INTRODUCING COSMOLOGY
Cosmology is the study of the universe as a unit. It includes such things as the size and shape of the universe, how it got to be as it is today, how it began and how it will end.
THE BEGINNING.
For many years the universe was thought to be eternal, that is, always was here and always will be here. As such it had no beginning and no end.
Albert Einstein noted that the equations of the Theory of Relativity seemed to indicate that the universe should either be contracting or expanding. Because it was generally accepted at the time that the universe was static, that is neither expanding nor contracting, Einstein added an extra term to his equations so that they indicated a static universe. He called the term the Cosmological Constant.
This constant was equivalent to a type of negative gravity which repelled rather than attracted and grew stronger with distance. It exactly counteracted the tendency of gravity to pull the universe together and cause a collapse.
Albert
Einstein
........more about Einstein here >>>
THE BIG BANG THEORY
..................Edwin
Hubble
After many years work an astronomer Edwin Hubble, was able to show in 1929 that the universe was expanding.
Once it was realised that the universe was expanding there was no need for the cosmological constant. Einstein called it his "greatest blunder".
It stood to reason that if the universe was expanding as time passed, then if the “clock” were to be run backwards at some time in the past the universe must have been smaller. In fact if you were to go back far enough the known universe would shrink to a point. This gave rise to the Big Bang theory of the universe in which the universe began 13.7 billion years ago in an infinitely dense, infinitely hot state which rapidly expanded in a huge explosion that has been flying apart ever since.
STEADY STATE THEORY
Not everyone was convinced that the expansion of the universe indicated that it had a beginning. Three astronomers, Fred Hoyle, Thomas Gold and Herman Bondi developed the Steady State theory which stated that although the universe is indeed expanding, new matter is being created to fill in the gaps left by the expansion of the universe. If you were to run a steady state universe backwards it would not shrink to a point. As galaxies crowded together the matter would thin out leaving the universe looking the same. The universe on a sufficiently large scale would always look the same at any time, in other words a steady state. Rather than the universe beginning and then evolving the steady state universe would have no beginning or end and would always look the same.
more about Fred Hoyle here >>> .......more about Herman Bondi here >>>....... more about Thomas Gold here >>>
BIG BANG - STEADY STATE RIVALRY
Throughout the 1950's and well into the 1960's rivalry existed between the Big Bang and Steady State theories. Given the technology of the time it was not possible to determine which theory was correct. This state of affairs ended abruptly in 1965 when a discovery was made which completely disproved one theory and put the other in a dominant position which has grown even stronger over the years.
END OF THE STEADY STATE
Two scientists, Arno Penzias and Robert Wilson, were working at Bell Labs in Homdel, New Jersey designing sensitive receivers intended for radio astronomy observations. In the course of their work in1964 they found a signal they could not identify. The signal seemed to be coming from all over the sky so they assumed that it was interference from something nearby. Having eliminated all the possibilities they could think of they published their findings.
Very soon the nature of the signal was realised, it was nothing less than the left over radiation from the Big Bang fireball itself. This signal is known as the cosmic microwave background. Here was powerful evidence of the Big Bang theory, the fireball could be detected and analysed by instruments on Earth. This marked the end of the Steady State theory as it had no way of explaining the cosmic microwave background. Since then the Big Bang theory has reigned supreme.
Arno Penzias and Robert Wilson were awarded the Nobel Prize for physics in 1978 for their discovery.
The
horn antenna that Penzias and Wilson used to discover the cosmic
microwave background radiation
© Matthew Wallace 2006