- #1
- 24,775
- 792
http://arxiv.org/abs/astro-ph/0605173
Steinhardt Turok, inventors of colliding brane cyclic ("ekpyrotic") universe, have followed Smolin's lead in proposing an EVOLUTIONARY MECHANISM that relaxes the cosmological constant down to near zero.
It is not a "natural selection" mechanism with differential reproduction rates but it is a mechanism by which Lamda repeatedly evolves towards lower values in later editions of the universe.
Abstract: "... In this paper, we show that a cyclic model of the universe can naturally incorporate a dynamical mechanism that automatically relaxes the value of the cosmological constant,...
..., nearly every volume of space spends an overwhelming majority of the time at the stage when the cosmological constant is small and positive, as observed today."
Page 12, conclusions: "... our result is a universe in which the cosmological constant Lambda(t) is an ultra-slowly varying function of time t and in which virtually every patch of space proceeds through stages of evolution that include ones in which Lambda(t) is small enough to be habitable for life. It is interesting to contrast this situation with the anthropic picture, especially versions based on inflationary cosmology, for which the fraction of habitable space is infinitesimally small. All other things being equal, a theory that predicts that life can exist almost everywhere is overwhelmingly preferred by Bayesian analysis (or common sense) over a theory that predicts it can exists almost nowhere...."
This article of Steinhardt Turok was published in journal Science 5 May 2006.
Some buzz was made of it on space.com here:
http://www.space.com/scienceastronomy/060508_mm_cyclic_universe.html
Steinhardt Turok, inventors of colliding brane cyclic ("ekpyrotic") universe, have followed Smolin's lead in proposing an EVOLUTIONARY MECHANISM that relaxes the cosmological constant down to near zero.
It is not a "natural selection" mechanism with differential reproduction rates but it is a mechanism by which Lamda repeatedly evolves towards lower values in later editions of the universe.
Abstract: "... In this paper, we show that a cyclic model of the universe can naturally incorporate a dynamical mechanism that automatically relaxes the value of the cosmological constant,...
..., nearly every volume of space spends an overwhelming majority of the time at the stage when the cosmological constant is small and positive, as observed today."
Page 12, conclusions: "... our result is a universe in which the cosmological constant Lambda(t) is an ultra-slowly varying function of time t and in which virtually every patch of space proceeds through stages of evolution that include ones in which Lambda(t) is small enough to be habitable for life. It is interesting to contrast this situation with the anthropic picture, especially versions based on inflationary cosmology, for which the fraction of habitable space is infinitesimally small. All other things being equal, a theory that predicts that life can exist almost everywhere is overwhelmingly preferred by Bayesian analysis (or common sense) over a theory that predicts it can exists almost nowhere...."
This article of Steinhardt Turok was published in journal Science 5 May 2006.
Some buzz was made of it on space.com here:
http://www.space.com/scienceastronomy/060508_mm_cyclic_universe.html
Last edited: