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Ten Weirdest Types of Computers
An anonymous reader writes to mention that New Scientist has a quick round-up of what they consider to be the ten weirdest types of computers. The list includes everything from quantum computers, to slime molds, to pails of water. "Perhaps the most unlikely place to see computing power is in the ripples in a tank of water. Using a ripple tank and an overhead camera, Chrisantha Fernando and Sampsa Sojakka at the University of Sussex, used wave patterns to make a type of logic gate called an "exclusive OR gate", or XOR gate."
Conway's Life is Turing complete. I guess, to a computer scientist, it's not really surprising that an automaton could be Turing complete, but it's still pretty damn awesome to think that little cells replicating on the screen are capable of carrying out any arbitrary computation -- as well as self-reproduction.
I wonder, with a large enough simulation, if self-reproducing, intelligent entities could evolve out of just a few simple rules (and it's really only one rule, if you code it a certain way).
In his early Known Space stories collected in Tales of Known Space Larry Niven forsaw a future 1975 (ha) where the brains of people managled in car accidents are integrated into spacecraft for guidance, allowing them to continue contributing to society even if their bodies are gone. This entire idea of "brain in a jar" science fiction seems to have faded out with the 1970s.
When I worked in manufacturing I would occasionally rig up some logic circuits using a series of pneumatic valves. If only a few conditions had to be met (like don't open door if bucket raised) it was cheaper and easier than installing a PLC.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
My personal favorites are computers built in Game of Life and a model railroad.
You know, someone on Youtube showed off logic gates in K'nex. But it was only and, or, and not.
Has anyone figured out how to do an xor in k'nex without horrible permutations along the lines of (in scheme, since it's easy for me to think in today)
(define (xor a b) (and (not (and a b)) (or a b)))
?
Some better examples:
http://en.wikipedia.org/wiki/Conway's_Game_of_Life
It is possible for gliders to interact with other objects in interesting ways. For example, if two gliders are shot at a block in just the right way, the block will move closer to the source of the gliders. If three gliders are shot in just the right way, the block will move farther away. This "sliding block memory" can be used to simulate a counter. It is possible to construct logic gates such as AND, OR and NOT using gliders. It is possible to build a pattern that acts like a finite state machine connected to two counters. This has the same computational power as a universal Turing machine, so the Game of Life is as powerful as any computer with unlimited memory: it is Turing complete. Furthermore, a pattern can contain a collection of guns that combine to construct new objects, including copies of the original pattern. A "universal constructor" can be built which contains a Turing complete computer, and which can build many types of complex objects, including more copies of itself.[4]
...Also, I didn't know Buggalo could fly.
They're all impressed by using waves for building logic circuits.
Want to build your own cheap, brilliantly visual set of logic gates to show kids how digital computing works? Nightlights. Each one is a NOT gate. You put two close to a third's sensor and you have a NOR. Put them some distance away with some blocking material around them (this is fussy) and you can get a NAND. A little bit of thinking and combinatorial logic and you can build anything else from those. I've built stacked, carrying half-adders this way, and it's pretty cool to watch small binary numbers get added.
Two nightlights, each with its bulb by the other's sensor, are a flip-flop. Now you have memory.
For extra credit, you can build a ring oscillator by putting an odd number of nightlights in a ring, so each is seeing the next one's sensor, and use that to clock your half-adders and flipflops.
If I had a lot of money and time, it'd be fun to see how far this could be extended (before I had to start hiring kids as tube runners to keep the whole works going.)
Nostalgia's not what it used to be.
You'd be interested to know that rat's brain cells have already (the linked article is from 2004) been harnessed to fly a virtual F-22.
The singularity, as the man said, is near.
"Be light, stinging, insolent and melancholy"
OK, let's go back a ways and look at the weirdest storage systems.
Mercury delay lines are a good one. Delay lines in general, actually. I recall readong once about a free-space delay line using a laser beam between Earth and a retroreflector on the moon.
CRT storage tubes are another.
Using ripples in a container, you can do Fourier transforms and similar things.
In fact, the ear organ does exactly that (channeling waves through liquids in a properly wound casing and picking up the resulting vibrations at different locations corresponding to different frequencies).
An XOR gate is rather embarrassing...
Multiplication, always a problem with analog computers at the time, was very simply, quickly and cheaply done by an AND chip (one of the inputs had to be decorrelated of the other by a delay line to avoid parasitic correlations). The addition was a little more tricky, but getting (p1+p2)/2 could be achived with just three basic circuits, if I remember well. Of course you had to remember that the value was scaled, well, exactly the same king of caution you had to observe with analog synthetizers at the very same time.
Details here for whoever is interested... and knows somebody reading French ;-)
http://fr.wikipedia.org/wiki/Calculateur_stochastique The complexity of keeping trace of scaling, decorrelations and the like could be taken away by monitoring them from an associated PC, now that I am thinking about it. Try it ! You will like it ;-)
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Many puzzles have been shown to effectively be nondeterministic computers. E.g., you can make a sliding-block puzzle that is solvable if and only if a given traditional computation succeeds.
Science News story:
http://www.sciencenews.org/articles/20020817/bob10.asp
Personal plug:
Games, Puzzles, and Computation
What about the Antikythera mechanism?
The game.
In A.K.Dewdney's Scientific American column (and subsequent books) he documents many unusual mechanical computing devices that solve a range of computationally expensive problems. In a chaptered entitled Analog Gadgets in the book The Armchair Universe he describes several mechanical computing devices that solve a number of many computationally expensive problems (with some caveats):
* a spaghetti powered sorting machine
* computing a convex hull using a board, nails and a rubber band
* finding the shortest path joining two nodes of a graph network using brass rings and string
* finding the minimum Steiner-tree for any number of nodes using pegs sandwiched between parallel sheets of plastic dipped in a soup solution
* a prime calculator using a pair of lasers and parallel mirrors
In the next chapter, Gadgets Revisited, he presents:
* a way to compute the best-fit trend of a graph using a board, nails, rubber bands, and a rod
* finding the longest path through a network of nodes using segments of string knotted together
* computing the forth power of a number based on the principle of elasticity and the deflection of a bar of aluminum
* or the third power of a number by using the same principle applied to a weight placed on the bar
* light refraction computed with soap film suspended between stepped surfaces
* optimal position for a refinery using a board with holes, string, a brass ring, and weights proportional to the cost of transportation for each source of raw material
* number averaging using interconnected graduated glass cylinders
* cubic polynomial solver using a water tank, a balance beam, two scalepans, and a variety of solids to represent terms of the equation: a cone for x, a paraboloid for x and cylinder for cx, and a sphere for d
+0 Meh
This article reminds me of a very interesting video on youtube about a marble adding machine. It is constructed out of wood, and the creator also has made a video explaining how it works, in case anyone would like to build one on his own.
This article makes me think, of course, of my experiments in domino digital logic
The brain is Turing-complete, as in it can emulate a Turing machine.
So does that make people computers by definition?
I have developed a truly marvelous proof of this comment, which this signature is too narrow to contain.
These are all (interesting) variation of basic logic gates implemented without electronic components. I was expecting something in the vein of the transputer...
The Game of Life (and cellular automata in general) can produce very complex behavior from a very small set of rules. If I run through a set of random live/die rules (one cell dies if it's surrounded by 4, not surrounded by four, surrounded by 3 or 5, etc) I'll eventually come up with one that does something interesting. It could be totally automated and random, but leaving each cellular automata to run and then checking on it and looking for complexity will produce some patterns that /look/ "designed" but are actually produced by a totally random set of rules.