tony dimauro

Most symmetries of dynamical systems have the profound consequence that some quantity in the system is conserved. This was proved by the German mathematician Emmy Noether in 1915 when she showed that a symmetry implies a conservation law, and vice versa. For example, the results of experiments do not depend on where the experiments are performed, or on the orientation of the apparatus. The consequence of these particular symmetries is that linear and angular momenta are both conserved. Similarly, the laws of physics do not depend on the time at which they are determined, a symmetry which has the consequence that energy is conserved. Furthermore, experiments are insensitive to the overall phase of quantum-mechanical wavefunctions - a property known as gauge invariance - which leads to the conservation of electric charge.

An interesting article. . .
Atoms of Space and Time
By Lee Smolin
    We perceive space and time to be continuous, but if the amazing theory of loop quantum gravity is correct, they actually come in discrete pieces
      Little more than 100 years ago most people--and most scientists--thought of matter as continuous. Although since ancient times some philosophers and scientists had speculated that if matter were broken up into small enough bits, it might turn out to be made up of very tiny atoms, few thought the existence of atoms could ever be proved. Today we have imaged individual atoms and have studied the particles that compose them. The granularity of matter is old news.
     In recent decades, physicists and mathematicians have asked if space is also made of discrete pieces. Is it continuous, as we learn in school, or is it more like a piece of cloth, woven out of individual fibers? If we could probe to size scales that were small enough, would we see "atoms" of space, irreducible pieces of volume that cannot be broken into anything smaller? And what about time: Does nature change continuously, or does the world evolve in series of very tiny steps, acting more like a digital computer?
The Quantum World
      "Do not take the lecture too seriously . . . just relax and enjoy it. I am going to tell you what nature behaves like. If you will simply admit that maybe she does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself "But how can it be like that?" because you will get...into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that." Feynman
A planet from the early universe
Ron Cowen
      Astronomers have found the oldest and most distant planet known in the universe. OLD ORB. Artist's view of the planet (top) orbiting a pulsar and its white dwarf companion (two brightest dots at lower left) in the globular cluster M4. NASA and G. Bacon/STScI Residing 7,200 light-years away, the planet weighs 2.5 times as much as Jupiter and formed when the universe was an infant.
Testing times for strings
Ignatios Antoniadi
      The "hidden" dimensions of string theory may be much larger than was previously thought and may soon come within experimental reach, together with the strings themselves. Ignatios Antoniadis gives an introduction to string physics and describes how it may soon be testable at particle colliders.
Ice at the Lunar Poles
That the Moon harbors ice at high latitudes is well known. The source of that water, however, may come as something of a surprise
Richard R. Vondrak ,Dana H. Crider
     Since the 1960s planetary scientists have considered the possibility that the Moon may harbor deposits of water ice in permanently shaded regions near the lunar poles. In 1998, the Lunar Prospector mission largely confirmed the presence of water ice on the Moon. The authors explore how that ice came to be and suggest what information the study of lunar ice cores may one day provide to scientists interested in the ancient history of the Earth-Moon system.

Taking free-electron lasers into the X-ray regime
Elke Plönjes, Josef Feldhaus and Thomas Möller
Imagine making movies of chemical reactions, watching surfaces melt in real time or taking photographs of individual molecules. These are just some of the ambitious goals that researchers have set for powerful new X-ray "free-electron lasers" that are currently being developed at the Deutsches Elektronen Synchrotron (DESY) laboratory in Hamburg and the Stanford Linear Accelerator Center (SLAC) in California.

Wilkinson Microwave Anisotropy Probe
Tests of the Big Bang
     The CMB The Big Bang theory predicts that the early universe was a very hot place and that as it expands, the gas within it cools. Thus the universe should be filled with radiation that is literally the remnant heat left over from the Big Bang, called the “cosmic microwave background radiation”, or CMB.
Antarctic bone crushers could soon be back
Warming set to return Southern Ocean to its cut-throat past.
     Global warming could threaten Antarctic sea life with a re-invasion by powerful, fast-moving predators that deserted the area 35 million years ago, researchers announced this week at a meeting in London.
     One thing that children are taught in science class is that all "stuff" is made of matter. But that's not quite true. All of the common stuff around us, from the air we breathe to the computers we surf the web with, is made of matter - but that's not everything in the universe.
In the beginning, scientists think, the big bang created both matter and antimatter. Every particle in atoms - from protons and electrons to the tinier quarks that make up those particles - has a corresponding antiparticle. Much of the original antimatter annihilated itself when it collided with ordinary matter, releasing energy. But somewhere out there lurk wandering patches of antimatter.
Dark energy tops science class
By Paul Rincon
    A series of breakthroughs in the quest to identify the mysterious fabric of the Universe has topped a list of the 10 key scientific advances of 2003.       The winning discoveries provide further evidence that the Universe is composed largely of dark matter and dark energy. The eagerly awaited top 10, which is compiled annually by the journal Science, is always controversial, and this year's proves to be no exception.
Quantum Gravity
     Gamma ray bursts -- those terrific and mysterious flashes of high-energy light now considered to be probes to the farthest reaches of the Universe and earliest moments of time -- may have yet another secret to reveal: quantum gravity. Not yet observed in nature, quantum gravity is the long-sought missing link between Einstein's General Relativity and Quantum Mechanics, the two incongruous pillars of modern physics. NASA's Gamma-Ray Large Area Space Telescope (GLAST), planned for a 2005 launch, may be able to detect for the first time the effects of quantum gravity in the speed of gamma-ray burst photons, according to two NASA scientists.
Hydrogen-fueled Cars Not Best Way To Cut Pollution
     As politicians and the public leap aboard the hydrogen fuel bandwagon, a University of California, Berkeley, energy expert suggests we all step back and take a critical look at the technology and consider simpler, cheaper options. In a paper appearing in the July 18 issue of Science magazine, Alex Farrell, assistant professor of energy and resources at UC Berkeley, and David Keith, associate professor of engineering and public policy at Carnegie Mellon University, present various short- and long-term strategies that they say would achieve the same results as switching from gasoline-powered vehicles to hydrogen cars. "Hydrogen cars are a poor short-term strategy, and it's not even clear that they are a good idea in the long term," said Farrell. "Because the prospects for hydrogen cars are so uncertain, we need to think carefully before we invest all this money and all this public effort in one area."