they show 'scale free' or 'power law' behavior, where the size of an event is inversely proportional to its frequency by some exponential function. Some recent data has shown power-law dynamics in neural populations (a lot of other data doesn't show power-law dynamics).
One big problem with the critical stability hypothesis is that it doesn't deal well with the noise-saturation dilemma: it needs to cause the same general size of avalanche whether it's hit by one grain of sand, or 10^10 grains of sand.
None of this is particularly new, neural-avalanches (albeit in a different context) were postulated in the early 70s. Could some systems in the brain exploit self-organized criticality? Sure, but there is a lot of data out there that's inconsistent with it being the primary method of neural organization.
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With regard to question 2) No.
Question 1 is an ongoing field of research. Some of the work that I've found helpful in approaching the question:
-The Computational Beauty of Nature (Gary William Flake)
-Barriers and Bounds to Rationality (Peter Albin; there are free pdf copies available online).
-A New Kind of Science (Stephen Wolfram; also available free online).
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I'm pretty sure that the neurons that are firing at 0 Hz don't contribute to the noise-saturation delimma (unless you are using some "sufficiently large values of zero"). ;-)
.
Re:Sand in our Brain (Score:4)
Actually, since neurons have functional homeostatic pruning and nonlinear membrane responses, there are quite large values of zero when we're recording firing rate.
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Obviously his brain is working enough to make him speak...
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Could it be that neurons simply don't store new information except the first time and that all experiences are stored as an incremental backup, i.e. it's only the changes that are stored?
This solves the stability-plasticity dillemma: the first experience that comes is stored as a whole, and then similar experiences are only stored as a delta from the initial experience - thus allowing the brain to maintain some 'forever' experiences like touching a hot stove but also be flexible enough to remember new exper
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I think they have simply used a too dumbed down simile. Perhaps a better one would be a chain reaction with an catalytical agent. The chain reaction varies according to the catalysing agent or agents, whether internal bioelectrical stimuli, released hormones, drugs, dietary surges or direct physical stimulation. Also the current state of brain and the individual coincidental states of brain cells in molecular transition. So no simple sand pile.
Physicists have a long history with Neuroscience (Score:2)
1999? (Score:1)
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I think you just had a brain sand avalanche.
Another model (Score:1)
I prefer the "Dust in the Wind" model.
Something is missing (Score:2)
I even Read The Fine Article but I still get the sense there is supposed to more to this than just the self-evident "if a system reaches a state of instability it stops being stable".
Song about that? (Score:1)
"Sand in the clowns"
Sand in our Brain (Score:1)
Sand in the brain - cloudflare in the way? (Score:1)
What's with the "cloudflare" website middleman stuff? Kind of feels like someone's breaking net neutrality. I can't read the link unless I go through a middleman SSL & whatnot?
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What's with the "cloudflare" website middleman stuff? Kind of feels like someone's breaking net neutrality. I can't read the link unless I go through a middleman SSL & whatnot?
Cloudflare's basically a CDN.
The site owner intentionally uses Cloudflare as a middleman to cache their content in locations around the globe and to improve security (Cloudflare can block attacks before they hit the actual server). Cloudflare also offers SSL proxying to site owners so visitors can connect securely to the local Cloudflare cache, which in turn connects securely to the source server.
It's quite similar to, say, Akamai, and doesn't "break net neturality" (the site owner specifically elects to us
Ick (Score:2)
Re:Ick (Score:4, Funny)
Can We stop artificially dividing the brain and the Mind, please? The two ideas are likely the same and their distinction speaks of lingering medieval mysticism.
See that? I even put in the gratuitous capitalization!
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Argue? I was going for a funny mod. Too subtle? Somebody got it, I see it's currently moderated higher than the original.
Ha ha first reading I thought you said "Aspergers" and was going to ask if you found blind adherence to medieval mysticism sorry, renaissance philosophy, a trait of that disease. I've found people who quote Descartes as if he were an oracle of truth rather than a dude who believed the pituitary was the gateway to other dimensions are more likely to be the social types who argue with ea
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Alright, lemme go find you all those reported cases where someone's brain was fucked up but their mind kept chugging along just fine.
Oh wait. I can't. Because all evidence from every reported case of stroke [wikipedia.org], trepanning [wikipedia.org], or lobotomy [wikipedia.org] shows that the mind is tied to the hip with the brain.
But hey, sure, there is a difference. The brain is the hardware. The mind is the software. But since there's a 1:1 correlation so far with brains and minds, the distinction is fairly pointless.
Maybe, maybe. (Score:2)
But any time a scientist (particularly a theoretical physicist; they're especially prone to that) claims, within minutes, to revolutionize a different field of science in which everybody has apparently been wrong for decades, this should be taken sceptically. Obligatory xkcd: https://xkcd.com/675/ [xkcd.com]
An analogy (Score:2)
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Depends on what you usually use for thinking.
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Shannon died after a long bout with alzheimers. That brilliant mind had died long before its body.