Issue 3: Scientific Theories: the Big Bang and Evolution
Scientific Perspective on the Origin of the Universe:
The Big Bang
You will now watch a clip ‘The History of the Universe in 10 Minutes’
Did you know that The Big Bang Theory was first proposed by a Catholic priest named Georges Lemaitre in 1931? He was also a fully qualified scientist he called this theory the ‘hypothesis of the primeval atom’. The theory comes under the general scientific heading of cosmology.
The theory proposes the Big Bang happened 15 BILLION years ago involving a huge explosion bringing matter, time, energy and space all into existence in an instant of singularity as a super hot, super dense mixture of everything. Some scientists refer to this as a ‘cosmic egg’. The Big Bang Theory offers a scientific explanation for the formation of the Universe. Many scientists believe that the biblical account of creation by God was used to fill in the gaps in human knowledge, and now that science has given a real explanation of the Big Bang, there is no need for a creator God.
The Big Bang Theory begins from the observation of the universe as it is at the moment, and on the basis of these observations, calculates what happened at the beginning of the universe. Scientists agree that there was an actual starting point to the universe because it is an observable fact that the galaxies now are still expanding and moving apart. The galaxies further away from us are moving faster than those closer to us and, on the basis of that fact, scientists argue that at one time all the galaxies were closer together and are moving apart in different directions from a single point.
If the universe is expanding is all different directions, then what caused this expansion to take place? This is where the Big Bang theory comes in: an enormous explosion of energy that set the process of expansion in motion; this is called space-time singularity. This is important because it is the point at which space and time are created simultaneously. As a result of this explosion, matter in the form of hot gas spread out over enormous distances. As it began to cool, it condensed to form stars and galaxies that make up the universe. This process eventually developed the capacities for human life to evolve on our planet.
Evidence supporting The Big Bang Theory
- The Expanding Universe
Cosmological Red Shift
When you hear the noise of a fire engine coming towards you and then moving away from you, you’ll notice the pitch of the siren changes from high to low (NEE NAW, nee naw, nee naw). This is caused by the Doppler Effect where the sound waves of the siren are compressed and then stretched as the vehicle moves around you. A similar process happens with light. The astronomer Edwin Hubble discovered that light coming from distant galaxies was all shifted towards the red end of the light spectrum known as the cosmological red shift. This red shift is understood to mean that things in the universe were moving apart from each other. Hubble proposed that the universe must in fact be expanding. This led him back to inferring that there must have been a point of singularity.
Ten years before Hubble’s discovery, Albert Einstein might just have beaten him to it in the discovery of the Big Bang stating that the universe did not have an infinite store of energy and as a result must have had a starting point to set it in motion. Einstein’s Theory of Relativity supports the Big Bang Theory stating the whole Universe was changing in size and time and not just standing still.
- Cosmic Background Radiation Levels
The second piece of evidence for the Big Bang came in 1965 when two astronomers found that their radio reception had a fuzzy noise coming from it, like the hiss you get when your TV is not tuned into a channel. This fuzz seemed to be coming from every point in the universe and had a temperature of -270 degrees.
After some confusion, physicists agreed that the background fuzz was left over ‘heat’ in the form of radiation from the Big Bang. The background heat is still cooling 15 billion years after the Big Bang, this is evidence as it is a remaining signature in the form of microwave radiation that can be observed and measured today and is referred to as cosmic background radiation. This again points back to a point of singularity when everything began in an instant.
- Relative abundance of the elements
The universe today contains the elements, basic atom and chemical building blocks for everything that exists. The amounts of these (relative abundance) in the universe today points very strongly towards a particular process of their creation, in fact it points to the Big Bang. For example, hydrogen is the most abundant element in the universe, 90% of atoms in the universe are hydrogen atoms, but why so much? The proportion of hydrogen in the universe today is exactly what you would expect if the universe had been started by a Big Bang.
What caused the Big Bang?
“…the way I would express it is that the Universe of space- time and matter is internally consistent and self contained. Its existence does not require anything outside of it; specifically no prime mover is needed.” –
Paul Davies “The Mind of God” 1992 page 83
In physics therefore, the Big Bang requires no cause other than the laws of nature. The question still remains: did the laws of nature come into being at the Big Bang? If they did then they could not have caused the Big Bang because they existed before it. The search for the ‘initial conditions’ goes on today and remains the key to the complete understanding of the Big Bang.
So then to sum up:
The Big Bang was an explosion that happened 15 Billion years ago which started off the universe.
Space, time, energy and matter began at this point.
We have evidence for the Big Bang in
- The expanding universe
- Cosmic background radiation levels
- Relative abundance of the elements
The Big Bang caused itself