The Big Bang Theory
The Big Bang Theory
The big bang theory (left) is the most common and most widely accepted of all theories of the origin of the universe. It states that the universe began approximately 10 to 20 billion years ago, from a point of microscopic proportions blasting out in a gigantic explosion of mass or matter. This point no bigger than an atom was called a 'singularity' and all of what we know today was formed from this singularity. The theory also suggests that nothing, not even time or light, existed before the big bang. That all of a sudden there was the boom of sound, the flash of light, temperature came to exist, gravity was initiated, the first elements of hydrogen and helium became known and from there nuclear fusion provided this 'space' with other elements to form stars, galaxies, planets and asteroids that all came into existence. And so, the universe was born. The big bang theory also says that it is still expanding, although at a much slower rate. This can be described much like a never ending balloon being inflated. It is not known what caused this small atom to expand or further exist at all, but it can be seen that, due to research from Albert Einstein, Stephen Hawking, Isaac Newton and many others, the formation of elements in the universe had a lot to do with gravity and imperfection. Without this basis, there would have been no structures formed, and the universe would have remained in one state for billions of years.
This theory was first suggested by a Belgian priest by the name of Georges Lemaitre in the 1920's. He was the first person to theorise that the universe began as a single primordial atom. His theory was further boosted by Edwin Hubble's observations of the red shift and from Arno Penzias and Robert Wilson's discovery of cosmic microwave radiation.
Evidence: The evidence supporting this theory is that of the red shift. The red shift is a phenomena that was first discovered by Edwin Hubble in the early 20th century. This scientist discovered that distant galaxies had taken on a more reddish hue than they should have, meaning that their wavelength was longer than expected. This led to further investigation which in turn led to the uncovering that this reddish colouring of distant galaxies showed that they were moving, and in this case, outwards. The fact that they were moving was discovered with the help from the research of what happens to sound waves when a source of sound travels away from the observer. What happens is the moving object has a lower pitch if it is travelling away from the person, therefore increasing the wavelength, so the waves move more into the red zone of the spectrum. This is called the 'Doppler effect' after the Austrian mathematician, Andreas Doppler, who identified this fact of sound waves. So, it was discovered that due to the reddish 'shift' of distant galaxies, the universe was and is moving outwards.
Another piece of evidence that supports the big bang theory was the discovery of cosmic microwave radiation by Arno Penizas and Robert Wilson. Cosmic microwave radiation can be described as the leftover, cooled radiation detected to be from the early universe. These two scientists discovered this radiation with a device called the Holmdel Horn Antenna (they won the Nobel prize for this discovery in physics in 1978). This discovery led to the end of the competing Steady State theory at the time.
This theory was first suggested by a Belgian priest by the name of Georges Lemaitre in the 1920's. He was the first person to theorise that the universe began as a single primordial atom. His theory was further boosted by Edwin Hubble's observations of the red shift and from Arno Penzias and Robert Wilson's discovery of cosmic microwave radiation.
Evidence: The evidence supporting this theory is that of the red shift. The red shift is a phenomena that was first discovered by Edwin Hubble in the early 20th century. This scientist discovered that distant galaxies had taken on a more reddish hue than they should have, meaning that their wavelength was longer than expected. This led to further investigation which in turn led to the uncovering that this reddish colouring of distant galaxies showed that they were moving, and in this case, outwards. The fact that they were moving was discovered with the help from the research of what happens to sound waves when a source of sound travels away from the observer. What happens is the moving object has a lower pitch if it is travelling away from the person, therefore increasing the wavelength, so the waves move more into the red zone of the spectrum. This is called the 'Doppler effect' after the Austrian mathematician, Andreas Doppler, who identified this fact of sound waves. So, it was discovered that due to the reddish 'shift' of distant galaxies, the universe was and is moving outwards.
Another piece of evidence that supports the big bang theory was the discovery of cosmic microwave radiation by Arno Penizas and Robert Wilson. Cosmic microwave radiation can be described as the leftover, cooled radiation detected to be from the early universe. These two scientists discovered this radiation with a device called the Holmdel Horn Antenna (they won the Nobel prize for this discovery in physics in 1978). This discovery led to the end of the competing Steady State theory at the time.
The steady state theory
The big bang compared to the Steady State
This Steady State theory was proposed in the late 1940's by Fred Hoyle, Hermann Bondi and Tommy Gold. These people proposed the idea that if any space was left behind from old galaxies and stars moving apart, materials would be gathered and a new galaxy would form to fill the space.
This theory was the major alternate theory to that of the big bang during the mid 20th century. It states that the universe does not appear different no matter the viewpoint, and in order for this to have happened it means that the universe had to have no beginning and therefore no end. This theory explains the universe as, yes, it is expanding, but only due to the constant generation of new matter meaning that the universe generates new matter at a rate proportional to that of its growth (left). It describes the universe as existing with a constant density. The reason it competed so much with the big bang theory was because if, as the big bang theory says, the universe is expanding, theoretically, the materials in the universe should be thinning out, but they weren't. So the theory that new matter was created to support the growing universe and keep everything looking the way it was, struck a chord with many scientists. However, more research into the depths of the universe proved faults in this perfect cosmological principle. Some of these faults were the existence of quasars and cosmic microwave radiation. Quasars were discovered to be the highly luminous cores of distant galaxies. This was a fault in the steady state theory as the quasars showed how ancient the galaxies were father away from us, whereas our nearby galaxies were relatively younger. Since the steady state theory states that everything looks and is the same, this theory could not be true. Also cosmic microwave radiation, which seemed to be the left over radiation from the big bang theory, proved another fault and the Steady State theory no longer had reasonable evidence to support itself.
This theory was the major alternate theory to that of the big bang during the mid 20th century. It states that the universe does not appear different no matter the viewpoint, and in order for this to have happened it means that the universe had to have no beginning and therefore no end. This theory explains the universe as, yes, it is expanding, but only due to the constant generation of new matter meaning that the universe generates new matter at a rate proportional to that of its growth (left). It describes the universe as existing with a constant density. The reason it competed so much with the big bang theory was because if, as the big bang theory says, the universe is expanding, theoretically, the materials in the universe should be thinning out, but they weren't. So the theory that new matter was created to support the growing universe and keep everything looking the way it was, struck a chord with many scientists. However, more research into the depths of the universe proved faults in this perfect cosmological principle. Some of these faults were the existence of quasars and cosmic microwave radiation. Quasars were discovered to be the highly luminous cores of distant galaxies. This was a fault in the steady state theory as the quasars showed how ancient the galaxies were father away from us, whereas our nearby galaxies were relatively younger. Since the steady state theory states that everything looks and is the same, this theory could not be true. Also cosmic microwave radiation, which seemed to be the left over radiation from the big bang theory, proved another fault and the Steady State theory no longer had reasonable evidence to support itself.
The Big Crunch Theory
The Big Crunch theory
It is not known which scientist initially proposed the big crunch theory, but it is known that this theory was based on Albert Einstein's work on General Relativity. It describes a consequence for the beginning of the universe.
The big crunch theory (left), in a way, symbolises the main fear for everyone and every animals' basic instincts. Death, to be exact. This theory states that, instead of the universe expanding forever, as said in the big bang theory, it will eventually stop developing and reverse itself. Meaning that the universe will once again be forced back into that one tiny singularity. So basically this theory states that time will move in reverse. This theory indicates that everything will move closer and closer towards each other until finally individual galaxies would be forced to meld together and after billions of years one mega-galaxy would be formed. After this occurrence, stars in this huge space element would come to merge together which would cause temperatures of the entire universe to raise higher than the Sun. Ultimately, these stars would at sometime burst into black holes that would suck up all the materials around them and after a time they would also come together and form a monstrosity of a black hole that would pull the universe closed until the only thing left would be that minuscule singularity. The big crunch theory is actually linked to other theories such as the big bounce theory and the recycling universe which indicate that the universe would continually grow and collapse throughout eternity. Cosmologists and astronomers continually debate over this theory, deciding whether it would or wouldn't happen, the only thing certain is that nothing will occur for trillions of years.
The big crunch theory (left), in a way, symbolises the main fear for everyone and every animals' basic instincts. Death, to be exact. This theory states that, instead of the universe expanding forever, as said in the big bang theory, it will eventually stop developing and reverse itself. Meaning that the universe will once again be forced back into that one tiny singularity. So basically this theory states that time will move in reverse. This theory indicates that everything will move closer and closer towards each other until finally individual galaxies would be forced to meld together and after billions of years one mega-galaxy would be formed. After this occurrence, stars in this huge space element would come to merge together which would cause temperatures of the entire universe to raise higher than the Sun. Ultimately, these stars would at sometime burst into black holes that would suck up all the materials around them and after a time they would also come together and form a monstrosity of a black hole that would pull the universe closed until the only thing left would be that minuscule singularity. The big crunch theory is actually linked to other theories such as the big bounce theory and the recycling universe which indicate that the universe would continually grow and collapse throughout eternity. Cosmologists and astronomers continually debate over this theory, deciding whether it would or wouldn't happen, the only thing certain is that nothing will occur for trillions of years.