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Maximum Minimum

The search for particles was perhaps one of the most intense quests for physicists during the 20th century. But the rewards are great: we may eventually understand how matter was created, and how the universe was born.

Posted by Tormod Guldvog
13 September, 2001 04:09:00

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When Albert Einstein published his Theory of General Relativity on 1915, it was widely believed that the proton and the electron, the main constituents of the atom, were the fundamental particles of which all matter was created. With the discovery that light consists of finite "packets" of energy, scientists began to realize that the proton consisted of yet smaller forces.

The primary search resulted in what was later termed "quarks" by Murray Gell-Mann in 1964. These tiny structures where believed to be objects without mass, but with an electromagnetic charge which would bind several of them together to form a proton. In effect, a quark is energy in the form of matter, which could explain how all matter is created from energy.

As soon as the proton barrier had been crossed, a waterfall occurred. Scientists continued to find new fundamental particles all the time. In the 50s, 60s, and 70s, a standard model for quantum physics was developed, in which the particles were grouped and ordered. Huge particle smashers were built to find out which particles a proton or an electron decayed into when they were torn apart. Eventually a standard model for quantum mechanies was created, which included sets of baryons (quarks and leptons) which are the matter consituents, and bosons, which are force carriers.

With a standard model so big, scientists have realized that there must be an even smaller, underlying force which can explain how these particles are created. This would in fact be a kind of Grand Unified Theory - a theory which would unite all forces, as well as the convertion of matter into energy. But the standard model is not yet complete, although one of the last predicted particles has recently been found (the Higgs particle).

This week's hypography consists of links to research institutions, articles, results, graphs and websites which give some background information on the search for particles.

Related Links

A NEW FORM OF MATTER: Bose-Einstein Condensation and the Atom Laser
http://online.itp.ucsb.edu/online/plecture/ketterle/
Bose-Einstein condensed atoms are a novel form of matter which consists of a giant matter wave. They are produced by cooling a dilute atomic gas to the lowest temperatures ever achieved. Professor Wolfgang Ketterle (MIT) will describe how matter is manipulated and observed at such low temperatures, and how Bose condensates were used to realize an atom laser.

What is matter made of?
http://public.web.cern.ch/Public/SCIENCE/Whatismatter.html
An easy-to-grasp introduction to particle physics by CERN, the European Organization for Particle Physics.

Encarta: Quark
http://encarta.msn.com/encyclopedia_761576347/Quark.html
A thorough reference entry on quarks, with history and relevant people

Encarta: Ernest Rutherford
http://encarta.msn.com/find/Concise.asp?ti=069AB000
Encarta has a biography of Ernest Rutherford, who received the Nobel price for developing the first model of the atom.

Nuclear Physics: Past, Present and Future
http://library.thinkquest.org/3471/
A great website from ThinkQuest, with lots of texts and illustrations on nuclear particles and how they are found.

Visualization of Quarks and Gluons
http://www.physics.adelaide.edu.au/cssm/lattice/index.html
This page has some nifty animations which show how quarks and gluons fluctuate.

Quarks and the Scale of Things
http://pdg.lbl.gov/atlas/physics4.html
A simple comparison chart showing how small the quark really is.

Fireballs of Free Quarks
http://www.sciam.com/2000/0400issue/0400scicit1.html
A Scientific American report on quark-gluon plasma, which existed only a few moments after the Big Bang.

Leaping Leptoquarks!
http://www.sciam.com/explorations/032497lepto/032497horgan.html
A Scientific American special feature on a new quark called the "leptoquark".

The Discovery of the Top Quark
http://www.sciam.com/0997issue/0997tipton.html
A Scientific American feature article on how scientists found the sisxth quark.

CERN physicists get an extra month to hunt for the most prized particle
http://www.newscientist.com/dailynews/news.jsp?id=ns225674
Article in New Scientist.

Caltech Particle Theory
http://www.theory.caltech.edu/
Caltech conducts research in superstring theory, quantum gravity, quantum field theory, cosmology, and particle phenomenology.

Experimental Particle Physics
http://ppewww.ph.gla.ac.uk/
The Particle Physics Experimental (PPE) Group in the Department of Physics and Astronomy at the University Of Glasgow.

Life, the Universe, and the Electron
http://www.ioppublishing.com/Physics/Electron/Exhibition/
An exhibition about the electron, with lots of interesting information with illustrations.

The Standard Model of Fundamental Particles and Interactions
http://www.cpepweb.org/cpep_sm_large.html
An illustration of the standard model.

Particle Phyisics in the UK
http://hepweb.rl.ac.uk/ppUK/
A website with history, resources and links to relevant information on particle physics.

A journey through special relativity
http://www.fourmilab.ch/cship/cship.html
Fourmilab has created a virtual journey through matter at the speed of light!

The Particle Adventure
http://particleadventure.org/
The Particle Adventure is an award-winning site that introduces the theory of fundamental particles and forces, called the Standard Model.

The Equivalence of Mass and Energy
http://library.thinkquest.org/3471/energy_mass_equivalence.html
ThinkQuest has a page which shows how Einstein derived his famous equation e=mc2.