Summary of after the first three minutes

Abstract

Readers of the New York Times over the past few years have variously learned that: the Big Bang is dead; dark matter isn’t cold; the Universe is bubbly, spongy, periodic, replete with Great Voids, Attractors and Walls. And every six months or so obituaries appear for the CDM model of cosmic structure formation. The observational evidence for the Hot Big Bang model, for dark matter, for the large scale structure of the Universe as revealed by galaxy surveys and for the very large scale structure as constrained by microwave background observations was thoroughly explored in After The First Three Minutes. From this meeting we learned that: The Hot Big Bang model is healthier than ever. There is evidence from IRAS surveys that Ω≳0.5, but from Big Bang nucleosynthesis that ΩB≥0.07, suggesting a great deal of nonbaryonic dark matter exists, which cannot be vacuum energy (nonzero Λ). There are fewer viable candidates for cold dark matter (CDM) after the LEP results from CERN, but searches are still promising. Hot dark matter in the form of light massive neutrinos got a boost from the MSW solution of the solar neutrino problem.The standard ‘‘biased’’ CDM model, the ‘minimal’ inflation model with adiabatic Gaussian scale invariant fluctuations and cold dark matter, probably should have been ‘unbiased’ in its primordial amplitude all along — although some galaxy types and their relative velocities would be biased. The indications for extra density fluctuation power on large scales over that of the ‘minimal’ CDM model continue to firm up. The emerging dilemma is what can give the observed large scale structure, and yet such CMB isotropy on slightly larger scales. The key clue may reside in cosmological background radiation. All wavebands are being experimentally mined to unearth it. Energy injection models with hot gas or dust are already under pressure in the sub‐mm. The recuring invocation of the cosmological constant to solve our cosmological problems causes theorists to either shudder from the extreme fine tuning required or hope that resolution of the greatest unsolved mystery in physics will clarify our cosmology.