What is the Big Bang Theory?
Why do scientists think the Universe began with the Big Bang?
Scientists think that the Universe began several billion years ago indeed. If that’s right – then no one was around to watch it happen and we can’t make it happen again. So why do scientists think the Big Bang theory is probably right?
Science is all about observations. We can’t observe the Big Bang happening but luckily, there are useful observations to be made by looking at what is here today. These observations do not ‘prove’ that the theory is right. For the moment, however, most scientists seem to think the case is convincing.
What Astronomers see
What are the observations that support the Big Bang theory?
One is that scientists have noticed that the light that comes to us from any star that is a long way away is redder than we might expect. It’s called the ‘red shift’.
The Red Shift
Red shift … red shift … it’s all because of the RED SHIFT! You hear it mentioned so often, but what does it mean? It’s got something to do with the idea that the Universe is expanding … but what?
Ok, all will now be revealed. Here’s what the red shift is all about.
Astronomers have observed that the light coming from distant stars is redder than they would expect. The change of colour is called the Red Shift.
What is the Red Shift?
It’s tricky to explain, but the first thing to know is that light travels through space as a wave. A tightly squeezed wave corresponds to a blue colour of light. A more stretched out wave corresponds to redder colour of light.
The second thing to know is that if a light source is moving away, then this has the effect of stretching the waves of light from that source. You can hear something similar happening when a car passes you by.
The sound shifts in pitch as the car passes – so it goes something like this: ‘eeeeeeaaaowwww’.
This shift happens because the sound waves are more bunched up as the car comes towards you and are more stretched as the car moves away.
But the red shift is something to do with light, right?
That’s right. If the stars are moving away, when their light reaches us, we would expect to see a redder colour of light.
This isn’t the only reason that light might be red-shifted, but it does fit the observation. What’s more we have also observed that the further the star is from us, the greater the red shift … so that suggests that stars which are further away are moving faster! If scientists trace all this hypterthetical motion back through time, it seems to show that billions of years ago, everything was crowded into one spot … and that would have been 13.7 billion years ago.
The Big Bang theory is exciting and mind-boggling, but is it right? Here’s what Professor Jim Al-Khalili thinks (watch the video below).
Many people present the Big Bang Theory as fact! But, it’s not!
It’s important to remember that the Big Bang Theory is just that – a theory. Like all theories, it has been constructed upon a number of assumptions that might or might not stand the test of time . . . What’s more if one assumption is shown to be untrue, the whole theory could collapse!
So one day, the theory might change or even be scrapped, but meanwhile, it seems to present a thorny conundrum for those who believe in a Creator God. That’s what we turn to next.
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