Anti-Matter by Anmol Subba
ANTI-MATTER
by Anmol Subba(Dept. of Physics)Anti-matter may sound like a science fiction but it is a real stuff (it exists). Scientist have not only detected but also produced them in laboratories. We may a vague idea on anti-matter but this article will enlighten you with more knowledge of them.
WHAT IS ANTI-MATTER?
He put together Einstein's Special relativity equation (which says light is the fastest moving thing in the universe) and quantum mechanics (which describes what happens in an atom) and came up with the above equation. He discovered that the equation worked for electrons with negative as well as with positive charge.
Classical physics only allowed systems to have positive energy. But Dirac's new theory of relativistic quantum mechanics allowed for a particle with negative energy solution, as a counterpart to the familiar positive-energy electron. After ruling the possibility that this particle was simply the proton which has a huge mass, Dirac predicted the existence of a new particle with the same mass of the electron but with a charge that was positive rather than negative.
That particle was found experimentally on 2 August 1930. Carl Anderson was observing the trails produced in the particle shower that was created in his cloud chamber when cosmic rays passed through it. His observation included a particle with same mass as the electron but opposite charge- its track bent in the wrong direction in a magnetic field. Anderson coined the name "positron for his new discovery.
In 1933 Dirac went on to predict the existence of the anti-proton, the counterpart to the proton. It was discovered in 1955. It is now understood that all particles have an equivalent antimatter particle with opposite charge and quantum spin- although some are their own antiparticle. Later scientist were able to produce artificially -positron, anti proton, anti neutrons, anti nuclei, anti hydrogen atoms(consisting of an anti proton and positron), anti helium atom, and so on...
So basically Antimatter is a material composed of so called antiparticles. Antiparticles are subatomic particles having same mass as a given ordinary particle but opposite electric or magnetic properties.
Where to find anti-matter?
Positrons and antineutrinos are produced naturally in Beta decays of radioactive isotopes. Scientists have also discovered positron originating from thunderstorm clouds; positrons are in gamma-ray flashes created by electrons accelerated by strong electric fields in the clouds. Antiprotons have also found to exists in the Van Allen Belts around the Earth. Satellite experiments have found evidence of positrons and few anti protons in cosmic rays. And that's it, we haven't observed other antimatter in the universe.
It is hypothesized that during the period of baryogenesis (big bang), when the universe was extremely hot and dense, matter and antimatter were continually produced in equal amounts and annihilated.
If matter and anti matter were made equally then where did anti matter go? Why do we only observe a lot of ordinary matter and not antimatter? The presence of remaining matter and absence of detectable antimatter is called baryon asymmetry. The exact reason leading to baryon asymmetry remains an unsolved problem till date.
Wait a minute! so if matter and antimatter annihilate, and we and everything else are made of matter, why do we still exists? This mystery arises because we find ourselves living in a universe made exclusively of matter. Didn't matter and antimatter completely annihilate at the time of the Big Bang? Perhaps this antimatter still exists somewhere else? Otherwise where did it go and what happened to it in the first place?
I am not trying to scare you off, just look at the above equation and just see the beauty that predicts the existence of anti-matter. This equation is known as Dirac Equation, proposed by English physicist, Paul Dirac in 1928. He is also called "the greatest British theorist since Sir Isaac Newton.''
He put together Einstein's Special relativity equation (which says light is the fastest moving thing in the universe) and quantum mechanics (which describes what happens in an atom) and came up with the above equation. He discovered that the equation worked for electrons with negative as well as with positive charge.
Classical physics only allowed systems to have positive energy. But Dirac's new theory of relativistic quantum mechanics allowed for a particle with negative energy solution, as a counterpart to the familiar positive-energy electron. After ruling the possibility that this particle was simply the proton which has a huge mass, Dirac predicted the existence of a new particle with the same mass of the electron but with a charge that was positive rather than negative.
That particle was found experimentally on 2 August 1930. Carl Anderson was observing the trails produced in the particle shower that was created in his cloud chamber when cosmic rays passed through it. His observation included a particle with same mass as the electron but opposite charge- its track bent in the wrong direction in a magnetic field. Anderson coined the name "positron for his new discovery.
In 1933 Dirac went on to predict the existence of the anti-proton, the counterpart to the proton. It was discovered in 1955. It is now understood that all particles have an equivalent antimatter particle with opposite charge and quantum spin- although some are their own antiparticle. Later scientist were able to produce artificially -positron, anti proton, anti neutrons, anti nuclei, anti hydrogen atoms(consisting of an anti proton and positron), anti helium atom, and so on...
So basically Antimatter is a material composed of so called antiparticles. Antiparticles are subatomic particles having same mass as a given ordinary particle but opposite electric or magnetic properties.
Where to find anti-matter?
Positrons and antineutrinos are produced naturally in Beta decays of radioactive isotopes. Scientists have also discovered positron originating from thunderstorm clouds; positrons are in gamma-ray flashes created by electrons accelerated by strong electric fields in the clouds. Antiprotons have also found to exists in the Van Allen Belts around the Earth. Satellite experiments have found evidence of positrons and few anti protons in cosmic rays. And that's it, we haven't observed other antimatter in the universe.
It is hypothesized that during the period of baryogenesis (big bang), when the universe was extremely hot and dense, matter and antimatter were continually produced in equal amounts and annihilated.
If matter and anti matter were made equally then where did anti matter go? Why do we only observe a lot of ordinary matter and not antimatter? The presence of remaining matter and absence of detectable antimatter is called baryon asymmetry. The exact reason leading to baryon asymmetry remains an unsolved problem till date.
Wait a minute! so if matter and antimatter annihilate, and we and everything else are made of matter, why do we still exists? This mystery arises because we find ourselves living in a universe made exclusively of matter. Didn't matter and antimatter completely annihilate at the time of the Big Bang? Perhaps this antimatter still exists somewhere else? Otherwise where did it go and what happened to it in the first place?
The subject of anti-matter/anti-particle always intrigued me since I first got to know about it, while studying in the 12th grade. Thank you for this article. Best wishes to the science club!
ReplyDeleteThanks Manisha for the comment. Like you and many others, I find anti matter to be very interesting especially the unsolved anti-matter and matter asymmetry. I first came to know about anti matter through a sci-fiction novel "Angels and Demons" by Dan Brown. It was a very interesting read.
Delete