Top all-time · #1326
John Denker
Personal blog · av8n.comsciencemath
John Denker writes Welcome to Av8n.com, a personal blog at av8n.com about science and math. Since 2007, 56 different Hacker News readers have linked it 143 times, most often “Electromagnetism using geometric algebra versus components”. No feed was found, so read it on the site itself.
A new spin on the perceptions, procedures, and principles of flight. 20 chapters, over 200 illustrations.
Most-linked posts?
- /how/6 people · 6 mentions · first linked 2016-07-22
- Electromagnetism using geometric algebra versus components5 people · 10 mentions · first linked 2015-02-12
- A new spin on the perceptions, procedures, and principles of flight5 people · 7 mentions · first linked 2009-07-26
- See How It Flies – Airfoils and Airflow (2005)5 people · 5 mentions · first linked 2011-04-18
- Turbid: A High-Entropy Random Generator4 people · 9 mentions · first linked 2011-04-18
- Introduction to Clifford Algebra4 people · 5 mentions · first linked 2013-10-22
- Introduction to Clifford Algebra (2006)3 people · 3 mentions · first linked 2020-02-10
- /how/htm/airfoils.html3 people · 3 mentions · first linked 2015-12-10
- Learning, Remembering, and Thinking2 people · 2 mentions · first linked 2017-11-20
- /physics/spacetime-welcome.htm2 people · 2 mentions · first linked 2015-06-19
What Hacker News says?
I am somewhat unconvinced that quaternions are more challenging, or at least a worse way to think about the issue : https://eater.net/quaternions And speaking of Maxwell's Equation"s" : http://www.av8n.com/physics/maxwell-ga.htm#sec-preview
Comment linking /physics/maxwell-ga.htm
on “Monumental (if correct) advance in number theory posted to ArXiv by Yitang Zhang”Submitted Introduction to Clifford Algebra (2006) as a story · 189 points
HN discussionIt depends on what you consider "similar", but no, the rotation of the paper has nothing to do with the rotation of helicopter blades during autorotation. In that case, the blades act like ordinary wings and they do an ordinary glide, albeit in a circular direction because the blades are fixed at one end. What happens with the paper is different. The axis of rotation is horizontal rather than vertical. However, ther…
Comment linking /how/htm/airfoils.html
on “Nascar driver stuns to qualify for championship with GameCube move”Submitted Electromagnetism using geometric algebra versus components as a story · 111 points
HN discussionIt depends on how you interpret the parent comment, but my guess is no. The autorotation you're speaking of happens in a plane roughly parallel to the ground. This is a very powerful and stable way for a wing to generate lift: https://www.av8n.com/how/htm/spins.html#sec-samara There's another option, which is counter-rotation along an axis parallel to the ground, and orthogonal to the direction of travel. This mecha…
Comment linking /how/htm/airfoils.html
on “Nascar driver stuns to qualify for championship with GameCube move”Submitted Security recommendations for any device that depends on random numbers (2013) as a story · 64 points
HN discussionI see, though I do consider that part of YouTube to be a net negative for everyone but Google considering how it's keeping people on the platform, and therefore less likely to look for more varied sources. But what I meant is that people share links around, whether in public like here, or in one-on-one discussions (and blogs do have their own recommended lists), so it's quite possible that you would still have found…
Comment linking /
on “How I animate 3Blue1Brown [video]”Submitted See How It Flies (2014) as a story · 41 points
HN discussionThat's just words for you... Intellectual property isn't property, at least not a full-blown one. http://www.av8n.com/physics/weird-terminology.htm
Comment linking /physics/weird-terminology.htm
on “I do not agree with Github's use of copyrighted code as training for Copilot”Submitted Turbid: A High-Entropy Random Generator as a story · 32 points
HN discussionUh, getting rid of pseudo-vectors ? Maxwell's Equations? http://www.av8n.com/physics/maxwell-ga.htm
Comment linking /physics/maxwell-ga.htm
on “Let's remove quaternions from every 3D engine (2018)”Submitted Learning, Remembering, and Thinking (2006) as a story · 31 points
HN discussionMaxwell's equations : much more consistent without the god damned pseudo-vectors that are vectors except when they aren't ! http://www.av8n.com/physics/maxwell-ga.htm
Comment linking /physics/maxwell-ga.htm
on “Let's remove quaternions from every 3D engine (2018)”Submitted Turbid: A High-Entropy Random Generator (2005) as a story · 26 points
HN discussionHere you go : http://www.av8n.com/physics/clifford-intro.htm
Comment linking /physics/clifford-intro.htm
on “Let's remove quaternions from every 3D engine (2018)”Submitted Introduction to Scaling Laws as a story · 21 points
HN discussionCheck out "See How It Flies": https://www.av8n.com/
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on “Enroute Airbus A380 wake flips Challenger business jet upside down”Submitted High-entropy randomness generator using calibrated soundcard as a story · 15 points
HN discussionNonsense. See here: https://www.av8n.com/how/htm/airfoils.html#sec-fluid
Comment linking /how/htm/airfoils.html
on “Enroute Airbus A380 wake flips Challenger business jet upside down”Submitted See How It Flies – Airfoils and Airflow (2005) as a story · 13 points
HN discussionConcerning the horizontal stabiliser providing negative lift: it's possible and frequently so, but not necessary for stable flight. (If I understand correctly, what is required is that its angle of attack is lower than the one of the main wing, or equivalently (if the wings have the same shape) its wing loading.) See section 6.1 here, for example: http://www.av8n.com/how/htm/aoastab.html#sec-basic-stability
Comment linking /how/htm/aoastab.html
on “Flying-V: Flying long distances energy-efficiently”Submitted Turbid: A High-Entropy Random Generator (2005) as a story · 4 points
HN discussionIt's one equation in geometric algebra. https://www.av8n.com/physics/maxwell-ga.htm#eq-max-ga Also there is a new community for geometric algbera people https://bivector.net/ . Check out the demo https://observablehq.com/@enkimute/animated-orbits Watch the SIGGRAPH talk https://youtu.be/tX4H_ctggYo Join the discord https://discord.gg/vGY6pPk
Comment linking /physics/maxwell-ga.htm
on “Intuitive Guide to Maxwell's Equations”Submitted Learning, Remembering, and Thinking as a story · 3 points
HN discussionIt's also interesting once you understand what Maxwell's equations mean to look at their geometric algebra formulation[1]. In particular it makes their use in special and general relativity somewhat more elegant, since the GA form explicitly includes a spacetime component. Of course that page isn't an elementary introduction, it assumes familiarity with GA and the divergence & curl operators, as well as some concept…
Comment linking /physics/maxwell-ga.htm
on “Intuitive Guide to Maxwell's Equations”Submitted Introduction to Scaling Laws as a story · 3 points
HN discussionFlaps do 2 things: smaller flap deployments increase lift without increasing drag much; larger increase drag without increasing lift much (beyond that of using flaps at all). You want to be going as slow as possible when you land (aircraft make poor racecars), and most aircraft call for some level of flaps on landing. Increasing lift lowers the stall speed, which is good, and increasing drag allows you to lose altit…
Comment linking /
on “Gimli Glider”Submitted Turbid: A High-Entropy Random Generator as a story · 3 points
HN discussionThere is already a project whose name sadly escapes me that does this, using information theory to derive lower bounds on the number of bits of entropy in data read from a line-in jack. EDIT: I'm thinking of Turbid: http://www.av8n.com/turbid/paper/turbid.htm EDIT2: There's also a wealth of information in this thread from the metzdowd cryptography mailing list: http://www.metzdowd.com/pipermail/cryptography/2013-Sep…
Comment linking /turbid/paper/turbid.htm
on ““We cannot trust” Intel and Via’s chip-based crypto, FreeBSD developers say”Submitted Turbid: A High-Entropy Random Generator as a story · 2 points
HN discussion
