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Gerard ’t Hooft, Theoretical Physics as a Challenge

Gerard ’t Hooft, Theoretical Physics as a Challenge
by Gerard 't Hooft Note: This web site will soon be removed from its present address. An updated and renewed version is available at: This is a web site for young students - and anyone else - who are (like me) thrilled by the challenges posed by real science, and who are - like me - determined to use their brains to discover new things about the physical world that we are living in. In short, it is for all those who decided to study theoretical physics, in their own time. It so often happens that I receive mail - well-intended but totally useless - by amateur physicists who believe to have solved the world. It should be possible, these days, to collect all knowledge you need from the internet. I can tell you of my own experiences. Theoretical Physics is like a sky scraper. Note that this site NOT meant to be very pedagogical. Languages:English is a prerequisite. French, German, Spanish and Italian may be useful too, but they are not at all necessary. Return to List Algebraic equations.

Related:  Quantum Mechanics

Physics of Collective Consciousness by Attila Grandpierre Attila Grandpierre, Ph.D. Konkoly Observatory of the Hungarian Academy of Sciences H-1525 Budapest P. O. Box 67., Hungary February 6, 1996 Usenet Physics FAQ Version Date: March 2014 This list of answers to frequently asked questions in physics was created by Scott Chase in 1992. Its purpose was to provide good answers to questions that had been discussed often in the sci.physics and related Internet news groups. Pythagorean cup Cross section Cross section of a Pythagorean cup. A Pythagorean cup (also known as a Pythagoras cup, a Greedy Cup or a Tantalus cup) is a form of drinking cup that forces its user to imbibe only in moderation. Credited to Pythagoras of Samos, it allows the user to fill the cup with wine up to a certain level. If he fills the cup only to that level, the imbiber may enjoy a drink in peace.

A Double Slit Quantum Eraser Experiment A Double-Slit Quantum Eraser Experiment This web-page was created as an assignment for PHY 566, taught by Prof. Luis Orozco at Stony Brook University in the fall semester of 2002. Astronomy Interactives This site provides ranking tasks for teaching introductory astronomy. Pencil-and-paper versions as well as computer-based versions are available grouped by topic. New materials will be added as the computer-based versions are completed. Physics Simulations and Artwork Here is a 3D view of a hydrogren atom in the 4f state. The left image was made in C++ using a technique described by Krzysztof Marczak to make it volumetric like a cloud of smoke. The right image was made in Mathematica by adding 2D cross-sectional layers. The animations were made in POV-Ray using DF3 density files. The right animation shows what a "12o" orbital might look like.

News - Magnetic bacteria may help build future bio-computers 7 May 2012Last updated at 09:40 GMT Tiny magnets form inside magnetic bacteria Magnet-making bacteria may be building biological computers of the future, researchers have said. A team from the UK's University of Leeds and Japan's Tokyo University of Agriculture and Technology have used microbes that eat iron. As they ingest the iron, the microbes create tiny magnets inside themselves, similar to those in PC hard drives. quantum mechanics - Interference and which-path information So, to be clear, my understanding of your setup is that you are doing SPDC in a noncollinear geometry, so you get photons entangled in transverse momentum, and you basically want to get the momentum of one photon from the other, by studying the wall. To get interference, the momentum change must be indistinguishable in principle, not just practically. How could this happen? Well, the wall itself is also a quantum object, so if its two possible momenta from the photon are both within the uncertainty of its total momentum, it is not possible to distinguish the two cases. In the case of this setup, really what you are suggesting is a quantum eraser experiment, in a way.

8 shocking things we learned from Stephen Hawking's book From the idea that our universe is one among many, to the revelation that mathematician Pythagoras didn't actually invent the Pythagorean theorem, here are eight shocking things we learned from reading physicist Stephen Hawking's new book, "The Grand Design," written with fellow physicist Leonard Mlodinow of Caltech. The book, covering major questions about the nature and origin of the universe, was released Sept. 7 by its publisher, Bantam. 1. The past is possibility According to Hawking and Mlodinow, one consequence of the theory of quantum mechanics is that events in the past that were not directly observed did not happen in a definite way. Instead they happened in all possible ways. This is related to the probabilistic nature of matter and energy revealed by quantum mechanics: Unless forced to choose a particular state by direct interference from an outside observation, things will hover in a state of uncertainty.

Can hot water freeze faster than cold water? [Physics FAQ] - [Copyright] Written Nov, 1998 by Monwhea Jeng (Momo), Department of Physics, University of California Yes — a general explanation Bell's Theorem with Easy Math Bell's Theorem with Easy Math By David R. Schneider IntroductionAuthor's note: This article is based on Bell's Theorem (2). I have reformulated the presentation to make it a little easier to follow if your math skills are a little rusty.

'Schrödinger's hat' could spy on quantum particles An international team of physicists has proposed a new device that could detect the presence of waves or particles while barely disturbing them. Called a "Schrödinger's hat", the device has not yet been built in the lab but the team believes that it could someday be used as a new type of sensor for quantum-information systems. In the microscopic world of quantum mechanics, direct observation of the property of a particle – the position of an electron, for example – causes the collapse of the particle's wavefunction. The result is that the particle that you set out to measure has been changed in a significant way.

Atomic-scale magnetic memory The world's smallest bit Scientists from IBM Research have been investigating and controlling matter on an atomic scale for decades. So, naturally, their latest quest would involve greatly decreasing the storage capacity needed for one bit of data, which on today's computers stands at about 1 million atoms. They set out to develop the ultimate memory chips of the future. Starting at the very beginning of density—single atoms—they created the world’s smallest magnetic memory bit and answered the question of how many atoms it takes to reliably store one bit of magnetic information at a low temperature: 12. By studying the behavior of atoms, researchers can identify crucial factors for building smaller, faster and more energy-efficient devices for business and consumers.

Entangled In the Past: “Experimental delayed-choice entanglement swapping” – Uncertain Principles Enough slagging of beloved popularizers– how about some hard-core physics. The second of three extremely cool papers published last week is this Nature Physics paper from the Zeilinger group in Vienna, producers of many awesome papers about quantum mechanics. Ordinarily, this would be a hard paper to write up, becase Nature Physics are utter bastards, but happily, it’s freely available on the arxiv, and all comments and figures are based on that version. You’re just obsessed with Zeilinger, aren’t you?