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24 posts tagged with physics by kliuless.

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24 posts tagged with physics by kliuless.

Displaying 1 through 24 of 24.

## The observer at the end of time: Of immortal watchers and imaginary data

In a Multiverse, What Are the Odds? "Testing the multiverse hypothesis requires measuring whether our universe is statistically typical among the infinite variety of universes. But infinity does a number on statistics." (previously) [more inside]

## 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)

## 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 ;)## 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]

## conservation of information

A Black Hole Mystery Wrapped in a Firewall Paradox - "A paradox around matter leaking from black holes puts into question various scientific axioms: Either information can be lost; Einstein's principle of equivalence is wrong; or quantum field theory needs fixing." [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]

## 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]

## An Interview with Yanis Varoufakis

The New Priesthood - "The hapless economist uses the same tools as acclaimed physicists and astronomers. She has trained for years to speak precisely the same language as them, to understand the same advanced mathematics, to deploy most complex statistical methods which are an essential part of the scientific toolbox. It is, understandably, incredibly difficult to accept that her work is a form of higher order superstition; a religion couched in the language of mathematics and statistics. Tragically, this is precisely what it is." [more inside]

## TEDxCaltech

## from complexity, universality

## spacetime must organise itself in a way that maximises entropy

Gravity from Quantum Information

*At the heart of their idea is the tricky question of what happens to information when it enters a black hole. Physicists have puzzled over this for decades with little consensus. But one thing they agree on is Landauer's principle: that erasing a bit of quantum information always increases the entropy of the Universe by a certain small amount and requires a specific amount of energy.*(via mr)## Roger Penrose is looking more credible

Quantum processes involved in photosynthesis? "[A]lgae and bacteria may have been performing quantum calculations at life-friendly temperatures for billions of years. The evidence comes from a study of how energy travels across the light-harvesting molecules involved in photosynthesis. The work has culminated this week in the extraordinary announcement that these molecules in a marine alga may exploit quantum processes at room temperature to transfer energy without loss. Physicists had previously ruled out quantum processes, arguing that they could not persist for long enough at such temperatures to achieve anything useful." (via mr)

## it from bit

Emergent Gravity - Erik Verlinde has a theory that "gravitational attraction could be the result of the way information about material objects is organised in space..." Here's some related weblog discussions and follow along on twitter! (via /. & bruces ;)

## space and time do not commute

TOE breaking Lorentz invariance - "by treating space and time differently as well as separately, the infinities in the quantum mechanics equations vanish, and gravity behaves as it should." [more inside]

## Newtonian dynamics unmodified

## maybe the Sarumpaet Rules will be worked out afterall

Before the Big Bang - way,

*way*out of my depth, but I thought this comment was intriguing: "The paper as published, along with a longer follow up paper, looks to my untrained eye a nearly complete quantum gravitation theory, which is an exciting prospect in itself. However, as with all physical theories, we will await for experimental support before popping the cork." Here's some more on loop quantum gravity, spin networks, the big bang and*ekpyrosis*.## Negative knowledge (or more precisely negative information)

Know less than nothing!?

*What could negative knowledge possibly mean? In short, after I tell you negative information, you will know less...*"In this week's issue of Nature, however, Michal Horodecki and colleagues present a fresh approach to understanding quantum phenomena that cannot be grasped simply by considering their classical counterparts." [via slashdot :]## 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)## (S/W)AP

Smolin vs. Susskind on the anthropic principle. For those keeping score: Stephen Hawking is for it. Brian Greene is not.

## On phenotropy and causal bandwidth

Jaron Lanier talks about philosophy, computer science and physics.

*Suppose poor old Shroedinger's Cat has survived all the quantum observation experiments but still has a taste for more brushes with death. We could oblige it by attaching the cat-killing box to our camera. So long as the camera can recognize an apple in front of it, the cat lives.*## Describing a New Entropy

Describing a New Entropy A reformulation of Boltzmann-Gibbs entropy by one Constantino Tsallis is causing quite a buzz/stir in the theoretical physics community. It was originally published in 1988, but it sounds like it's only recently hit its stride. There's going to be a conference on "Tsallis entropy" in October co-chaired by Murray Gell-Mann!

Reading through

*Physics Today*(as I'm wont to do on occasion) I came across this absolutely enthralling article on Wolfgang Pauli of whom I've never heard. Truly an admirable specimen among*Physicus Intellectus*. Also, it behooves me to mention "A Remembrance of Pauli in 1950."Page:
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