The Landscape "avant la lettre"

TL;DR

The paper addresses whether string theory yields a unique fundamental description or a vast landscape of vacua, and whether anthropic reasoning can select the observed Standard Model from this landscape. It advocates a large, non-unique landscape of string vacua and positions the anthropic principle as a natural selection mechanism, even suggesting that the landscape size could be bounded by less than about $10^{80}$ vacua and that the cosmological constant problem involves around $120$ orders of magnitude of tuning. The author’s historical perspective predates later flux-compactification results, framing the landscape as a potential paradigm shift in fundamental physics where uniqueness gives way to a landscape of ground states. This perspective emphasizes that understanding why our universe has its particular parameters may require mapping the landscape and its life-permitting regions, rather than deriving them from a single theory. The work also underscores the limits of current knowledge and the need for concrete formulations of how landscape features influence vacuum selection and observables.

Abstract

This is a translation of an inaugural speech given originally in Dutch in 1998. The topic of that speech, intended for a general audience, was what is now called "The Anthropic Landscape of String Theory".