Essay On Particle Physics And Cosmology

Particle Physics plays an important role in attempting to answer many modern cosmological theories, notably: dark matter, structure formation, baryogenesis and nucleosynthesis. I am going to discuss some of connections between particle physics and cosmology and investigate how experimental particle physics and cosmology can complement each other and how dependable the connections are.

Dark Matter

There is now strong evidence pointing towards the existence of dark matter in the universe, derived from a variety of precision measurements; it is now believed that the universe is made up of roughly 5% baryonic matter, 25% dark matter and 70% dark energy (Ade, et al., 2013). Evidence exists to suggest that the dark matter cannot be made up of normal baryonic matter (Weiss, 2006) (Raine & Thomas, 2001) and it is in the investigation of the non-baryonic components that cosmology turns to particle physics. The study of elementary particle physics can provide clues as to what this non-baryonic matter could be made up of, with current possibilities being: neutrinos with mass, weakly interacting massive particles (WIMPs), axions and magnetic monopoles. These are all primeval and interact weakly with baryonic matter. I will now discuss each of these.

Neutrinos with mass

In order for neutrinos to be a significant contribution to dark matter they need to have mass. Neutrinos as they are currently understood have zero mass or mass so close to zero that it cannot be distinguished from zero (karagiorgi, et al., 2007), however, there is currently no reason for neutrinos to have zero mass and by studying neutrino oscillations (when neutrinos undergo transitions from one flavour to another) it is possible to infer a mass, as the rate at which they ...

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...tories on Earth. Particle physicists use specialist knowledge in large scale computing, high energy interactions and detector technology to make significant contributions to cosmological experiments, for example, digital electronics and large scale and cost effective detectors.

It is evident that cosmology uses particle physics in a whole host of cosmological theories; the experiments discussed above are just a few examples of where this has and is being practiced. Extrapolating from particle physics models on earth to the cosmological models of the early universe is speculative as the conditions that existed shortly after the universe was created are completely unique from anything that can be re-created on earth. However, the only way that we can approach trying to re-create the conditions of the early universe is through high-energy particle collisions.