Electronic Newsletter -- #3 Winter, 1998

Items for this newsletter should be emailed to the editor: asgrg *AT* hotmail *DOT* com

  • ANNOUNCEMENT: Notice of Biennial General Meeting
  • ACGRG2, Sydney, 6-11 July, 1998, Draft Programme
  • MEDIA EXCERPTS: "Sound Reasoning" (David Blair, Panorama, December 1997)


    The Bienniel General Meeting of the ASGRG will be held on at 4 pm, Wednesday, July 8th, in the Carslaw Lecture Theatre at the University of Sydney.

    Nominations for the positions of President, Secretary, Treasurer, and members of the committee should be forwarded to the secretary, Tony Lun, prior to the meeting, by 12:00 Tuesday, 7 July. (According to the rules, no person may be elected to the same office for more than two consecutive terms - however, we have only been "official" for one term til now.)

    1. Minutes of 1st BGM, Adelaide, 13 February, 1996.
    2. President's report.
    3. Treasurer's and auditor's reports.
    4. Appointment of auditor for next session.
    5. Election of officers.
    6. Date and venue for ACGRG3. 
    7. Other business:
       (i)  Matters arising.


                                   July 6-11 1998
                           University Of Sydney, Australia
           The final circular will be distributed to those who have registered.
    The draft programme is included here for the benefit of potential
    late registrants who have not yet made up their mind:      



    Dr Susan Scott has been recently appointed to the position of Lecturer (Continuing) in the Department of Physics and Theoretical Physics, ANU.


    FROM Panorama Dec 1997, pp. 114-119 (Ansett inflight magazine)


                 The human race is on the threshold of something
                 dramatically new that may rival the greatest
                 scientific discoveries of all time - something
                 that may totally alter our view of the universe.
                 David Blair looks at new research which will
                 allow us to hear the scream of dying stars.  
    Most of what we know about the world at large we know through sight and sound.
    Our exquisitely sensitive ears allow us to hear vibrations almost as small as
    an atom, while our eyes can detect much less than a millionth of a billionth of
    a Watt of light power from a faint star on a moonless night.
    Modern technology has dramatically extended our sense of vision. Now,
    night-vision glasses allow us to see infra-red light that we otherwise only
    feel as the warm glow from a fire. X-rays are simply a higher-energy form of
    light which we can't feel at all, but which allow us to see our insides as well
    as the contents of our bags at security counters. Radio is a low-energy form of
    light. Although we use it to encode sounds and send voices around the world,
    radio has nothing to do with sound at all. We can equally well send sounds by
    encoding them in light pulses, as happens with most of our long-distance
    telephone conversations. Using radio, we have also enormously extended our
    vision -- radio telescopes are now able to see objects in fine detail far
    across the universe.
    Almost all of what we know about our vast universe we know from our extended
    sense of vision. Telescopes using every conceivable part of the light spectrum
    peer out at the universe, giving humanity an almost unbelievable wealth of
    views across both space and time. Some of the light we see has been travelling
    towards us for almost the age of the universe itself. What we see in this light
    is an image of the universe when it was much less than a million years old,
    long before stars and galaxies had formed and 10 billion years before the birth
    of our own solar system.
    Have you ever looked at a beautiful landscape painting or photograph and
    imagined the sounds of the sea and the wind and the birds? Or an 18th-century
    battle scene where the clash of armour and the booms of the cannons are silent?
    Because we can hear, we are able to imagine and fill in the silences. But what
    if we were a deaf species? Could we guess at the sounds of the forest or
    imagine the sounds of battle?
    Well, we are a deaf species! True, we can hear sounds made on the surface of
    our planet. But we are deaf to the universe.
    "Well, of course," you say. "Sounds go through air, but they can't go through
    the vacuum of space." Right? No, wrong!
    Sounds are vibrations-pressure waves of vibrating atoms that make our eardrums
    vibrate -- and Albert Einstein proved 80 years ago that vibrations can indeed
    travel through space. They are called gravity waves, carry prodigious amounts
    of energy, travel at the speed of light and are almost unstoppable. And, soon,
    humanity will have the bionic ears it needs to listen to them.
    So what will the universe sound like? That question is a bit like asking a deaf
    person to describe the sounds of a forest. Almost an unfair question, but this,
    of course, is where science excels. After decades of effort, physicists can now
    make some pretty good guesses and, surprisingly, we expect the universe to
    sound a bit like a forest. Black holes will make short, sharp clicks like those
    of a woodpecker. Pairs of neutron stars will make chirrups like bird calls. The
    deaths of the first generation of stars in the universe 12 billion years ago
    will combine to make a sound like the wind in the treetops. Spinning neutron
    stars will make pure whistles.
    The harnessing of gravity waves for astronomy is being pioneered by a rapidly
    growing army of physicists around the world. The first detectors in the world
    were huge, supercooled metal bars equipped with the most sensitive microphones
    ever made. Four of these are now in continuous operation: two in Italy, one in
    Perth and one in Louisiana. The Perth and Italian detectors have seen
    tantalising signs of possible signals but need even more sensitivity to be able
    to say, "We have detected gravity waves." Every major industrialised country is
    building new and improved detectors. In the United States, half a billion
    dollars is being spent building two enormous gravity-wave detectors, one in
    Washington State, the other in Louisiana. The detectors are among the biggest
    machines ever made, with eight kilometres of vacuum tunnels through which
    powerful laser beams are used to detect vibrations a billion times smaller than
    the softest sound. Big new projects in Italy, France, japan, Germany, Britain
    and the Netherlands are underway, and physicists are in enormous demand to take
    part in this exciting challenge.
    In Australia, a consortium of physicists from Perth, Adelaide, Canberra,
    Melbourne and Sydney have been planning a modestly sized but very powerful new
    gravity-wave detector for a site at Gingin near Perth, with support from the
    West Australian government. The new detector will be able to match the much
    more expensive projects in the US and Europe because of a breakthrough in the
    use of artificial sapphire for high-power laser optics. So far, Australia is
    one of the world leaders in this field but many fear that, yet again, this
    country will fail to capitalise on its innovation and leadership.
    The Nobel Prize for the proof of the existence of gravity waves was only
    awarded in 1993. Still, they have not been directly detected, but physicists
    know they are onto something good -- just as in 1886, when Heinrich Hertz
    proved the existence of electromagnetic waves. He never guessed that radio and
    TV and mobile phones would have revolutionised the world 100 years later. We
    have no idea what will come out of this totally new spectrum, apart from lots
    of wonderful technological innovations like the sapphire clock -- the most
    stable clock in the world -- which came out of gravity-wave developments in
    Perth-and which now supports a new Australian high-tech export industry.
    David Blair is a physicist at the University of Western Australia. His new book, Ripples in a Cosmic Sea, co-authored by Geoff McNamara, tells the whole story. It was published by Allen and Unwin in October 1997.

    OCKHAM'S RAZOR - Radio National listeners should note that the importance of gravitational wave detection will get a tiny mention in a broader piece in which your trusty editor defends physics against the enemies of science; to be broadcast sometime in the next couple of months.