There are many different ways to observe the laws of physics in action. Throw a ball in the air and it will come back down to you due to gravity, connect a circuit correctly and you will see see the light bulb glow, however observing physics in a smaller scale is much more challenging. Experiments have taken place over the years to try to further investigate the aspects of physics that are too miniscule to see with the naked eye or through a microscope. Particle physics is one of these phenomena, and the most common two ways of investigating particles in our era are to use a particle accelerator or to detect particles from space. These two methods allow for us in some cases to detect particles that would otherwise be unseen. This week, two scientific papers have confirmed the existence of a neutrino of cosmic origin which has the greatest energy ever recorded for a particle and this could lead us to a better understanding of cosmological events as well as the particles themselves.
There are many different types of particles in our universe. The ones we are most familiar with are protons, neutrons and electrons, however these are only part of the story. Electrons are part of the lepton family of particles. This group comprises of electrons, muons and tau particles which have a lepton number of 1 and their corresponding anti-particles (known as positrons) which are the exact same although with opposite charge and have a lepton number of -1. When these particles interact with each other, the charge and the lepton number have to be the same on both sides of the interaction. For these values to be conserved, there needs to be a second type of particle, and this is the neutrino. There is a neutrino and an anti-neutrino for all six of the leptons, and they have the same lepton number as its counterpart, a neutral charge and negligible mass.
Many particles are detected from space including neutrinos, however recently scientists have detected a neutrino with a difference. The Big Bird Neutrino as it is named, has an energy of 2 Peta-electron volts PeV, or 2 million billion eV, which can be converted to approximately 0.0003 Joules. Although this energy may seem very small, for one particle to have this amount would make them extremely energetic. This is approximately the same amount of energy that it possessed when it was formed, as neutrinos travel through space without interacting with other matter, which has aided scientists in their investigation. As well as Big Bird, other Sesame Street characters have had a particle named after them. A year ago two particles were found named Bert and Ernie which were previously the most energetic particles. These had half of the energy that the Big Bird neutrino possesses so this is a huge discovery for physics, and especially for those at the IceCube Neutrino Observatory at the South Pole who discovered all three of these particles.
The discovery of this highly energetic particle holds a number of promising possibilities, including the fact that it can help us understand how great the energy of particles can become in real life situations. These energetic particles have been formed from cosmological events such as supermassive black holes and supernovas, and help us to understand these phenomena in greater detail. As it seems that the energies of these particles peak at the early PeVs, further investigations will be underway to look for particles with even higher energies, if there is such thing.
Physics, astronomy and cosmology have become more mainstream in the media, with news updates such as these being reported to everyone inside and out of scientific and academic communities. Science is becoming more exciting and interesting to young and older generations alike and discoveries such as these are allowing more people to get involved and learn more. With more interested in the field and developing technology, we are limitless as to what we can discover and how we can develop our understanding.
How will the discovery of the Big Bird Neutrino lead to more detections much like this in the future?