6 research outputs found
Predictive Power of Strong Coupling in Theories with Large Distance Modified Gravity
We consider theories that modify gravity at cosmological distances, and show
that any such theory must exhibit a strong coupling phenomenon, or else it is
either inconsistent or is already ruled out by the solar system observations.
We show that all the ghost-free theories that modify dynamics of spin-2
graviton on asymptotically flat backgrounds, automatically have this property.
Due to the strong coupling effect, modification of the gravitational force is
source-dependent, and for lighter sources sets in at shorter distances. This
universal feature makes modified gravity theories predictive and potentially
testable not only by cosmological observations, but also by precision
gravitational measurements at scales much shorter than the current cosmological
horizon. We give a simple parametrization of consistent large distance modified
gravity theories and their predicted deviations from the Einsteinian metric
near the gravitating sources.Comment: 12 pages, Latex, to be published in New Journal of Physic
APOLLO: the Apache Point Observatory Lunar Laser-ranging Operation: Instrument Description and First Detections
A next-generation lunar laser ranging apparatus using the 3.5 m telescope at
the Apache Point Observatory in southern New Mexico has begun science
operation. APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation)
has achieved one-millimeter range precision to the moon which should lead to
approximately one-order-of-magnitude improvements in the precision of several
tests of fundamental properties of gravity. We briefly motivate the scientific
goals, and then give a detailed discussion of the APOLLO instrumentation.Comment: 37 pages; 10 figures; 1 table: accepted for publication in PAS