History And The Physics Of The Early Universe In A Nutshell

Where did we come from? How did the universe begin? Are we alone in the universe? These are the questions that human beings have asked ever since they first looked up at the heavens. Many ancient Greek philosophers viewed the universe as a divine, living being whose innermost essence was harmony. According to them, understanding the universe was key to revealing where we came from and our place in the universe.

In 1917 Albert Einstein published his General theory of Relativity (GR). GR not only explained how gravity worked but also predicted the evolution of the universe: The universe should expand. Vesto Slipper in 1917 and Edwin Hubble in 1929 soon verified this prediction experimentally. If the universe is expanding continuously and if we could rewind time, then eventually we would get to a point when the universe was very small, very dense, and very hot. In 1927, based on GR, Monseigneur Georges Lemaître proposed that the universe must have expanded from an initial extremely dense and extremely hot “ball of light”. The Big Bang Theory was born. Lemaître suggested that this initial “ball” would be smaller than the size of the atomic nucleus (about 0,0000000000000015 m). To give you some sense of the extreme dense and temperature of this ball of light, you can imagine compressing the sun to the size of the atomic nucleus. At such high temperature atoms or nuclei start to melt. This melted state is called a “plasma state”. The early universe existed in a plasma state in which electrons, quarks and elementary particles were free. At around 10-35 s (i.e. 0,00000000000000000000000000000000001s), the universe expanded tremendously fast in a fantastically small amount of time, a phenomenon called inflation. As the universe expanded, the plasma cooled down and the atomic particles were able to cluster together into atomic nuclei. 300,000yrs after the Big Bang, the atomic nuclei of the lightest chemical elements such as hydrogen, helium, and lithium were formed. As the universe further expanded at an ever increasing rate due to this inflation, the universe cooled further down and the electrons bound to the atomic nuclei, forming the first atoms. As a consequence of this, light (photons) was set off to travel through the universe.

In the ..s, two astronomers discovered that the expansion of the universe is accelerating. Physicists proposed that this expansion is due to the so-called “dark energy”, which is an elusive matter that pushes everything apart. Dark matter seems to act like anti-gravity. On the other hand, there is something called dark matter, which is holding the galaxies together. Dark matter is “invisible” (i.e. they cannot be seen using standard imaging techniques) because it does not interact with matter or light.

Dr. Ali Mozaffari is a visiting lecturer in Physics at St. Mary’s University and a cosmologist who is working on the problem highlighted above. His area of research is based on gravity and cosmology. One of the areas that he and his collaborators are looking at is the effect of modifying the theory of gravity in different ways and then understanding the effects this has on observable physics in both the solar system and our galaxy (the Milky Way), along with the repercussions on early universe cosmology. Dr Mozaffari said that “The rationale behind these ideas is that although Dark Matter has been long held up as part of the standard model of cosmology, increasingly some scientist are once again getting concerned that the lack of experimental verification or direct observation of a candidate particle (in both earth based and space based experiments) indicates that we need to rethink our gravity and cosmological models”. Modifying gravity in such a way as to produce GR in some limit whilst at the same time produce a noticeable deviation without introducing extra matter fields and/or playing around with other gravitational tests, is very difficult.

Dr. Mozaffari works with colleagues from Oxford and Cardiff Universities as well as with some industries including the aerospace design company Astrium. He and his collaborators are all working towards the common goal of persuading the European space agency to attempt an audacious gravitational physics experiment with one of their missions LISA Pathfinder. In addition to that probe having a very different mission, “we also have to move around political and economic boundaries, thus having collaborators with experience of this also helps” said Dr Mozaffari.

There are many advantages of an international collaboration of this kind and these include:
(1) Bringing new and exciting perspectives into research
(2) Allowing those from different university systems to work together, increasing the overall knowledge base of the community
(3) Bringing different resources and areas of expertise.