The Big Bang Theory
So, the Big Bang Theory. We all hear that the universe was born, was created, nearly 14 billion years ago. But since no-one was around then, how can you prove it? You can’t do an experiment to prove that. So we have to look out into space and see if the evidence is still out there. Like a detective. Are there any fingerprints that give away that there was a Big Bang so many billions of years ago, and there is evidence for it.
We now…if we look out in our telescopes at the distant galaxies we see they’re all moving apart. So if they’re moving apart then in the past, they must’ve been closer together. And if you go back far enough, everything was all in one place. That one place is the Big Bang.
And we know more than that; we have more evidence to support the Big Bang because the Big Bang suggests that deep space should be at a particular temperature. If you stick a thermometer out in deep space it should register a particular temperature, just above absolute zero, about minus 170 degrees centigrade. And sure enough, that’s the temperature of deep space! So that, again, gives us confidence that the Big Bang really did happen.
The other reason why we believe that the Big Bang happened is because the Big Bang predicts how all the atoms are made in the universe. Because when the universe was very young, just after the Big Bang, it was also very, very hot and when it’s very, very hot all the particles in the universe are all moving around very, very quickly and as it cooled down they started to stick together. But it wasn’t just cooling down, it was also getting bigger and bigger, so all the particles were starting to get further apart from each other and weren’t able to reach out and stick together. Only a few of them could stick together.
Now, physicists who studied the Big Bang said that we should only have been able in the Big Bang to have made hydrogen and helium gas, and we should have so much of it. And, sure enough, you look out in space and that’s exactly what you see: hydrogen and helium. All the other atoms, all the atoms that make up our bodies – oxygen, carbon, nitrogen – they were all cooked inside stars billions of years later and we understand that, that’s nothing to do with the Big Bang.
So there are lots of different pieces of evidence that come together that suggest that the Big Bang must have happened. And we’ve got no other theory to explain what we see other than the Big Bang.