I am a Professor in the physics department at
UCSD, and the Associate Director of
CASS, the Center for
Astrophysics and Space Sciences.
From 2003–2020, I led the APOLLO project
as an ultra-precise test of General Relativity using the technique of lunar
laser ranging. My interests are transitioning to quantitative assessment of
the challenges associated with long-term human success on a finite planet.
In November 2021, I was one of five founders of the Planetary Limits Academic Network, aiming to connect scholars from all disciplines who are concerned about the deep systemic challenges humanity faces this century. Our "launch" paper gives the background, titled Modernity is Incompatible with Planetary Limits: Developing a PLAN for the Future.
In 2014, I started a company (Aircraft Avoidance Systems) to provide
safety devices for observatories using lasers for scientific research.
My apologies for a bare-bones and infrequently updated personal page. See also the official bio on the CASS Website.
Energy And Human Ambitions on a Finite Planet
I released a new textbook in March 2021 addressing the challenges facing
humanity this century relating to growth, energy resources, and human factors.
The book is available as a free PDF at eScholarship, and as a paperback (at print-cost) at
A page on this site is also provided for submitting corrections and other feedback.
Selected Publications (PDF)
BASH Compendium: collection of CASS e-mails from Nathan Johnson about weekly social hour
- Review of Lunar Laser Ranging: Reports on Progress in Physics, 76, p. 076901 (2013)
- Description of the APOLLO instrument: P.A.S.P., 120, p. 20 (2008)
- Millimeter Range Performance: Classical and Quantum Gravity, 29, 184005 (2012)
- Absolute Calibration System for APOLLO: Classical and Quantum Gravity, 34, 245008 (2017)
- Gravitomagnetism in the lunar orbit: Phys. Rev. Lett., 98, 071102 (2007)
- Gravitomagnetism perspective: Space Science Reviews, 148, 217, (2009)
- Finding the lost Lunokhod 1 rover: Icarus, 211, 1103, (2011)
- Degraded lunar reflector performance: Icarus, 208, 31, (2010)
- Eclipse observations confirm reflector dust: Icarus, 231, 183, (2014)
- Thermal effects on corner cube reflectors: Applied Optics, 51, 8793, (2012)
- Diffraction and polarization properties of corner cube reflectors: Applied Optics, 52, 117, (2013)
- A transponder-based aircraft detector (TBAD): P.A.S.P., 124, 42, (2012)
Do the Math Blog on Energy, Growth, Options
Have a Revolutionary Idea?
If you are contemplating sending your physics idea to me, first
try taking this quiz and see how it fares.