Antimatter came about as a solution to the fact that the equation describing a free particle in motion (the relativistic relation between energy, momentum and mass) has not only positive energy solutions, but negative ones as well! If this were true, nothing would stop a particle from falling down to infinite negative energy states, emitting an infinite amount of energy in the process--something which does not happen. In 1928, Paul Dirac postulated the existence of positively charged electrons. The result was an equation describing both matter and antimatter in terms of quantum fields. This work was a truly historic triumph, because it was experimentally confirmed and it inaugurated a new way of thinking about particles and fields.
In 1932, Carl Anderson discovered the positron while measuring cosmic rays in a Wilson chamber experiment. In 1955 at the Berkeley Bevatron, Emilio Segre, Owen Chamberlain, Clyde Wiegand and Thomas Ypsilantis discovered the antiproton. And in 1995 at CERN, scientists synthesized anti-hydrogen atoms for the first time.
When a particle and its anti-particle collide, they annihilate into energy, which is carried by "force messenger" particles that can subsequently decay into other particles. For example, when a proton and anti-proton annihilate at high energies, a top-anti-top quark pair can be created!
An intriguing puzzle arises when we consider that the laws of physics treat matter and antimatter almost symmetrically. Why then don't we have encounters with anti-people made of anti-atoms? Why is it that the stars, dust and everything else we observe is made of matter? If the cosmos began with equal amounts of matter and antimatter, where is the antimatter?
Experimentally, the absence of annihilation radiation from the Virgo cluster shows that little antimatter can be found within ~20 Megaparsecs (Mpc), the typical size of galactic clusters. Even so, a rich program of searches for antimatter in cosmic radiation exists. Among others, results form the High-Energy Antimatter Telescope, a balloon cosmic ray experiment, as well as those from 100 hours worth of data from the Alpha Magnetic Spectrometer aboard NASA's Space Shuttle, support the matter dominance in our Universe. Results from NASA's orbiting Compton Gamma Ray Observatory , however, are uncovering what might be clouds and fountains of antimatter in the Galactic Center.
We stated that there is an approximate symmetry between matter and antimatter. The small asymmetry is thought to be at least partly responsible for the fact that matter outlives antimatter in our universe. Recently both the NA48 experiment at CERN and the KTeV experiment at Fermilab have directly measured this asymmetry with enough precision to establish it. And a number of experiments, including the BaBar experiment at the Stanford Linear Accelerator Center and Belle at KEK in Japan, will confront the same question in different particle systems.
Antimatter at lower energies is used in Positron Emission Tomography (see this PET image of the brain).
But antimatter has captured public interest mainly as fuel for the fictional starship Enterprise on Star Trek.
In fact, NASA is paying attention to antimatter as a possible fuel for interstellar propulsion. At Penn State
University, the Antimatter Space Propulsion group is addressing the challenge of using antimatter
annihilation as source of energy for propulsion. See you on Mars?
Answer originally posted October 18, 1999
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8 Comments
Add CommentSir it is a very intresting topic where we need a lot of reserch and its application. I like to have more information of this theory in space applications.
Reply | Report Abuse | Link to thisI hope that anyone that reads this, knows that the quantity of antimatter produced, could only light a lightbulb for a couple minutes. We're lots of years short of having anything antimatter based. As well as if they will even launch it to our government, it's highly dangerous, costs a ton, and uses massive amounts of electricity. So, what they talk about could be very possible, but don't get your hopes up.
Reply | Report Abuse | Link to thisUpdate Concepts
Reply | Report Abuse | Link to thisElectron: The Present Universe Runs ONLY Forward
A. From "Sizing up the Electron"
Measuring the inner shape of the famous particle could help solve a cosmic mystery
http://www.sciencenews.org/view/feature/id/69229/title/Sizing_up_the_Electron
- "Physicists suspect that electric dipole moments exist because they allow particles to violate what's known as time-reversal symmetry. Although symmetry sounds like a good thing, scientists know that processes involving other particles (such as B mesons) behave differently whether running forward or backward, a violation of time-reversal symmetry. In order for this to happen, the electron (and other fundamental particles) must have an internal structure, something an electric dipole moment can reveal."
- "The Big Bang should have created matter and antimatter in equal amounts".
B. The Universe is SPACEDISTANCE, NOT SPACETIME. It runs ONLY FORWARD.
From "Commonsensical Cosmic Rebirth", comment on "Cosmic reincarnation idea may be dead"
http://www.sciencenews.org/index/generic/activity/view/id/67788/title/Cosmic_reincarnation_idea_may_be_dead
Rethink
- A Basic Physics Tenet: SpaceDistance, in lieu of SpaceTime.
- The universe in which we live: It is a dualistic, mass-energy, cyclic array.
C. The Big Bang was the start of the still ongoing D>0, of the still growing D
in E=Total[m(1 + D)]
The Big Bang did not create matter or antimatter, in any amount. It was the start of the still ongoing reconversion of m into E. It was the culmination of the 10^-35 seconds long singularity.
Dov Henis
(Comments From The 22nd Century)
Dispel Some Figments Of 2010 Science Imagination
http://pulse.yahoo.com/_2SF3CJJM5OU6T27OC4MFQSDYEU/blog/articles/245540
03.2010 Updated Life Manifest
http://www.the-scientist.com/community/posts/list/54.page#5065
28Dec09 Updated "Implications Of E=Total[m(1 + D)] "
http://www.the-scientist.com/community/posts/list/180/122.page#3108
Cosmic Evolution Simplified
http://www.the-scientist.com/community/posts/list/240/122.page#4427
"Gravity Is The Monotheism Of The Cosmos"
http://www.the-scientist.com/community/posts/list/260/122.page#4887
Evolution, Natural Selection, Derive From Cosmic Expansion
http://darwiniana.com/2010/09/05/the-question-reductionists-fear/
Again:
Reply | Report Abuse | Link to thisMatter and antimatter are products of evolution of mass along its route of reconversion into energy, started at Big Bang.
Dov Henis
(Comments From The 22nd Century)
If a proton is its own antimatter then how does it exist?
Reply | Report Abuse | Link to thisyes i meant photon not proton
Reply | Report Abuse | Link to thisScientists postulate that there is an imbalance to the amount of matter relative to anti matter in the universe seeing as both should have been created equally. If the imbalance of the amount of anti matter in the universe is unaccountable for, is that indicative of there having been unequal amounts of matter to anti matter to begin with and what we have as tangible is more matter than anti matter in the original sum? What we can use as evidence in all of this to explain any existence of anti matter is the fact that we can produce and store it at will, even though that is in minuscule amounts. If anti matter can be produced at will using relatively lots of energy doesn't that mean that anti matter can only be made in all possible settings by energy being applied to matter to the extent that its spin is reversed thus creating anti matter? Maybe the working out that matter and anti matter were created equally at the beginning of this universe is wrong. Anti matter can be shown to be created from matter in laboratories and there is no evidence to show that anti matter can be created from any other source and manner. I wrote the latter some time as questions to CERN's Google + hangouts but they never answered. The text is still retrievable from their Google+ hangout you tube pages.
Reply | Report Abuse | Link to thisScientists postulate that there is an imbalance to the amount of matter relative to anti matter in the universe seeing as both should have been created equally. If the imbalance of the amount of anti matter in the universe is unaccountable for, is that indicative of there having been unequal amounts of matter to anti matter to begin with and what we have as tangible is more matter than anti matter in the original sum? What we can use as evidence in all of this to explain any existence of anti matter is the fact that we can produce and store it at will, even though that is in minuscule amounts. If anti matter can be produced at will using relatively lots of energy doesn't that mean that anti matter can only be made in all possible settings by energy being applied to matter to the extent that its spin is reversed thus creating anti matter? Maybe the working out that matter and anti matter were created equally at the beginning of this universe is wrong. Anti matter can be shown to be created from matter in laboratories and there is no evidence to show that anti matter can be created from any other source and manner. I wrote the latter some time as questions to CERN's Google + hangouts but they never answered. The text is still retrievable from their Google+ hangout you tube pages.
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