Fifteen Most Famous Transcendental Numbers

(physics.wisc.edu)

63 points | by vismit2000 3 hours ago

8 comments

  • brianberns 2 hours ago
    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!
  • mg 59 minutes ago
    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.

    • testaccount28 11 minutes ago
      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?

      • tantalor 2 minutes ago
        Pick a digit, repeat, don't stop.
      • mg 6 minutes ago
        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?

  • drob518 14 minutes ago
    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?
    • tantalor 1 minute ago
      Yes, it occurs in the nature of the mathematician's mind.
    • Strilanc 8 minutes ago
      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.

    • zeeboo 11 minutes ago
      If 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.
  • nuancebydefault 2 hours ago
    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!

  • adrian_b 53 minutes ago
    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.

    • d-us-vb 12 minutes ago
      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.

  • senfiaj 2 hours ago
    > 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?

    • auggierose 2 hours ago
      Because it still might be transcendental. Just because you don't know if the list is correct, doesn't mean it isn't.
      • senfiaj 55 minutes ago
        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.
      • loloquwowndueo 2 hours ago
        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.

        • chvid 1 hour ago
          I think the Oscars should go to the algebraic numbers - think about it - they are far less common ...
  • barishnamazov 2 hours ago
    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.

    • servercobra 12 minutes ago
      Both Euler's and Catalan's list "(Not proven to be transcendental, but generally believed to be by mathematicians.)". Maybe updated after your comment?
  • zkmon 2 hours ago
    If a number system has a transcendental number as its base, would these numbers still be called transcendental in that number system?
    • moefh 2 hours ago
      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.
    • frutiger 2 hours ago
      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).
      • tocs3 1 hour ago
      • JadeNB 1 hour ago
        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.)

      • kinkyusa 2 hours ago
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    • kinkyusa 2 hours ago
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