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Michael Hartl

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Michael Hartl
Headshot of Michael Hartl wearing a blue collared shirt
Michael Hartl
Born
United States
NationalityAmerican
EducationHarvard University, California Institute of Technology
Occupation(s)Physicist, entrepreneur, writer
Notable workThe Tau Manifesto
Websitewww.michaelhartl.com

Michael Hartl is an American physicist, author, and entrepreneur.[1][2] He is best known as the creator of the Ruby on Rails Tutorial,[3][4][5] founder of Tau Day,[1][6][7][8] and author of The Tau Manifesto,[1][9][10] in which he proposes replacing pi (π) with tau (2π).[7][11]

Education

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In the 1990s, Hartl attended Harvard University for his undergraduate studies, graduating with a bachelor's degree in physics.[12] Hartl obtained his PhD in Physics from the California Institute of Technology (Caltech) in 2003, where he researched black hole dynamics. His dissertation was titled Dynamics of Spinning Compact Binaries in General Relativity.[13]

Career

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Physicists Michael Hartl, Kip Thorne, and Stephen Hawking in front of a blackboard with physics formulas and diagrams
Michael Hartl with Kip Thorne and Stephen Hawking in 2012

After finishing his PhD, Hartl served as Caltech's editor on a corrected and expanded version of The Feynman Lectures on Physics at the request of Kip Thorne.[14][15] Explaining in the preface why he chose Hartl for the task, Thorne noted that "Hartl understand physics deeply, he is among the most meticulous physicists I have known, and like Feynman he is an outstanding pedagogue."[14][15] Thorne also noted that Hartl is the only Caltech graduate student to be granted a "lifetime achievement award for excellence in teaching" by Caltech's undergraduates.[14][15][16]

As an entrepreneur, Hartl participated in the Y Combinator program in 2008.[17] In 2010, he published the first edition of the Ruby on Rails Tutorial book[18][19] and screencasts,[20] which teach web development using the Ruby on Rails web application framework. The Ruby on Rails Tutorial quickly became both a critical and commercial success,[3][21] eventually going through seven editions.[22] In 2011, Hartl received a Ruby Hero Award for his service to the Ruby community, with the citation mentioning both the Ruby on Rails Tutorial and his first book, RailsSpace.[23][24] In 2013, Wikipedia co-founder Jimmy Wales described the Ruby on Rails Tutorial as his "favorite book."[25]

Hartl later co-founded the online education company Learn Enough to expand on the Ruby on Rails Tutorial, adding tutorials on other computer technologies and including online courses.[26][27][28] In partnership with Pearson Education, Hartl authored or co-authored five books published under the brand Learn Enough to Be Dangerous.[29][30][31][32][33] Learn Enough was acquired by a tech private equity group in 2022.[34]

The Tau Manifesto

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Michael Hartl standing onstage holding a microphone with the letters BIL in the foreground answering questions after his Tau Talk at the BIL Conference
Michael Hartl speaking about tau at the BIL Conference in 2015

In 2010, Hartl published The Tau Manifesto, in which he proposed using the Greek letter tau to represent the circle constant τ = C/r = 2π,[35] the first time tau was publicly proposed for this purpose.[1][6] The Tau Manifesto proved popular,[36] and a revised edition was published in 2019,[37] followed by a print edition in 2021.[38][39] As of 2022, The Tau Manifesto had been translated into seven different languages.[40]

With the initial publication of The Tau Manifesto in 2010, Hartl founded Tau Day as a mathematical celebration and to promote adoption of the new constant.[8] Observed annually on June 28, or 6/28 (in analogy with the celebration of Pi Day on 3/14),[6][8] Tau Day has become a widely celebrated mathematical holiday.[1][6][41][42] Hartl's constant has also seen significant adoption, including support for tau in the official Google calculator[43] and inclusion in programming languages such as Microsoft.NET,[44] Java,[45] and Python.[46][47] Notable supporters of tau and Tau Day include MIT,[41][48][49] SLMath,[42] Vi Hart,[50][51] Vitalik Buterin,[52][53] and Elon Musk[54] (who named one of his children after the constant[55]).

Selected publications

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Scientific articles

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  • Hartl, Michael D. (2003). "Lyapunov exponents in constrained and unconstrained ordinary differential equations". Phys. Rev. E. arXiv:physics/0303077. Bibcode:2003physics...3077H.
  • Hartl, Michael D. (2003). "Dynamics of spinning test particles in Kerr spacetime". Physical Review D. 67 (2): 024005. arXiv:gr-qc/0210042. Bibcode:2003PhRvD..67b4005H. doi:10.1103/PhysRevD.67.024005. ISSN 0556-2821.
  • Hartl, Michael D. (2003). "Survey of spinning test particle orbits in Kerr spacetime". Physical Review D. 67 (10): 104023. arXiv:gr-qc/0302103. Bibcode:2003PhRvD..67j4023H. doi:10.1103/PhysRevD.67.104023. ISSN 0556-2821.
  • Hartl, Michael; Buonanno, Alessandra (2005). "Dynamics of precessing binary black holes using the post-Newtonian approximation". Physical Review D. 71 (2): 024027. arXiv:gr-qc/0407091. Bibcode:2005PhRvD..71b4027H. doi:10.1103/PhysRevD.71.024027. ISSN 1550-7998.

Books

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  • Hartl, Michael; Prochazka, Aurelius (2007). RailsSpace: Building a Social Networking Website with Ruby on Rails. Addison-Wesley Professional Ruby Series. ISBN 978-0321480798.
  • Hartl, Michael (2022). Ruby on Rails Tutorial. Boston Columbus New York San Francisco Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montreal Toronto Delhi Mexico City Sao Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo: Addison-Wesley Professional Ruby Series. ISBN 978-0-13-804984-3.
  • Hartl, Michael (2022). Learn Enough Developer Tools to Be Dangerous. Addison-Wesley Professional. ISBN 978-0-13-784345-9.
  • Donahoe, Lee; Hartl, Michael (2022). Learn Enough HTML, CSS and Layout to Be Dangerous. ISBN 978-0-13-784310-7.
  • Hartl, Michael (2022). Learn Enough JavaScript to Be Dangerous. Addison-Wesley Professional. ISBN 978-0-13-784374-9.
  • Hartl, Michael (2022). Learn Enough Ruby to Be Dangerous. Addison-Wesley Professional. ISBN 978-0-13-784413-5.
  • Hartl, Michael (2023). Learn Enough Python to Be Dangerous. Boston: Addison-Wesley Professional. ISBN 978-0-13-805095-5.

References

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  1. ^ a b c d e McMillan, Robert (August 13, 2012). "For Math Fans, Nothing Can Spoil Pi Day—Except Maybe Tau Day". The Wall Street Journal. Archived from the original on March 14, 2020. Retrieved July 11, 2024.
  2. ^ "Michael Hartl". InformIT. Retrieved July 11, 2024.
  3. ^ a b Cooper, Peter (July 30, 2020). "A Q&A with Michael Hartl". Superhighway Ruby Interview Series. Retrieved July 11, 2024.
  4. ^ Olsen, Russ (August 13, 2012). "An Interview with Michael Hartl: Ruby on Rails, the "Magic" Problem, and the Higgs Boson". InformIT. Retrieved July 11, 2024.
  5. ^ Bazinet, Robert (April 12, 2011). "Learning Ruby on Rails with Michael Hartl". InfoQ. Retrieved July 11, 2024.
  6. ^ a b c d Landau, Elizabeth (June 28, 2011). "In case Pi Day wasn't enough, it's now 'Tau Day' on the Internet". CNN. Retrieved July 11, 2024.
  7. ^ a b Bartholomew, Randyn Charles (June 25, 2014). "Why Tau Trumps Pi". Scientific American. Retrieved June 8, 2024.
  8. ^ a b c Hartl, Michael (August 13, 2012). "Tau Day". tauday.com. Retrieved July 11, 2024.
  9. ^ Hartl, Michael (June 28, 2010). "The Tau Manifesto". tauday.com. Retrieved July 11, 2024.
  10. ^ Hartl, Michael (June 28, 2010). "The Tau Manifesto". Amazon.com. Retrieved July 11, 2024.
  11. ^ Aron, Jacob (2011). "Michael Hartl: It's time to kill off pi". New Scientist. 209 (2794): 23. Bibcode:2011NewSc.209...23A. doi:10.1016/S0262-4079(11)60036-5.
  12. ^ "Michael Hartl". LinkedIn. Retrieved July 11, 2024.
  13. ^ Hartl, Michael (2003). Dynamics of Spinning Compact Binaries in General Relativity (PhD thesis). Pasadena, California: California Institute of Technology. Retrieved June 8, 2024.
  14. ^ a b c Feynman, Richard; Leighton, Robert B.; Sands, Matthew. The Feynman Lectures on Physics including Feynman's Tips on Physics: The Definitive and Extended Edition. p. x. ISBN 978-0805390452.
  15. ^ a b c Thorne, Kip. "Preface to the Definitive Edition" (PDF). Retrieved July 13, 2024.
  16. ^ "ASCIT Teaching Awards Recipients 1999-2000". Retrieved August 8, 2024.
  17. ^ "Social Networking Goes Open Source With Insoshi". TechCrunch. August 13, 2012. Retrieved July 13, 2024.
  18. ^ Hartl, Michael (July 28, 2010). "The Ruby on Rails 3 Tutorial book (including PDF downloads) is out". Learn Enough News. Retrieved July 13, 2024.
  19. ^ Hartl, Michael (2010). Ruby on Rails 3 Tutorial: Learn Rails by Example. ISBN 978-0321743121.
  20. ^ Hartl, Michael (October 12, 2010). "The Ruby on Rails 3 Tutorial screencast series". Learn Enough News. Retrieved July 13, 2024.
  21. ^ Riley, Mike (November 10, 2010). "Ruby on Rails Tutorial: Learn by Example Review". Archived from the original on October 11, 2020. Retrieved July 13, 2024.
  22. ^ Hartl, Michael (2022). Ruby on Rails Tutorial: Learn Web Development with Rails (7th ed.). ISBN 978-0-13-804984-3.
  23. ^ Ruby Hero Awards. YouTube. May 17, 2011.
  24. ^ Hartl, Michael (2022). RailsSpace: Building a Social Networking Website with Ruby on Rails. ISBN 978-0321480798.
  25. ^ Wales, Jimmy (March 6, 2013). "What is Jimmy Wales' favorite book?". Quora. Retrieved July 13, 2024.
  26. ^ "Learn Enough to Be Dangerous". Learn Enough News. September 18, 2015. Retrieved July 13, 2024.
  27. ^ Hartl, Michael (September 18, 2015). "Learn Enough Command Line Draft". Learn Enough News. Retrieved July 13, 2024.
  28. ^ "The Learn Enough Courses". Learn Enough. Retrieved July 13, 2024.
  29. ^ Hartl, Michael (2022). Learn Enough Developer Tools to Be Dangerous: Command Line, Text Editor, and Git Version Control Essentials. ISBN 978-0-13-784345-9.
  30. ^ Hartl, Michael (2022). Learn Enough JavaScript to Be Dangerous: Write Programs, Publish Packages, and Develop Interactive Websites with JavaScript. ISBN 978-0-13-784374-9.
  31. ^ Hartl, Michael (2022). Learn Enough Ruby to Be Dangerous: Write Programs, Publish Gems, and Develop Sinatra Web Apps with Ruby. ISBN 978-0-13-784413-5.
  32. ^ Donahoe, Lee; Hartl, Michael (2022). Learn Enough HTML, CSS and Layout to Be Dangerous: An Introduction to Modern Website Creation and Templating Systems. ISBN 978-0-13-784310-7.
  33. ^ Hartl, Michael (2023). Learn Enough Python to Be Dangerous: Software Development, Flask Web Apps, and Beginning Data Science with Python. ISBN 978-0-13-805095-5.
  34. ^ Hartl, Michael (September 18, 2015). "Learn Enough and the Rails Tutorial have been acquired". Learn Enough News. Retrieved July 13, 2024.
  35. ^ Hartl, Michael (March 14, 2010). "The Tau Manifesto" (PDF). Archived (PDF) from the original on July 18, 2019. Retrieved August 5, 2019.
  36. ^ Landau, Elizabeth (June 27, 2017). "The Tao of Tau". Scientific American. Retrieved July 11, 2024.
  37. ^ Hartl, Michael (March 14, 2019) [2010-03-14]. "The Tau Manifesto". Archived from the original on June 28, 2019. Retrieved September 14, 2013.
  38. ^ Hartl, Michael (June 28, 2021). "State of the Tau 2021 Print edition". tauday.com. Retrieved July 15, 2024.
  39. ^ Hartl, Michael. "The Tau Manifesto: No, really, pi is wrong". Amazon.com. Retrieved July 15, 2024.
  40. ^ Hartl, Michael (June 28, 2022). ""State of the Tau 2022"". Retrieved August 19, 2024.
  41. ^ a b @MIT (June 28, 2019). "Three cheers for double Pi! #TauDay http://mitsha.re/i9TP50uP4Id
    Image: Chelsea Turner/MIT"     (Tweet). Retrieved July 11, 2024 – via Twitter.
  42. ^ a b "Tau Day 2024". Simons Laufer Mathematical Sciences Institute. June 20, 2024. Retrieved July 11, 2024.
  43. ^ "tau*1". google.com. Retrieved July 11, 2024.
  44. ^ "Add Math.Tau, MathF.Tau #37517". github.com. Retrieved July 11, 2024.
  45. ^ "TAU". Math (Java SE 20 & JDK 20). oracle.com. Retrieved July 11, 2024.
  46. ^ "Add math.tau". python.org. Retrieved July 11, 2024.
  47. ^ "math.tau". Python 3.12.4 documentation. python.org. Retrieved July 11, 2024.
  48. ^ McGann, Matt (March 12, 2012). "Pi Day, Tau Time". Retrieved August 19, 2024.
  49. ^ A., Paolo (February 20, 2021). "in honor of tau". Retrieved August 19, 2024.
  50. ^ Hart, Vi (March 14, 2011). Pi Is (still) Wrong. YouTube.
  51. ^ Hart, Vi (June 28, 2012). A Song About A Circle Constant. YouTube.
  52. ^ @VitalikButerin (March 14, 2020). "I'm boycotting pi day because tau day is better: https://tauday.com" (Tweet). Retrieved August 16, 2024 – via Twitter.
  53. ^ @VitalikButerin (June 28, 2023). "Happy tau day!" (Tweet). Retrieved August 16, 2024 – via Twitter.
  54. ^ @elonmusk (February 22, 2022). "tau > pi" (Tweet). Retrieved August 16, 2024 – via Twitter.
  55. ^ Hawkinson, Katie; Dean, Grace (September 11, 2023). "New Elon Musk biography says he has 3rd child with Grimes named Techno Mechanicus". Business Insider. Retrieved August 16, 2024.
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