Linear Force Law:Back to Newton?

Ofer Lahav University College London

Present: Dark Energy or Modified Gravity?

Abate & OL, arXiv:0805.3160

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From low-z SN Ia peculiar velocities

LCDM

DGP

Future: Dark Energy Surveys (2010-2020)

one of five DES lensesCTIO 4m: the DES platform

“Dark Energy”: 10, 90 or 320 years old?

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Past: back to Newton’s Principia?Weak field limit of GR:F = -GM/r2 + /3 r

X *

Lucy Calder & OLA&G Feb 08 issuehttp://www.star.ucl.ac.uk/~lahav/CLrev.pdf (revised)

Newton, Principa (1687, Book I, Proposition 77, Theorem 37)

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Forces inside and outside a spherical shell

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CL 08

The Mach connection

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Newton

Einstein

Can we infer ?!

Open Questions

• Should be Newton (& Hooke) be credited for the Lambda-term (linear force)?

• Why didn’t 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’?