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The Big Bang Theory

All you need to know at GCSE is that 'current evidence suggests that the universe is expanding (see red shift) and that matter and space expanded violently and rapidly from a very small initial point. i.e. the universe began with a big bang'.

According to the Big Bang model of how the Universe began, the Universe expanded initially from an extremely dense and very hot tiny point called a singularity - and continues to expand today.

The Big Bang theory does not deal with what was before the 'big bang' or what 'caused it'.

Time is thought of as coming into existance at the Big Bang - if you think beyond (or before) it you are into the realms of philosopy and religion.

A common analogy is to think of space itself expanding, carrying galaxies with it, like raisins in a muffin as it is baked - or to fix coins for galaxies on a balloon and then blow the balloon up and see the coins get further apart as the balloon expands. (The coins won't expand - just the distance between them will increase!)

The idea that the Universe is expanding is supported by Red Shift observations.

The time over which the initial stages of expansion occurred is difficult to conceptualize as it is so small.

At GCSE you do not need to know all of the stages but they are fascinating to read about!

In the beginning matter was not in any form we have experience of.

After a few minutes hydrogen and deuterium nuclei existed at a temperature of about a billion kelvin - but it then took about 379,000 years before the temperature had reduced enough for atoms to form!

Electromagnetic radiation was then released from matter's hold on it and continued through space largely unimpeded.

Cosmic Background Radiation

This 'relic radiation' is known as the cosmic microwave background radiation (CMBR).

In all directions we observe radio/microwave radiation that is the remnants of that initial burst of released electromagnetic radiation that has been redshifted as the Universe expanded.

Cosmologists can glean a lot of information from that radiation and it is generally thought of as evidence to support the Big Bang Theory.

Another piece of evidence that supports the Big Bang Theory is Red Shift - see the linked page.

There are many ideas as to what will happen eventually - will the Universe expand on and on forever?.... or will it start to contract back again to a tiny point.... and if so has that oscillation gone on and an forever...???

Here are some videos for you to look at:

Here is something to make you think - and brings in both religious thinking and scientific thinking