Theories of the origins of the Universe
Since the beginning of human history, Man has sought to understand the world around him. The answers he has come up with over the years have been varied and only infrequently based on observed fact.
The Egyptians had numerous gods, all fathered (if you follow the line back) to Ra, the mighty sun god. The Jewish, Christian and Islamic faiths also believe in a single, all-powerful creator.
The Greeks on the other hand, did not believe in divine intervention as being the beginning of everything. They believed that the universe had always existed in its present state.
In the 6th Century, Thales a Greek philosopher from Miletus, in Asia Minor- is believed to be the first person to abandon mythology and to consider only the world around him for answers. He thought the earth was flat and surrounded by water.
Aristotle (384-322BC) spoke of a universe that had always existed. His theory was that the Earth was a globe surrounded by a finite universe.
In 1543, Nicolaus Copernicus, a Polish astronomer, published his book De Revolutionibus Orbium Coelestium’ (On The Revolutions of The Celestial Spheres) in which he stated that the Earth was not the center of the universe, around which everything else revolved. Copernicus who, was also a clergyman, avoided enraging the Church because he began his book by stating that, his system was a mathematical model, not scientific fact. His views are very important for us today, as this theory is essential to modern cosmology.
Galileo Galilei (1564-1642), was an Italian mathematician, astronomer and physicist. In 1609 he was the first person to turn a telescope on the night sky. His discovery of Jupiter’s four moons proved that the Earth was not the center of everything. He further claimed that the Heavens and Earth have the same natural laws governing both which could be observed and documented by careful observations.
Sir Isaac Newton (1642-1727) was an English physicist and mathematician, he did not believe the universe needed God’s constant attention. Newton felt that the universe was like a clockwork watch that had been wound and left to run unaided. He proposed that if an apple flung into the air naturally follows a curved path as it falls, then why should the Moon need divine help to maintain its orbit around the Earth? His proposition means that the universe must be moving, as a static universe would collapse in on itself, due to the force of its own gravity. His views could have led him naturally to an expanding universe, but he failed to see this and believed that the universe was infinite and static in size.
In 1905, Einstein published his Special Relativity Theory. This theory unites space and time into space-time’, giving a real significance to the speed of light. Space-time diagrams show positions in time as well as space. In 1915, he published his General Relativity Theory: space-time is not flat, but curved by the matter and energy within it. This shows that everything is attracted to everything else by gravitational forces, even light. The bending of light rays by the Sun was first seen in 1919 during an eclipse of the Sun and was predicted by Einstein’s Theory. However, Einstein agreed with Newton and as his original equations of General Relativity predicted that the universe is either expanding or contracting he added another variable called the Cosmological Term’, to cancel out this result.
Einstein’s views held until 1929, when an American astronomer (Edward Hubble) observed that galaxies moving away from the Milky Way were in the red end of the color spectrum (low frequency of light). Hubble also noticed that the movement was the same, regardless of which direction the observer looked. This led him to believe that the universe is expanding. Hubble’s formula states that V=Hr (speed increases with distance). When taken in reverse, this predicts that all the matter in the universe was condensed into an infinitely dense, infinitely hot and infinitely small area. This exploded outwards, into our present universe, billions of years later this is the Big Bang Theory’. The major question about this theory is that it relies on the laws of the universe having been the same in the infinitely different universe of the past.
To avoid this worrisome question, the Steady State Theory’ was put forward by Hermann Bondi, Thomas Gold and Fred Hoyle in 1948. They believe, as did Aristotle, that the universe had the same, overall appearance at all times. This also avoided any creation events’, with their religious implications. However to explain the expansion of the universe, which would leave gaps in their universe with no matter to fill it, they postulated that new matter was continuously created in minute amounts, in exactly the correct quantities, thus keeping its appearance constant.
This theory was disproved in 1964, when Arno Penzias and Robert Wilson identified the background microwave radiation that was left over from a colossal explosion that took place billions of years ago; there is no reasonable mechanism to generate such microwaves in the Steady State Theory, and it was abandoned.
In Indian mythology, the universe is believed to go through cycles of life and death (expansion and contraction), over vast periods of time. This is very similar to a modern cosmological theory called the Oscillating Theory’. We know the universe is expanding, but if the average density of matter in the universe is great enough, then its own gravity will force it to eventually contract. This theory is considered very speculative.
The Big Bang Theory’ has its beginnings in the belief that the universe came in to being 15-20 billion years ago in a great explosion. In 1960, Steven Hawking and Roger Penrose proved that Einstein’s General Relativity Theorem predicted that space-time is curved in on itself. This implies that there should be naked singularities (a kind of black hole), places where space-time could have a beginning or an end: it could have had a beginning in the Big Bang.
At present, the Big Bang Theory is the most widely accepted one. This does not mean however that it is correct. In August 2007, during the cosmology conference at the University of Sussex, UK, a new theory was proposed by Cristiano Germani, a cosmologist at the international School of Advanced Studies in Trieste, Italy. This theory is based on a string theory model; rather than a Big Bang he suggests a slingshot.
Science is the process of examining evidence and constructing theorems based on that empirical evidence. When new data is available any theory must maintain its integrity or be discarded. Many of the early beliefs outlined in this article appear ridiculous to us in modern times, however in another Century our solid facts may appear patently wrong.
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Clive Kilmister, The nature of the universe’, 1971, Thames & Hudson, 30 Bloomsbury St, London, WC1B 3QP.
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Paul Murdin, Focus, The Big Bang’, Mar 1994 Astronomy Now.
Zeeya Merali, Bye-bye big bang, adios inflation, p12, 8 Sept 2007, Newscientist.