The Galactic Halo: Bright Stars & Dark Matter

Will the Universe expand forever, or will it eventually re-collapse due to the relentless pull of its own gravity?

Professor Michael Turner, of the University of Chicago, will address this fundamental question at an international conference of over 100 astrophysicists when they meet in Canberra today.

Said Turner: 'Cosmologists have been trying to answer this question for more than 60 years. We are coming close to an answer, and it is much more interesting than just 'yes' or 'no.' In addressing this seemingly simple question cosmologists have:

• studied the nuclear reactions that took place seconds after the Big Bang;
  
• measured the slowing of the Universe's expansion;
  
• weighed giant clusters of galaxies; and
  
• measured the small variations in the intensity of the cosmic microwave background radiation.'

While we do not yet have a complete answer that meets the high standards of scientific certainty, we are reasonably sure that:

• Most of the matter in the Universe is not in the form of stars. Instead it is dark, with its presence revealed only by its gravitational pull.
• Ordinary matter, such as you and I are made of, accounts for only one seventh of this dark matter.
• The rest of the dark matter is comprised of elementary particles, left over from the earliest, fiery moments of the Big Bang.
• There is not enough dark matter to halt the expansion of the Universe;

But:

• The expansion of the Universe is speeding up rather than slowing down, due to the presence of an odd form of energy ('vacuum energy'), first discussed by Einstein.
• Taken all together, the mass-plus-energy of the Universe is equal to a critical value which makes space 'flat' rather than 'curved'. This is as predicted by the celebrated inflationary model of cosmology.

Professor Turner points out that a host of measurements are currently being made that will firm up (or bring down) this picture.

The Galactic Halo: Bright Stars and Dark Matter is an international meeting organised by Mount Stromlo and Siding Spring Observatories of the Australian National University. It runs over 17-21 August 1998 at the Australian Academy of Science in Canberra.

Michael Turner is the Chair of the Astronomy and Astrophysics Department, and the Bruce V. and Diane M. Rauner Distinguished Service Professor, at The University of Chicago. He is also a Scientist at the Fermi National Accelerator Laboratory. He has received his university's Quantrell Award for excellence in undergraduate teaching, and the Lilienfeld Prize of the American Physical Society for his research contributions and his ability to convey scientific results to experts and layman alike.

Media Contacts:

Before 17 August 1998:

Professor John Norris	Dr. Don Faulkner	Mrs. Fiona Aplin
Ph: (02) 6279 8034	Ph: (02) 6249 0258	Ph: (02) 6249 0266
Fax: (02) 6249 0233	Fax: (02) 6249 0233	Fax: (02) 6249 0260
jen@mso.anu.edu.au	djf@mso.anu.edu.au	director@mso.anu.edu.au

During the Conference (17-21 August 1998):

Becker House			Ph: 014 685 255 (Fiona Aplin)
Australian Academy of Science			Fax: (02) 6247 5373 (attention: Don Faulkner)
Gordon Street
Canberra City ACT 2601

Fixed line for phone interviews: (02) 6248 8872
(but please arrange interviews on mobile number above)

Third Stromlo Symposium web site: http://msowww.anu.edu.au/~tss.

Back to the main meeting page.