Dark 2002 and beyond 1 Dark Matter on Different Distance Scales

Salient aspects of the meeting are summarized, including our knowledge of dark matter at different cosmological and astrophysical distance scales, ranging from large-scale structure to the cores of galaxies, and our speculations on particle candidates for dark matter, including neutrinos, neutralinos, axinos, gravitinos and cryptons. Comments are also made on prospects for detecting dark matter particles and on the dark energy problem. The speakers at this conference have come from different backgrounds, from that of macrophysics namely astrophysics and cosmology, and from that of microphysics namely that of particle physics experiments and theory. We have come together to discuss a weighty subject namely the nature of most of the stuff in the Universe. In this brief summary, I shall not be able to do justice to all the interesting talks we have heard, and I apologize in advance to those whose work is unjustifiably underemphasized. Inevitably, my summary adopts personal points of view, that you may not share. This talk is ordered according to a sequence of decreasing distance scales, from the overall size of the Universe at ∼ 10 pc down to the Planck length of 10 cm ∼ 10 pc. Astrophysical scales that we meet along the way include the ∼ 10 pc of clusters of galaxies, the ∼ 10 pc of galactic haloes, the ∼ 10 pc of the cusps of rotation curves, and the ∼ 1 pc of the central region of the Milky Way. Among the distance scales of particle-physics experiments that we meet are the ∼ 10 pc traveled by solar neutrinos, the ∼ 10 pc travelled by atmospheric neutrinos, the ∼ 10 pc of long-baseline neutrino experiments, and the ∼ 10 pc size of the LHC accelerator. Typical particle sizes we meet include the Compton wavelength ∼ 10 pc of the neutrino, the Compton wavelength ∼ 10 pc of supersymmetric particles, and the characteristic wavelength ∼ 10 pc of the ultra-high-energy cosmic rays. Somewhere along this trail, the puzzle of dark matter will surely be solved, even if we do not yet know where. 1 Dark Matter on Different Distance Scales 1.1 Cosmological Density Parameters As we have heard at this meeting, there is abundant evidence for the dominance of dark matter and dark energy on the largest distance scales. The cosmological