Fifteen Most Famous Transcendental Numbers
94 points
5 hours ago
| 12 comments
| sprott.physics.wisc.edu
| HN
brianberns
4 hours ago
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I read this with pleasure, right up until the bit about the ants. Then I saw the note from myself at the end, which I had totally forgot writing seven years ago. I probably first encountered the article via HN back then as well. Thanks for publishing my thoughts!
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xnorswap
3 hours ago
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The ants argument feels rather like a retelling of Zeno's Paradoxes.

https://en.wikipedia.org/wiki/Zeno%27s_paradoxes

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tzs
30 minutes ago
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If we are including numbers that aren't actually proven to be transcendental but that most mathematicians think are, I'd put Lévy's constant on the list.

It is e^(pi^2/(12 log 2))

Here's where it comes from. For almost all real numbers if you take their continued fraction expansion and compute the sequence of convergents, P1/Q1, P2/Q2, ..., Pn/Qn, ..., it turns out that the sequence Q1^(1/1), Q2^(1/2), ..., Qn^(1/n) converges to a limit and that limit is Lévy's constant.

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mg
3 hours ago
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Three surprising facts about transcendental numbers:

1: Almost all numbers are transcendental.

2: If you could pick a real number at random, the probability of it being transcendental is 1.

3: Finding new transcendental numbers is trivial. Just add 1 to any other transcendental number and you have a new transcendental number.

Most of our lives we deal with non-transcendental numbers, even though those are infinitely rare.

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canjobear
1 hour ago
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> 1: Almost all numbers are transcendental.

Even crazier than that: almost all numbers cannot be defined with any finite expression.

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testaccount28
2 hours ago
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how can i pick a real number at random though?

i tried Math.random(), but that gave a rational number. i'm very lucky i guess?

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andrewflnr
1 hour ago
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You can't actually pick real numbers at random. You especially can't do it on a computer, since all numbers representable in a finite number of digits or bits are rational.
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tantalor
2 hours ago
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Pick a digit, repeat, don't stop.
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markusde
1 hour ago
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Exactly right. You can pick and use real numbers, as long as they are only queried to finite precision. There are lots of super cool algorithms for doing this!
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mg
2 hours ago
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How did you test the output of Math.random() for transcendence?

When you apply the same test to the output of Math.PI, does it pass?

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BeetleB
1 hour ago
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All floating point numbers are rational.
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jmgao
1 hour ago
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Well, except for inf, -inf, and nan.
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Someone
39 minutes ago
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and, depending on how you define the rationals, -0.

https://en.wikipedia.org/wiki/Integer: “An integer is the number zero (0), a positive natural number (1, 2, 3, ...), or the negation of a positive natural number (−1, −2, −3, ...)”

According to that definition, -0 isn’t an integer.

Combining that with https://en.wikipedia.org/wiki/Rational_number: “a rational number is a number that can be expressed as the quotient or fraction p/q of two integers, a numerator p and a non-zero denominator q”

means there’s no way to write -0 as the quotient or fraction p/q of two integers, a numerator p and a non-zero denominator q.

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kridsdale1
50 minutes ago
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Use an analog computer. Sample a voltage. Congrats.
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why-o-why
39 minutes ago
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Sample it with what? An infinite precision ADC?

This is how old temperature-noise based TRNGs can be attacked (modern ones use a different technique, usually a ring-oscillater with whitening... although i have heard noise-based is coming back but i've been out of the loop for a while)

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why-o-why
41 minutes ago
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I can't believe Champerowne's constant was only analyzed as of 1933.

Seems like Cantor would have been all over this.

https://en.wikipedia.org/wiki/Champernowne_constant

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drob518
2 hours ago
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Some of these seem forced. For instance, does Chapernowne's number (number 7 on the list, 0.12345678910111213141516171819202122232425...) occur in nature, or was it just manufactured in a mathematical laboratory somewhere?
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zeeboo
2 hours ago
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It is indeed manufactured specifically to show the existence of "normal" numbers, which are, loosely, numbers where every finite sequence of digits is equally likely to appear. This property is both ubiquitous (almost every number is normal in a specific sense) and difficult to prove for numbers not specifically cooked up to be so.
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drob518
1 hour ago
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Okay, fair. It just seemed to me to have pretty limited utility.
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Strilanc
2 hours ago
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It's fame comes from the simplicity of its construction rather than its utility elsewhere in mathematics.

For example, Graham's number is pretty famous but it's more of a historical artifact rather than a foundational building block. Other examples of non-foundational fame would be the famous integers 42, 69, and 420.

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jerf
1 hour ago
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All the transcendental numbers are "manufactured in a mathematical laboratory somewhere".

In fact we can tighten that to all irrational numbers are manufactured in a mathematical laboratory somewhere. You'll never come across a number in reality that you can prove is irrational.

That's not necessarily because all numbers in reality "really are" rational. It is because you can't get the infinite precision necessary to have a number "in hand" that is irrational. Even if you had a quadrillion digits of precision on some number in [0, 1] in the real universe you'd still not be able to prove that it isn't simply that number over a quadrillion no matter how much it may seem to resemble some other interesting irrational/transcendental/normal/whatever number. A quadrillion digits of precision is still a flat 0% of what you'd need to have a provably irrational number "in hand".

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5ver
59 minutes ago
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It appears quantum phenomena are accurately described using mathematics involving trig functions. As such we do encounters numbers in reality that involve transcendental numbers, right?
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kevin_thibedeau
52 minutes ago
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They're accurately modeled. Just as Newtownian phenomena are accurately modeled, until they aren't. Reality is not necessarily reflective of any model.
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tantalor
2 hours ago
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Yes, it occurs in the nature of the mathematician's mind.
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tshaddox
1 hour ago
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> Did you know that there are "more" transcendental numbers than the more familiar algebraic ones?

Indeed. And by similar arguments, there are more uncomputable real numbers than computable real numbers. (And almost all transcendental numbers are uncomputable).

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keepamovin
1 hour ago
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This guy's books sounds fascinating, Keys to Infinity and Wonder of Numbers. Definitely going to add to Kindle. pi transcends the power of algebra to display it in its totality what an entrace

I think I read a book by this guy as a kid: it was an illustrated mostly black and white book about Chaitin's constant, halting problema and various ways of counting over infinite sets.

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zkmon
4 hours ago
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If a number system has a transcendental number as its base, would these numbers still be called transcendental in that number system?
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moefh
4 hours ago
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Yes. A number is transcendental if it's not the root of a polynomial with integer coefficients; that's completely independent of how you represent it.
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frutiger
4 hours ago
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I think the elements of the base need to be enumerable (proof needed but it feels natural), and transcendental numbers are not enumerable (proof also needed).
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tocs3
3 hours ago
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JadeNB
3 hours ago
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I think your parent comment was speaking of a "base-$\alpha$ representation", where $\alpha$ is a single transcendental number—no concerns about countability, though one must be quite careful about the "digits" in this base.

(I'm not sure what "the elements of the base need to be enumerable" means—usually, as above, one speaks of a single base; while mixed-radix systems exist, the usual definition still has only one base per position, and only countably many positions. But the proof of countability of transcendental numbers is easy, since each is a root of a polynomial over $\mathbb Q$, there are only countably many such polynomials, and every polynomial has only finitely many roots.)

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barishnamazov
4 hours ago
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Don't want to be "that guy," but Euler's constant and Catalan's constant aren't proven to be transcendental yet.

For context, a number is transcendental if it's not the root of any non-zero polynomial with rational coefficients. Essentially, it means the number cannot be constructed using a finite combination of integers and standard algebraic operations (addition, subtraction, multiplication, division, and integer roots). sqrt(2) is irrational but algebraic (it solves x^2 - 2 = 0); pi is transcendental.

The reason we haven't been able to prove this for constants like Euler-Mascheroni (gamma) is that we currently lack the tools to even prove they are irrational. With numbers like e or pi, we found infinite series or continued fraction representations that allowed us to prove they cannot be expressed as a ratio of two integers.

With gamma, we have no such "hook." It appears in many places (harmonics, gamma function derivatives), but we haven't found a relationship that forces a contradiction if we assume it is algebraic. For all we know right now, gamma could technically be a rational fraction with a denominator larger than the number of atoms in the universe, though most mathematicians would bet the house against it.

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servercobra
2 hours ago
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Both Euler's and Catalan's list "(Not proven to be transcendental, but generally believed to be by mathematicians.)". Maybe updated after your comment?
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nuancebydefault
4 hours ago
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I would have expected more numbers originating from physics, like Reynolds number (bad example since it is not really constant though).

The human-invented ones seem to be just a grasp of dozens man can come up with.

i to the power of i is one I never heard of but is fascinating though!

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senfiaj
5 hours ago
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> Euler's constant, gamma = 0.577215 ... = lim n -> infinity > (1 + 1/2 + 1/3 + 1/4 + ... + 1/n - ln(n)) (Not proven to be transcendental, but generally believed to be by mathematicians.)

So why bring some numbers here as transcendental if not proven?

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rkowalick
1 hour ago
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As far I know, Euler's constant hasn't even been proven to be irrational.
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auggierose
4 hours ago
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Because it still might be transcendental. Just because you don't know if the list is correct, doesn't mean it isn't.
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senfiaj
2 hours ago
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Yes it's "likely" to be transcendental, maybe there are some evidences that support this, but this is not a proof (keep in mind that it isn't even proven to be irrational yet). Similarly, most mathematicians/computer scientist bet that P ≠ NP, but it doesn't make it proven and no one should claim that P ≠ NP in some article just because "it's most likely to be true" (even though some empirical real life evidence supports this hypothesis). In mathematics, some things may turn out to be contrary to our intuition and experience.
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auggierose
1 hour ago
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It comes with the explicit comment "Not proven to be transcendental, but generally believed to be by mathematicians."

That's really all you can do, given that 3 and 4 are really famous. At this point it is therefore just not possible to write a list of the "Fifteen Most Famous Transcendental Numbers", because this is quite possibly a different list than "Fifteen Most Famous Numbers that are known to be transcendental".

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senfiaj
1 minute ago
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So "Fifteen Most Famous Transcendental Numbers" isn't the same as "Fifteen Most Famous Numbers that are known to be transcendental"?

I might be OK with title "Fifteen Most Famous Numbers that are believed to be transcendental" (however, some of them have been proven to be transcendental) but "Fifteen Most Famous Transcendental Numbers" is implying that all the listed numbers are transcendental. Math assumes that a claim is proven. Math is much stricter compared to most natural (especially empirical) sciences where everything is based on evidence and some small level of uncertainty might be OK (evidence is always probabilistic).

Yes, in math mistakes happen too (can happen in complex proofs, human minds are not perfect), but in this case the transcendence is obviously not proven. If you say "A list of 15 transcendental numbers" a mathematician will assume all 15 are proven to be transcendental. Will you be OK with claim "P ≠ NP" just because most professors think it's likely to be true without proof? There are tons of mathematical conjectures (such as Goldbach's) that intuitively seem to be true, yet it doesn't make them proven.

Sorry for being picky here, I just have never seen such low standards in real math.

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loloquwowndueo
4 hours ago
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So it’s like “15 oldest actors to win an Oscar” and including someone who’s nominated this year but hasn’t actually won. But he might, right?

No, my dudes. Just no. If it’s not proven transcendental, it’s not to be considered such.

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chvid
3 hours ago
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I think the Oscars should go to the algebraic numbers - think about it - they are far less common ...
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adrian_b
2 hours ago
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It should be noted that the number e = 2.71828 ... does not have any importance in practice, its value just satisfies the curiosity to know it, but there is no need to use it in any application.

The transcendental number whose value matters (being the second most important transcendental number after 2*pi = 6.283 ...) is ln 2 = 0.693 ... (and the value of its inverse log2(e), in order to avoid divisions).

Also for pi, there is no need to ever use it in computer applications, using only 2*pi everywhere is much simpler and 2*pi is the most important transcendental number, not pi.

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d-us-vb
2 hours ago
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This comment is quite strange to me. e is the base of the natural logarithm. so ln 2 is actually log_e (2). If we take the natural log of 2, we are literally using its value as the base of a logarithm.

Does a number not matter "in practice" even if it's used to compute a more commonly use constant? Very odd framing.

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BigTTYGothGF
13 minutes ago
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What an odd thing to say. I find that it shows up all the time (and don't find myself using 2pi any more than pi).
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qnleigh
1 hour ago
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Uuuuuum no?

e^(ix) = cos(x) + isin(x). In particular e^(ipi) = -1

(1 + 1/n)^n = e. This is part of what makes e such a uniquely useful exponent base.

Not applied enough? What about:

d/dx e^x = e^x. This makes e show up in the solutions of all kinds of differential equations, which are used in physics, engineering, chemistry...

The Fourier transform is defined as integral e^(iomega*t) f(t) dt.

And you can't just get rid of e by changing base, because you would have to use log base e to do so.

Edit: how do you escape equations here? Lots of the text in my comment is getting formatted as italics.

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lutusp
58 minutes ago
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> Edit: how do you escape equations here? Lots of the text in my comment is getting formatted as italics.

Just escape any asterisks in your post that you want rendered as asterisks: this: \* gives: *.

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lutusp
1 hour ago
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> It should be noted that the number e = 2.71828 ... does not have any importance in practice, its value just satisfies the curiosity to know it, but there is no need to use it in any application.

In calculations like compound financial interest, radioactive decay and population growth (and many others), e is either applied directly or derived implicitly.

> ... 2*pi is the most important transcendental number, not pi.

Gotta agree with this one.

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