Wednesday, September 18, 2013


Every now and then we need new words and phrases come into our lexicon, like the unfortunate "twerking", but here's another "tl;dr", short for "too long; didn't read". I'm guessing it started as an insult/excuse not to read a long document, blog post or email. Respond "tl;dr" and you've put the blame on the writer for being too loquacious to the tweet-friendly generation.

Now I see tl;dr used as a short synopsis sometimes by the author themselves, the new executive summary if the executive has six seconds to read. Maybe I should tl;dr my class lectures: "Finite Automata: Easy to analyze but too weak to do much interesting".

Are we really moving to this brave new world of micro-attention spans? Is this just another reason that newspapers are dying and blogs are passé? When I write email should I keep it short and be misunderstood, make it long and have it not be read or add a tl;dr summary and get the worst of both worlds?


  1. I don't see the change for newspapers. Isn't the subhead almost the same as tl;dr?

    I have never seen a subhead for blog articles, so a tl;dr offers the possibility to get to know if the article might be interesting.

    Another reason for a tl;dr is that it's most of the time much simpler to understand. So a tl;dr might be nice for class lectures as your students can check if they understood at least the essence of the section/chapter.

  2. I'm less worried than some people by the idea that the internet encourages a short attention span. There is so much material there that we need ways of deciding efficiently what is worth spending time on. It's not obvious to me that it isn't a good strategy to read a lot of things very superficially and only occasionally to decide to invest a bit of time reading something in full. The tl;dr abbreviation is just a rather brutally frank acknowledgement of this situation.

  3. Sometimes I notice that my SLIDES on a topic are an easier read and
    more informative than my PAPER on the topic. High level descriptions can be
    better and more informative. I've heard it said

    People who KNOW what you are talking about won't need the details
    and can do them themselves.

    People who DO NOT KNOW what you are talking about- the details won't help.

    Of course, you shouldn't carry this to extremes.

  4. The best lesson I was taught about writing: always keep your audience in mind.

    Those who write unnecessarily long posts and emails pay no attention to the time a reader needs to spend to read it. Would you prefer to spend your time reading an unnecessarily long email from a stranger to being with your daughter?

  5. Lance is of course entirely correct that lengthy articles (or lectures or emails, etc.) whose narrative is largely or entirely predictable are "tl;dr" material.

    However, Bohr-dual to Lance's Great Truth is the Great Truth that lengthy STEM missives can be delightful … provided that their narrative is largely or entirely unpredictable.

    As an example of the latter, please let me commend Nima Arkani-Hamed's lengthy-yet-lively on-line lecture The Amplituhedron and also its accompanying lengthy-yet-lively preprint "Scattering Amplitudes and the Positive Grassmannian" (arXiv:1212.5605v1)

    (minute 43:20) "We can't just keep making equivalences between ideas that were essentially handed to us from the early part of the 20th century. We have to find really new things!"

    "Maybe I'll just end with this. A slogan that many of you have heard many times is that space-time has gotta be emergent. But I think it's very unlikely that *just* space-time is emergent. It seems very unlikely to me that quantum mechanics just going to sit there with space-time being emergent. I think space-time *and* quantum mechanics have to emerge hand-in-hand from some more primitive principles."

    Conclusion  Arkani-Hamed's directive "We have to find really new things!" is the kernel that amply justifies the length of his various-and-evolving narratives. This shows us that even the longest "tl;dr" missives can be enjoyable and valuable, when we appreciate that their narratives can provide — from an engineering perspective — concrete guidance like Arkani-Hamed's.

    1. LOL … the above engineeering-level appreciation for Arkani-Hamed's work has found its Bohr-dual in the deprecation of Arkani-Hamed's work that Scott Aaronson has just posted on his own Shtetl Optimized weblog under the title The Unitarihedron: The Jewel at the Heart of Quantum Computing.

      Scott's essay has the self-duality property that many of Scott's best technical writings possess: it can enjoyably be read twice, once for its sardonicism, and again for its lyricism.

      Both readings are highly recommended!

    2. "Scott's essay has the self-duality property that many of Scott's best technical writings possess: it can enjoyably be read twice, once for its sardonicism, and again for its lyricism."

      Alright John, you win: your 3-month ban from my blog is hereby commuted to time served. :-)

    3. Thank you, Scott. It was distressing to contemplate that my various "burning arrows" (as Dick Lipton and Ken Regan aptly call them) might never again be honored by banishment by Shtetl Optimized.

      Three essays will be held-in-waiting to be posted at some future date for the dilection of Shtetl Optimized readers:

      Hilbert Space Considered Harmful  Inspired by Edsger Dijkstra's "GOTO Considered Harmful" (1968).

      It All Hinges On Naturality  Jointly inspired by Bill Thurston's "On Proof and Progress in Mathematics" (1994) and Wendell Berry's "It All Hinges On Affection" (the USA's Jefferson Lecture of 2012).

      Quoth the Whimbrel: Measure More!  Jointly inspired by Edgar Allen Poe's poem "The Raven" (1845) and by Poe's essay upon its construction "The Philosophy of Composition" (1846).

      Needless to say, to the best of my ability all three essays will be scrupulously respectful, literal, and good-natured — even blythe! — because as Thurston's and Berry's essays show us (and modern cognitive science affirms) some teachings are ineffectively communicated by satire, ambiguity and sardonicism. That is why these essays (and others in the same vein) will be posted only after the present Zombie-outbreak of Arkani-Hamed criticism has exhausted itself.

      Hopefully these future essays will inspire future Shtetl Optimized banishments; otherwise I will fear that I am losing my touch!

      Most importantly of all, please let me say that I admire the vigor and integrity of Shtetl Optimized very much (even when I thoroughly disagree with its various arguments and/or conclusions), and that I (and many folks) hope to enjoy many more Shtetl Optimized columns to come.

      Thank you, Scott Aaronson! And the same sincere appreciation and thanks are extended to you, Lance Fortnow and Bill GASARCH!

    4. Erratum  Wendell Berry's 2012 Bill Thurston-esque Jefferson Lecture is titled It All Turns On Affection, (not, as was posted, It All Hinges On Affection).

      A suggested reading of Berry's lecture is "agriculture" ⇔ "STEM culture" and "rural communities" ⇔ "academic communities".

      Having witnessed with considerable grief the ruinous destruction of the former in my lifetime, by the path of unreasoned obeisance to "efficient markets" and "low-cost services", it grieves me also to apprehend the onset of the ruin of the latter, by a similarly unreasoned path. This need not happen!

  6. I prefer the term "abstract" to "tl;dr". And I agree with Tim Gowers.