CapitalistImperialistPig

I recently watched a few episodes of the television show Salvation , a science fiction, disaster thriller with soap opera overtones.  It's a Deep Impact knock-off - MIT grad student discovers asteroid headed for Earth, improbable conspiracies of silence are revealed, beautiful people fall into bed with each other. I know that appreciating this sort of thing requires a big effort at suspension of disbelief, and I was prepared to ignore to ignore giant plot holes, the grad student's attempts to solve the 3-body problem using "gravimetric data" (WTF?), and the Elon Musk type inventor demanding and getting billions to develop a Newton's Third Law violating EM drive, but they managed to break me anyway. The last straw was the arrogant and pig-headed government scientist (all the scientists here are dull, arrogant, pig-headed, and spend a lot of time saying "you're insane," mostly to the Elon Musky guy) declaring that they would crash a Jupiter probe ...

And as imagination bodies forth  The forms of things unknown, the poet’s pen  Turns them to shapes and gives to airy nothing  A local habitation and a name.  Such tricks hath strong imagination,  That if it would but apprehend some joy,  It comprehends some bringer of that joy.  Or in the night, imagining some fear,  How easy is a bush supposed a bear!...................Midsummer Night's Dream, Act V, Scene 1 Sometimes the pen belongs to a physicist or a mathematician. Are virtual particles real?  Are imaginary numbers real?   How about negative numbers? As usual, it all depends on what we mean by real.  Not many mathematicians, physicists, or engineers would quarrel with the reality of imaginary numbers, but most of us would admit, I think, that the natural numbers are a bit more "real" than all those other numbers, including the Real Numbers. The world is constructed of such figments of our imagination, and ...

Describes the evolution of a fluid. Quanta magazine has a nice article on mathematicians' attempts to probe the limits of the equation, and more importantly, for me, a lovely video of a Kelvin-Helmholtz instability evolving under the equation. Mathematicians have long suspected that there might be something dodgy about the equation, and there is big money, a Millenium Prize, riding on the conjecture that the equation doesn't always have consistent solutions. Quanta notes that these potential problems don't bother physicists, but doesn't bother to say why. The more fundamental reason is that physicists know that the N-S is not a faithful description of nature. If you look at a fluid in close detail, it becomes a seething mass of individual particles, not infinitely divisible fluid elements. There is also another fact: because the NS has chaotic solutions, their predictivity is always limited in practice, whether it is in theory or not.

The central question in biology today is how life originated. It's not only the biggest unanswered question in biology, but it's also central to our understanding of the place of life in the universe. We now know that planets are extremely common in the universe, and it's at least plausible, that a lot of them have or had Earth like conditions. If we understood how life originated on Earth, we would be much more able to understand the probability of it existing elsewhere. Conversely, if we found life elsewhere, it would almost certainly provide potent clues to how life originated on Earth. The past decades have seen considerable progress in understanding some possibilities for early life, but we are far from concrete answers. Natalie Wolchover, writing in Quanta , has some news on one approach, dissipation driven organization. The idea is that some physical systems evolve to maximize their dissipation of energy and entropy increase. The biophysicist Jeremy England ...

I used this book by Cathie Clarke and Bob Carswell to study for the fluid dynamics portions of my Astrophysical Dynamics and Fluid Dynamics course, and found it very useful. The authors base the book on lectures they have given to third year students at Cambridge. For me, the level was about right. It assumes no fluid dynamics but expects reasonable proficiency in vector analysis. Nearly all physics equations are carefully derived, usually with no missing steps that were too difficult for me to fill in. Most of the book is devoted to inviscid compressible fluids, with a strong focus on astrophysical applications, although the last three chapters (which I haven't studied) treat viscous astrophysical fluids and plasmas. I worked my way through much of the book, usually deriving every equation, and it's pretty amusing if you like that sort of thing. There is always a payoff in physical insight. Convection, hydrostatic equilibrium, sound waves, supersonic flow, shock waves...

I've started reading Dark Sun, Richard Rhodes' award winning history of the development of the fusion (H) bomb. (Hat Tip, Fernando). I've barely started, but I have to say that Rhodes is a compelling writer. One thing that caught my eye was that key Russian scientists were aware of the possibility of a uranium bomb in 1939, and some were already advocating a strong program to try to build it. Two fundamental problems prevented it: the uncertainty as to whether a bomb would actually work, and the enormous expense required to find out. In the end it was decided that the necessary resources could be more usefully spent preparing for the coming war with Germany. The government did not trust the scientists enough to go for broke, and the scientists, with intimate knowledge of Stalin's terror, did not trust the government enough to go all out. Rhodes sums it up: Trust would not be a defining issue later, after the secret, the one and only secret—that the weapon worked—...

Steve Hsu is a physics prof with degrees from Harvard and Caltech, so he's got to be a smart guy, right? He writes a lot about IQ and it's genetic basis, and is evidently involved in efforts to isolate and cultivate those genetic elements, about which he blogs frequently . He is also, IMHO, a nut-job on the subject of IQ. He has, for example, expressed the opinion that genetic tinkering could produce humans with an IQ of 1000, something I think is as likely as genetic tinkering being able to produce a human who could run 100 meters in 2.0 seconds flat. Never mind that nobody has a clue as to what it means to have an IQ of 1000, or, for that matter, 210. His latest is entitled, The brute tyranny of g-loading: Lawrence Krauss and Joe Rogan, by which he implies that explaining gauge symmetry to Joe Rogan is prevented by the fact that Rogan is not smart enough to comprehend it. Now I don't know Rogan from Adam, and have no opinion on his IQ, and Hsu's post is a lot ...

The 2016 Nobel in Physics goes to (NYT): David J. Thouless, F. Duncan M. Haldane and J. Michael Kosterlitz were awarded the Nobel Prize in Physics on Tuesday for discoveries in condensed-matter physics that have transformed the understanding of matter that assumes strange shapes. All three were born in Britain but work in the United States. It might be the Nobel Committee's way of finessing the problem of exactly whom should receive the Nobel for discovery of gravitational waves. It's a tested Nobel tactic - wait until the extras die. UPDATE: Lumo has some background.

Another lovely article by Sabine Hossenfelder. Excerpt: It began after I started as a teaching assistant at the department of physics. The first note was a classic – it proved Albert Einstein wrong. The second one solved the problem of quantum mechanics by dividing several equations through zero, a feat that supposedly explained non-determinism. The next correspondent offered a Theory of Everything, and complained that the academic mainstream was ignoring his insights. I work in theoretical physics, specifically quantum gravity. In my field, we all get them: the emails from amateur physicists who are convinced that they have solved a big problem, normally without understanding the problem in the first place. Like many of my colleagues, I would reply with advice, references and lecture notes. And, like my colleagues, I noticed that the effort was futile. The gap was too large; these were people who lacked even the basic knowledge to work in the area they wanted to contribute to. With...

Sean has some more cool stuff on the LIGO accomplishment. A favorite quote: The fact that Einstein’s prediction has turned out to be right is an enormously strong testimony to the power of science in general, and physics in particular, to describe our natural world. Einstein didn’t know about black holes; he didn’t even know about lasers, although it was his work that laid the theoretical foundations for both ideas. He was working at a level of abstraction that reached as far as he could (at the time) to the fundamental basis of things, how our universe works at the deepest of levels. And his theoretical insights were sufficiently powerful and predictive that we could be confident in testing them a century later. This seemingly effortless insight that physics gives us into the behavior of the universe far away and under utterly unfamiliar conditions should never cease to be a source of wonder. The equations that Einstein wrote down predicted lasers, black holes, and gravitational ...

Lumo has an excellent post on the GR wave discovery. Highly recommended if you want some modestly technical detail. Here is a quote on the energy release: Kip Thorne has described the unbelievable power of the black hole merger differently. During the peak power, the black hole merger releases 50 times more watts in gravitational waves than all damn stars in the visible Universe combined. This is just shocking.

The detection of gravitational waves is not only a fantastic technological triumph and yet another attaboy for general relativity, but it opens up a brand new window on the universe. Gravitational waves are hard to see - so you got to be good looking - but the apparent source was really powerful, briefly radiating more power in GW than whole galaxies do in light. From Dennis Overbye's NYT article: The discovery is a great triumph for three physicists — Kip Thorne of the California Institute of Technology, Rainer Weiss of the Massachusetts Institute of Technology and Ronald Drever, formerly of Caltech and now retired in Scotland — who bet their careers on the dream of measuring the most ineffable of Einstein’s notions. I'm pretty sure Thorne's career was solid before, but he and colleagues should get the Nobel Prize pronto. Thorne is also an author of the influential textbook, Gravitation , the wonderful popular book on general relativity, Black Holes and Time Warps: E...

Via Steve Hsu: arxiv.org/pdf/1410.3831v1.pdf Claim: A deep connection between so-called deep neural networks and the renormalization group.

Leonard Susskind has published a couple of books based on his Theoretical Minimum lectures, one on classical mechanics and this one on Quantum Mechanics: The Theoretical Minimum , written with Art Friedman. I suppose I have a hundred or so books on various aspects of quantum mechanics, and I originally intended to just read through it like a novel, but guess what? It seems that I have forgotten quite a bit in the nearly half-century since I last studied QM. Anyway, I decided to read it carefully, going through every derivation and solving every problem, just like I was going to teach the book. The textbooks I learned from long ago (Gottfried, Merzbacher, Pauling and Wilson) were fairly substantial volumes, but not like the massive tomes of Cohen-Tannouji and or even Shankar. Susskind has gone to the opposite extreme, just 364 pages, with large print and a spare selection of topics. The concept is to teach just the fundamentals, and teach them in as simple and clear a fashion as p...

Kerson Huang's Fundamental Forces of Nature: The Story of Gauge Fields is one of the rare examples a semi-popular physics book with lots of equations. It tells the story of the gauge revolution and the standard model with many words and a sprinkling of equations. My own graduate work happened mostly before the gauge revolution in a department dominated by anti-field theory S-matrix people. My quantum field theory classes suffered from rather severe deficiencies in the book, the teacher, and, of course the student. Anyway, I didn't learn much. My work never used quantum field theory either. From time to time I've tried to remedy this gross deficiency in my education, and I've accumulated a considerably library of QFT books in the process, but somehow I always seem to get distracted or run out of energy before I get to renormalization - which, in any case, was mostly smoke and mirrors when I was a grad student. It's pretty hard for me to gauge (LOL) how much s...

I looked up "entanglement" in the indexes of half a dozen quantum mechanics texts I have around here. Didn't find it. The spooky quantum entanglement that so bothered Einstein doesn't feature heavily enough in any of them to make the index. Quantum Mechanics: The Theoretical Minimum isn't like that. Leonard Susskind and Art Friedman put quantum entanglement at the center of their book. For them, entanglement is the most novel and one of the most important features of quantum, as well as one that is consistently neglected in textbooks. I happened upon the book more or less by accident. I was wandering through a bookstore with one of my old graduate school office mates, arguing, as usual, about Bell's Theorem, realism in quantum mechanics, and so on. I suddenly realized that I really was a bit unclear on exactly what was meant by quantum entanglement. Since it was a bookstore and we were in the physics section, I looked around for a QM book and there w...

In Kerson Huang's book, The Fundamental Forces of Nature: The Story of Gauge Fields he notes that the principle of local gauge invariance "removes the last vestige of action at a distance from physics." The reason for this is that the job of keeping track of the field has been merged with spatial displacement via the replacement of the ordinary derivative in the Hamiltonian by a gauge covariant derivative. The notion of gauge was introduced into physics by Hermann Weyl, the distinguished mathematician, in an attempt to unify electromagnetism and general relativity. It didn't actually work out in its original version, because, as Einstein pointed out, it implied unphysical effects. As often happens, with a little reinterpretation it was quickly recognized as a key feature of electromagnetism, and with the rise of the standard model and the idea of Yang-Mills fields, the key principle for all the fundamental forces of nature. I find it mysterious but fascinating.

The world looks simpler when we confine ourselves to local interactions. We affect the world mostly by local interactions. If we want to move something, we usually need to push on it. When Newton discovered his law of universal gravitation, with its action at a distance, that conception of locality was profoundly challenged. He didn't like it, but he could discover no satisfactory hypothesis to explain it. Electricity and magnetism turned out to present similar challenges. The invention of the electromagnetic field by Faraday and Maxwell changed all that. Field strengths, and the forces they generated were now determined by the fields and charges in the local neighborhood, in effect pervading space with an ether that transmitted the forces. Einstein showed that the ether had to be Lorentz invariant and that gravity too could be localized, with the gravitational field now being determined by the matter and fields in the neighborhood. One reason this is interesting today is t...

The Lightness of Being: Mass, Ether, and the Unification of Forces by Frank Wilczek. Wilczek's book is aimed at the public, but it has a lot that I, a physicist whose experience has been distant from particle physics, found revealing and insightful. His themes are the modern version of the ether, which he calls the Grid, the origin of mass, and the unification of physics. At the center of these is the standard model, which he likes to call the Core, and especially Quantum Chromodynamics, or QCD, his contribution to which won him the Nobel Prize. It's focused squarely on the underlying ideas though there are a small number of those personal anecdotes that enliven many popular accounts of physics. His seem chosen to illustrate physics more than personality. One I liked was his account of how he baited Murray Gell-Mann (the inventor of quarks) by telling him that he was working on improving Feynman's Parton Model, which had been formulated to explain the results of prob...

Wolfgang leads us to Jester who finds a potentially disastrous uncertainty in the BICEP2 data. Jester: Barring a loose cable, the biggest worry about the BICEP signal is that the collaboration may have underestimated the galactic foreground emission. BICEP2 performed the observations at only one frequency of 150 GHz which is very well suited to study the CMB, but less so for polarized dust or synchrotron emission. As for the latter, more can be learned by going to higher frequencies, while combining maps at different frequencies allows one to separate the galactic and the CMB component. Although the patch of the sky studied by BICEP is well away from the galactic plane, the recently published 353 GHz polarized map from Planck demonstrates that there may be significant emission from these parts of the sky (in that paper the BICEP patch is conveniently masked, so one cannot draw any quantitative conclusions). Once the dust from the BICEP announcement had settled, all eyes were thus o...