The age of the Universe
(relatively speaking)

Lets have a look at a for instance arising from relativity. The universe is thought to have originated some 10 to 20 billion of our years ago in a big bang. This theory has been modified to include an inflation stage and is more recently subject to challenge. Anyway, the components of the bang have been flying apart ever since, gradually slowed by gravitational attraction. Due to the finite speed of light we observe objects at a distance from us as they were in the past when they were receding faster. Consequently, on a galactic scale, the further away we look the faster the recession velocity we observe, the edge, called the Hubble Limit, occurs where this velocity reaches the speed of light. We presume these observations to be the same for any observer anywhere and, despite the 3 dimensional geometric discomfort, that the edge is the big bang itself.

One of the more esoteric features of such a proposal is the initial state of the universe, theories about the nature of things down to minute fractions of a second after the big bang have developed to account for and predict observations. The question of what was about before or at time zero is often considered outside the realm of physics since less than nothing is a less than fulfilling answer. Perhaps Relativity can help to shed some light on the question or at least avoid it altogether.

Time actually moves slower in receding galaxies due to the time dilation effect, in every aspect of its effect on us this slower rate is significant, it is the real time from our viewpoint. If we observe a galaxy receding at 0.8c then the actual passage of time as measured by us will be slowed by a factor of 0.6. Hence if we observe an event in our galaxy that takes 9 years, the same event would be seen by us to take 9/0.6 = 15 years in the receding galaxy.

This actual slowing of time and consequent extended age increases without bound as the recession speed approaches the speed of light. The open ended scale often used to represent the evolution of the universe so as to give similar space to the first busy fractions of a second and subsequent billions of years may therefore be a more representative model of the universe from the viewpoint of any observer, than by encompassing all with ones own parochial time zone. Using our common sense time on such a scale is conceptually like trying to use a metre ruler to measure the circumference of the Earth, it is straight and so is the Earth on a local scale, but the Earth is bent on a large scale and so the ruler is inappropriate for the global scale. The conclusion I draw from the time dilation effect on a universal scale is that time is the wrong tool to determine a limit for the universe. In the real measure of time, which is subject to dilation with velocity and therefore distance, the universe is of unbounded age.

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This document was created on 23 August 1995
last modified on 23 August 1995
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