Margaret Wertheim – The limits of physics Theoretical physics is beset by a paradox that remains as mysterious today as it was a century ago: at the subatomic level things are simultaneously particles and waves. Like the duck-rabbit illusion first described in 1899 by the Polish-born American psychologist Joseph Jastrow, subatomic reality appears to us as two different categories of being. But there is another paradox in play. Physics itself is riven by the competing frameworks of quantum theory and general relativity, whose differing descriptions of our world eerily mirror the wave-particle tension. When it comes to the very big and the extremely small, physical reality appears to be not one thing, but two. Physicists are deeply aware of the schizophrenic nature of their science and long to find a synthesis, or unification. In string cosmology, the totality of existing universes exceeds the number of particles in our universe by more than 400 orders of magnitude Stop for a moment and take a look around you.
Grand Orbital Table by Manthey Grand Orbital Table All atomic orbitals with n<=10 are presented here. Note that the orbitals with negative m are identical to those with the same magnitude positive m value except for a rotation,and are not shown separately. The orbitals are presented in six different ways, n and l versus m, n and m versus l, l and m versus n, n-l and l-m versus m, n-l and m versus l-m, and l-m and m versus n-l. The later three are grouped more by shape than by quantum number. n and l versus m Return to top of page. n and m versus l l and m versus n n-l and l-m versus m n-l and m versus l-m l-m and m versus n-l Return to Atomic Orbitals or the Site Map.
The Strong Force for Beginners “I found I could say things with color and shapes that I couldn’t say any other way — things I had no words for.” –Georgia O’Keeffe When it comes to the Universe, it isn’t just the stuff that’s in it that’s important. Image credit: 2MASS Extended Source Catalog (XSC). It’s also how all that stuff interacts with itself and everything else. Image credit: Stichting Maharishi University of Management, the Netherlands. Some of them are familiar, like gravitation. Image credit: Mark Garlick / SPL. There’s no “anti-mass” or “anti-energy” that causes some objects to be gravitationally repelled while others are gravitationally attracted. But other forces and interactions can be more complicated than gravity in this regard. Image credit: copyright 2012. Instead of one type of charge where like-attracts-like, we have two types of electric charge: positive and negative, where like charges repel and unlike charges attract. Image credit: Science Photo Library. Related
The Everett Interpretation This FAQ shows how quantum paradoxes are resolved by the "many-worlds" interpretation or metatheory of quantum mechanics. This FAQ does not seek to that the many-worlds interpretation is the "correct" quantum metatheory, merely to correct some of the common errors and misinformation on the subject floating around. As a physics undergraduate I was struck by the misconceptions of my tutors about many-worlds, despite that it seemed to resolve all the paradoxes of quantum theory . The objections raised to many-worlds were either patently misguided or beyond my ability to assess at the time , which made me suspect (confirmed during my graduate QFT studies) that the more sophisticated rebuttals were also invalid. I have attempted, in the answers, to translate the precise mathematics of quantum theory into woolly and ambiguous English - I would appreciate any corrections. See "Does the EPR experiment prohibit locality?" eg "In quantum field theory the wavefunction becomes an operator".
New Theory Suggests Universe Could Ctrl-Alt-Delete Itself Life Get short URL It's certainly a grim thought to get your head around, but beyond mere scientific scaremongering, the theory does encourage serious debate among experts. This relates to the Higgs Field theory, also referred to as Higgs Boson, which is thought to permeate the entire universe. "Based on what we know about the Higgs Boson today, we cannot accurately tell whether our vacuum is stable (permanent) or metastable (temporary, albeit long-lived). Described as "the ultimate ecological catastrophe: if it were to occur, in layman's terms it would basically mean we could be here one second and then completely wiped out the next — and we wouldn't even see it coming. Could this theory relate to the demise of the dinosaurs? But the good news, and there is good news… the theory is very much just a theory. Much like the theory of robots and artificial intelligence turning sentinel, or the Simulation Hypothesis that we are all living in some kind of complex computer matrix.
Introduction to quantum mechanics Many aspects of quantum mechanics are counterintuitive and can seem paradoxical, because they describe behavior quite different from that seen at larger length scales. In the words of quantum physicist Richard Feynman, quantum mechanics deals with "nature as She is – absurd". For example, the uncertainty principle of quantum mechanics means that the more closely one pins down one measurement (such as the position of a particle), the less accurate another measurement pertaining to the same particle (such as its momentum) must become. The first quantum theory: Max Planck and black-body radiation Hot metalwork. Thermal radiation is electromagnetic radiation emitted from the surface of an object due to the object's internal energy. Heating it further causes the colour to change from red to yellow, white, and blue, as it emits light at increasingly shorter wavelengths (higher frequencies). Predictions of the amount of thermal radiation of different frequencies emitted by a body.
Quantum mysteries John Gribbin For seventy years, physicists have worried about what quantum mechanics means. They can use quantum physics, to be sure; witness the successful designs of lasers and computer microchips, and the understanding of molecules that makes genetic engineering possible. In fact, few physicists worry about such things. The archetypal example of the quantum mysteries is the "experiment with two holes", where the measured position of a single electron that passes through two holes in a screen can only be explained in terms of the wave function travelling through both holes at once and interfering with itself. Imagine that we have a source which will emit a single quantum particle in a random direction (ordinary radioactive nuclei do exactly this, so there is nothing special about the source). So far, simple enough. But a giant leap in what might be called quantum philosophy has recently been taken by the American physicist John Cramer. It works like this.
Physics for the 21st Century Course Overview Welcome to Physics for the 21st Century: an on-line course that explores the frontiers of physics. The 11 units, accompanied by videos, interactive simulations, and a comprehensive Facilitator's Guide, work together to present an overview of key areas of rapidly-advancing knowledge in the field, arranged from the sub-atomic scale to the cosmological. About This Course | Using This Site
Northern Light Show Visits South Nature put on one of her most spectacular shows last night when the "aurora^ borealis-northern lights . Reproduced with permission of the copyright owner. Further reproduction or distribution is prohibited without permission. David Tong: Quantum Field Theory These lecture notes are based on an introductory course on quantum field theory, aimed at Part III (i.e. masters level) students. The full set of lecture notes can be downloaded here, together with videos of the course when it was repeated at the Perimeter Institute. Individual sections can be downloaded below. PostScript PDF Videos 0. Philip Tanedo, who took this course long ago, has put together a useful literature review of quantum field theory textbooks. The late Sidney Coleman taught the quantum field theory course at Harvard for many years, influencing a generation of physicists in the way they view and teach QFT. Part 1 Part 2 These notes were subsequently latexed and posted on the arXiv. Another, older legendary QFT course was given in 1951 by Freeman Dyson.
The Transactional Interpretation of Quantum Mechanics John G. Cramer This paper was originally published in Reviews of Modern Physics 58, 647-688, July (1986). It is copyrighted (©1986) by John G. See also "Generalized absorber theory and the Einstein-Podolsky-Rosen paradox", published in Physical Review D 22, 362-376 (1980), "An Overview of the Transactional Interpretation of Quantum Mechanics", published in the International Journal of Theoretical Physics 27, 227 (1988), and "Velocity Reversal and the Arrow of Time", published in Foundations of Physics 18, 1205 (1988). Note: Some browsers seem to fail in printing this paper from the HTML files. The interpretational problems of quantum mechanics are considered. Table of Contents Continue to Section 1.0 This page was created by John G.