Linear Force Law: Back to Newton

1
Linear Force LawBack to Newton?

• Ofer Lahav
• University College London

2
Present Dark Energy or Modified Gravity?

LCDM
DGP
From low-z SN Ia peculiar velocities

Abate OL, arXiv0805.3160
3
Future Dark Energy Surveys (2010-2020)

one of five DES lenses
CTIO 4m the DES platform
4
Dark Energy 10, 90 or 320 years old?
5
Past back to Newtons Principia?
Weak field limit of GR F -GM/r2 ?/3 r
X

Lucy Calder OL AG Feb 08 issue http//www.star.
ucl.ac.uk/lahav/CLrev.pdf (revised)

6
Newton, Principa (1687, Book I, Proposition 77,
Theorem 37)
7
Forces inside and outside a spherical shell
CL 08
8
The Mach connection
Newton
Einstein
?!
Can we infer
9
Open Questions

• Should be Newton ( Hooke) be credited for the
  ?Lambda-term (linear force)?
• Why didnt Newton consider superposition of the
  inverse square and linear laws?
• Was Einstein aware of the linear force in
  Principia?
• Does the Machian connection between ? and the
  total mass of the universe hold a clue for the
  origin of Dark Energy?

10
Evidence for Dark Energy

• Observational data
• Type Ia Supernovae
• Galaxy Clusters
• Cosmic Microwave Background
• Large Scale Structure
• Gravitational Lensing
• Physical effects
• Geometry
• Growth of Structure
• Both depend on the Hubble expansion rate

H2(z) H20 ?M (1z) 3 ?DE (1z) 3 (1w)
(flat)