| Looping eruptions on the Sun, like this one on July 24, 1999, create antimatter.Earth is shown for size comparison.Researchers at NASA's Marshall Space Flight Center developed this sketch of a hypothetical antimatter rocket of the future.Antimatter_sun Antimatter sounds like the stuff of science fiction, and it is.Antimatter is created and annihilated in stars every day."Antimatter is around us each day, although there isn't very much of it," says Gerald Share of the Naval Research Laboratory.Simply put, antimatter is a fundamental particle of regular matter with its electrical charge reversed.The common proton has an antimatter counterpart called the antiproton.It has the same mass but an opposite charge.The electron's counterpart is called a positron.This makes its nucleus unstable, and a positron is emitted to stabilize the situation.But positrons don't last long.When they hit an electron, they annihilate and produce energy."So the cycle is complete, and for this reason there is so little antimatter around at a given time," Share said.The antimatter warsTo better understand the elusive nature of antimatter, we must back up to the beginning of time.In the first seconds after the Big Bang, there was no matter, scientists suspect.As the universe expanded and cooled, particles of regular matter and antimatter were formed in almost equal amounts.That was all the edge needed for regular matter to win the longest running war in the cosmos."When the matter and antimatter came into contact they annihilated, and only the residual amount of matter was left to form our current universe," Share says.Antimatter was first theorized based on work done in 1928 by the physicist Paul Dirac.Potential powerAntimatter has tremendous energy potential, if it could ever be harnessed.That's enough to power the United States for two days.Antimatter didnt get a bad name, but it sunk into the collective consciousness as a purely fictional concept.Given some remarkable physics breakthrough, antimatter could in theory power a spacecraft.But NASA researchers say it's nothing that will happen in the foreseeable future.Meanwhile, antimatter has proved vitally useful for medical purposes.The fleeting particles of antimatter are also created by the decay of radioactive material, which can be injected into a patient in order to perform Positron Emission Tomography, or PET scan of the brain.Here's what happens: A positron that's produced by decay almost immediately finds an electron and annihilates into two gamma rays, Share explains.Sun's atmosphere, producing antimatter.If that were the case, the density would cause the antimatter to annihilate almost immediately.Share's team examined gamma rays emitted by antimatter annihilation, as observed by NASA's RHESSI spacecraft in work led by Robert Lin of the University of California, Berkeley.The research suggests the antimatter perhaps shuffles around, being created in one spot and destroyed in another, contrary to what scientists expect for the ephemeral particles.But the results are unclear.They could also mean antimatter is created in regions where extremely high temperatures make the particle density 1,000 times lower than what scientists expected was conducive to the process.Details of the work will be published in Astrophysical Journal Letters on Oct.Unknowns remainThough scientists like to see antimatter as a natural thing, much about it remains highly mysterious."We cannot rule out the possibility that some antimatter star or galaxy exists somewhere," Share says."Generally it would look the same as a matter star or galaxy to most of our instruments."Theory argues that antimatter would behave identical to regular matter gravitationally."However, there must be some boundary where antimatter atoms from the antimatter galaxies or stars will come into contact with normal atoms," Share notes."When that happens a large amount of energy in the form of gamma rays would be produced.This article is part of SPACE.This antielectron would be expected to have the same mass as the electron, but opposite electric charge and magnetic moment.One particle made a track like an electron, but the curvature of its path in the magnetic field showed that it was positively charged.This result gave credibility to the idea that for every particle there is a corresponding antiparticle.For example, when an electron and a positron annihilate at rest, two gamma rays, each with energy 511 keV, are produced.These gamma rays go off in opposite directions because both energy and momentum must be conserved.The annihilation of positrons and electrons is the basis of Positron Emission Tomography (PET) discussed in the section on Applications (Chapter 14).When a proton and an antiproton annihilate at rest, other particles are usually produced, but the total kinetic plus rest mass energies of these products adds up to twice the rest mass energy of the proton (2 x 938 MeV).Antimatter is also produced in some radioactive decays.When 19Ne decays, a proton decays to a neutron plus a positron, e+, and an electron neutrino, .An antilepton is an antiparticle.In each reaction, one lepton and one antilepton is produced.Although from a distance matter and antimatter would look essentially identical, there appears to be very little antimatter in our universe.This conclusion is partly based on the low observed abundance of antimatter in the cosmic rays, which are particles that constantly rain down on us from outer space.All of the antimatter present in the cosmic rays can be accounted for by radioactive decays or by nuclear reactions involving ordinary matter like those described above.As a result, we believe that essentially all of the objects we see in the universe are made of matter not antimatter.Stanford Linear Accelerator and at the LEP facility at CERN.Physicists are now searching for very small differences between the properties of matter atoms and antimatter atoms.What is the future of space travel?Engineering, stand by for warp drive.It just hasn't been achieved yet.Photo courtesy NASA
Antimatter spacecraft like this one could some day shorten a trip to Mars from 11 months to one month.See more pictures of antimatter spacecraft.In the Pinto, you'll eventually get to the finish line, but it will take 10 times longer than in the Indy car.In this edition of How Stuff Will Work, we will peer a few decades into the future of space travel to look at an antimatter spacecraft, and find out what antimatter actually is and how it will be used for an advanced propulsion system.Article Page Tools : DELICIOUS : Click')); window."How Antimatter Spacecraft Will Work".For Mac Firefox we have to add this kludge to prevent our scrollbar from
bleeding through to the other layers of the TabBox.How could Antimatter Destroy Earth?SMART Car Heads to the U.For Mac Firefox we have to add this kludge to prevent our scrollbar from
bleeding through to the other layers of the TabBox.Dedicated to the exhibition and nurturing of film and video as art, Antimatter has grown into the premier showcase of experimental cinema in the west.Encompassing screenings, installations, performances and media hybrids, Antimatter provides a noncompetitive festival setting in Victoria, British Columbia, free from commercial and industry agendas.Reciprocally, Antimatter delivers curated programs of new Canadian work to international audiences through our Foreign Matter tours.Since 1998, the quality and creativity of its programming, commitment to audience development, and respect for filmmakers and their work have made Antimatter one of the most important media arts events in Canada, and the world.Initiated in 2000, Foreign Matter is an international curatorial series screened as part of the festival.Antimatter works with selected curators, cooperatives and other festivals to assemble programs of film and video from specific countries or regions.Past Foreign Matter programs have represented the United Kingdom, Czech and Slovak Republics, Latin America, Russia, New Zealand, Colombia, Australia, Mexico, Singapore, Philippines, Austria, Germany, Hong Kong, Belgium, France, Iceland, Brazil, Finland and Sweden.See Archives for details.Foreign Matter programs and other special projects at Antimatter 2008.You may give each page an identifying name, server, and channel on
the next lines.In a sense, matter and
antimatter are the yin and yang of reality: Every type of subatomic particle
has its antimatter counterpart.But when matter and antimatter collide, they
annihilate each other in an immense burst of energy.During the Cold War, the Air Force funded numerous scientific studies of
the basic physics of antimatter.Following an initial inquiry from The Chronicle this summer, the Air
Force forbade its employees from publicly discussing the antimatter research
program.Still, details on the program appear in numerous Air Force documents
distributed over the Internet prior to the ban.These include an outline of a March 2004 speech by an Air Force official
who, in effect, spilled the beans about the Air Force's high hopes for
antimatter weapons.In that talk, Edwards discussed the potential uses of a type of
antimatter called positrons.Physicists have known about positrons or "antielectrons" since the early
1930s, when Caltech scientist Carl Anderson discovered a positron flying
through a detector in his laboratory.That discovery, and the later discovery
of "antiprotons" by Berkeley scientists in the 1950s, upheld a 1920s theory of
antimatter proposed by physicist Paul Dirac.One fundamental
difference between matter and antimatter is that their subatomic building
blocks carry opposite electric charges.The real excitement, though, is this: If electrons or protons collide
with their antimatter counterparts, they annihilate each other.The energy from colliding positrons and antielectrons "is 10 billion
times ...Edwards explained in his March speech.For example:
One millionth of a gram of positrons contain as much energy as 37.TNT, according to Edwards' March speech.TNT, according to the FBI) at the
Alfred P.Murrah Federal Building in Oklahoma City in 1995.Unlike regular nuclear bombs, positron bombs wouldn't eject plumes of
radioactive debris.When large numbers of positrons and antielectrons collide,
the primary product is an invisible but extremely dangerous burst of gamma
radiation.Edwards' speech onNIAC's Web site emphasizes this advantage of
positron weapons in bright red letters: "No Nuclear Residue."George Dyson of the Institute for
Advanced Study in Princeton, N.Still, Dyson adds,
antimatter weapons are "a long, long way off."One reason is that at present, there's no fast way to
mass produce large amounts of antimatter from particle accelerators.If positrons can't be stored for long periods, they're as useless to the
military as an armored personnel carrier without a gas tank.Edwards' point man in that effort is Gerald Smith, former chairman of
physics and Antimatter Project leader at Pennsylvania State University.Smith's storage effort is the "world's first attempt to store large
quantities of positronium atoms in a laboratory experiment," Edwards noted in
his March speech.Reached by phone in late September, Edwards repeatedly declined to be
interviewed.Air Force spokesman Douglas Karas at the Pentagon also declined to
comment last week.Washington State University in Pullman, Wash.One goal: to see if positrons
generated by the accelerator can be stored for long periods inside a new type
of "antimatter trap" proposed by scientists, including Washington State
physicist Kelvin Lynn, head of the school's Center for Materials Research.Besides, Lynn is enthusiastic about antimatter because he believes it
could propel futuristic space rockets.Another man killed in S.Man Cuts Off, Microwaves His Own HandAppeals court allows S.Ed Jew tenders resignation from S.RETAIL
Petsmart PetsHotel San Carlos hiring."Are you sure you want to block this user?I'm walking the line between the overtly emotional stuff a la 'Planetary Confinement', and the more rockier material I was into on 'Lights Out'.Thomas' Myspace Editor V4."Are you sure you want to delete this comment?"With the dust and the promises of decades awayThe dark, deep woods have grown more lovely than tearsAnd will we still discuss these things in similar waysWhen our hesitations ring the bells at the end of our years?Ten Wishes in the New Year Our wish for you ...We wish for you to be happiness each day.We wish for you to use your talents to there fullest to make others happy.We wish for you to do your best and leave the rest to God.We wish for your day to be free from worry.We wish for you to see the bright side of life.We wish for you to have a kind word and deed for everyone.We wish each morning for you to remember you are a child of God and you are love.Hoping to see you in Barcelona this year, happy 2008 !Dear friends,Have a beautiful and successful New Year 2008!It gives me wings and let my fly far away...Your tunes are exceptional.Best wishes for you and your music.Have a cool end of this year and more cooler new one when it comes!Really love your music.....Already best wishes for the new year!!!!Thanks for the addGreetings from Tunisiawww.Have a nice holiday season!Have a good Holiday!!!!!!!!Merry Christmas and aHappy New Year.Have a great Christmas and New Year too!!!This could be an attempt to steal your username and password.This is not a MySpace login page, please do not enter your MySpace login information (email address or password). |
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