It all seemed so simple. At the beginning of the twentieth century the universe was regarded as infinite and unchanging. All was right with the world. Physicists thought we had got the ideas about right with just a few odds and ends to tidy up. Young people were warned against taking up physics at university because we almost know it all and by the time you are looking for a serious job there will be no more physics to study.

A clerk in the Swiss patents office (Einstein) began to cause some problems when he found that with a bit of imagination and some fancy mathematics he could suggest that things like time,distance and velocity are not as simple as we would like. They are connected. The faster you move the slower people think your watch is running. But strangley you think it is their watch that is running slowly. But enough of this.

This clerk also reckoned that his ideas meant that the universe must be expanding. He found this idea so ridiculous that he added a fudge factor into his calculations to make them work differently. He put in an extra force to stop the expansion and which made his model look the way the astronomers said it should.

This was fine until Edwin Hubble drove his team of lady photographic checkers almost to blindness with their examination and measurement of the tiny rainbows produced by many thousands of images of the fuzzy blobs called galaxies. He was looking for the story of how the galaxies were formed. He found a few answers to this question but his photcheckers found two things that were much more interesting.

They found that the images of galaxies looked redder than they should be. They also found that the dimmer the image the redder the image. What did this mean. The red bit was fairly easy.

When a cop car speed away from you with its siren going the sound goes from a high prepubescent treble to a more mature alto or soprano. This is because the movement of the car stretches the sound waves and gives them a lower frequency when they reach your ears. It was obvious that the galaxies were speeding away and so the light waves were being stretched. The longer a light wave the redder the colour. So the redder the rainbow the faster the galaxy is moving. So far so good. Galaxies are moving - no problem we expected that.

It was the second discovery that was the shocker. The dimmer the galaxy the redder it was. If you make the assumption that to a good approximation all of the galaxies are the same brightness then dimmer means further away. So this tells us that the further away a galaxy is the faster it is moving. The worrying thing was that with the exception of a few very close galaxies all of the galaxies were moving away from us. Did this make us special or had we just said the wrong thing?

With all those billions of galaxies to choose from why should we be the special one? No reason. In fact highly unlikely. The only viable explanation was that the universe is expanding. Old Einstein was right after all. He described putting in his fudge factor as his biggest mistake.

So we do a few more experiments and take a few more measurements. Some people cannot handle the idea of a beginning (and an end) so they come up with ideas like the steady state. They have such contempt for the expanding universe idea that they give it a silly name. The Big Bang. The name sticks so when discoveries like quasars and (the clincher) the cosmic microwave background are made who has egg on their face?

So as with most science a state of dogma sets in. The Big Bang is taught in schools as fact. The end of cosmology is predicted.

All we need to know now iw whether the universe will carry on expanding or if gravity will eventually make it run in reverse and end with the big crunch.

There were some cracks already appearing. First Fritz Zwicky and later more accurately Vera Rubin found that galaxies were spinning too fast for the amount of matter that could be seen in them. Odd but probably no big deal - just a detail to be tidyed up.

Then we have a problem. By studying the brightness and red shift of special exploding stars in very distant galaxies we find that the universe is not simply expanding but actually increasing the speed at which it is doing it. What!!! This is important

The most logical explanation is that there is more matter out there than we can see. Not only that but this matter is likely to be almost everywhere, even here on the keyboard in front of me. But it does not interact with light so we cannot see it ( how many angels on a pin head). Some people called it transparent matter but the name that has stuck is Dark Matter.

Not suprisingly some people do not like the idea of matter that is invisible but which controls the fate of the universe. Other ideas have been put forward such as Newton being wrong or that Einstein was wrong or even both. Who said physics was finished.