ANTIMATTER AND UNIVERSE

All of us who read science know that ordinary matter consists of atoms. The atoms in turn consist of the positively charged protons and the neutral Neutrons in the nucleus. The negatively charged electrons orbit the nucleus.

In antimatter, the charges are reversed. The orbiting electrons would have a positive charge and the protons in the nucleus have a negative charge. The electrons of antimatter are known as Positrons, Protons as Antiprotons, and Neutrons as Antineutrons. This too is known to most of the science students. 

Antimatter was first predicted by the English physicist Paul Dirac in 1928. Dirac said that every particle in the universe had a mirror image. The American physicist Carl Anderson discovered the Positron in 1932 and Dirac received the Nobel Prize in Physics in 1933 while Anderson got it in 1936.

When particles of matter and antimatter meet, they annihilate each other and produce energy. The laws of physics for particles and antiparticles are the same.

At the time of Big Bang, equal amounts of matter and antimatter would have been present, but today there is very less antimatter left in the Universe. What can be the reason for that is difficult to understand. Perhaps an explanation can be that originally there is much more matter than antimatter like today and so most of the antimatter got annihilated by coming into contact with ordinary matter. That is only a probability, but the scientists see no reason why that should be so. The presence of very little  antimatter in the Universe is a mystery to scientists.   

Did you know that a Banana produces a particle of antimatter every 75 minutes? Bananas contain a small amount of Potassium-40, an isotope of Potassium. When Potassium 40 decays, occasionally it spits out a positron. Our bodies also contain Potassium 40, so we also emit positrons. However these particles are very short lived and get annihilated.

Very less amount of antimatter has been artificially created by humans. That is only about some nanograms (nanogram is one billionth of a gram).

Just a small amount of antimatter can produce a huge amount of power (because it completely annihilates itself when it comes into contact with matter)  making it usable as fuel for space vehicles on lomg distance travel. Of course the challenge is to make that much antimatter, which is not yet possible for us. As mentioned above, humans have thus far produced only a few nanograms of antimatter.

ANTIMATTER IN MEDICINE:

PET(Positron Emission Tomography) uses positrons to produce high resolution images of the body. Positron emitting radioactive isotopes are attached to substances like Glucose. These are injected into the bloodstream where they release positrons that meet electrons in the body and annihilate. That produces gamma rays that are used to construct the images.

Scientists at CERN (European Organization for Nuclear Research)  have studied antimatter as a potential candidate for cancer therapy. They discovered that they can target tumors with beams of particles that would release their energy only after passing through the healthy tissue. This technique was successful on a Hamster (a rodent like the rat but much smaller), but they have not yet tried it on humans.