Lego Turing machine

January 30, 2009 4:34 PM

Lego Turing machine (SLYT)
posted by pompomtom (22 comments total)

So... when is it going to run Linux?
posted by jkaczor at 4:41 PM on January 30, 2009

Not so much when, jkaczor, but where.

I'd love to actually see it in action.
posted by lucidium at 4:46 PM on January 30, 2009

Not to impinge on the excessive geekiness of it all, but if it is in fact computer-controlled, doesn't that just make it an elaborate bit-storage system instead of an actual Turing machine?
posted by neckro23 at 4:46 PM on January 30, 2009 [2 favorites]

I feel like I'm in the Diamond Age
posted by bystander at 5:02 PM on January 30, 2009

They spent all that time making a Lego Turing machine and they couldn't even make it non-deterministic?
posted by christonabike at 5:07 PM on January 30, 2009 [1 favorite]

The next logical thing is to build an organ.

Because an organ is a church machine.
posted by shadytrees at 5:45 PM on January 30, 2009 [4 favorites]

neckro23: I was trying to decide that. From what I could discover, there hasn't really been any building of Turing machines beyond hypotheticals and simulations. With my understanding, it looks like it would be possible to build a (very complex) mechanical Turing machine, and no doubt it's doable something with a bunch of transistors. But isn't a Turing machine basically "an elaborate bit-storage" and modifying machine?

(The above could possibly be entirely incorrect. IANAL)
posted by niles at 5:49 PM on January 30, 2009

This reminds me of the guys a few years ahead of me who, as EE freshmen, built a for-real RISC processor out of 7400 series TTL chips on breadboards. Took a lot of TTL chips and a lot of breadboards.

But yeah, what do we call this being pedantic?

On the one hand, it quacks like a duck, but on the other hand guy sort of built a duck by putting a duck in a duck suit. (Not that it's not an excellent project.) An emulated Turing machine? Maybe we need to make "Rube Goldberg machine" into CS jargon.
posted by TheOnlyCoolTim at 6:27 PM on January 30, 2009 [1 favorite]

This is awesome.
posted by Godbert at 8:17 PM on January 30, 2009

My wife: "Are you watching The A-Team?"

Me: "No, it's a YouTube video that's using the theme song from The A-Team."

My wife: "Oh."

Me: "Can I just say how awesome it is that I married a woman who knows the A-Team theme song?

My wife: "Well, only just -- "

Me: "Your stock just went way up with me."

My wife: "Well, it's really only just recently that -- "

Me: "IT DOESN'T MATTER DON'T RUIN THIS FOR ME."
posted by middleclasstool at 8:24 PM on January 30, 2009 [8 favorites]

Not to impinge on the excessive geekiness of it all, but if it is in fact computer-controlled, doesn't that just make it an elaborate bit-storage system instead of an actual Turing machine?

Actually, that question doesn't really make much sense, because a computer is* a Turing machine. That's the whole point. But most likely, the computer is running a program that emulates a finite state machine. A Turing machine is a finite state machine with a tape, and it doesn't matter if the finite state machine is implemented with hardware or software.

_{*Actually the computer would be a Von Neumann Machine, which can do everything a Turing machine can do, and vice versa}
posted by delmoi at 9:00 PM on January 30, 2009

His Nibs: "That's the theme song from the A-Team you're listening to."

Me: "Yeah, I know."

His Nibs: "Oh yeah? Since when would any woman know something like that?"

Me: "Can I just say how disappointing it is that I'm stuck here with a chauvinist?"

His Nibs: "Well, only just -- "

Me: "Your stock just went way down with me."

His Nibs: "Well, it's really only just recently that -- "

Me: "IT DOESN'T MATTER DON'T RUIN THIS FOR ME."
posted by de at 9:32 PM on January 30, 2009 [2 favorites]

De, it's not that only men know the theme song, it's that only 80s kitsch obsessed geeks know the theme song. There's a difference.
posted by Nonce at 11:44 PM on January 30, 2009

Oh wait, you were telling a conversation of your own, not casting aspersions. I'm sorry. I'm an idiot.
posted by Nonce at 11:46 PM on January 30, 2009

In other Lego-machinery goodness: V8 engines.
posted by Ljubljana at 2:25 AM on January 31, 2009

Last week on the MeFi Interesting Turing Machine Implementations Channel, a Turing machine built within Conway's Game of Life^.

delmoi: Actually, that question doesn't really make much sense, because a computer is* a Turing machine. That's the whole point.

If I understood neckro23's point correctly, that's sort of what he was saying: because every computer is a Turing machine, a Turing machine constructed in such a way that it depends upon a computer to function is only a Turing machine in a fairly mundane sense. Even if it was incorrectly designed or had broken down, it would still be a Turing machine anyways because it's got a working computer in it; it's more the computer that someone else built which makes it a Turing machine rather than anything the designer did. As niles pointed out above, actually constructing something like a mechanical Turing machine would be much more significant.

Speaking of non-computer-dependent Turing machines, has anyone else noticed that most of the cytological mechanisms involved in handling DNA look suspiciously like Turing machines when they're functioning? A ribosome transcribing mRNA into protein, for example. WTF is with that? I always meant to sit down and figure out whether any of those mechanisms actually qualify as Turing machines but I never get around to it.
posted by XMLicious at 3:53 AM on January 31, 2009 [2 favorites]

Man, I miss the days when people made webpages for stuff, instead of just recording video and uploading it to youtube. It's nice to click on a link and immediately get the gestalt of something based on a few images and some text. Then, if you want more info, you can load the embedded video.
posted by Eideteker at 5:11 AM on January 31, 2009 [1 favorite]

How does:
Me: "Can I just say how awesome it is that I married a woman who knows the A-Team theme song?

Become:
His Nibs: "Oh yeah? Since when would any woman know something like that?"

I feel like I'm taking crazy pills!
posted by wayofthedodo at 2:55 PM on January 31, 2009

XMLicious: Speaking of non-computer-dependent Turing machines, has anyone else noticed that most of the cytological mechanisms involved in handling DNA look suspiciously like Turing machines when they're functioning?

See chapter 16 of Gödel, Escher, Bach, in which Hofstadter examines the strange-loopiness of DNA and draws explicit parallels between it and computers/computer programs.

(See also the rest of GEB, since it's a fantastic book.)
posted by The Pusher Robot at 11:39 PM on January 31, 2009

Yeah, I've been meaning to check out GEB, I've browsed through it a bit. I'm a bit turned off to it, though, because - apart from any actual qualities of the book, I'm sure - it appears to me to have become an article of pop science.

The contexts in which many people mention the ideas in that book have taken on many of the worse aspects of pseudoscience. (Again, probably not the book itself but its lay readers.) For some people, trimmed-down principles of science that it presents appear to have become deus ex machina in their personal philosophies: they use concepts like emergent behavior as a sort of a priori rationale to believe things that otherwise aren't on any sort of rational footing.

Then they'll rattle off some buzz words from the book like "Gödel's incompleteness theorems", which I just barely have enough mathematical background to sort of grasp (AB in mathematics), and it's like... I really don't think that has anything to do with what you're talking about, dude.

Or even more alarming is to be in the course of an ethical or moral discussion and have someone say to you, in response to an exploration of why something is right or wrong, say "It's consciousness! It's emergent behavior!" and reference that book. I consider myself an atheist and I regard that as as poor a basis for ethical or moral reasoning as "It's the will of God!". I think in that case the ideas from GEB have actually become a psychological device for the person which he or she is using to justify right and wrong. If one is going to pull a rabbit out of a hat one should just straight-up admit that's what's being done - not instrumentalize God or science to cater to one's own existential insecurities and spackle over genuine philosophical problems.

(Can you tell I've gotten a bit aggravated on occasion? ;^) But seriously, thanks for mentioning those passages of the book.)
posted by XMLicious at 2:55 AM on February 1, 2009 [1 favorite]

To be fair, the entire book is about drawing connections between things that you wouldn't think have anything to do with each other. :P

But yeah, GEB is pretty much silent on the moral/ethical implications of the ideas being discussed. (Hofstadter's latest book, I Am a Strange Loop, covers that area a bit more.)
posted by The Pusher Robot at 11:09 AM on February 1, 2009

That's not quite what I mean. I mean that some people I've met who are big fans of the book subsequently try to use "emergent behavior" or "the mystery of consciousness" to handily prove anything they like to be true or to spackle over logical problems in their reasoning, much the same way "the will of God" or "it's divine justice beyond mortal ken" is used in some theological thought - as a one-size-fits-all universal wrench that applies an easy fix to any intellectually challenging problem or philosophical quandary.

I was using morality and ethics as an alarming example of this because when people start punting on ethical questions that way - when they take up a device that allows them to rationalize or justify anything in any context - you often get results similar to the War in Iraq or the current global financial crisis or the eugenics movement. (But like I said, it's probably more to do with the shallowness of the readers than any sort of shortcoming in GEB; it's just that it's left a bad taste in my mouth.)
posted by XMLicious at 9:43 PM on February 1, 2009