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What Computers Really Can't Do
What can't computers do? Why don't we hear more about their limitations, along with the mushroom clouds of hype about their limitless capabilities? By now, the public might well expect computing to restore the environment, cure cancer, prolong life and reason through the world's most complex and intractable problems.
Not so fast.
The good news, writes author David Harel in his new book, "Computers LTD: What They Really Can't Do," from Oxford University Press, is that computers are indeed incredible, capable of amazing feats.
The bad news is that they also face major problems, serious limitations on what they can ever be expected to accomplish, and that few people, even with advance computer science degrees, really grasp that there are fundamental barries no amount of hardware, software, brainpower or money can ever overcome.
Harel explores the boundaries of computable and noncomputable problems, and find's a lot to be pessimistic about. "..our hopes for computer omnipotence are shattered. We now know that not all algorithmic problems are solvable by computers, even with unlimited access to resources like time and memory space." In fact, he adds, problems relating to computer programs, particularly running time and memory space -- he calls these difficulties computational complexity -- severely limit just how much computers will ever be able to do.
Harel, who's a mathematics and computer science dean at Israel's Weizmann Institute of Science, may have written one of the first books in recent memory that focuses on the limits of computers. For a community grown understandably arrogant by years of hubris and hype, this is probably a much needed dose of reality. Why focus on the negative?, the author asks. His answer:
l. To satisfy intellectual curiousity. Computer scientists need to know what can be computed and what can't.
2. To discourage futility. Computer experts who tackle problems that are simply insoluble need to stop wasting their time.
3. To encourage the development of new paradigms. Many of the most exciting areas of computer science research -- including parallelism, randomization and quantum and molecular computing would not be advancing at their current speeds if it weren't for increased understanding about what computers can't accomplish.
4. To make possible the otherwise impossible. (The author saves much of the answer to what might be possible a surprise in the book, so I can't give it away here).
Harel acknowledges that our society could barely function without them. But he warns against the widespread mythology that computers will be able to do almost anything we can think up.
Typically, Harel writes, when people have problems making computers do what they want them to do, their excuses that fall into three categories: more money would buy larger, more sophisticated computers; being younger would permit us to wait longer for time-consuming programs to be terminated; being smarter could lead us to solutions we don't currently seem able to find.
But the truth is that computers are simply not equal to solve many complex problems. Harel raises, then mostly sidesteps, the debate over whether computers can be endowed with human-like intelligence. "In its wake," he writes, "a host of questions arise concerning the limits of computation, such as whether computers can run companies, carry out medical diagnoses, compose music or fall in love."
For non-techs, this book is on a pretty high plane. Even with Harel's impeccable credentials and engaging writing style, plenty of concepts are rough for someone who's not a programmer or computer scientist to grasp, especially when he gets to tiling and algorithms.
But the question is significant. The limitless potential power of computing has all kinds of implications for technology, education, culture and politics. We do need to know more about what's realistic. This splash of cold water is welcome, and more than a little shocking.
Purchase this at ThinkGeek.
Flip open any biology or medical publication and see how many details of biology are still being discovered, thus couldn't be simulated even if you had a computer powerful enough for the job.
Where did this idea come from precisely? Maybe i don't read to same books, see the same movies, etc. but I've never seen computer porteyed as all knowing and/or all powerful. From Star Trek to the Matrix, even the most advanced computers seem to need human intervention to function and/or are vulnerable to human sabotage and control. I really don't see where the author, or katz, came up with this idea.
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"Darkness beyond Twilight"
Apparently it's only shocking to Katz and to other true believers of the one faith of computers©. Anybody involved with computers that has any semblance of sanity realizes that computers are not capable of solving every problem/question humanity has ever formulated. And the chances are that they never will. Even people that are into far-future sci-fi style writing usually keep a realistic stance about such things. Dan Simmons, a great author of many styles, wrote of a future with AI (autonomous intelligences, not artificial) computer units that were so intellectually superior to humans that most humans could not even fathom the depths of their 'minds', yet even these great beings couldn't answer some of the most fundamental of questions. Who are we? Why are we here? Who else is out there? How do we do
The whole premise of pure (and completely unfounded) belief in the abilities of machines is just as laughable as any religiously clung to belief. If you believe without question, then you lose your ability to see reality. If Katz sees this as a splash of cold water, then perhaps he needs to regain some perspective.
BTW, has anyone else noticed that Katz has shifted gears over the past few weeks from the "computer people are the smartest, bestest, wonderfullest, most misunderstood" to "computers suck, and they are damaging our society beyond repair"? I wonder if he just had a major system crash a few weeks ago?
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Well, some would argue that people are also just automata who respond in a predictable manner, if you know everything about their life from conception till the moment of the action in question. The issue is that humans are so complex, and have such a complex web of influences and forces, that the human mind cannot reliably predict what another human may do. In some sense humans, it could be argued, are psuedo-random, we are predictable, just not to any intellect we have yet spwaned or encountered.
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"Darkness beyond Twilight"
So now this Harel decides that a problem is insoluble? If a team of researchers try to solve a problem, should they stop because Harel says it can't be done? Who does this guy thinks he is, the All-knowing deus? Isn't it so that the effort to solve a problem can yield other results? Isn't that what science is about?
How to make a sig
without having an idea
Lets assume that the current trend of rapid increases in computing power continues a decade or two.
;)
The most interesting problems crunched on today (IMHO) with computers are simulation and complex problem solving. The latter meaning various algorithms for finding optimal solutions to combinatorial problems.
Simulation meaning the ability to predict the behavior of physical structures, chemicals, processes, etc.
Combinatorial optimization solving traveling salesman, design - VLSI, chemical engineering, etc. using algorithms such a simulated annealing, genetic or eveolutionary, nueral networks, etc.
These types of processing will continue to grow in power and flexibility to a point where we can design incredibly complex systems entirely in silico.
Once this is accomplished, the majority of human 'work' will consist of manual labors, or 'creative' tasks. The engineering types of processes, VLSI, CAD/CAM, structure design, will be crunched out by computers at a fraction of the cost, using incredibly powerful eveolutionary processes to find solutions no human could dream of.
This is already happening in quite a few fields of expertise.
Thus, we will be the eternal dreamers, searching for the endless areas of which to apply our computing power, and provide direction for its use. The rest will be done by the black box brutes.
At least, that's my opinion...
Computers are just simple turing machines. This means that everything they do is utterly predictable. The very essence of being conscious is an ability to behave in a random fashion, also known as free will.
:).
Devil's advocate time:
Prove this.
As far as I can see, a human mind is indistinguishable in practice from a very large deterministic system in a chaotic environment. Apparently nondeterministic actions are adequately explained by strong sensitivity to input and the chaotic, effectively unpredictable nature of this input.
So, rather than making a blanket statement that the human mind can't be emulated by a deterministic machine, you're going to have to prove that it isn't already one
I'm using "human mind" instead of "conscious mind" above because you're going to have one hell of a time defining "consciousness".
Harel, [...], may have written one of the first books in recent memory that focuses on the limits of computers.
...
Search on Amazon.com (or others) for books on "Complexity Theory" or "Theory of Computation". I get 277 hits.
We now know that not all algorithmic problems are solvable by computers,
Now? This has been known for 50 years (The halting problem, etc). The book might be very good, but please don't make it sound like this is news.
-- Slef
I'd probably disagree with most of this book. There's no reason that even a Turing machine couldn't simulate a problem solving device as complex as the human brain, provided you'd figured out all of the physiological properties that contribute to intelligence.
But even before that goal is reached, computers are going to go a very long way in enhancing our own intelligence and problem solving capabilities. Hell they already have.
Another point is that the solution to some of these problems may not take the form this guy expects. We could change the laws of physics by building a virtual reality indistinguishable from reality, putting everyone into it and then changing the rules.
Computers are tools and they will solve whatever problems we tell them to, eventually.
2. To discourage futility. Computer experts who tackle problems that are simply insoluble need to stop wasting their time.
4. To make possible the otherwise impossible.
Computers are unable to interpret English to discover typos in words spelled correctly. Forget the unsolvable problems, I prefer insoluble ones more. They go so much better with tea.
They can't make the author appear smarter either. First I will state computers cannot solve a problem, then I will say I will use computers to solve problems which were once impossible.
Huh. That really flies in the face of what we thought about the power of computers back...when? Circa Fritz Lang's Metropolis?
Perhaps the above should read:
"My hopes for computer omnipotence are shattered. I now know that not all algorithmic problems are solvable by computers, now that I've read through decades' worth of essays written by some of the greatest computer scientists ever to live."
information wants to be expensive...nothing is so valuable as the right information at the right time.
Obliteracy: Words with explosions
Computers are just simple turing machines. This means that everything they do is utterly predictable.
Unless you have a Real Random Number Generator (RRNG) card plugged in.
The very essence of being conscious is an ability to behave in a random fashion, also known as free will.
Oh no! my RRNG has consciousness. What's more, it has free will! Even more disturbing is that this means dice are sentient while being rolled. To not roll the dice is cruelty. I heard that there are dice in Las Vegas not being used now. I urge all of you to go to Vegas and shoot craps all day and all night. I urge that we form a society for the prevention of cruelty to dice.
Computers will never have free will and will never be conscious, not in their present Turing Machine form, anyway.
The really scary thing is that nobody can prove that the brain isn't just a sophisticated neural network. Maybe consciousness is an illusion. To believe otherwise is, at this point, a matter of faith.
It is for the best, anyway. I don't want to be superceded mentally and made redundant, like the industrial revolution made my muscles redundant.
So, you don't want to be promoted to mid-level management?
So I am very glad conscious computers are impossible. It would be dangerous for us if they were.
Can you prove either of these statements? The current state of computers is not proof; neither are any Hollywood movies where intelligent computers take over the world.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
-y
150 Opening BINARY mode data connection for slashdot.sig (129323052 bytes).
Warning: Some might consider this flame bait. Caveat Emptor.
Katz is a hack. He doesn't really care to think or challenge anything. All he wants to do is make a name for himself, sell "books", etc. To do that, when you have mediocre skills and limited intelligence, you must find your niche. Katz does this by being the loudest voice in the heard.
When computers are "hot", he'll be their greatest cheerleader. When the internet is hot, he'll be there too. But when the Dot Coms start crashing, and there is a large sentiment that he can cash in on AGAINST it, he'll be there just as quickly. Never mind consistency. Just read his stuff over the past couple of years.
I see Katz as a Clintonesque figure, albeit, without the charisma, intelligence, etc...always holding his finger out to the wind of public opinion or, rather, his niche audience of teenage "geeks".
Has a slashdot user bashed Katz? Is this just another rehash of decidability and intractability? Or is there something new here?
My mommy always said, if you don't have anything nice to say, STFU.
Some moderator marked the above as flamebait. That's bollocks. This is a highly valid point and totally on-topic for the subject of "what computers can't do".
"Contentious" does NOT equal flamebait. Stuff like that NEEDS to be discussed. We can't just pretend a subject will go away just because some people feel passionately about it.
SEWilco is quite right. You can't model what you don't know.
In addition, computers require absolute parameters. Not only can you not model what you don't know, but you can't do worthwhile simulations (ie. those used for human life or death decisions) based on educated guesses.
I only have respect for anti-vivesectionists who are vegans- not only in diet, but in clothes, tools, furniture and cosmetics too. Either animals are something we eat, or something we don't. Any half-way stance is hypocrytical.
Since there is absolutely no chance of any nation enforcing veganism on it's population, anti-vivisectionism is ultimately futile.
What I personally feel doesn't come in to it. There is no point arguing for a law if it will never get voted in or be enforced.
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Andrew Oakley - www.aoakley.com
The question to Multivac (and its incarnations throughout Time) was (moreorless) "How to stop the eventual heat death of the Universe."
"Dogs and cats, living together...it's mass hysteria!"
>> Computers are just simple turing machines. This
>> means that everything they do is utterly
>> predictable. The very essence of being conscious
>> is an ability to behave in a random fashion,
>> also known as free will.
> Devil's advocate time:
> Prove this
See Roger Penrose's book on the subject The Emperor's New Mind wherein he uses rather a lot of words to explain why he believes hard AI is not possible. It's an opinion I personally don't agree with (and as an earnest teenager I was delighted to be able to read a book by such a well respected academic, and find myself capable of actually disagreeing with it!).
Penrose's central theme is that computers are deterministic and that the human brain is not. My angle is that any sufficiently complex deterministic system can appear non-deterministic (hey, that's Chaos Theory) -- and anyway, even if that's not the case, you could easily hook up a random noise source to an A/D convertor and have your computer AI grab input from that for its "free will".
I say, if it can be done in wetware, it can be done in software -- to deny this is to invoke the supernatural, to say the Soul is seperate from the physical brain, and that's something I personally can't agree with.
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There are two famous books by the phenomenologist philosopher Hubert Dreyfus on the folly of Artificial Intelligence.
"What Computers Can't Do: A Critiqe of Artificial Reason"
"What Computers Still Can't Do: A Critiqe of Artificial Reason"
AI folks hate these books for many reasons, but especially because Dreyfus is a technical doofus. He consistently misunderstands what computation is, how computers are programmed, etc. (Sometimes with comical results -- there's a great story in Levy's "Hackers" about Dreyfus claiming (in the 1960s) that no computer would ever play decent chess and then being soundly defeated by a primitive chess-playing program shortly thereafter.)
It's pretty clear that the title of Harel's book ("What Computers Really Can't Do") plays on the titles of Dreyfus's books, reasoning soundly about the formal limits of computation rather than insinuating rhetorically about what computation cannot be based on a particular philosophical (phenomenological) critique.
Here's one thing computers *can't* do:
Shorten the work week.
Technology was initially embraced because, allegedly, it would give us more leisure time. Popular Mechanics magazine has made some of the funniest wrong predictions over the years. One of my favorites was that in 1950, they said that by the year 2000, we'd all be working only 2 days a week, and machines would take the drudgery out of menial tasks by simply eliminating our need to do them.
Of course, that hasn't happened: if anything, the reverse is true.
An ex-neighbor of mine has an interesting collection: he collects lawn mowers. So, he's got a gadget called "The Lawn Ranger". It's a late-1980s computer controlled lawnmower that uses optical sensors to figure out where it has and hasn't already cut. You put it in the middle of your lawn, press the start button, and it goes merrily along, destroying your garden hose, the toys that the kids left in the lawn, and generally wreaking havoc. It's cool, and the task of mowing the lawn is pretty braindead, but it's hard for the computer to grasp it.
He's also got a far more practical device called a Hovermower. It has no wheels, and uses a fan built onto the blades to hover above the lawn like a hovercraft. It, too, is great: sweep it around corners. But, like the Lawn Ranger, it's not a very good idea: when it runs out of gas, as the motor slows down, it ceases to produce enough lift, and the blades end up tearing up a big chunk of sodding. And you don't want to ever leave the thing idling unattended, as it has a tendency to slide around like a puck on a crooked air hockey table.
Technology, and all associated good ideas, have their limits.
Sure, we're more productive during our working ours because of technology. And it's given society a whole lot *more* career choices than before, when you could basically either be a farmer or a burden to your family.
Computers are merely an incremental step along the path away from a one-lifestyle existance, whereever that path may lead. They simply join the ranks of everything starting from the steam engine and Jaquard's Loom all the way to the modern transportation infrastructure and the fax machine.
Cars can't do everything.Nope. But they've freed us from the shackles of public transportation, allowed us to independently venture further than the first town down the road, and given us the ability to be more productive in the workplace. And, in doing so, they entertain us and diversify the working world.
This is prolly a good book and all but get real people, computers are just tools and the audience this book was intended for knows this.Agreed. But I'd wager there are some reading this discussion right now to whom computers are *everything*; while that's not necessarily wrong if your work and hobbies involve nothing else, but it's a very narrow (ie. wrong) view of the big picture.
Computers are cool toys. And then when you've got valuable information spinning around at 7,200 RPM on your hard disks, then they're very important tools.
A slot screwdriver can be used for turning screws. Or, it can be used as a pry-bar (I have a big one that my buddies and I call "The Persuader"). Or a chisel. Or as a weapon. Even as a fireplace poker. They're a very versatile tool.
A computer is simply a very versatile tool: They're the 21st century screwdriver.
And that is a rational perspective.
Fire and Meat. Yummy.
On compensatory mechanisms: Who says we haven't? Perhaps epilepsy is merely what happens to a brain when one or more of these mechanisms fails?
On random data: And what is the input into your ears and eyes, if not "random" data? Yes, our sensory processing mechanisms are engineered to process and react to external stimuli -- but many of those stimuli are essentially random.
Sorry, Mr. Penrose. Yelling "tubules" and "quantum" over and over again in Emperor's New Mind doesn't refute hard AI. It just means that the CPU in the deterministic Turing machine may need an embedded random-number generator based on a random physical process.