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52 posts tagged with physics *and* math.

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## Famous Fluid Equations Are Incomplete

The Singular Mind of Terry Tao - "Imagine, he said, that someone awfully clever could construct a machine out of pure water. It would be built not of rods and gears but from a pattern of interacting currents." (via) [more inside]

## Stephen Hawking is not part of the solution, he is part of the problem.

The equations on the blackboard may be the problem. Mathematics, the language of science, may have misled the scientists. “The idea,” says physicist Lee Smolin, “that the truth about nature can be wrestled from pure thought through mathematics is overdone… The idea that mathematics is prophetic and that mathematical structure and beauty are a clue to how nature ultimately works is just wrong.” [more inside]

## √2N

At the Far Ends of a New Universal Law

The law appeared in full form two decades later, when the mathematicians Craig Tracy and Harold Widom proved that the critical point in the kind of model May used was the peak of a statistical distribution. Then, in 1999, Jinho Baik, Percy Deift and Kurt Johansson discovered that the same statistical distribution also describes variations in sequences of shuffled integers — a completely unrelated mathematical abstraction. Soon the distribution appeared in models of the wriggling perimeter of a bacterial colony and other kinds of random growth. Before long, it was showing up all over physics and mathematics. “The big question was why,” said Satya Majumdar, a statistical physicist at the University of Paris-Sud. “Why does it pop up everywhere?”

## 21st Century Wiener

Norbert Wiener: The Eccentric Genius Whose Time May Have Finally Come (Again) - "The most direct reason for Wiener's fall to relative obscurity was the breakthrough of a young mathematician and engineer named Claude Shannon." [more inside]

## there is no soundtrack

Finite time blowup for an averaged three-dimensional Navier-Stokes equation - "[Terence Tao] has shown that in an alternative abstract universe closely related to the one described by the Navier-Stokes equations, it is possible for a body of fluid to form a sort of computer, which can build a self-replicating fluid robot that, like the Cat in the Hat, keeps transferring its energy to smaller and smaller copies of itself until the fluid 'blows up.' " [1,2,3] (previously)

## That’s why it doesn’t matter if God plays dice with the Universe

Discovering Free Will (Part II, Part III) - a nice discussion of the Conway-Kochen "Free Will Theorem". [more inside]

## John Baez on the maths of connecting everyone (and everything) on earth

Network Theory Overview - "The idea: nature and the world of human technology are full of networks! People like to draw diagrams of networks. Mathematical physicists know that in principle these diagrams can be understood using category theory. But why should physicists have all the fun? This is the century of

*understanding living systems and adapting to life on a finite planet*. Math isn't the main thing we need, but it's got to be part of the solution... so one thing we should do is develop a unified and powerful theory of networks." (via ;)## The perfect billiards break

## I Was Told There Would Be No Math

M.I.T. professor Max Tegmark explores the possibility that math does not just describe the universe, but makes the universe.

## binding the andat

Closing in on the twin prime conjecture (Quanta) - "Just months after Zhang announced his result, Maynard has presented an independent proof that pushes the gap down to 600. A new Polymath project is in the planning stages, to try to combine the collaboration's techniques with Maynard's approach to push this bound even lower." [more inside]

## My God, it's full of... everything

Revelations in the field of quantum physics have resulted in the discovery of the Amplituhedron, a jewel-like higher dimensional object whose volume elegantly predicts fundamental physical processes that took the brilliant Dr. Richard Feynman hundreds of pages of abstruse mathematics to describe.
The theoretical manifold not only enables simple pen-and-paper calculation of physics that would normally require supercomputers to work out, but also challenges basic assumptions about the nature of reality -- forgoing the core concepts of locality and unitarity and suggesting that space and time are merely emergent properties of a timeless, infinitely-sided "master amplituhedron," whose geometry represents the sum total of all physical interactions.

**More:**The 152-page source paper on arXiv [PDF] - Lead author Nima Arkani-Hamed's hour-long lecture at SUSY 2013 - Scans of Arkani-Hamed's handwritten lecture notes - A far more detailed lecture series "Scattering Without Space Time": one, two, three - Arkani-Hamed previously on MeFi - A hot-off-the-presses Wikipedia page (watch this space)## Paperscape

Paperscape is a searchable 2-dimensional visualization of the 800,000+ scientific papers (mostly in physics and math) on the arXiv preprint server.

## Assume A Cylindrical Cow

## The number of constituent particles in one mole of a given substance.

Avogadro Project - The International Avogadro project relates the kilogram to the mass of a fixed number of atoms by measuring the number of atoms in a sphere of silicon.
I'll leave this here.

## Aspiring Animators & Game Designers, Study Your Calculus & Combinatorics

Every film Pixar has produced has landed in the top fifty highest-grossing animated films of all time. What's their secret? Mathematics. Oh, and 22 Rules of Storytelling. [more inside]

## Oliver Heaviside

Surely you've heard of the physicist Maxwell, but what about Oliver Heaviside? Oliver Heaviside: A first-rate oddity.

## OMG SCIENCE!

Henry Reich of Minute Physics shares his favorite science blogs, video channels, and other resources on the web. (Minute Physics previously) [more inside]

## the power and beauty of mathematics

## direct realism

The Nature of Computation - Intellects Vast and Warm and Sympathetic: "I hand you a network or graph, and ask whether there is a path through the network that crosses each edge exactly once, returning to its starting point. (That is, I ask whether there is a 'Eulerian' cycle.) Then I hand you another network, and ask whether there is a path which visits each node exactly once. (That is, I ask whether there is a 'Hamiltonian' cycle.) How hard is it to answer me?" (via) [more inside]

## no stairway?

Q: How many miles is it to the crab nebula? How does one even figure this out?
A: The cosmic distance ladder! Here's a talk by Fields medalist Terrence Tao on methods for indirect calculation of distances to astronomical objects. Here's Tao's blog post on the subject, including the slides for the talk. And here's a Wikipedia page. [more inside]

## The Cause of the Formation of Meanders in the Courses of Rivers and of the So-Called Baer’s Law

## Fun with kinematics!

Racetrack is a game with very simple rules which nonetheless does a surprisingly good job of simulating the acceleration, braking, and handling of a race car. It can teach not only about inertia and kinematics, but also about optimal racing lines. Racetrack can be played with nothing more than a piece of graph paper and a pen, but there is also an online implementation called Vector Racer.

## noncommutative balls in boxes

Morton and Vicary on the Categorified Heisenberg Algebra - "In quantum mechanics, position times momentum does not equal momentum times position! This sounds weird, but it's connected to a very simple fact. Suppose you have a box with some balls in it, and you have the magical ability to create and annihilate balls. Then there's one more way to create a ball and then annihilate one, than to annihilate one and then create one. Huh? Yes: if there are, say, 3 balls in the box to start with, there are 4 balls you can choose to annihilate after you've created one but only 3 before you create one..." [more inside]

## Ice

## A snack of classical mechanics

What is the Dzhanibekov effect? Known as the Tennis Racket theorem in English and documented by Vladimir Dzhanibekov in 1985 space, it is the result of unstable rotation about a principle axis.

## A Shory Biography of Emmy Noether

## The Earth Is Flat (to a certain approximation)

Old Theories As Limits of New Ones -- Theoretical physicist, Lubos Motl, takes a brief tour through the history of physics, and explains the simple mathematical relationship of old theories to the theories that replace them.

## The Cartoon Guide to Life, the Universe, and Everything

Larry Gonick is a veteran American cartoonist best known for his delightful comic-book guides to science and history, many of which have previews online. Chief among them is his long-running

*Cartoon History of the Universe*(later*The Cartoon History of the Modern World*), a sprawling multi-volume opus documenting everything from the Big Bang to the Bush administration. Published over the course of three decades, it takes a truly global view -- its time-traveling Professor thoroughly explores not only familiar topics like Rome and World War II but the oft-neglected stories of Asia and Africa, blending caricature and myth with careful scholarship (cited by fun illustrated bibliographies) and tackling even the most obscure events with intelligence and wit. This savvy satire carried over to Gonick's Zinn-by-way-of-*Pogo*chronicle*The Cartoon History of the United States*, along with a bevy of*Cartoon Guides*to other topics, including*Genetics, Computer Science, Chemistry, Physics, Statistics, The Environment*, and (yes!)*Sex*. Gonick has also maintained a few sideprojects, such as a webcomic look at Chinese invention, assorted math comics (previously), the*Muse*magazine mainstay*Kokopelli & Co.*(featuring the shenanigans of his "New Muses"), and more. See also these lengthy interview snippets, linked previously. Want more? Amazon links to the complete oeuvre inside! [more inside]## Nature Special Issue on the Future of the PhD

## What is reality?

Horizon asks "What is reality?" -- youtube for links for those outside the UK: 1, 2, 3, 4. It's a hard question. To help you answer it, Stanford has a set of free courses available on line by Leonard Susskind:
General Relativity, Cosmology, New Revolutions in Particle Physics, Quantum Entanglement, Special Relativity, Classical Mechanics, Statistical Mechanics, The Standard Model. (Each link is to lecture 1 of a full college course of a dozen or so lectures.) If you need help with the math, the Khan Academy should help get you up to speed.

## Snail Ball

The Geometry of the Snail Ball [pdf] - an interesting article (with some DIY advice at the end) about a toy shop curiosity you may have encountered.

## from complexity, universality

## That Was the This Week's Finds That Was

The 300th issue of This Week's Finds in Mathematical Physics will be the last. It is not an exaggeration to say that when John Baez started publishing TWF in 1993, he invented the science blog, and an (academic) generation has now grown up reading his thoughts on higher category theory, zeta functions, quantum gravity, crazy pictures of roots of polynomials, science fiction, and everything else that can loosely be called either "mathematical" or "physics."
Baez continues to blog actively at n-category cafe and the associated nLab (an intriguingly fermented commune of mathematicians, physicists, and philosophers.) He is now starting a new blog, Azimuth, "centered around the theme of

*what scientists can do to help save the planet*."## Economics and Physics Envy

"Take a little bad psychology, add a dash of bad philosophy and ethics, and liberal quantities of bad logic, and any economist can prove that the demand curve for a commodity is negatively inclined." MIT economist Andrew Lo and string theorist turned asset manager Mark Mueller on the "physics envy" that plagues economics, and how to stop worrying and love uncertainty.

## Contact is the secret, is the moment, when everything happens. Contact....

From 1980 - 1988, a science education series called 3-2-1 Contact ran on PBS. Produced by Children's Television Workshop, the series was geared toward an older audience than other popular CTW offerings Sesame Street and The Electric Company, and focused on teaching kids about science, math and the world around them. [more inside]

## Would you like to buy an fuzzy multi-instanton knot?

"...the best place to hide bulls**t is in a refereed journal that’s not open-access!" The math-physics blog n-category cafe digs into the curious case of M.S. El Naschie. El Naschie is editor-in-chief of the journal Chaos, Solitons, and Fractals, published by the well-respected scientific publisher Elsevier and sold to academic libraries for US$4,520 a year. The problem? El Naschie has published 322 of his own papers in the journal -- papers that John Baez (of "This Week's Finds in Mathematical Physics" and "The Crackpot Index") describes as "vague, dreamlike imagery," "undisciplined numerology larded with impressive buzzwords," and "total baloney." Is El Naschie a reverse Sokal? Or a Markov process for producing random publishable papers? One thing's for sure -- he knows how to cure cancer.

## Two mathematicians walk into a bar...

A math professor was explaining a particularly complicated calculus concept to his class when a frustrated pre-med student interrupts him. "Why do we have to learn this stuff?" the pre-med blurts out. The professor pauses, and answers matter-of-factly: "Because math saves lives." "How?" demanded the student. "How on Earth does calculus save lives?" "Because," replied the professor, "it keeps certain people out of medical school."

## Symmetry. Shakespeare. Islamic medicine. Creative writing challenges.

Symmetry. Shakespeare. Islamic medicine. Creative writing challenges. Four podcast series from University of Warwick.

## Impossible Crystals

"This is a story of how the impossible became possible. How, for centuries, scientists were absolutely sure that solids (as well as decorative patterns like tiling and quilts) could only have certain symmetries - such as square, hexagonal and triangular - and that most symmetries, including five-fold symmetry in the plane and icosahedral symmetry in three dimensions (the symmetry of a soccer ball), were strictly forbidden. Then, about twenty years ago, a new kind of pattern, known as a "quasicrystal," was envisaged that shatters the symmetry restrictions and allows for an infinite number of new patterns and structures that had never been seen before, suggesting a whole new class of materials...."

Physicist Paul J. Steinhardt delivers a fascinating lecture (WMV) on tilings and quasicrystals. However, it turns out science was beaten to the punch: a recent paper (PDF) suggests Islamic architecture developed similar tilings centuries earlier.

Physicist Paul J. Steinhardt delivers a fascinating lecture (WMV) on tilings and quasicrystals. However, it turns out science was beaten to the punch: a recent paper (PDF) suggests Islamic architecture developed similar tilings centuries earlier.

## Physics simulators. Lots of physics simulators.

PhET - Physics Education Technology offers this astoundingly large library of online physics simulations. Play orbital billiards. Land on a cheesy moon. Experiment with sound. Or try more advanced quantum physics simulators. Still bored? Try the "cutting edge" catagory. Here's the complete index. (Warnings: Frames, Flash, Javascript, Java applets, graphics, sound, quantum timesuck.)

## Raft to the Future

Raft to the Future: An article about the weirdness of physical models of the universe, how that weirdness correlates to the inherent incompleteness of mathematical systems, and how time itself can

*emerge*at the fringes of these incomplete models.## Show Your Work

Condoleezza holds a watermelon just over the edge of the roof of the 300-foot Federal Building, and tosses it up with a velocity of 20 feet per second. Using the formula provided, when the watermelon will hit the ground? Bellevue Community College President Jean Floten asked the Pluralism Steering Committee to take the lead on this, and to complete their task quickly.

## This Week's Finds in Mathematical Physics

This Week's Finds in Mathematical Physics. A geek's paradise. Reminiscent of Scientific American's

*Mathematical Games.*## ...almost, but not quite, entirely unlike tea.

"...the answer to Life, the Universe, and Everything is..." "Yes? Yes!?" "...42."

via Dyson, Montgomery, Princeton, a cup of tea - as presented by Seed Magazine.

via Dyson, Montgomery, Princeton, a cup of tea - as presented by Seed Magazine.

## Ripple Tank Simulation

Ripple Tank Simulation is a delightful, mesmeric java applet simulation of a ripple tank. It demonstrates two dimensional wave phenomena such as interference, diffraction, refraction, resonance, phased arrays, and the Doppler effect (do try the 3D view). From Paul Falstad's fantastic collection of Math, Physics and Engineering Applets.

## Nerd Porn

Flash Animations for Physics. Animations and interactive demos available in many varieties, such as classical mechanics, nuclear, quantum, and relativistic. There's even a nice explanation of the forces at work in Curling. And if that doesn't wet your geek whistle, then take a peek at the patterns of Visual Math.

## Math You Don't Know, and Math You Didn't Know You Didn't Know.

Jim Loy's Mathematics Page is (among other things) a collection of interesting theorems (like Napoleon's Triangle theorem), thoughtful discussions of both simple and complex math, and geometric constructions (my personal favorite); the latter of which contains surprisingly-complex discussions on the trisection of angles, or the drawing of regular pentagons.

Similarly enthralling are the pages on Billiards (and the physics of), Astronomy (and the savants of), and Physics (and the Phlogiston Theory of), all of which are rife with illustrations and diagrams. See the homepage for much more.

If you like your geometric constructions big, try Zef Damen's Crop Circle Reconstructions.

Similarly enthralling are the pages on Billiards (and the physics of), Astronomy (and the savants of), and Physics (and the Phlogiston Theory of), all of which are rife with illustrations and diagrams. See the homepage for much more.

If you like your geometric constructions big, try Zef Damen's Crop Circle Reconstructions.

## Java applets to help visualize various concepts in math, physics, and engineering

## The Complexity of a Controversial Concept

The Logic of Diversity "A new book,

*The Wisdom of Crowds*[..:] by The New Yorker columnist James Surowiecki, has recently popularized the idea that groups can, in some ways, be smarter than their members, which is superficially similar to Page's results. While Surowiecki gives many examples of what one might call collective cognition, where groups out-perform isolated individuals, he really has only one explanation for this phenomenon, based on one of his examples: jelly beans [...] averaging together many independent, unbiased guesses gives a result that is probably closer to the truth than any one guess. While true — it's the central limit theorem of statistics — it's far from being the only way in which diversity can be beneficial in problem solving." (Three-Toed Sloth)## What do you call a young eigensheep?

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