Antineutrinos and neutrinos
Anyone who has studied basic Chemistry and Physics understands that everything is made out of matter and that matter is made out of smaller substances called atoms. Further, atoms are made out of 3 subatomic particles - protons, neutrons and electrons. The nucleons ( protons and neutrons) are found in the nucleus of the atom and the electrons orbit around the nucleus.
These are some basics that everyone knows, but some things that only a fraction of the people know is that there are particles called neutrinos that hardly interact with matter and that there is a thing called antimatter as well. Antimatter just like normal matter is made up of small substances, like - anti-atoms which are made of - antielectrons, antineutrons and antiprotons. Now you must be wondering about the existence of anticars, antibuildings or antipeople for that matter and why we don't see them. The answer is very simple, matter and antimatter particles annihilate each other on contact emitting a large amount of energy. This is because matter and antimatter particles have exactly the same properties as each other, other than the charge. That’s why they annihilate each other as soon as they come into contact. So remember if you ever meet your antiself please don't shake hands with him or her!
In addition, scientists also know that equal amounts of matter and antimatter were created at the beginning of the Universe which is approximated to be 13.7 billion years ago. This fact raises a mind-boggling question, why is there something instead of nothing? According to theoretical and experimental physicists, the symmetry between the amount of matter and antimatter should have finished off the universe as it started because of the matter and antimatter annihilating each other in attoseconds. However, we know this wasn’t the case because well we are present here in a matter dominant Universe. So there has to be a difference between the behaviour of antimatter and matter that prevented the Universe from collapsing.
The answer is ‘neutrinos’. Neutrinos are particles predicted by the standard model of particle physics. Neutrinos interact with matter so weakly that 50 trillion neutrinos from the sun hit you every second and you don't even realise. Neutrinos come under the category of particles called Leptons and there are 3 kinds - muon, electron and tau neutrinos. Neutrinos like all the other matter particles have their own antimatter twin (antineutrino). Neutrinos have one interesting characteristic, they can oscillate into different kinds. For ex- a muon neutrino can change into an electron neutrino. Antineutrinos also share this same characteristic. To find the difference in the way neutrino and antineutrinos behave, the T2K collaboration ( a team of researchers including Imperial college London) fired a beam of muon neutrinos and antineutrinos from the J-PARC facility in Tokai, Japan to the Super Kamiokande detector 295 KM away. Super Kamiokande detector is a neutrino detector in Japan. They conducted this experiment to find differences in the way neutrinos and antineutrinos oscillate. The results showed that neutrinos were much more likely to change their form than antineutrinos.
This difference between the behaviour of neutrinos and antineutrinos might be the answer to why we live in a matter dominant universe. This will surely revolutionize the way we look at our universe. Professor Yoshi Uchida said that this discovery is like a ‘dream’ come true. Teams like the T2K are on top of all the research and are working towards a breakthrough that will finally answer the question of, why there is something instead of nothing?
- Imperial College London