Research

Understanding the fundamental physics from space observation
  • CMB anisotropy & polarization measurements
  • The dark sector: dark energy and dark matter
  • Probes of large scale structure
  • Links to early universe through string theories
  • Development of space and advanced intrumentation

Understanding the origin of the universe is one of the oldest human dreams but has only entered the realm of science quite recently. Our technological capabilities have advanced to the point of answering fundamental questions. Indeed it was only about 15 years ago that cosmology became regarded as a precision science when the COBE satellite showed the blackbody form of the cosmic microwave background (CMB) and discovered its anisotropies [Smoot et al. 1992]. In this sense this is a unique time in human history when we can truly start to unravel the mysteries of the universe. We are poised on the brink of understanding the fundamental science of the universe through a combination of advanced technology, observation and theoretical efforts coupled to computer simulations.

Measurements of CMB anisotropies and its polarization have been, by far, the most influential cosmological observations driving recent advances in current cosmology and are well recognized as a prime thrust area of cosmology. Besides the precise determination of the parameters of the 'standard cosmological model', these observations have also established some of the basic tenets of cosmology and structure formation in the universe. The anisotropy and polarization of the CMB are arguably the most promising probes of the physics that governs the earliest moments of cosmological evolution from the Big Bang, in particular the generation of primordial perturbations that seeded the large-scale structure in the universe. Observations of the CMB also independently probe the enigmatic dark energy content of the universe through the late integrated Sachs-Wolfe effect and secondary anisotropies like the Sunyaev-Zel'dovich effect and strongly complement supernovae distance-redshift measurements of the recent accelerating expansion. The CMB provides the foundation of our understanding of the large-scale structure in the distribution of matter gained through data from baryon acoustic oscillations and gravitational weak lensing.

In addition to the CMB measurement, in the last 10 years the major discovery in cosmology that the expansion of the universe is accelerating [Perlmutter et al. 1999, Riess et al. 1998] has been a paradigm shifting transformation in physics, impacting the foundations of quantum theory, gravitation, and cosmology. This has delivered a clear indication that there is physics beyond the Standard Model of Cosmology but has not revealed what it is - its origin and nature. Acceleration in the early universe (the inflationary epoch) and in the current universe (the dark energy epoch) are equally intriguing and fundamental. The National Academy of Sciences panel of the Beyond Einstein Program Assessment Committee identified understanding dark energy and the early universe as two of the most exciting and transformational science questions [National Research Council 2005].

The rich array of structure in the universe ? stars, quasars, galaxies, and clusters of galaxies - carries further information for understanding our universe and the physics that drives it. This can be analyzed in terms of the spectrum of overdensities and underdensities, known as the mass power spectrum, as a function of cosmic time or redshift. One leading approach to the measurement of the matter power spectrum is gravitational weak lensing, which traces dark matter directly, but can only be measured as a two dimensional projection. Another is galaxy clustering, including baryon acoustic oscillation features, either in redshift space or in angular position (perhaps supplemented by photometric redshift information), which has higher signal to noise, but requiring assumptions of how galaxies trace dark. Finally, on smaller scales and higher redshifts the quasar Lyα forest has proven to be the most effective.

These observational research efforts, along with LHC (Large Hadron Collider) experiment, will give significant implications on theoretical investigations of fundamental physics such as gravitation, quantum field theories and string theories. Recent theory developments suggest new viewpoints on the nature of space-time such as supersymmetry, extra dimensions, brane worlds and the holographic principle. The earliest universe probes the highest energies and may reveal new states of energy, topological defects such as cosmic strings. The extremely accurate observations of CMB by the PLANCK satellite mission can give critical evidence or constraints on them. The interaction of theory and data windows through inflation and dark energy scenarios, such as those involving supersymmetry breaking and grand unification, to uncover new physics.

Studying the early universe, the accelerating universe, and in turn deep space will open a new era of science; however this is not possible without significant improvement of present technology or breakthroughs in instrumental technology. Such innovative leading edge technologies are essential particularly in the field of micro/millimeter wave hardware, optics, sensor and detector, electronics, and even emerging interdisciplinary technologies such as MEMS and NEMS [Yoo et al. 2008].

In this project, we propose investigating the origin of early universe by integrating three main approaches: (i) active participation in the world-class satellite-borne experiments such as PLANCK and DEM (Dark Energy Mission) and related ground-based observations, (ii) theoretical investigation and modeling, (iii) development of space and advanced instrumentation for future observations which will have technological spin off. All these research programs have common ground in the development of high-performance computational algorithms and sophisticated analysis and software techniques for mining large data sets. The theoretical foundations unify and synthesize interdisciplinary fields of physics, mathematics, statistics, and computer science, and attract the brightest students, building up the national scientific infrastructure.

The main theme of implementation of this proposal is "interdisciplinary research" between the most fundamental science and the cutting edge technology, and among elementary particle physics, astronomy, astrophysics, and space science, and among precision microwave space technology, optics, semiconductor sensors, electronics, MEMS technologies, while pursuing to solve one of the most important and fundamental science problems.

Expected Research Outcomes

Academic development
Economic development
Social development