The Greatest Questions about the Universe

The late Douglas Adams opened his book "Hitchhiker's Guide to the Galaxy" with the lines: "Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space." Using his inimitable brand of humour he was trying to impress on us just how vast the Universe was and how small we are in comparison.

The study of the Universe or cosmology has come on in leaps and bounds in recent years and is now a vast field of knowledge with scientists sparring to prove their own theory correct. For our May 2004 lecture, Dr Alan Longstaff, gave us a whistle-stop tour of the latest news from the frontiers of knowledge.

In recent years a NASA spacecraft named Wilkinson Microwave Anisotropy Probe (WMAP) has pinned down some of the Universe's vital statistics. Over the period of a year, from an orbit a million miles away, it has taken pictures of the whole sky in microwaves. You might wonder what is so special about that, but these microwaves first set out a mere 380,000 years after the Big Bang so they have been travelling across space for billions of years. By analysing this sky map in microwaves, (also known as the cosmic microwave background or CMB) researchers have calculated that the Universe is 13.7 billion years old. They have also found that the very first stars started to shine only 200 million years after the Big Bang; much earlier than was predicted.

The data they have gleaned have also vindicated the Big Bang theory itself and the sudden exponential expansion of the Universe called Inflation that occurred just a fraction of a second after its birth. Oddly enough, the name the Big Bang was coined by the late astronomer Sir Fred Hoyle. He did not believe that the Universe had a beginning but thought it was in a "steady state" whereby new galaxies were forming as older ones moved apart. He must have been dismayed when his derisory title for a rival theory took on a life of its own and has remained to this day.

In fact the Big Bang is not an explosion at all. This is a misleading notion that cosmologists would like to correct but the label has stuck fast. The "Big Bang" is the expansion or stretching of space. It is not that things are flying out from a point but that all things are moving away from each other. It is like having an infinite rubber sheet with people sitting on it. Stretch the rubber sheet, and all the people will move away from one another. Each person thinks they are at centre of an explosion but it is merely an optical illusion - everybody moves away from everybody else and there is no centre.

In about 3 years time the European Space Agency plans to launch a mission named Planck, in honour of the Nobel Prize-winning physicist Max Planck. Instruments onboard will measure the 'CMB' with unprecedented precision, mapping temperature fluctuations to within one thousandth of a degree. Hopefully, after the scientists have scrutinized the data they will be able to tell us a little more about our place in the Universe.