When choosing my topic for the research project I wanted to spend the two weeks investigating a subject that was not too narrow. Something that would be beneficial to my future. I looked into the unsolved mysteries that physicists are still trying to understand and wanted to find a subject that would link directly to why Earth and our universe is here. The two topics of physics that I currently have greatest interest in are particle physics and astrophysics. On the Royal Society website I came across something that seemed to combine the two: ‘Ghosts in the universe’. The topic is based on neutrinos and how they may have caused Baryon Asymmetry; the observation that our universe is made up of matter, whilst anti-matter is very rare.
Anti-matter is made up of anti-particles which supposedly have the same mass and properties as matter but with opposite charge. If a proton is made from two up quarks and a down quark, an anti-proton is made from two anti-up quarks and one anti-down quark. Baryon asymmetry is still a mystery to us, but physicists in Japan have made discoveries that could lead us to the answer.
Einstein’s theory of Pair Production tells us that whenever matter is created, an equal amount of anti-matter is created. At the Big Bang, when a huge amount of energy converted into mass, an equal amount of matter and anti-matter should have been created. Where did the anti-matter go? Is there an anti-matter Earth out in space? Matter and anti-matter must act slightly differently or else there would be no universe today: when matter and anti-matter meet they anhilate one another, converting into a huge amount of energy.
Our universe is made up of quarks and leptons. These consist of up, down, strange, charm, bottom and top quarks, and of electrons, muons and taus with their corresponding neutrinos, electon neutrinos, muon neutrinos and tau neutrinos. These are the three ‘flavours’ of neutrino. Neutrinos only interact through the weak force and are very difficult to detect as they have almost no mass and hardly ever interact with matter. *1
Although the standard model states that neutrinos are chargeless and massless, we now know this is not true. Neutrinos have mass, and if they didn’t neutrino oscillations would not be possible. There is a spectrum of neutrino mass eigenstates (insert diagram) each with corresponding different masses. Each of the three flavours of neutrino can also be described as a combination, or sum of a variety of eigenstates. …… *6
The T2K project in Tokai, Japan is taking place in J-PARC (Japan Proton Accelerator Research Complex). Physicists there are observing neutrino oscillations. This is when a neutrino changes from one flavour to another. This was discovered in 2013. They create powerful beams of neutrinos and anti-neutrinos and observe these, looking for CP violation. CP symmetry (charge conjugation parity symmetry) is the concept that the laws of physics would be the same if a particle was replaced with an anti-particle, therefore a CP violation is some evidence to show that matter and anti-matter don’t act in the same way. Some of the latest results from the T2K experiment show CP violation: there is evidence showing whilst 32 muon neutrinos oscillated to become electron neutrinos, only 4 anti-muon neutrinos became anti-electron neutrinos. Although the researcher still don’t know completely what this means, it is the kind of evidence we will need to look further into to understand why matter and anti-matter acted differently after the big bang. *3
*4 J-PARC consists of three proton accelerators. These stimulate the production of pions, which decay into muons and muon neutrinos. They then pass through a layer of graphite and only the neutrinos are left. There are two detectors to measure if oscillations have occurred in the neutrino beam and any other changes: one of these detectors is within J-PARC, only 280 metres from the beam of neutrinos being produced. The other is 295 kilometres away, at the Super-Kamiokande Detector in Kamioka. Although originally they were just looking at neutrino oscillations in the neutrinos, in 2014 the T2K projects started to use a muon anti-neutrino beam also to compare.*1 By 2015, the neutrino beam at the particle accelerator was working regularly at power levels above 300kW.
If we still do not know the reason behind baryon asymmetry, should we continue to research it? Have we come to a dead-end? If we have, and we know it may be thousands of years before we have the technology to prove a theory for Baryon Asymmetry, so is it worth continuing? Looking at evidence from the history I would say it is. Just over a hundred years ago they found out about …(research more ideas about philosophy in physics)
It’s amazing how quickly our knowledge of the Earth and Universe has expanded. To me it is very important that we continue to research and experiment, because each time we discover something new it leads to discoveries of lots of other things. Although it seems as if finding out why matter and anti-matter are not balanced in the universe is no longer relevant, it is. Just because the big bang was billions of years ago, by finding out why the matter and anti-matter didn’t anhilate we will understand far greater the properties of matter and anti-matter and from this we may be able to use it: anhilation of matter and anti-matter releases a huge amount of energy and could be used as alternative fuel, but the amount of fuel needed to create anti-matter is far greater than the amount of energy it will make, and this type of energy can also release high-energy gamma rays which are very damaging, breaking apart molecules in cells and fragmenting atoms.
What really intruigues me is how some of the smallest particles in our universe, that hardly affect matter could be the reason why all of us are here. Inicially I thought that to discover big things about space you would need to be an astrophysicist, but now I realise that particle physicists are often at the heart of the discoveries that change our understanding of space.