MATTERS of GRAVITY, a Newsletter for the Gravity Community, Number 3
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MATTERS OF GRAVITY Number 3 Spring 1994 Table of Contents Editorial ................................................... ................... 2 Correspondents ................................................... ............ 2 Gravity news: Open Letter to gravitational physicists, Beverly Berger ........................ 3 A Missouri relativist in King Gustav’s Court, Clifford Will .................... 6 Gary Horowitz wins the Xanthopoulos award, Abhay Ashtekar ................ 9 Research briefs: Gamma-ray bursts and their possible cosmological implications, Peter Meszaros 12 Current activity and results in laboratory gravity, Riley Newman ............. 15 Update on representations of quantum gravity, Donald Marolf ................ 19 Ligo project report: December 1993, Rochus E. Vogt ......................... 23 Dark matter or new gravity?, Richard Hammond ............................. 25 Conference Reports: Gravitational waves from coalescing compact binaries, Curt Cutler ........... 28 Mach’s principle: from Newton’s bucket to quantum gravity, Dieter Brill ..... 31 Cornelius Lanczos international centenary conference, David Brown .......... 33 Third Midwest relativity conference, David Garfinkle ......................... 36 arXiv:gr-qc/9402002v1 1 Feb 1994 Editor: Jorge Pullin Center for Gravitational Physics and Geometry The Pennsylvania State University University Park, PA 16802-6300 Fax: (814)863-9608 Phone (814)863-9597 Internet: [email protected] 1 Editorial Well, this newsletter is growing into its third year and third number with a lot of strength. In fact, maybe too much strength. Twelve articles and 37 (!) pages. In this number, apart from the ”traditional” research briefs and conference reports we also bring some news for the community, therefore starting to fulfill the original promise of bringing the gravity/relativity community closer together. As usual I am open to suggestions, criticisms and proposals for articles for the next issue, due September 1st. Many thanks to the authors and the correspondents who made this issue possible. If everything goes well this newsletter should be available in the gr-qc Los Alamos bul- letin board under number gr-qc/9402002. To retrieve it send email to [email protected] (or [email protected] in Europe) with Subject: get gr-qc/9402002 (issue 2 is available as gr-qc/9309003). Or email me. Have fun. Jorge Pullin Correspondents 1. John Friedman and Kip Thorne: Relativistic Astrophysics, 2. Jim Hartle: Quantum Cosmology and Related Topics 3. Gary Horowitz: Interface with Mathematical High Energy Physics, including String Theory 4. Richard Isaacson: News from NSF 5. Richard Matzner: Numerical Relativity 6. Abhay Ashtekar and Ted Newman: Mathematical Relativity 7. Bernie Schutz: News From Europe 8. Lee Smolin: Quantum Gravity 9. Cliff Will: Confrontation of Theory with Experiment 10. Peter Bender: Space Experiments 11. Riley Newman: Laboratory Experiments 12. Peter Michelson: Resonant Mass Gravitational Wave Detectors 13. Robbie Vogt: LIGO Project 2 Open letter to gravitational physicists Beverly Berger, Oakland University I believe the time has come to create a Topical Group (TG) in Gravitation within the American Physical Society (APS). Substructures of the APS include Divisions (e.g. Particles and Fields, Nuclear Physics, Astrophysics), TG’s (e.g. Metrology, Laser Science), and Fora (e.g. Physics and Society). The APS constitution states “If at least two hundred members wish to advance and diffuse the knowledge of a specific subject or subfield of physics, they may petition the Council [of the APS] to establish a Topical Group.” If the membership of the TG becomes sufficiently large, the TG can then become a Division. Although the existing divisions of Particles and Fields and Astrophysics have interests which include various aspects of gravitational physics, their primary concerns lie elsewhere. There are many reasons to develop a TG at this time. Such a group would allow us to define and promote our interests and enhance our visibility within the larger community of physicists. The construction of LIGO and the Grand Challenge Supercomputing Project on the two black hole problem are only two examples of the significant developments in our field that render such advocacy essential. There are several other advantages to the formation of the TG. As a subgroup of APS, we would have access to APS public relations activities (e.g. press releases, lobbying) that might be marshaled for our benefit. Some of our local meetings and workshops (e.g. the Pacific Coast or Midwest Meetings) could become TG meetings with access to APS publicity and possibly support. Members of the TG could organize sessions at APS general meetings. The TG would be a distinct entity through which to support the positions and activities of the International GRG Society. (Many countries already have separate national general relativity societies.) Finally, members of the TG can nominate candidates to become APS Fellows. The procedures to form the TG are the following: As quoted above, a petition signed by 200 APS members requesting formation of the TG must be received by the Executive Council of the APS. (The signed petitions must be actual hard-copy rather than electronic mail.) The council, in consultation with existing APS divisions and TG’s may either accept or reject the petition. If the signatures are obtained and the petition is accepted, an organizational structure including TG officers and bylaws must be put into place. At that point, the TG comes into existence. Any APS member may join the TG for an additional $5 per year. 3 The APS is open to physicists of any nationality for an annual dues of approximately $80 per year (less for students, postdocs, and retirees). One benefit of APS membership is the opportunity to subscribe to some journals at a reduced rate. The list includes Physical Review, Physical Review Letters, Journal of Mathematical Physics, and Classical and Quantum Gravity among others. If you agree with the need to form a TG in gravitation and are an APS member please print out the attached petition, sign it, urge your colleagues who are APS members to sign it, and mail the completed petition to me. I also invite 10-20 public spirited theoretical and experimental relativists who are APS members to act as an ad hoc organizing committee. The function of this committee would be to generate the bylaws of the organizational structure required for the TG and to serve as an initial nominating committee for TG officers. I welcome your comments and questions. Sincerely, Beverly K. Berger Physics Department Oakland University Rochester, MI 48309 (810)370-3422, (313)971-0345 [email protected] 4 PETITION TO THE COUNCIL OF THE AMERICAN PHYSICAL SOCIETY We, the undersigned members of the American Physical Society, petition the Council of the American Physical Society to establish a Topical Group in Gravitation. Areas of interest to the proposed Topical Group include, but are not limited to, experiments and observations related to the detection and interpretation of gravitational waves, experimental tests of gravitational theories, computational general relativity, relativistic astrophysics, solutions to Einstein’s equations and their properties, alternative theories of gravity, classical and quantum cosmology, and quantum gravity. The purpose of the Topical Group is to provide a unified forum for these areas of current research which now span several Divisions of the Society. Signature Name(Printed) Affiliation Return to: Beverly K. Berger Physics Department Oakland University Rochester, MI 48309 5 A Missouri Relativist in King Gustav’s Court Clifford Will, Washington University, St. Louis The award of the 1993 Nobel Prize in Physics to Joseph Taylor and Russell Hulse of Princeton University for their discovery of the binary pulsar PSR 1913+16 puts a welcome seal of approval on general relativity. It was a long time coming. Einstein’s general theory has revolutionized our view of space and time and the universe. Yet the Nobel prize has never, until now, been awarded for work so directly related to general relativity. Even Einstein’s Nobel in 1921 was for his work on the photoelectric effect, not for relativity. Part of the problem is that theory is difficult to test, and the Nobel committees historically prefer to reward work that has had experimental confirmation. Until 1974, the solar system provided the principal testing ground for GR. However, the discovery of the binary pulsar in the summer 1974 [1] showed that certain kinds of distant astronomical systems may also provide precision laboratories for testing general relativity. The system consists of a 59 ms period pulsar in an eight-hour orbit with a companion that has not been seen directly, but that is generally believed to be a “dead” neutron star. The unexpected stability of the pulsar “clock” and the cleanliness of the orbit allowed Hulse and Taylor and later co-workers to determine the parameters of the system to extraordinary 3 accuracy. Furthermore, the system is highly relativistic (vorbit/c ≈ 10− ). Observation of o o 1 the relativistic periastron advance (4 .22663 ± 0 .00002 yr− ), and of equivalence-principle effects on pulse arrival times (gravitational redshift, time dilation – 0.07% accuracy) can be used, assuming that general relativity is correct, to determine the pulsar and companion masses, with the result mp = 1.4411 ± 0.0007M and mc = 1.3873 ± 0.0007M . The measurement of the rate of decrease of the orbital⊙ period in 1979 [2] gave the