Friday 06 April, 2001
Universal Understanding
Astronomers and physicists are beginning to change the way they look at space. Instead of regarding it as a clockwork machine (as Isaac Newton might have done) they now see it more like a living organism.
In Living Universe, Martin Redfern highlights the latest in astronomical research that is uncovering the secrets of the universe around us.
Model Skies
The universe is so unimaginably vast and ancient that we have to use metaphors to help us understand it. Each age has used descriptions or models appropriate to the times.
To the ancient Greeks, the structure of the heavens resembled musical harmonies and mathematical ratios. At the time of Newton, the motions of planets were compared to the workings of a clockwork machine. In the 19th century it was more like a steam engine, slowly cooling to thermal equilibrium.
The mid-20th century saw the nuclear age of the atom bomb and the idea of the Big Bang universe flying out from an initial explosion. Following closely on that was the computer age, and the recognition of the importance
of information processing in the universe.
Living Universe
There is another metaphor that has its roots in many ancient mythologies and which is coming into use again. The universe is like a living organism.
Astronomers today use words like growth, development and even evolution to describe the history of the universe and the stars and galaxies within it. The descriptions seem strangely appropriate as philosophers and cosmologists speculate on how it is that the universe has developed such complexity as life itself, at least on one small planet.
| In Living Universe, I explore the latest advances in astronomy from that viewpoint. It leads to the conclusion that life in general, and we in particular, are more than passive observers of a dead universe but are ourselves part of the action. |
|
Anglo-Australian Telescope
One evening in January, I was staying at the motel on the edge of the Warrumbungles National Park in New South Wales. As night fell I set off up the winding road to Siding Spring Mountain, driving slowly to avoid the Kangaroos. The last kilometre was even slower as I had switched out my lights so they didn't catch the sensitive instruments on the great Anglo- Australian Telescope above me.
Once I had arrived, the observatory director, Brian Boyle, took me outside so I could see the stars for myself: the magnificent band of our Milky Way Galaxy.
| 'The multitude of star was so thick they look like a cloud across the sky.' |
|
But the great telescope was not looking at that. It was gazing at what seemed like empty, black sky well away from our galaxy. But it can detect objects far fainter than our eye can see.
For many years the AAT was one of the best telescopes in the Southern Hemisphere. Now, there are new giants opening on clear, dry mountain sites in Chile. So the Australian astronomers had to do something to keep at the
forefront of observations and take full advantage of the AAT's wide field of view.
3D Map of the Universe
2dF, the instrument that resulted from AAT's research, can study up to 400 distant galaxies at a time. The light from each is piped down optical fibres to be analysed into rainbow spectra which reveal the nature of the galaxy and how fast it is speeding away from us due to the expansion of the universe.
Each exposure lasts more than an hour and while it is in progress, a robot is positioning another 400 fibres with hair's breadth accuracy ready for the next set of galaxies.
The result of the survey so far is a three dimensional map of a section of the universe with information on a quarter of a million galaxies. It reveals the way they are clustered into what looks like a foam of bubbles and voids, hundreds of light years across.
The survey also reveals regions where concentrations of matter are making the galaxies stream out in certain directions. From that, astronomers can estimate the total density of the universe!
Dark Energy
It seems that there is a lot more matter up there than we can see. But still it is not enough to slow up and halt the expansion of the universe. There seems to be another force at work out there, a strange, dark energy that is causing the expansion of the universe to accelerate.
If that is true, it will force a major rethink of our understanding of the universe. Ultimately, it may mean the end of astronomy, since all the galaxies beyond our local group will accelerate out of sight from telescopes.
But there is no need to panic. We've probably got in excess of 100 billion years before that happens. It does, however, leave you feeling very small.
|  |  | | | Universal Wallpaper |  |
| | The survey carried out using the 2dF instrument at the Anglo-Australian Observatory is bigger than any other study. The 2dF can capture structure on scales of up to 1000 million light-years, which has never been possible before.
Professor Brian Boyle, survey co-leader and Director of the AAO explains the importance of the survey:
'Imagine the universe is a room. Previous surveys have involved peering through the keyhole to try to make out the pattern of the wallpaper. Now we've opened the door at least a chink.'
|
|  |
| |
