**
About physics - information about physical properties, particles and forces
Physics is the sicence about the basic building blocks in the nature, the elementary particles. It is also the science of the most basic properties of matter. Such properties are mass, charge momentum, and elementary particles properties called charm, color and spin.
It is also the science about the forces in the nature and the laws gowerning their behaviour. These forces work on both the cosmological level, the everyday macroscopic level, the microscopic level and the elementary particle level.
A force is actually an event that leads to the exchange of energy between two particles, so that one of them loose velocity and the other gain velocity. Forces in the opposite direction can however work against each other so that the net energy exchange dimminishes or is zero.
The forces are of many kinds, for example gravity, electromagnetic force, strong force and weak force. In dayly life only electromagnetic forces and garvity are directly observed. The other forces belong to the elementary particle world only because they only work over a short distance.
A certain force can only work between tho objects if the objects have the same special kind of propery. Mass makes it possible for two objects to attract each other with gravity. Electric charge is necessary for electromagnetic force. Some forces exist in two or theree variants, for example exists the electromagnetic charge as negative and positive charges. The chrarge of particles interacting determines the direction of the force. The same charge effect repulsing force, opposite charges result in attracting force.
These forces are basically the same at all the size levels, but certain aspects of them have most impact on the cosmological level and high energy level and certain of them have most impact on very small scales.
It is very impractical to take concideration of all the aspects every time you have to compute some force and their result, and one has not yet managed to develop any theory that take into concideration all aspects simultanously. Therefore one usually applies theories that only take into concideration the most important aspects.
On very large scales, great velocities and on very great anergy levels one uses the theory of relativity. On everyday calculations one uses Newtonian physics that is the most simple of them. On the elementary particle level quantum mechanics is the theory used.
The theory of relativity takes into concideration the relativistic aspects. These tell that such things as length, time and mass appear to change when the velocity of an observed object is very great. Length contracts according to the measures, time slows and the mass increases and goes to infinity when the velocity approches the velocity of light. Therefore no object can reach or exceed the velocity of light according to the standard theory of relativity.
Quantum mechanic tells that the movement of particles cannot be predicted exactly, because the particles move somewhat unpredictably. But you can use functions to predict the chance of a particle being at a place at a given time. The distribution of the location chances often have a wave-like pattern, and hence the functions are called wave functions.
When a particle interacts with another particle or its location is measured, the particle appears at a specific spot.
Also the development of other properties in a particle or a system of particles exhibit this statistical behavior.
Because particles move in a wave-like pattern, the movements also exhibit wave-like properties like interference.
Also it is impossible to measure all things regarding a particle exactly at the same time, because the apparatus you use to measure position, momentum, energy and other properties also behaves somewhat unpredictably. You can however set up observations so that one property is measured exactly, but that will blurr out observations of other properties.
Also the forces between particles exhibit a statistical property. There is at any given time a chance for an interaction to occur, but it may not occur. However, if it occurs, the interaction takes place in form of lumps of exchanged energy and other properties. One or more lumps can be exchanged, but these lumps, called quanta, cannnot be divided.
This statistic behaviour is however mostly observed at the elementary particle level. At greater levels, the chances of the results from all the elementary particle the object consists of sums to a nearly certainty of observing a force with a certain strength and observing the object at one particular place.
When the situation gradually changes from those where relativistic and quantum effects are easily found to the scales observed at everyday situations, the results calculated from the theory of relativity and quantum mechanics gradually appoach the results one can obtain from Newtonian mechanics.
**

**
String Theory - What is That
String theory is a theory within physics which is under development and which aims at explaining all forces and particles of nature from more basic principles.
Currently one uses two traditional theories which are not 100% correct, but which work well within great but differnt areas. One is the standard theory wich is based on quantum mechanical principles and that can explain the electromagnetic force, the weak force and the strong force. This theory works very well for very small objects and small distances, but the theory is very clumpsy with several constants that are set by measurement, and not by the theory itself.
The other is the general theory of relativity that can explain the gravitational force, and the differences measured in length, time, velocity and mass for the same object when one changes from one referance frame to another. This theory works best when the masses and distances are great.
String theory and a more developed version of it, M-theory, is based on the principles of quantum mechanics and relativity and can explain all forces, all particles and most constants based on more fundamental notions.
String theory, is based on an axiom that there are more than 3 spatial dimmentions, and hence more that 3 directions that stand in a right angle at each other, actually 10 in the current version of M-theory which is described in the following.
Objects or particles can have a shape of all from 0 to 10 dimmentions. These are called N-branes where N is the number of dimmentions the object have. Branes can also be of any sizes from that of tiny elementary particles to the size of an universe. A 2-brane is also called a string.
Our universe is an enormous 3-dimmentional object, a so-called 3-brane or word-brane, that is placed in an even greater super-universe with more that 3 dimmentions, and with possibly many more universes formed as branes. In that super-universe there are possibly also other 3-dimmentional universes.
Many of the dimmentions are however shrunken to tiny bubles around the particles, but that can happen in many ways, so that the boubles get different shapes and are wrapped around each other in different ways.
Ordinary particles, like electrones, photons and quarks are actually strings with to dimmentions. Some of these have free ends, while others are formed as rings.
The strings can vibrate in several ways, and they can be oriented in several ways inside the shrunken dimmentions that are wrapped around them. All these possibilities of vibration and orientation of a string gives it different combination of properties, and actually the same properties that the differnt known particles have, like electrical charge, spin, charm, colors, mass, energy, boson and fermion properties and the like.
In modern quantum mechanics, forces are explained as emission of particles called bosons, having integer spin, from one particle, and caching of that boson by another particle, so that the energy and other properties in the boson is transfered between the two particles. The different vibrations and orientations also explain the bosons of various kind and thus the various kind of forces.
The strings which have free ends are all glued to a 3-dimmentional universe object or word-brane. They can move freely withing that word-brane, but can only stick out a tiny bit into a higher dimmention.
Ring-formes strings may possibly move out of the word-brane and transverse the superspace over to another word-brane. Gravitons that transfere the gravitational forse is thought to act that way. In this way our universe and other universes may interfere with each other by gravitation. This may explain why the gravitational force is felt so weak and possibly also the hidden mass acting in our universe.
The shrinking of many dimmentions and the confinement to the 3-dimmentional word-brane is the cause that our world looks 3-dimmentional to us.
The M-theory is not any complete work yet. There are several things it has to explain in a credible way. For example has it to explain how the different big objects of various doimmentions do not usually get in the way for each other and disturbe each other. If there really are several universes, they also must be alligned parallelly within the higher dimmentions so that they usually do not collide or otherways disturbe, at least not greatly.
If gravitons are leaking over to other parallel universes, the space between our universe and the next porallel universes must be very even at any point so that the force of gravitation is the same all places where we can measure it, and the distance must be very neatly fit, so that the gravitaion has is felt with a practically useful strength for galaxes, solor systems and planets to evolve
**

**
Physics kit for hobby and eductation
**

This textbook provides a complete course in quantum mechanics for students of semiconductor device physics and electrical engineering. It provides the necessary background to quantum theory for those starting work on micro- and nanoelectronic structures and is particularly useful for those going on to work with semiconductors and lasers. This bookintroduces the main concepts of quantum mechanics which are important in everyday solid-state physics and electronics. Each topic includes examples which have been carefully chosen to draw upon relevant experimental research. It also includes problems with solutions to test understanding of theory. For the second edition significant new material has been added to each chapter, providing updated connections with relevant experiments and device concepts. New references and new problems are included. |

Suitable for advanced undergraduates, this thorough text focuses on the role of symmetry operations and the essentially algebraic structure of quantum-mechanical theory. Based on courses in quantum mechanics taught by the authors, the treatment provides numerous problems that require applications of theory and serve to supplement the textual material. Starting with a historical introduction to the origins of quantum theory, the book advances to discussions of the foundations of wave mechanics, wave packets and the uncertainty principle, and an examination of the Schrdinger equation that includes a selection of one-dimensional problems. Subsequent topics include operators and eigenfunctions, scattering theory, matrix mechanics, angular momentum and spin, and perturbation theory. The text concludes with a brief treatment of identical particles and a helpful Appendix. |

Acclaimed as "excellent" ( Nature ) and "very original and refreshing" ( Physics Today ), this collection of self-contained studies is geared toward advanced undergraduates and graduate students. Its broad selection of topics includes the Mssbauer effect, many-body quantum mechanics, scattering theory, Feynman diagrams, and relativistic quantum mechanics. Author Harry J. Lipkin, a well-known teacher at Israel's Weizmann Institute, takes an unusual approach by introducing many interesting physical problems and mathematical techniques at a much earlier point than in conventional texts. This method enables students to observe the physical implications and useful applications of quantum theory before mastering the formalism in detail, and it provides them with new mathematical tools at an earlier stage for use in subsequent problems. |

This edition has been completely revised to include some 20% of new material. Important recent developments such as the theory of Regge poles are now included. Many problems with solutions have been added to those already contained in the book. |

Quantum electrodynamics is an essential building block and an integral part of the gauge theory of unified electromagnetic, weak, and strong interactions, the so-called standard model. Its failure or breakdown at some level would have a most profound impact on the theoretical foundations of elementary particle physics as a whole. Thus the validity of QED has been the subject of intense experimental tests over more than 40 years of its history. This volume presents an up-to-date review of high precision experimental tests of QED together with comprehensive discussion of required theoretical work. |

Sponsored by Bundesministerium fr Unterricht, Bundesministerium fr Handel und Wiederaufbau, Steiermrkische Landesregierung and the International Atomic Energy Agency |

Quantum Electrodynamics focuses on the formulation of quantum electrodynamics (QED) in its most general and most abstract form: relativistic quantum field theory. It describes QED as a program, rather than a closed theory, that rests on the theory of the quantum Maxwellian field interacting with given (external) classical sources of radiation and on the relativistic quantum mechanics of electrons interacting with a given (external) classical electromagnetic field. |

A clear, plain-English guide to this complex scientific theory String theory is the hottest topic in physics right now, with books on the subject (pro and con) flying out of the stores. String Theory For Dummies offers an accessible introduction to this highly mathematical "theory of everything," which posits ten or more dimensions in an attempt to explain the basic nature of matter and energy. Written for both students and people interested in science, this guide explains concepts, discusses the string theory's hypotheses and predictions, and presents the math in an approachable manner. It features in-depth examples and an easy-to-understand style so that readers can understand this controversial, cutting-edge theory. |

Proceedings of the NATO Advanced Study Institute, Cargse, France, May 24-June 5, 1999 |

**
Places where you can find scientific items for hobby and education and other exciting hobby products
**

**
Trendtime Toys - science kits, RC models and other hobby items
- This is a general hobby
store where you can find chemistry kits and other science kits among other types
of hobby items - physics kits, mechanics kits, biology kits, electronic sets.
You can also find RC models of all types and airsoft guns in this store. The
store has hobby products for all age groups, from small kids to adult persons.
HobbyTron - a general hobby store for science kits, modelling, electroncis and
much more -
Hobbytron is a general hobby store where
you can find chemistry sets, physics sets, electronic sets, science kits, RC
models and airsoft guns. It is exceptionally well equipped in the fileds
elctronic building kits and electronic components.
**

**
Imaginova a dedicated shop for hobby science
- All types of hobby science equipment: Chemistry, atronomy, biology, meteorology,
electronics, computing, automatation, physics and more.
**