 |
28 April 2005
Our description of Nature, based on general relativity and the standard model of particle physics, contains two dimensionful parameters--the vacuum energy and the electroweak scale--that are tremendously smaller than expected, and are furthermore "finely tuned", in the sense that various huge contributions to their values must be chosen to cancel to one part in 10120 and 1030 respectively. Understanding the origin of these apparent tunings will almost certainly involve new physical principles, and has been a driving force for constructing extensions of the standard model over the past 25 years. The usual hypothesis has been that the tunings are only apparent, and that new dynamical mechanisms will be revealed which make the tininess of the vacuum energy and weak scale "natural".
An alternative possibility has recently gained attention--our universe is not unique, but only one of vast "landscape" of different possible ground states of a fundamental short-distance theory (like string theory). This opens up the possibility that the tininess of the vacuum energy and also perhaps the weak scale is a consequence of environmental selection effects in this multiverse.
In this talk I will discuss concrete theories for new physics suggested by each picture, with sharp experimental predictions for physics at the Large Hadron Collider set to begin operation in 2007.
Keynote Speaker
Respondent
|
|
