John Templeton Foundation

AT TOP: According to string
theory, our universe is ten
dimensional. It can be often
represented as a product of our
4D spacetime and a 6D compact
Calabi-Yau space, which may
have very nontrivial topological
properties. The cover figure is a
3D representation of a specific
Calabi-Yau manifold called
quintic. It allows us to
appreciate the complexity of the
Calabi-Yau space, which is one
of the reasons for muti-vauum
structure of string theory.

Credit: Jean-Francois COLONNA
(CMAP/Ecole Polytechnique, FT
R&D, http://www.lactamme.

Home Approach Chair Participants

Contact: Mary Ann Meyers, Ph.D., Senior Fellow

The concept of a multiplicity of possible or actual universes is a very ancient one. In recent years, however, advances in physics and cosmology have given the “multiverse” idea a plausible scientific basis. Its new lease on life can be traced to the theory of inflation, which in its original form, suggested by Alan Guth, held that a split second after the Big Bang the universe abruptly jumped in size by a huge factor. Most theorists agreed that inflation could explain many puzzles about the structure and evolution of the universe. In the variant introduced by Andrei Linde, inflation spawns a network of branching “bubble” universes with different laws of physics operating inside of them. It has become fashionable to invoke some species of the multiverse theory to account for the well-known examples of parameter fine-tuning associated with the emergence of life in the observable universe where Earth has its home. A small group of physicists and philosophers met at Stanford University in the spring of 2003 to examine various conjectures spawned by multiverse theories. In the two years since the original gathering, scientific work on the subject, particularly in the context of string theory (the best candidate for the “theory of everything”), has proceeded apace. Stanford’s Leonard Susskind coined the term “stringy landscape”—the landscape of all possible vacuum states in string theory—for the set of ideas embedded in a paper by Shamit Kachru, Renata Kallosh, Linde, and Sandip Trivedi that gave strong arguments for string theory possessing a vast landscape of metastable vacua, each giving rise to a possible low-energy world with different physical laws and different values of the cosmological constant. Significant progress in investigation of the stringy landscape and counting the number of possible vacua was achieved by Michael Douglas of Rutgers University and by several other investigators. It seems undeniable that the possibility of a multiplicity of different universes raises deep scientific, philosophical, and theological questions. What can we say about the properties of different parts of the multiverse (different vacua) in string theory? How does the concept of the multiverse modify our understanding of the origin and the fate of the physical universe? Does the cosmos reproduce eternally? Will it, or some of its parts, eventually collapse and disappear? Can the multiverse theory be made consistent with Occam’s razor? Is the theory falsifiable, and if so, how? Can science ever provide an “ultimate explanation” for the “laws of nature”? What context of cultural and intellectual currents affect the way scientists today think about our world? Under the aegis of the John Templeton Foundation, sixteen researchers from several disciplines have again come together at Stanford to explore the difficult and interlocking questions that are currently enlarging our cosmic perspective so dramatically.