Our own John Waterhouse on the Age of the Universe

John said that the Universe had been in existence for 13.8 billion years. A level of exactitude that he had mentioned several times in the past but Alan Morrell had not taken the number on board until he had heard it on the television. He explained that it was possible to calculate this number fairly exactly by analysing the Hydrogen Absorption Spectrum (HAS) from distant galaxies. The further away the galaxy the longer the wavelength of the such that it was possible to compute how far the galaxy was away. Thus, looking to the most distant galaxies and comparing them to nearer ones it was possible to calculate a point of origin.

Further calculations could also be made based on the now widely accepted theory that the Universe started with a "Big Bang". The first calculation being the aforementioned HAS analysis. The second way is by measuring the Afterglow of the Big Bang more commonly referred to as cosmic radiation. These are the left-over particles of heat from the Big Bang. They are extremely cold - just less than 3 degrees over absolute zero on the Kelvin scale. By measuring the differences in these temperatures it is possible again to age profile different stars and galaxies leading to an expected date that they were created.

The third way of measuring is by analysing the abundance of light elements in the universe today. As these light elements (Hydrogen, Helium, Deuterium and to a lesser extent Lithium) combined to make heavier elements there existence reduces over time. Calculating this decay in their presence again leads to a very good estimate of the time since the Big Bang.

The fourth method is by calculating the Large Scale Structure of the Universe. The Universe is made up of a large foam like structure in which galaxy groups, galaxy clusters, superclusters, sheets, walls and filaments, are separated by immense voids creating a vast foam-like structure. By measuring the distances along these strands of the universe, both now and in the past, we can come back again to the point of origin.

What is interesting about all these measurements is that they all point to the time of the Big Bang being approximately 13.8 billion years ago.

One postulation from the Big Bang theory was that there would be gravitational after shock waves from the Big Bang resounding around the Universe. The problem was that these were so faint as to be undetectable in the past. However, with the construction of LIGO ( A Laser Interferometer Gravitational-Wave Observatory based in the USA  ) gravitational after shock waves have now been recorded and it is hoped that as more and more of these are identified we will be able to use them to establish the age of the Universe.

During his discussion of the age of the Universe John  also touched on the gravitational effects that large bodies can have in bending light as well as Black Holes, their formation and what if anything escapes them. These are all topics that John has covered in previous talks.