Gravitational lens A light source passes behind a gravitational lens (point mass placed in the center of the image). The aqua circle is the light source as it would be seen if there was no lens, white spots are the multiple images (or Einstein ring) of the source. A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's general theory of relativity. (Classical physics also predicts the bending of light, but only half that predicted by general relativity.) Although Einstein made unpublished calculations on the subject in 1912, Orest Khvolson (1924) and Frantisek Link (1936) are generally credited with being the first to discuss the effect in print. Description 1. 2. 3. History Notes
Accelerators The Large Hadron Collider is latest member of CERN's collection of extraordinary high-energy facilities and is the world's largest and highest-energy accelerator. It occupies a 27 kilometer circumference circular tunnel near Geneva which overlaps the Swiss-French border, the same tunnel that contains the LEP. Successful particle beams were produced in the LHC in 2008 and in 2010 the two beams reached 3.5 TeV, half the target maximum for the accelerator. Currently the work at the LHC is divided into six experiments denoted by the names ATLAS, CMS, ALICE, LHCb, TOTEM and LHCf. A major current objective for the LHC is the search for the Higgs boson. Though a small difference, it is a newly discovered difference between matter and antimatter and could contribute to the solution of the "antimatter problem" in cosmology. References: CERN Home CERN Document Server Wiki Large Hadron Collider
Not Even Wrong Graham Farmelo has posted a very interesting interview he did with Witten last year, as part of his promotion of his forthcoming book The Universe Speaks in Numbers. One surprising thing I learned from the interview is that Witten learned Calculus when he was 11 (this would have been 1962). He quite liked that, but then lost interest in math for many years, since no one gave him more advanced material to study. After years of studying non math/physics subjects and doing things like working on the 1972 McGovern campaign, he finally realized physics and math were where his talents lay. He ended up doing a Ph.D. at Princeton with David Gross, starting work with him just months after the huge breakthrough of asymptotic freedom, which put in place the final main piece of the Standard Model. If only back in 1962 someone had told Witten about linear algebra and quantum mechanics, the entire history of the subject could have been quite different. About the landscape:
arXiv.org e-Print archive National Geographic Magazine Gravitational microlensing Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects ranging from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit lots of light (stars) or large objects that block background light (clouds of gas and dust). These objects make up only a tiny fraction of the mass of a galaxy. Microlensing allows the study of objects that emit little or no light. When a distant star or quasar gets sufficiently aligned with a massive compact foreground object, the bending of light due to its gravitational field, as discussed by Einstein in 1915, leads to two distorted unresolved images resulting in an observable magnification. Since microlensing observations do not rely on radiation received from the lens object, this effect therefore allows astronomers to study massive objects no matter how faint. How it works History . . . . .
Pacific Northwest National Laboratory Interactions.org 579 - A 1939 Map of Physics | Strange Maps Geography was my favourite subject in school; physics the one I disliked the most. If only I’d known about this Map of Physics! This spatial representation of the subject, dating from 1939, defines itself as Being a map of physics, containing a brief historical outline of the subject as will be of interest to physicists, students, laymen at large; Also giving a description of the land of physics as seen by the daring sould who venture there; And more particularly the location of villages (named after pioneer physicists) as found by the many rivers; Also the date of founding of each village; As well as the date of its extinction; and finally a collection of various and sundry symbols frequently met with on the trip. Perhaps, by representing physics as a continent and its main branches as rivers, it would have made that vast, mysterious subject more graspable to a mind more attuned to geography. Sounds like we need a new map!
Victorian Infographics A time table indicating the difference in time between the principal cities of the World and also showing their air-line distance from Washington. IN: 'Mitchell's New General Atlas, Containing Maps Of The Various Countries Of The World, Plans Of Cities, Etc., Embraced In Ninety-Three Quarto Maps, Forming A Series Of One Hundred and Forty-seven Maps and Plans, Together With Valuable Statistical Tables..' by Samuel Augustus Mitchell Jr, 1883; published in Philadelphia by WM Bradley. Tableau d'Astronomie et de Sphère IN: 'Atlas Universel d'Histoire et de Geographie Anciennes et Modernes, de Mythologie, des Religions, d'Astronomie, de Physique, de Geologie, de Histoire Naturelle, de Grammaire, de Rhetorique..' by Henri Duval, 1834; published in Paris by L Houbloup. Tableau d'Astronomie et de Sphère [detail] The Solar System. IN: 'General Atlas Of The World: Containing Upwards Of Seventy Maps. Northern Celestial Hemisphere. IN: 'General Atlas Of The World: Containing Upwards Of Seventy Maps...
Physics World reveals its top 10 breakthroughs for 2011 The two physics stories that dominated the news in 2011 were questions rather than solid scientific results, namely "Do neutrinos travel faster than light?" and "Has the Higgs boson been found?". However, there have also been some fantastic bona fide research discoveries over the last 12 months, which made it difficult to decide on the Physics World 2011 Breakthrough of the Year. But after much debate among the Physics World editorial team, this year's honour goes to Aephraim Steinberg and colleagues from the University of Toronto in Canada for their experimental work on the fundamentals of quantum mechanics. Using an emerging technique called "weak measurement", the team is the first to track the average paths of single photons passing through a Young's double-slit experiment – something that Steinberg says physicists had been "brainwashed" into thinking is impossible. We have also awarded nine runners-up (see below). 1st place: Shifting the morals of quantum measurement
News in Brief: Particle caught flip-flopping | Physics A particle with an identity crisis could provide the next big discovery at the world's largest particle accelerator. The D meson has been caught in the act of flipping between matter and antimatter, researchers report online March 5 in Physical Review Letters. D mesons, like other mesons, are short-lived particles that emerge from the shrapnel of proton collisions at CERN’s Large Hadron Collider outside Geneva. The next step, says Syracuse University physicist Steve Blusk, one of about 600 members of the team that made the discovery, is to compare the number of D meson decays with the number of anti-D meson decays.