CONTENTS

X CANARY ISLANDS WINTER SCHOOL OF ASTROPHYSICS "Globular Clusters"

USEFUL ASTROPHYSICS FOR THE FUTURE

"Astronomy’s main achievement over its long history has been to put us in our place: first, removing the Earth from the centre of the Universe, then the Sun, the solar system, the Galaxy itself, and finally sweeping away the concept of a centre altogether. Similarly, timescales in the Universe have gone from something inconceivably vast. Ever more exotic objects and processes have been discovered, and the conditions required to give rise to us are now understood to be almost impossibly stringent. These discoveries hold a great fascination in our society, fuelling art, music, and poetry.

Astronomy’s greatest contribution in coming decades may simply stem from its capacity to stir the imagination of an increasingly jaded and materialistic culture."

"Astrophysics has already given a good job, giving to mankind an understandable picture of the sky and a general overview on the evolutionary history of the Universe. This is slowly producing great effects on the psychology of human beings. During the next few decades astrophysics will probably cooperate with basic physics and cosmology to reveal still unsuspected features of such evolution, but the big step has been already done!"

"The essence of scientific work is that most major advances take us in quite unexpected directions and I would anticipate that to be the case in the next century. These advances have often led directly or indirectly to important practical applications. After all it was the puzzle of how the sun produced its energy that led to the idea of nuclear power. We cannot be sure what the future advances in astrophysics will be. However we can certain that training in astrophysics will, if properly conducted, equip young people with the necessary technical skills and the powers of reasoning scientifically which will enable them to make important contributions not only in astronomy but in many walks of life in the next century."

"In the broadest sense, the next millennium will not be any different from the previous three, four, or ten. Astronomy gives humans a unique window on the physical universe. We learn to look upward instead of just at each other. We learn that the cosmos is indescribably large and that we are connected to it in unexpected ways. We learn that there are marvellous things out there – black holes, galaxies, an entire cosmic history – that we would have no conception of if we just studied what we see around us on the Earth. These things are a marvellous learning experience for any thinking person, and any society. A willingness to explore these ideas is one of the things that makes any society worth living in.

What about the next decades in particular? I think it is likely that we will finally be able to fill in some of the very big remaining ‘gaps’ in our knowledge of cosmic history – how the gas emerging from the post-recombination epoch turns itself into stars and galaxies; what are the values of the big cosmological numbers such as omega and lambda; and better ideas about the elusive dark matter. And maybe – although I think is a very long shot – the SETI experiments will succeed. If that happens, it will change human society in ways we can’t even imagine.

In some sense, there have to be ‘ultimate’ limits to what astronomy, or any other science, can accomplish. We are finite beings, and there are many fundamental questions that we can state but are unable to answer. And beyond that, there must be levels of questions that we are not even smart enough to state. (Could a cat ask what causes the Sun to rise, or what the stars are?) But we are still very far from any such limits. We need no worry about running out of ideas yet!"

"It will be foolish to try to guess."

"A part from timely prediction of catastrophic impacts (now a fashionable subject for fiction), I think the most interesting topic for common people may be the discovery of planets apt to host life. Various techniques have been developed to search extra-solar planets, and a few successful hits were made. We now know about ten such objects, ranging from exotic objects like planets around pulsars (likely not a pleasant place for life), to more familiar Jupiter-like systems. Within a couple of decades, direct imaging of some of these systems will be possible through interferometric techniques. Of course, there is a big step from finding planets apt for life, and to find extra-terrestrial life, but this is a first step."

"Astronomy has grown from roots put down in very practical application - timekeeping and navigation being the two most obvious. Many of these applications are still important. The hyper-accurate rotation of pulsars, for example, will probably be harnessed for time-keeping purposes. Navigation can and will fix itself to an astrometric "zero point" of distant celestial objects (indeed, the plaques on the Pioneer spacecraft shows the location of our Sun with respect to the nearest pulsars) – ultimately to the most distant quasars. Astronomical navigation and time-keeping will grow in importance as the space age progresses.

Astronomy shares needs and drives technological developments with a number of fields that require cutting-edge imaging, image processing, modelling of extreme physical environments, high speed computing, etc. Some of these applications happen to be military in nature (satellite surveillance, guidance systems, simulations of explosions, etc.) but civilian applications abound: monitoring the Earth’s surface from satellites, measuring changes in the global climate, thermal infrared and x-ray imaging, even developing new materials for industrial application. A new, more direct use of astronomy lies in the ability more practically to detect potentially planet-threatening events - nearby supernovae, nearby gamma ray bursts, solar flares - as well as the recent favourite of Hollywood, the danger of comet and asteroid impacts.

Of course, there is always the touchy-feely answer that astronomy reveals our origins and our place in the Universe. The great astronomical advances of the twentieth century have been in understanding the origin of the universe and structures within it. The next century, even the next decade, bring the promise of great achievements in understanding more personal factors, such as the origin of life in the universe. We are already finding planets around other stars, and there is a surge of interest in understanding potential biochemical processes in extraterretrial contexts. Apart from the possibility that biochemistry happens on other worlds, there is also the exciting possibility that exobiology may have had great bearing on the origin of life in the primordial environment of the earth. I can’t think of a more profound contribution of astronomy to mankind than to fill in the missing details that link human origins to the stars."

"I think the main contribution of Astrophysics to humanity in the coming decades should be, quite apart from its purely stimulating role and its use as a testbench for various kinds of innovative technologies, to provide us with a rational and coherent picture of the Universe with which to bolster our confidence that scientific analysis and the disinterested combination of efforts (at least to a certain point) will be able to tackle the most pressing issues facing humanity."