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A Model Railroad That Computes
tri44id writes "Several blogs have noted an Austrian team that has built a model train set that is a primitive computer. I have to point out, though, that it's actually only a Finite State Machine, like a pocket calculator, not a general-purpose device. Their plan for a general purpose layout is for an infinite-state machine, not a FSM+tape that Turing envisioned in his original paper. Turing took the concept a further step, by presenting a Universal Turing Machine that embodies a special set of states and transitions that allows its tape to be programmable to emulate any other TM. Do Slashdot readers know of any mechanical implementations of a truly Universal Turing Machine? (Danny Hillis' famous tinkertoy tic-tac-toe machine has neither infinite tape nor programmability, and is thus yet another FSM. It shouldn't be hard to elaborate the Austrian model train FSM to use a series of cars carrying movable magnets to represent Turing's tape cells writable with different symbols, and thus become a true TM or even UTM."
I haven't been fortunate enough to find a computer that was more powerful than a sufficiently large finite-state machine.
Dyslexics have more fnu.
Could they use it to control another digitally controlled model railroad once they build the more advanced system?
Life is just nature's way of keeping meat fresh.
I just wasted about half a day compiling and recompiling my linux kernel to get it "just right".
But still, I feel even I have the authority to say that some people just have too much time.
That is really awesome! The idea of a model railroad being a computer is not new though. I read a book by Desmond Bagley (or was is Alistair Maclean) many years ago where a scientist who wanted his work to remain secret built a model railroad/computer. His dying act is to give his model railroad timetables to the main character. The main character later realises that the timetables are actually code for this unique computer.
It's interesting to note that almost everything we find weird and wonderful about computers, and about the culture that builds, modifies and programs computers for the sheer love of intellectual challenge, stems from the MIT Model Railroad Club.
The hackers who loved switches, relays, automation systems and doing beyond-tomorrow stuff with all of it irritated the hell out of the guys who liked collecting little models of trains, and eventually went on to be the Midnight Hackers of fame.
SoupIsGood Food
A Turing Machine is a simple model of computation that encompasses anything that can be computed by a computer. The strongest claim about the ability of a programming language is that it's "Turing Complete", which means that anything that can be computed on a Turing Machine can be computed in a language. Turing Machines are designed to be very simple, and they're good for theoretical things about computer science.
A Universal Turing Machine is a Turing Machine that takes, as its input, an encoding of another Turing Machine, then simulates it. As such, you can prove that with a Turing Machine, you can compute anything that any other Turing Machine can.
By contrast, Finite State Machines, or Finite Automata, are far less complex models of computation. If you treat them as language acceptors (i.e., everything that they compute is whether or not a string is valid in a language) they are only as powerful as simple regular expressions. They can be modelled very quickly by computers, though, since they are deterministic and require no lookahead.
I have to point out, though, that it's actually only a Finite State Machine, like a pocket calculator, not a general-purpose device
Yes, and your desktop computer is also another example of a finite state machine. Granted, all those little silicon switches have an enomorous number of possible states, but rest assured, the total number is indeed finite.
Would a UTM Railroad be a train of thought?
Is this not a Choo-Chooring machine?
Given the requirement for an infinitely long tape, I suspect the answer to this question might be no.
If I seem short sighted, it is because I stand on the shoulders of midgets
AFAIK the only truly universal turing machine must be implemented with reversible logic and be based on quantum mechanics. http://www.holbornbooks.co.uk/details.aspx?sn=3917 4This book explains it fairly well.
Do Slashdot readers know of any mechanical implementations of a truly Universal Turing Machine?
Of course not. A truly Universal Turing Machine needs an infinite amount of tape. Or RAM. Or HDD. Or Spaghetti. Or any other infinite amount of storage device. Hell, the submitter makes this clear in their spiel, just after they ask the vacuous question above. I guess they should read what they write a little closer; or stop prancing around like a tit, trying to sound profound and knowledgable.
Tubal-Cain smokes the white owl.
I'm currently at work, graveyard, and this thing just blew my mind. Someone said this thing is terribly slow, (I doubt they meant it as an insult) but if you wanted to solve that problem you could make a three dimentional roller coaster version. That would be MUCH faster.
Don't you mean.. BIZZARO!
I bet they still don't run on time.
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Thomas the tank engine has been solving problems for ages now, and in multi task more he keeps the kids amused while he does it.
Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
What truth?
There is no dupe
There was a 70s adventure novel - I believe by Hammond Innes although the title eludes my memory) in which a bomb-scientist who had promised to do no further research when he left government service is kidnapped
Investigators found that he had a large model railway which was controlled by a computer and the answers to calculations were reported by numbered wagons being arranged in certain orders and locations.....
It wasn't a very good book, actually.
I have been a user for about 10 years. This ends Feb 2014. The site's been ruined. I'm off. Dice, FU
Do Slashdot readers know of any mechanical implementations of a truly Universal Turing Machine?
No, but I have an infinite tape lying around in my shed, so if you know how to do the logic stuff, we can team up.
sudo ergo sum
If they didn't have the model train, they wouldn't have gotten the idea for the big trains
You're trying to be clever but I hope you do know that having a "finite number of states" is not in and of itself a definition of a FSM. He wasn't trying to be clever, just accurate. Your computer is a finite state machine; It is not a Turing machine. We tend to think of them as Turing machines only because they have an enormous number of states; thus they seem to act like Turing machines as long as we don't do anything that requires more states than the computer has. However, when you run out of ram and/or disk space, you've just recognized the limitation of your desktop FSM. It is demonstrably the case that a finite state machine cannot be programmed to run a JVM or a Python interpreter. That is incorrect. Every computer program is a FSM.
This layout is horrible! Get some trees in there! Some buildings? This guy made up the computer idea to hide the fact that he couldn't use plaster-of-Paris.
One man's Funny is another man's Offtopic.
You were right the first time. Desmond Bagley wrote "The Enemy" and it featured a model railway that computed genetic manipulations.
It was bought by the main character at an auction, for 31000 pounds. When his boss heard that he had bought a train set for such an ungodly amount of money he said "You expect me to be able to clear that through Expenses?" To which the character replied "Call it by its real name, a computing device."
'Twas a fine yarn that story. Nearly as good as Running Blind.