## The "Omega Number" & Foundations of Math 247 247

speck writes

*"Here's a link to an article in New Scientist about mathemetician Gregory Chaitin, who seems to have thrown some of the basic foundations of math into question with his work on the 'omega number.' Among the more provocative statements in the article: '[Chaitin] has found that the core of mathematics is riddled with holes. [He] has shown that there are an infinite number of mathematical facts but, for the most part, they are unrelated to each other and impossible to tie together with unifying theorems. If mathematicians find any connections between these facts, they do so by luck.' Also of interest is the transcript of a lecture Chaitin gave at CMU, which explains some of the theory in quite accessible language."*
## Re:Misconceptions (Score:1)

## Re:This IS surprising! (Score:1)

First question, and this is an important and nontrivial one, why does omega exist and are you sure it's a fixed finite number? I have a degree in math and I have no idea where to even begin proving that it exists. It occurs to me that this is a ratios of inifity problem, any halting Turing machine can be made in to a non-halting Turing machine with relative ease so there is at least one non-halting Turing-machine for every halting Turing-machine. I'd assume that the relation is something like this: non-halting >> halting in much the same way that card(

R) >> card(Z)I propose this isomorph of what he is saying:

Zare infinite, I'll leave the proof as an excercise to the reader, itistrue.Rare infinite andR>>>Z.in fact,

Ris so much larger thanZthat the ratio between the two cannot be calculated and the limit of card(Z)/card(R) -> 0Zthen anything we know aboutZis known about a remarkably minute set of numbers so it can be extracted that we know nothing about numbers as a whole. ie: We know a lot aboutZbut that means zip in the grand scheme becauseZmakes up ~0% of the numbers.Or something like that.

My instinct is that he is trying to make sweeping statements about what we know of math as a whole. That's an easy one, we know next to nothing but what we do know can be proven. In my school we started with 5 axioms and we proved our way through the rest, there are no holes, does that mean we know much about math? Hell no! But it also doesn't mean that math is full of holes or bullshit. Now if he is trying to prove that there is a lot more to know than we can prove then I'll buy it. Is there infinitely more things to know than can be proven? Certainly.

I'll do the rest for you: what can be proven is countably infinite while what cannot be proven in incountably infinite, thus card(provable)/card(unprovable) -> 0 so the most we can possibly know and prove is ~0% of what there is to know. => We know nothing about math . . . QED

Only that's a remarkably simplisitic way of seeing things.

## Re:This is not surprising (Score:2)

Not at all! If you found a system of mathematics in which some theorem could be proven both true and false, mathematicians would just say that your system was

inconsistent(italicised 'cos I'm using that word in it's maths jargon sense, not it's everyday sense) and be uninterested in it. They'd be uninterested 'cos in a formal system, if any false theorem can be shown to be true, then any theorem can be shown to be true (if 2=1, it logically follows that I'm the Pope).The basic foundation of maths that Chaitin's work questions is the belief that mathematics is a solid body of knowledge waiting to be discovered, and that we can "get to" proofs in any part of it from where we are now. His work shows that maths is more like the distribution of matter in space: lots of lumps all over the place, with huge gaps between them and no way to travel from one to the other.

## Re:This IS surprising! (Score:1)

Are you sure they're not compressible? I'm just thinking of a trivial example like gzip. Every algorythm can be expressed as an implementation of gzip and along with a string of 0's and 1's fed into it that unpacks into the original algorthm. If the two together are smaller than the original algorythm, then it is compressible. This obviously isn't always the case, but is certainly true some of the time.

## Re:2 + 2 = ? (Score:1)

You could also talk about rings where such as the integers mod 3 where 2+2=1. (the integers mod x can be thought of as the set of all possible remainders when you divide a positive integer by x. For example 7 mod 3 = 1.) So maybe freedom should be the freedom to say 2+2=1

## Re:This IS surprising! (Score:1)

Hmmm... I agree that stuff over the average isn't always compressible, but once in a while it is. Once is enough to invalidate the authors point that it's not compressible. Now you have me wondering why we are usually interested in the (usually) compressible stuff.

## This IS surprising! (Score:5)

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## Re:Would you define "random Turing machine"? (Score:1)

This number depends on your choice of M, but that's no big deal.If they can't even prove that Omega is independent of M (and the TM encoding scheme), then Omega surely doesn't deserve the title "probability that a random TM halts". It's just some non-canonically defined uncomputable but definable real number. There are lots of those.

Give me a canonically defined "inherently meaningful natural constant" that's uncomputable, and I might be impressed. The criterion for "canonical" is that all sufficiently advanced foreign intelligences will know about the number, just like they know Pi, E etc. They won't know the number's digits, of course, but they will know its definition.

--

## Re:Two to One odds (Score:1)

If you want to study this idea, I would suggest a good undergraduate-level Analysis class. The ideas you would want to pay attention to are least upper bounds, greatest lower bounds and the least upper bound theorem.

As far as the original article - there are always going to basic, unprovable ideas behind mathematics.

Actually, if you want to bring up a point with one assumption that math relies on, ask why math must assume that 1 does not equal 0.

-Hank, mathematics major

## Re:broken link? No, it's more proof... (Score:2)

...that

New Scientistuses coin flips to generate the programs which run their site.## Would you define "random Turing machine"? (Score:3)

## Re:This IS surprising? (Score:2)

For W_UTM, no such compression exists. If you want to send, N bits of W_UTM to someone, then, including sending the decompressor program, you HAVE to send them at least N bits of data.

## Like Any Another (Score:1)

## Re:Like Any Another (Score:2)

Any branch or department of systematized knowledge considered as a distinct field of investigation or object of study; as, the science of astronomy, of chemistry, or of mind.

From That I believe you can mathematics a science

## Re:Misconceptions (Score:1)

The authors work deals with the vast number of statements that are true or un-true, but for which no 'proof' can ever be discovered. They are simply true by random chance.This seems to be, in the end, a fairly straight line conclusion from Godel (and actually fits how I try to explain Godel to non-math people).

Think of it this way: Godel tells me a single proof cannot encompass the system because there are undefined statements. Even if I add them one by one to the system as axioms I never finish. Why, because my 'new' system also suffers from this limitation.

If you define vast then simply take the system of choice and keep adding axioms...eventually you will have a vast list of unknowable (relative to the first system) statements and meet your explanation.

Herb

## Re:Old news... (Score:1)

But it sure does provide great proof of what happens when you let the ignorant moderate the moronic, like Slashdot does: you get outright lies marked up as "insightful."

Thank god we don't allow true democracy in our nations. The outcome would be horrendous!

--

## Re:Old news... (Score:3)

It's a "

Score 3: Good Hoax." Ludlum didn't write any books titled "The Omega Number." Geeesh. You've been *had*, fool.[

Here] is what Ludlum hasreallywritten. (Road to Gandalfo is, btw, quite a good hoot!) [ludlumbooks.com]--

## This stuff is constructive and fun (Score:1)

## Re:What would Penrose say about this? (Score:2)

## Re:too is wun (Score:2)

2) a^2 = ab

3) a^2 - b^2 = ab - b^2

4) (a - b)(a + b) = (a - b)b

5) a + b = b

6) 2b = b

7) 2 = 1

The problem with this is that to go from step 4 to step 5 you need to divide by zero. If you had a step 4.5 in there, it would look like this:

(a-b)(a+b) = (a-b)b

---------- ------

(a-b) (a-b)

a-b = 0

## What would Penrose say about this? (Score:3)

Well, if human mathematicians are basically wandering around the landscape digging up theorems at random, that sort of blows Penrose out of the water, doesn't it? It would mean that the special "human insight" into Mathematics was essentially a large sequence of random discoveries.

## Someone notify Einstein (Score:2)

thatwould happen!!"## Re:Misconceptions (Score:2)

Principa Mathematicaand related formal systems'## Misconceptions (Score:5)

This is partly true, but not point. Godel showed that incompleteness exists in any type of formal system capable of self reference. Ala the infamous "This sentence is false" translated into an equivalent in a formal system. The original is rather obscure and reads:

On Formally Undeciable Propositions inPrincipa Mathematicaand Related Systems"To every w-consistent recursive class 'k' of formulae there correspond recursive class-signs 'r', such that neither

vGenrnor Neg (vGenr) belongs to Flg(k) (where 'v' is the free variable of 'r')This is all well understood and old news at this point. What the author has done is taken Godel's theorem, and the halting problem, and turned them around a different way.

The essence of what he is trying to say is summarized nicely in this paragraph of the conference log:

"So I had a crazy idea. I thought that maybe the problem is larger and Gödel and Turing were just the tip of the iceberg. Maybe things are much worse and what we really have here in pure mathematics is randomness. In other words, maybe sometimes the reason you can't prove something is not because you're stupid or you haven't worked on it long enough, the reason you can't prove something is because there's nothing there! Sometimes the reason you can't solve a mathematical problem isn't because you're not smart enough, or you're not determined enough, it's because there is no solution because maybe the mathematical question has no structure, maybe the answer has no pattern, maybe there is no order or structure that you can try to understand in the world of pure mathematics. Maybe sometimes the reason that you don't see a pattern or structure is because there is no pattern or structure!He then describes how randomness would indicate an irreducible statement of truth that could not be compressed by finding a 'proof' that proves this truth. The idea being that a 'proof' is a program or function that generates truths, or verifies the truth of a statement.

Again, this is not groundbreaking, Godel proved essentialy the same thing with his proof. The turing halting problem is another variation, but this is where it gets interesting.

The author takes the halting problem and instead of determining whether the program halts or not, determines the probability of the program halting given a random program produced by flipping coins.

The equation to solve this is straightforward, the the 'proof' which is used to determine whether the program halts or not is the computer itself, and the statement is a program produced by random bits from a coin toss. Each bit determined by an individual coin toss.

What you then end up with is a statement that is well defined in number theory terms, but maximally unknowable. Every sample program produced from the random coin toss is a straight forward sequence of 1s or 0s, but the statement as a whole is irreducible.

Again, this seems rather unrelated, until you consider proofs as the computers which calculate the truth or non truth of a given statement.

It then becomes obvious that the truth or non truth of the statement requires a proof that can reduce the statements into a true or non true result. And there are a huge number of situations where such a proof

can notexist.So, godel's theorem deals with incompleteness in a formal system where a

singleproof cannot encompass the entire set of true and and un-true statements.The authors work deals with the vast number of statements that are true or un-true, but for which no 'proof' can ever be discovered. They are simply true by random chance.

Which holds a lot of interest for physicists because they have been dealing with truths that are random and true for no provable reason for decades...

## Re:2 + 2 = ? (Score:1)

## degree of inconsistency? (Score:2)

Goedel's proof just states that it is impossible

for a symbolic logical system ot be 100% consistent.

But what about 99.99999%?

These other guys try to quantify how good or bad

a system can be.

## Re:Misconceptions (Score:1)

Can any Floridians confirm this?

Rich

------

"Could you, would you, with a goat?"

## Re:provability (Score:1)

However, as mathematics advances, do we know if there are theorems which can never be proven?It depends what you mean by what's a proof and what isn't a proof. If you fix a particular proof system like ZFC, then yes, there are theorems which can never be proven. The Continuum Hypothesis (that there is no cardinality between the size of the natural numbers and the size of the real numbers) cannot be proven or disproven within ZFC.

Other proof systems do enjoy completeness; any theorem that can be expressed within that system can be proven or disproven. But these systems are generally too simple to be of any use.

If you don't fix a particular proof system, then things are fuzzier. Anything is provable, if you pick the right proof system. (To prove formula F, create a proof system with F as its only axiom.) It all comes down to what you choose as your axioms and your underlying logic. Mathematics will always have this issue at its foundations--mathematicians simply decide what they think the axioms should be. Whenever a mathematician proves a theorem, what they're really doing is saying, "If you believe this, this, and this, then you should also believe my theorem because..."

For example, when you learn the Mean Value Theorem, what you're really learning is that if you assume certain axioms, then the Mean Value Theorem is true. (In particular, if the axioms of Zermelo-Fraenkel set theory are true, then the Mean Value Theorem is also true. There are much simpler systems that can also prove the Mean Value Theorem.) Most mathematicians couldn't even tell you what the axioms of ZFC are, though, and this isn't as bad as it sounds. Foundational issues, like what axioms sit at the very bottom, don't have as much effect on the bulk of mathematical practice as people might think. When Russel produced his famous paradox, a few mathematicians scrambled to come up with a new foundation, and a few new systems were proposed, but 2+2=4 was not at much risk, and neither was the Mean Value Theorem. This is because the foundations are not chosen arbitrarily--they are chosen to capture, as simply as possible, what mathematicians see as mathematical reality. This has never changed overnight, but it has slowly evolved over time (and there's no consensus). Perhaps mathematicians of the future will take it as intuitively obvious that the continuum hypothesis should hold, and it will become common to assume that it's true.

## Re:Does 'lucky' mean NP-hard? (Score:1)

On a related note, can quantum computers solve NP complete problems in P time?I believe this is still an open question. If it's been resolved, then whoever solved it did so recently or didn't do a good job of getting the word out. I think the general belief, though, is that it's unlikely that quantum computers can do NP-complete problems in polynomial time. (Although, as you probably know, Peter Shor demonstrated an algorithm to factor numbers in polynomial time on a quantum computer.)

As for the nearby comment that quantum computers challenge the Church-Turing hypothesis: don't count on it. Turing machines can simulate quantum computers, albeit with an exponential slowdown. In other words, when it comes to computability, quantum computers can't do anything that Turing machines can't--they just do some things faster.

## Re:Question? (Score:1)

According to kolmogorov complexity, random means that it can't be described in a shorter way. But it is also 'described' by the turing machine that is analysed and the turing machine computing the number, which need not be of infinite length.The difference here is in what is allowed as a description. The Omega number for a particular universal self-delimiting Turing machine M has a short description: it's the sum of (1/2)^length(x) over all inputs x on which M halts. But this description is not particularly explicit (specifically, the formula that tells you whether a particular digit is 1 has an existential quantifier on it, so truth values can't be computed effectively). Kolmogorov complexity involves effective descriptions: codes for programs that

tellyou what some initial segment of Omega is. So there's no inconstency here.Omega's big property is that as N grows, the length of the shortest program needed to output the first N digits of Omega is roughly N. In this sense, Omega is incompressible. This is (very loosely) accomplished by hashing together 2^n bits of the halting problem to get the nth digit of Omega--so even if the halting problem (encoded as a sequence of 0's and 1's) is compressible, any statistical bias or weak pattern gets wiped out when you mash the halting problem down like this.

I have to say, though, that I don't agree with the article's gloomy assessment of mathematics. "He shattered mathematics with a single number"? It makes a dramatic magazine article, but it doesn't ring true. (You should be warned that I'm an evil logic student, though!)

## Re:Does 'lucky' mean NP-hard? (Score:1)

P is the class of sets that are computable by a Turing machine

that only runs for a polynomial length of time, and NP is the class of sets that are computable by a nondeterministic TM running in polynomial time. A set X is NP-complete if it's in NP and any other set in NP can be reduced to it in polynomial time (by a deterministic Turing machine). Both P and NP, though, are proper subsets of the class of computable sets--those sets for which there's a Turing machine (that can use as much space and time as it wants) that will, given any string, eventually tell you if that string is in the set or not.The Church-Turing hypothesis just says that Turing machines capture the intuitive notion of "computability". (Of course, the rigorous definition of computability is in terms of Turing machines, so the Church-Turing hypothesis really says that Turing machines are the "right" definition of computability. Fundamentally, it's subjective, although not that subjective: any reasonable notion of algorithm that has ever been produced has been reduced to Turing machines.) It doesn't say that Turing machines are necessarily efficient.

## Re:Would you define "random Turing machine"? (Score:3)

What you do is you fix a self-delimiting universal Turing machine M. This is a machine that takes its input, interprets it as another Turing machine, and simulates that other machine. Self-delimiting here essentially means that if it interprets "100011101" (or some other string) as a program, then it won't interpret any extension of that string as a program. In particular, if M halts on input "10001101", it won't halt on any extension of that string.

Define Omega_M (the halting probability of M) to be the sum of (1/2)^(length(x)) over all inputs x on which M converges. Because M was self-delimiting, this series will converge to some number between 0 and 1. (You can prove by induction on n that the sum restricted to x of length <=n is bounded by 1.)

This number depends on your choice of M, but that's no big deal.

So, to address your question a little more directly, we're calculating this probability by averaging over infinitely many Turing machines (as inputs to our universal Turing machine), and we're doing this by weighting the Turing machines with short codes more heavily--Turing machines of length n get weight (1/2)^n, and the self-delimiting nature of our universal TM makes the sum of these weights converge.

## this is NOT insightful (Score:1)

This is a joke,

it refers to the (very funny, imho) "Hitchhiker's guide to the galaxy" books,

and the earlier story about the gunzipped DeCSS prime number.

---

## Re:Summary, Impressions, Interpretations (Score:2)

So the non-existence of true randomness would have no effect on the result.

OTOH, if you wanted to argue that the concepts of infinite, including countable, were invalid then I'd say you might have a point. But then I've always been in favor of limiting the integers to, say, the power set of possible energy states of the universe. Some other maximal integer may be more appropriate. The question then would be, "Do you get an overflow error, or does it wrap around?"

Caution: Now approaching the (technological) singularity.

## Re:Situation of modern mathematics ;-) (Score:2)

Ever count clouds?

2 + 2 == 4 by definition. If it isn't true, we don't consider it integer arithmetic.

So there's no chance of it being thrown out.

Caution: Now approaching the (technological) singularity.

## Question? (Score:1)

## Meanwhile, back to DeCSS... (Score:2)

So this becomes a specific real number, and let's say I write it out in binary, ...And the truly amazing thing is that this binary number is the gzipped DeCSS code.

## Re:Old news... (Score:1)

(with an assist from an old LA Times Sunday crossword)

--## Re:Old news... (Score:1)

--

## Re:Old news... (Score:2)

But it was oddly propheticOf what?

--

## Re:This IS surprising! (Score:2)

## Most implications no news, yet Omega is intriguing (Score:1)

Perhaps you will be able to write formulas that resemble the formulas of certainty (anything we currently write down, folks!) but the presence of the omega number will turn them into the exact opposite. Odd, isn't it?

## Re:Philosophical interest (the future of science) (Score:1)

- New Scientist site is *still*

- Not really a "math person"

What do you mean by mathematical truths? If you mean theorems, aren't the theorems provable as consequences of particular assumed axioms? If you mean the axioms themselves, well, then mathematics isn't an especially special case is it? Isn't any system going to have to have certain fundamental axioms you take as true, that aren't proved?

I'm not sure I follow how you're tying your first philosphical point about the seeming discrepancy between mathematics and the physical sciences (or what Quine calls the double standard in ontology) with Chaitin's findings.

## It's not always so hard (Score:1)

Prob(halting) = 1.0

It's very easy to encode!

## Re:This is not surprising (Score:1)

(For those who don't know, Gödel proved that there are some mathematical hypotheses that can't be proven true or false. That was very surprising, but it didn't call into question any theorem which has been proven true. The only thing which could really throw the foundations of mathematics into an uproar would be to show that some hypothesis can be proven to be both true and false.)

## Re:This is not surprising (Score:1)

## Re:This IS surprising! (Score:1)

## Re:Misconceptions (Score:1)

irrationalnumbers, there is arationalnumber. And there are strictly more irrational numbers than rational numbers.## Re:Aleph-Zero is the Omega number?! (Score:1)

Different omega. And in Cantor's transfinite cardinality theory aleph-null is not the same as omega; aleph-null is a cardinal, omega is an ordinal.

Cheers,

Greg

## Re:Isn't this already known? (Score:2)

Goedel proved back in the 30's that there were many things (an infinite number?) which were true but for which proofs cannot be provided. OTOH Chaitin is a well known mathemetician (in some circles, anyway). Presumably he has something interesting to say, but I doubt it's as revolutionary as the post makes it sound.Oh, I dunno. I'd say that it's the equivalent of Quantum Mechanics, but for math.

Think about it... the Omega number puts a limit on the accuracy to which we can know mathematical theorems... Maybe it's the equivalent of the Heisenberg Uncertainty Principal?

... well, maybe.

That might actually be a good way to use the Omega number... build it in, turn everything to probabilities. *sigh*

Simon

## Re:Isn't this already known? (Score:2)

I wrote:"Think about it... the Omega number puts a limit on the accuracy to which we can know mathematical theorems... Maybe it's the equivalent of the Heisenberg Uncertainty Principal?"

The Heisenberg Uncertainty Principal is a mathematical theorem.Uhh... which is why I said maybe it's the

equivalentIt's a physical theorem. What I'm talking about is a wider application of this to cover

general mathsSimon

## Re:Misconceptions (Score:2)

The irrational numbers that you mention are drops in the bucket of irrational numbers.

## Re:"Then some magic happens" (Score:2)

IANAM, but I think they may be two aspects of the same thing -- the thing can be known as itself alone and not in any kind of short hand form. Each bit needs its own algorithm to derive.

It isn't about feeding a random file into gzip and sometimes (usually) getting a larger file out.

It's about feeding a specific number into a ANY compression algorithm you could create and ALWAYS getting a larger file out.

## Re:This IS surprising! (Score:2)

Maybe for any number N we could devise a system that generates the majority of true statements. Perhaps a mathematician could correct me, but it seems like omega is somehow linked with knowing what fraction of statements can be shown to be true in a finite number of steps. If this is the case, then we can't really know the bounds of our own ignorance.

## Re:Okay, so we didn't invent/create math. (Score:2)

Math is a bunch of islands (number theory, topology,

In fact, usually when someone such as Andrew Weil DOES build a bridge between a couple of these islands then we herald that as a rare triumph!

Also, as others have stated, it's a bit late to be worried about Godel's incompleteness theorem... kind of old news!

## Halting Problem Solved (Score:2)

Real computers don't just perform finite computations, doing one or a few things, and then halt. ... "Many computer applications are designed to produce an infinite amount of output," Becher says. Examples include ... operating systems such as Windows 2000.Oh, come now. I think we all know the answer to the halting problem for Windows.

## Re:This is not surprising (Score:2)

So, the integers aren't a set? I guess the integers are countable, but it is still impossible to "list" all of them. The reals aren't even countable...

While yes, you can get around Russell's paradox that way, you've weakened set theory to the point where it can't do everything that old set-theory can do (in fact, it can hardly do anything).

In *real* mathematics, you *can't* get rid of this inconsistency. That's what Godel proved in his Incompleteness Theorem.

## Re:interesting stuff (Score:2)

This is an uninformed statement, and an irrelavant one. It is uninformed because the Halting Problem says that it's impossible to know whether a TM will halt for a given input. Since probability is the number of "sucesses" over the total number of trialsm, it can't be computed unless sucesses can be found. It's also irrelavant because Chaitin was talking about random TMs, not random inputs to a given TM.

"The solution might be extremely complex, but I doubt it is impossible. "

I believe Chaitin *proved* it was impossible. You can't just doubt that - you would have to show that his proof is bad. But given that you can't even be bothered to read the article, I don't know how you would manage that.

## Re:This IS surprising? (Score:2)

nis equal to 1 if TM(n) halts, 0 if it doesn't. An algorithm that "compressed" that number would also solve the halting problem; therefore, it does not exist.So, explain to me again why this particular non-computable number is special?

## Re:This IS surprising! (Score:2)

largerthan the originals. See, assuming that gzip operates deterministically, a particular archive file will always generate the same output when decompressed. That means that there must be at least one unique compressed file for every unique uncompressed file. That means that over a sufficiently large set of files, the average compression ratio achieved by any lossless compression algorithm can never be better than 1:1. (Hmmm... I actually thought I'd proved that it must beworsethan 1:1, but I can't remember how I did that.)Anyway, fortunately for us, the files that gzip is able to shrink successfully tend to be the files that we're interested in. However, when you're talking about exotic pseudo-random numbers, that is not the case.

## Re:We create math everyday. (Score:2)

THERE ARE ALTERNATIVE MATHEMATICAL PHILOSOPHIES!Conveniently priced at $146.50 [barnesandnoble.com]

- - - - -

## Re:This IS surprising! (Score:2)

ω, which appears as .This works in any browser compliant with (I think) HTML since version 3, and XHTML 1.0. It at least works in Mozilla 0.8; I can't speak as to other browsers.

## Re:Random Numbers (Score:2)

Not quite, quantum theory in its simplest form is built on the idea that no matter how good our instruments, the more accurately we read the exact circumstances of an event, or small system, the more we alter it.It's not just our measurements. The Heisenberg Uncertainty Priciple (which is what you're talking about) is a statement about the universe, not our ability to measure it. More and more, it is apparent that this uncertainty is not because our instruments are too crude, but that this uncertainty

is inherent in nature. You can not measure well defined velocities and positions of particles on the quantum scale because they do not have well defined positions and velocities.Einstein had a hard time with that notion--that we live in a non-deterministic world, that chance is built into the universe--but that is the case.

The real power of quantum physics is that it gives us the means of treating these systems statistically without having to look at them on an individual basis.Systems of particles is really thermodynamics. In quantum mechanics, you can (and do) pay attention to a single particle.

## You know I have always been suspicious of zero (Score:2)

## "The Omega Number" (Score:2)

## Re:Misconceptions (Score:2)

## Re:Would you define "random Turing machine"? (Score:3)

You can get it in the limit from below, but it converges very, very slowly --- you can never know how close you are --- there is no computable regulator of convergence, there is no way to decide how far out to go to get the first N bits of W right.## Chaitin's homepage (Score:2)

Some entire book texts there, etc.

Quite difficult stuff, even for a CS major. Having at least familiarity with automatas and formal languages is recommended, although still far too little.

There's some quite weird stuff in some of his books. I can't say I would recommend reading his stuff without healthy sceptic attitude...

## Re:interesting stuff (Score:2)

I'd say yes. Take the flip of a coin, a very basic random number generator. You know what the probability is of it being heads if it is a fair coin. It's 0.5.

He's saying that he can't find the actual probability that any given program will halt or not. He's saying that probability is 'maximally unknowable'.

## interesting stuff (Score:4)

The interesting point of the matter deals with Turing machines and the halting problem. If you have a well defined turing machine, it will either halt or not depending upon its input (the program). Turing's idea was that you can't determine beforehand whether a given program will halt (for all possible programs). That is, the only guranteed way to see if a program halts or not is to run it. If it halts in the time you observe it, good. If not, then will it halt in n+1 time? Unknown.

Chaitin defines W as "the probability that a program generated by tossing a coin halts." And he says that this W will be a real number between 0 and 1 that is well-defined. He says once you define the language of the turing machine, W becomes well defined. He then claims that W is 'maximally unknowable' - that is, it is irrational like PI and e, having no mathematical structure. But it is not just irrational, he says that you can't generate W like e or PI from a formula.

He also claims that W is 'irreducible information' - it cannot be compressed because it is truly random.

From here it gets pretty complex, but my understanding of it is that this introduces true randomness into pure mathematics, which people think shakes things up quite a bit. He compares it to the introduction of quamtum mechanics into Physics.

## monte carlo methods for omega (Score:2)

## Philosophical interest (the future of science) (Score:2)

Here's what's interesting to me:

First, it's mysterious that mathematical truths are applicable to the "real world". This is a philosophical question that people have struggled over for a long time. Why is it that abstract mathematical structures discovered without any reference to physics often later turn out to be useful in physical theories?

Now consider what Chaitin is saying. Very few mathematical truths have any structure at all. That means that we can't prove the vast majority of true theorems, and if you were to pick a mathematical truth out of the air it is unlikely in the extreme that you could find a proof for it.

Put these two facts together. Isn't it awfully surprising that mathematics is so successful at describing the real world? Math is full of unproveable truths, and yet, we seem to be able to prove a bunch of really useful things.

Now why should that be? I don't know.

If you're an optismist, you might say, how lucky! It's a good thing that the universe is structured in a way that's mostly congruent with the proveable sections of mathematics.

If you're a pessimist, you might wonder how long our luck is going to last.

## There's a solution, sort of... (Score:2)

Sounds like another good reason to be a

constructivisit. In Constructive mathematics, numbers are defined in terms of a total function which computes them (or, for a "real" number, a function which can get you arbitrarily close to them). None of this "let n = 1 if the continuum hypothesis is true, 0 otherwise" stuff! Constructive mathematics is pretty nice, though some "obvious" stuff is not provable.Here's some links:

http://plato.stanford.edu/entries/mathematics-cons tructive/ [stanford.edu]

http://www.cs.cmu.edu/~fp/courses/logic/ [cmu.edu]

Of course, some classicists find delight in how insanely undecidable their mathematics is, and that's fine, too. =)

\Omega_{UTM} is a pretty cool idea, though, much worse than the standard trick of defining which has decimal digit n = 1 if turing machine n halts, 0 otherwise (also undecidable, but not as hopeless as his!). I wish I hadn't missed the lecture.

## Ah, mathematicians... (Score:2)

Two baloonists (the baloon with a basket) are lost and decide to land and ask for directions. They find an elderly gentleman strolling through the countryside and land the baloon next to him.

"Excuse me, sir, can you tell us where we are?"

The gentleman crossed his arms, scrathed his head, rested his chin in his palm and then gently said - "Why, you're in a baloon." and walked off.

The two baloonists just shrugged their shoulders and took off again. Once high up in the air, one of the baloonists turned to his friend and said:

"You know, I think that the elderly gentleman was a Mathematician."

"Really, how can you tell?"

"First, he was intelligent because he thought long before answering. Second, his answer was correct. Lastly, his answer hasn't helped us at all."

## Re:There's a solution, sort of... (Score:2)

On a related note, the halting problem is formally undecidable only for machines with infinite memory. With finite memory, eventually you either halt or repeat a previous state.

## Corollary (Score:3)

'If mathematicians find any connections between these facts, they do so by luck.'And if Slashdot posts a connection to these facts, the mathematicians website is out of luck.

## We create math everyday. (Score:2)

However, this belief has never been proven. It is nothing more than a belief, just like many people agree that their exists a God. Therefore, just as the belief in the existance of a God turns something into a religion; the belief in the Platonic idealism turns mathematics into a religion - rife with all of the problems associated with religions!

Great mathematicians such as L.E.J. Brouwer argued that such dogmatic beliefs should not be used within mathematics, because it causes horrible foundational problems of paradox, undecidability, and incompleteness. Brouwer went on to establish the mathematical philosophy of intuitionism, and then built an entire mathematical system ontop of that. In effect, he created mathematical intuitionism, just as each mathematician creates (or recreates depending on how you look at it) mathematical concepts in their mind.

The Platonic idealism has been a cancer on the foundation of mathematics for thousands of years. Please, stop and realize that the Platonic idealism is nothing more than a belief system, and witness how it has partially destroyed mathematics.

THERE ARE ALTERNATIVE MATHEMATICAL PHILOSOPHIES! [barnesandnoble.com]

## Occam's Razor (Score:2)

Note that I use the term "truth" with regards to scientific "truth", realizing that science can never in fact portray any absolute truth, as is the normal definition of truth (i.e. undeniable truth). This is why science has evolutionary mechanisms built in like peer review and disproving old theories.

## Re:Situation of modern mathematics ;-) (Score:2)

notbe proven to be consistant (free from contradiction), then there is the possibility that you could wake up one day and have 2+2=5. I am not claiming that any of this will happen, because I have no mathematical proof, but the whole problem with a lack of consistancy proof is the problem you have mentioned... waking up only to realize that your math was nothing more than a "Matrix" (in the movie sense) so to speak.Time and time again, the chosen philosophy of mathematics used for a foundation of mathematics as shown to cause huge differences in the actual mathematical system. Bertrand Russell's paradoxes (A set which contains all sets that do not contain themselves. This set both contains itself and doesn't contain itself.), Brouwer's Intuitionism (mathematics is complete, and undeniably consistant in with this philosophy), the Platonic Idealism (you have foundations that are of the quality of the foundations of Christianity), Formalism (Godel's Incompleteness Theorem says that we can never know if this system is flawed or not), etc...

Saying that philosophy does influence mathematics down to a consistancy level ignores hundreds of years of mathematical history! Philosophical foundations can lead to actual contradictions. This is why philosophy has an extremely important role in mathematics.

## Re:We create math everyday. (Score:2)

## Re:Like Any Another (Score:2)

## Re:Situation of modern mathematics ;-) (Score:2)

## Re:Like Any Another (Score:2)

## Re:This IS surprising! (Score:2)

They cannot be compressedWell, we could agree to call it W_UTM. Then all we would have to do to compress it is send W_UTM and people would know what it was.

Of course the codec would eventually become infinitely large, but as long as our pace of discovering stuff like this doesn't outpace Moore's law, we are fine.

I'm only semi-serious.

## Re:"Then some magic happens" (Score:2)

I don't get that either. What if I claim the number 'turns out' to be exactly 0.5 ? Can anybody disprove me ?

Salsaman

## Two to One odds (Score:2)

Two does equal one for sufficiently small values of 2.

Actually, using the old mathmatical parlour trick of showing that 1.99999. . . = 2 one could at least show that 2=1 when rounded to the lowest integer.

KFG

## 2 + 2 = ? (Score:2)

Freedom is the freedom to say 2 and 2 is 4, everything else follows from there.

## Old news... (Score:2)

"Do you realize what this means?" Johnson looked at the mathematician worriedly. "I have to report this to the CIA. I'm sorry.""But why? What does this have to do with national security?" asked Thomas.

"I can't tell you. In fact, it's--" Suddenly a shot rang out, and Thomas watched in horror as the Dean of Mathematics slumped forward, a surprised look on his face. He caught Johnson in his arms as half a dozen more shots were fired into the office, and dragged him frantically behind a desk.

He looked down and saw that the shirt was red. That was bad. Then he saw that the redness was spreading. That was very bad. The shots stopped, but Thomas' ears kept ringing.

"The...Omega number..." gasped Johnson.

"Don't talk! Save your strength!"

"I'm dead...anyway...you have to...tell the CIA...can't let...the Soviets...know...about the hole...the weaknesses...in our mathematical...model..."

The dean stopped, gave a pitiful little gasp, and went limp in Thomas' arms.

It's not his best work by any means. But it

wasoddly prophetic.## The ultimate program of life, the universe and 42? (Score:3)

--

## Re:2 + 2 = ? (Score:2)

Mathematics doesn't really have the kind of assumptions you can disagree with. Two, Four and plus are not the same things in mathematics that we may call two and four in the outside world. Two is by definition the successor of the succesor of 0 and four has a similar definition. Therefore the conclusion that two and two is four follows inevitably from the definitions of two, four and plus because by definition these are the things obeying the appropriate axioms (this may be confusing because we actually use the same words to refer to real world concepts, and concepts in various axiomatic systems which arent always the same thing).

## Re:Isn't this already known? (Score:2)

## Re:Isn't this already known? (Score:3)

His stuff is certainly interesting, and his results about the omega number are bizarre but you are right it isn't THAT revolutionary. Once you accept the results of Godel's theorem the fact that you can somehow concentrate all that unprovability in one place drives the strangeness home but isn't fundamentally upsetting.

## Oops...You are right! Mod Me Overrated (Score:2)

## These Statements need proof to back them. (Score:4)

First of all, the statement that mathematical theory is riddled with holes is questionable. Finding an unprovable statement is a rarity that happens once every so often. Most things can either be proven or separated out as an axiom (such as the Continuum Hypothesis). Granted, every formal algebraic system is going to have at least one unprovable theorem, but no one has attempted to count out the percentage of theorems that are provable.

The New Scientist is claiming that the percentage of provable theorems is small compared to the number of theorems in any given system. This is akin to the idea that the rational numbers are "sparse" on the real number line. Such a statement about a formal system, such as the ZFC axioms of set theory, needs to be proven.

It would be an interesting study to Godelize ZFC in an intuitive way and use automated theorem proving to see what percentage of statements of a given length are theorems, and what percentage of those could be proven with proofs of less than a certain length. Then by asymptotic analysis one might be able to make a statement to see if "most" theorems could be proven.

Such a study would be similar in method to Graphical Evolution, but would require quite a bit of supercomputer time. Even then, some really difficult proofs would have to be made. However, one does not know if the statement is provable :)

## Situation of modern mathematics ;-) (Score:4)

## Re:We create math everyday. (Score:2)

I rest my case!

--

#include "stdio.h"

## Re:We create math everyday. (Score:2)

--

#include "stdio.h"

## Re:Misconceptions (Score:2)

## "Then some magic happens" (Score:2)

I understand your argument that W_UTM is "unknowable" (non-computable, anyway--surely GOD knows it). And I understand how to write a number in binary. Then we hit this:

"Well, it turns out these 0's and 1's have no mathematical structure. They cannot be compressed."Yeah the old "it turns out" argument. I guess he's leaving that part up to the students? Or maybe the proof is "trivial"? I can understand leaving out details, but for crying out loud this is the whole POINT of the research. WHY don't they have structure?

In any case, I still say it's unsurprising. I would have been skeptical of a claim (Godel's) that there are an infinite number of theorems without there ALSO being an infinite source for those theorems to theorize about.

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## This is not surprising (Score:4)

Given a formal system of "sufficient power" there will always be theorems(And if you add the "missing theorem" to the system, the resulting system has the same "problem", ad infinitum)expressible but unprovablein that system.Considering that Godel's stuff came out in 1933(?) and if this work really IS just a restatement of that fact then I doubt the "foundations of mathematics are in an uproar".

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