physics
Acme Physics
... in 1990, he came across articles written by David Hestenes, a physicist at Arizona State. Hestenes got the idea for the series when a colleague came to him with a problem. The students in his introductory physics courses were not doing well: Semester after semester, the class average never got above about 40 percent. "I noted that the reason for that was that his examination questions were mostly qualitative, requiring understanding of the concepts rather than just calculational, using formulas, which is what most of the instructors did," Hestenes says. Hestenes had a suspicion students were just memorizing the formulas and never really getting the concepts. So he and a colleague developed a test to look at students' conceptual understanding of physics. ... more »
Road Runner cartoons can easily and meaningfully be worked into the physics and physical science curriculum. Many vignettes involve fairly direct misrepresentations of specific physical principles. I developed the table below for my own use in deciding which clips to show and when. The two compilation videos are still in print as far as I know. I hope you find the information useful. (An asterisk denotes a particularly useful cartoon or vignette.) ... more »
Quasicrystal
The matter that matters is now called "Quasicrystal" in which the arrangement of atoms follows a definable mathematical pattern, but the pattern is not repeated. There are aspects of this patterning seen in the ancient concept of the "Golden Mean" as well as in medieval Islamic mosaics, which provide for a lot of analogies and pretty language in explaining what this stuff is.
"There can be no such creature" is what Shechtman wrote in his lab notebook when he first observed the patterns that do not repeat themselves using electron diffraction. ... more »Your Hand + The LHC
Time Machines
Doubt is uncomfortable, certainty is ridiculous
Researchers from the Opera experiment at the Gran Sasso Laboratory in Italy, yesterday announced that they may have spotted their first oscillating neutrino... According to Opera spokesman Antonio Ereditato, confirming the muon-to-tau oscillation rules out the sterile neutrino hypothesis. But he pointed out that this is only Opera's first observed event, with a relatively low confidence level: there is still a 2% chance that their observation is an experimental artifact. “I would bet some money on it, but neither my life nor my scientific reputation” he told Nature. Ereditato will feel much more confident once Opera, which will run until the end of 2012, has spotted another three or four tau neutrinos, he says. The event is so unlikely that scientists do not expect it to happen more than ten times during the experiment's life. more »
Only entropy comes easy
Un Chien Andalou 1929In the 1970s, Hawking and Jacob Bekenstein showed that the information stored in a black hole is proportional to its surface area rather than its volume. This encoding of three-dimensional information on a two-dimensional surface came to be called the holographic principle. In 1997, Juan Maldacena of the IAS formalized the principle, showing that the string theory description of a black hole is mathematically equivalent to a quantum field theory without gravity that describes the surface of the black hole. more »
Verlinde uses the holographic principle to consider what is happening to a small mass at a certain distance from a bigger mass, say a star or a planet. Moving the small mass a little, he shows, means changing the information content, or entropy, of a hypothetical holographic surface between both masses. This change of information is linked to a change in the energy of the system. Then, using statistics to consider all possible movements of the small mass and the energy changes involved, Verlinde finds movements toward the bigger mass are thermodynamically more likely than others. This effect can be seen as a net force pulling both masses together. Physicists call this an entropic force, as it originates in the most likely changes in information content. more »
If it smells like entropy, and it behaves like entropy, it probably is entropy. more »Everything we call real is made of things that cannot be regarded as real
The problem is that galaxies rotate so fast that the matter they contain ought to fly off into space. Similarly, clusters of galaxies do not seem to contain enough mass to bind them together and so ought to fly apart. Since this manifestly doesn't happen, some force must be holding these masses in place. Astrophysicists have put forward two explanations. The first is that these galaxies are filled with unseen mass and this so-called dark matter provides the extra gravitational tug. The second is that gravity is stronger at these intergalactic scales and so does the job by itself, an idea called modified Newtonian dynamics or MOND. more »
The Importance Of Random
There is a growing sense among physicists that all physical processes can be thought of in terms of the information they store and process; by some accounts information is the basic unit of existence in our cosmos. That kind of thinking has extraordinary implications: it means that reality is a kind of computation in which the basic processes at work simply chomp their way through a vast bedrock of information. And yet this is at odds with another of the great challenges facing modern science: understanding the nature of randomness. more »
Prior Sin
I have an opinion which is slightly heterodox, about the standard ideas in cosmology. The inflationary universe scenario, that Alan Guth really pioneered, people like Andre Linde and Paul Steinhardt really pushed very hard. This is a wonderful idea, which I suspect is right. I suspect that some part of the history of the universe is correctly explained by the idea of inflation, the idea that we start in this little tiny region that expanded and accelerated at this super-fast rate. However, I think that the way most people, including the people who invented the idea, think about inflation is wrong. They are too sanguine about the idea that inflation gets rid of all the problems that the early universe might have had. There is this feeling that inflation is like confession — that is wipes away all prior sins. I don't think that is right. We haven't explained what needs to be explained until we take seriously the question of why inflation ever started in the first place. It's actually a mistake and something wrong on the part of many of the people who buy into inflation that inflation doesn't need to answer that question because once it starts it answers all the questions that you have.
more > WHY DOES THE UNIVERSE LOOK THE WAY IT DOES? (A Conversation with Sean Carroll)Whoa, Dude
Garrett Lisi first got some attention a couple years ago with an interesting idea about unified field theory and the mathematical entity known as E8. Recently I read a book called Symmetry And The Monster about Lie Groups the creation of the Atlas, and E8. Not that well written (always saying 'and later we'll get back to that' and never do), but incredibly interesting subject. And I will never be able to do the math. Ever. But the concepts, maybe... Although it might be more like the Bohr quote If anybody says he can think about quantum physics without getting giddy, that only shows he has not understood the first thing about them.
∴ notes from ebyx
The original nomadic inhabitants of Cbyx rode Modar from one oasis to the next, beasts captured and trained as cubs. The riders developed an extremely close relationship with the animals, the bond was carried over by legendists as ancient, noble, spiritual. While horses, as large as they were in the north, were not Modar. What were written as saintly men and women of Cbyx nature, quitely and stoically enduring, became Northern horsemen, cantankerous, drunken, combative, wild. And they in turn became fable for teleplays, books, programs. Their iconography graced everything having to do with the North. Of great fascination, and State disapproval was the brief war between the horsemen and the expanding industry of the previous century. The purposing of horses for labor was anathema to the tradition of the Cbyx riders, enough so that the horsemen, who rarely organized, did so enough to cause twenty years of havok for any State loving midlander who happened into their hills.
Feb 18 4:40 a.m.
Brynja took a streetcar. She was entitled to her own automobile, but disliked the quiet resentment that the privilege caused. The streetcars here were old style, electric, clattering. She found them comforting. She wondered about a world where everyone would be allowed an auotmobile, the chaos and inefficiency. She rode with other citizens, the cold night causing them to have bundled up, warming their hands on cups of tea sold at the back. A radio next to the driver relentlessly broadcast static peppered State news.
Feb 13 3:43 a.m.
524F474552 moved carefully around the crater. It had taken days. Before the uplink was removed he’d have had telemetry. Now all robots simply talked to one another. Many had no audio, so a system of semaphore was worked out. Some used lights, some used moving parts. As he rounded a small hill he saw, in the distance, another unit. The other unit acknowledged him by raising an arm. Then it raised another. And another. Its arms began to move directionally, independently. A message. 524F474552 focused attention. “B … E … W … A … R … E”. Well, he thought, that was intriguing.
Feb 06 4:13 p.m.
∴ findings
Letters from a Stoic: Epistulae Morales Ad Lucilium
To have someone to be able to die for, someone I may follow into exile, someone for whose life I may put myself up as security and pay the price as well. The thing you describe is not friendship but a business deal, looking to the likely consequences, with advantage as its goal.
Here one may recall Jane Jacobs's important distinction between visual orderliness on one hand and functional working order on the other. The city desk of a newspaper, a rabbit's intestines, or the interior of an aircraft engine may certainly look messy, but each one reflects, sometimes brilliantly, an order related to the function it performs.
Introduction -- Eloquent JavaScript
JavaScript is the language that is, at the moment, mostly being used to do all kinds of clever and horrible things with pages on the World Wide Web.
∴ knotesy
Krautrock - The Rebirth Of Germany Feb 22 9:25 a.m.
"This Is My Home" - Unique Dwelling In East Village Feb 21 10:38 a.m.
Financial Globalization, Inequality, And The Raising Of Public Debt Feb 21 8:44 a.m.
Ptak Science Books: History of Holes series: Holes in Airships (1919 and 1937) Feb 21 4:22 a.m.
Icelandic Anger Brings Debt Forgiveness Feb 20 11:49 a.m.
