Two years ago, the National Research Council (NRC) laid out 11 key scientific questions at the intersection of physics and astronomy in a report entitled "Connecting Quarks to the Cosmos" (see FYIs #67 and #68, 2002). Earlier this year, in response, an interagency working group of the National Science and Technology Council (NSTC) released a prioritized strategic plan for efforts across several government agencies to address those 11 questions. Exploring the nature of dark energy receives high priority in the new report. Other areas considered ripe for "immediate investment" are the study of dark matter, neutrinos, proton decay and the nature of gravity, while longer-term objectives include research into the heavy elements, nuclear astrophysics, the birth of the universe, high density and high temperature physics and high energy cosmic ray physics.
The Bush Administration's emphasis on setting milestones and measuring results of federal programs, spelled out in the President's Management Agenda, has led to a plethora of recent roadmaps and strategic planning documents for federal R&D investments. Some of these documents, like a report by a High Energy Physics Advisory Panel subpanel on long-range planning (see FYI #12, 2003), address only a specific discipline. Others, like the DOE Office of Science 20-year facilities roadmap (see FYI #150, 2003), span a broader range. The Interagency Working Group relied on many of these previous DOE, NSF and NASA planning documents for input as it determined what projects, facilities, and facility upgrades would be needed to address the 11 questions of the NRC report.
The new report, entitled "The Physics of the Universe: A Strategic Plan for Federal Research at the Intersection of Physics and Astronomy," is available at www.ostp.gov/html/physicsoftheuniverse2.pdf. According to OSTP Director John Marburger in a February 2004 letter accompanying the report, it represents "a new approach for coordinating and prioritizing research programs across the government to explore an emerging scientific frontier." The main participating agencies are DOE, NSF and NASA, although NIST and the National Nuclear Security Administration (NNSA) also receive mention.
The NSTC Interagency Working Group on the Physics of the Universe assessed priorities based on the potential for scientific advancement, the timeliness or urgency of each question, the technical readiness of projects, and the need to fill gaps in the suite of projects to address each question. The group "focused its work on the large-scale projects needed to support research activities aimed at understanding the physics of the universe," but noted that "concomitant investments in theory, simulation, data archiving, and user groups are essential" as well. It did not address cost and budgeting issues, nor how these projects fit in with goals, projects and facilities in other areas of physics or astronomy.
A summary of the report's recommendations in priority order, divided into near-term and longer-term efforts, follows. In the report, each recommendation is accompanied by a detailed discussion of the scientific question, relevant agency projects and proposals, findings that provide justification for the recommendations, and in many cases a suggested time frame for implementing the recommendation.
READY FOR IMMEDIATE INVESTMENT, DIRECTION KNOWN
Three projects to investigate Dark Energy are recommended: a still-to-be-defined NASA/DOE Joint Dark Energy Mission (JDEM); a study of "the weak lensing produced by Dark Matter" by a ground-based Large-aperture Synoptic Survey Telescope (LSST); and observations of galaxy clusters by space-based X-ray and ground-based Cosmic Microwave Background (CMB) observations.
Dark Matter, Neutrinos, and Proton Decay:
NSF and DOE should collaborate to "identify a core suite of physics experiments" for research into Dark Matter, neutrinos, and proton decay; and NSF should take the lead on conceptual development and formulation of a scientific roadmap for an underground laboratory facility.
Two efforts are recommended: enhanced numerical relativity research for more accurate simulation of gravitational wave sources; and "the timely upgrade of the Laser Interferometer Gravitational Wave Observatory (LIGO) and execution of the Laser Interferometer Space Antenna (LISA) mission."
NEXT STEPS FOR FUTURE INVESTMENTS
Origin of Heavy Elements:
The report calls for DOE and NSF to develop roadmaps for the proposed Rare Isotope Accelerator (RIA), and for "the major components of a national nuclear astrophysics program."
Birth of the Universe:
DOE, NSF and NASA should jointly develop "a roadmap for decisive measurements" of cosmic microwave background polarization.
High Density and High Temperature Physics:
NSF, DOE, NASA and NIST should generate a roadmap for major components of a "balanced, comprehensive" national high energy density physics program; DOE and NSF should develop a roadmap for upgrading the luminosity and maximizing the impact on high energy density physics of the Relativistic Heavy Ion Collider (RHIC); and at least one of NNSA's major compression facilities should include a high-energy, high-intensity laser capability "to observe and characterize the dynamic behavior of high-energy-density matter."
High Energy Cosmic Ray Physics:
DOE and NSF should work to "ensure that the Pierre Auger southern array [under construction in Argentina] is completed" and review its results to "consider plans for a possible northern array."