We pioneer new techniques to test and measure weak-field gravity, search for possible new interactions weaker than gravity and are involved in technology for LIGO.


1) Search for experimental signs of quantum gravity that violate Einstein's Equivalence Principle and/or the Newtonian inverse-square law.

2) Probe the largely unexplored region of possible interactions weaker than gravity.

3) Make sensitive tests for new interactions that couple to electron spin.

4) Develop sensitive low-noise instrumentation for the Laser Interferometer Gravitational Wave Observatory (LIGO).

Selected Publications:

A torsion-balance search for ultra low-mass bosonic dark matter (2021)
Initial Results from the LIGO Newtonian Calibrator
New Test of the Gravitational 1/r2 Law at Separations down to 52 μm Phys. Rev. Lett. 124, 101101  (2020)
Short-Range, Spin-Dependent Interactions of Electrons: A Probe for Exotic Pseudo-Goldstone Bosons Phys. Rev. Lett. 115, 201801 (2015)
Torsion-balance tests of the weak equivalence principle Class. Quantum Grav. 29, 184002 (2012), Phys. Rev. Lett. 100, 041101 (2008) 
Review of torsion-balance experiments Prog. Part. Nucl. Phys 62, 102 (2009)
Gravitational constraints on new particle physics Phys. Rev. Lett 98, 131104 (2007)
Test of gravity below 100 microns Phys. Rev. Lett 98, 021101 (2007)
Torsion Balance Test of Spin-Coupled Forces Physical Review Letters 97, 021603 (2006)
Review of Inverse Square Law Tests Ann. Rev. Nucl. Part. Sci., 53 77 (2003)
Measurement of the gravitational constant 
Phys. Rev. Lett 85 2869 (2000)

Eöt-Wash in the news:

LiveScience: Physicists who disproved '5th force' win $3 million 'Breakthrough' prize
Nature: Even at short range, Newton’s law still rules
Ars Technica: Experiment finds that gravity still works down to 50 micrometers
The Economist: The dark side of the universe
Nature: Frontier experiments: Tough science
Discovery Channel: Through The Wormhole with Morgan Freeman: Are There More Than Three Dimensions?
Physics for the 21st century: Gravity. Check out the video!!
Scientific American: String Theory's Extra Dimensions Must Be Less Than Half the Width of a Human Hair


Acknowledgement of Financial Support:

Our work is primarily supported by the National Science Foundation under Grant PHY-2011520, PHY-2012350, PHY-1812380. We are grateful for resources from the Department of Energy support for the Center for Experimental Nuclear Physics and Astrophysics. Our experiments are conducted on the University of Washington campus.