Alan J. Weinstein

Professor of Physics
A.B., Harvard University, 1978; Ph.D., 1983. Assistant Professor, Caltech, 1988-95; Associate Professor, 1995-99; Professor, 2000-.

My research focus in recent years has been in the search for gravitational waves (GWs) using the Advanced LIGO detectors, within the LIGO Scientific Collaboration.

GWs are produced by the most extreme environments and events in the universe, where gravitational fields are strongest and most repidly changing: black holes and the earliest moments of the Big Bang. GWs from neutron stars probe all the fundamental forces of nature, at energies and densities unobtainable in the laboratory.

I lead the gravitational wave astrophysical data analysis group at LIGO Laboratory, Caltech. Our group works in all aspects of the subject:

  • characterizing the performance and improving the quality of the data from the Advanced LIGO detectors;
  • studying the fundamental properties of GWs from astrophysical sources, and searching for properties beyond those predicted by General Relativity;
  • searching for GW signals from the inspiral and merger of compact binary systems (neutron stars and/or black holes) in distant galaxies;
  • studying the properties and populations of these systems using Bayesian inference; 
  • rapidly searching for electromagnetic (optical, x-ray, gamma ray, radio) counterparts to events detected in GWs to better understand the sources ("multi-messenger astronomy");
  • searching for GW burst signals from core-collapse supernovas in our galaxy and the Local Group, and studying the properties of those events;
  • searching for GW signals from spinning neutron stars in our galactic neighborhood, and using them to test General Relativity;
  • searching for GW signals from the Big Bang and from many weakly emitting astrophysical sources.

Our group works closely with the Caltech LIGO Laboratory Instrument Science group led by Prof Rana Adhikari , the Caltech TAPIR group led by Profs Christian Ott and Yanbei Chen, colleagues in Caltech Observational Astronomy, and colleagues in the LIGO Scientific Collaboration and its partner experiments around the world.

I have been involved in LIGO since 1998. From 1980-2000, I worked in experimental particle physics with high energy colliders (at SLAC, SCIPP, Cornell, and CERN), focusing on the physics of the heavy charm and bottom quarks, the heavy tau lepton, the properties of the Z0 weak boson, searches for the Higgs, and silicon tracker technology. From 2000-2004, I dabbled in observational cosmology with the SNAP space telescope; but NASA didn't give it a go. My interests lie in physical phenomena far removed from the human experience: the physics of the very small, and of the very large.

From 1998 - 2005, I led the development of the 40 meter laser interferometer prototype GW detector on the Caltech campus, which successfully tested a suite of Advanced LIGO technologies (mostly in sensing and control of the signal- and power-recycled Fabry-Perot Michelson interferometer configuration) which helped inform the final design of the detectors we have today.

I worked on the first searches for GW bursts in LIGO data.  I served as co-chair of the Compact Binary Coalescence (CBC) working group of the LIGO Scientific Collaboration (LSC) for five years in 2008-2013, during the last runs of Initial LIGO and the exciting Big Dog blind injection exerciseCurrently, I lead the LIGO Open Science Center (LOSC) and the LIGO Laboratory SURF REU program (around 30 undergraduates each summer at Caltech, LHO and LLO).

Much of my focus these days is on efficiently searching for binary black hole merger events in Advanced LIGO data. Our group must ensure the high performance of our advanced detectors and the quality of its data; find GW signals in advanced detector data as effectively and convincingly as possible; and exploit them for the best science we can do.

In Fall of 2015, my colleagues and I in the LIGO Scientific Collaboration made the first confirmed detections of gravitational waves, from the inspiral and merger of binary black holes in distant galaxies, and we have studied the properties of these events extensively. Me and our Caltech group played major roles in this endeavor. This is much more to come!

In recent years, I have been teaching junior-year classical mechanics (Ph 106), sophomore physics (Ph 12 - Waves, Quantum Mechanics, Statistical Mechanics), and Freshman Seminars on the physics and astrophysics of gravitational waves; frontiers of high energy physics ("the physics of the LHC"); and cosmology and astrophysics with open data. In the past, I have taught junior-year Quantum Mechanics (Ph  125), high energy astrophysics (Ay 125), particle physics (Ph 135), and Freshman Seminars on "Major Unsolved Problems in Fundamental Physics" (Ph 4).



Selected Awards: 
Fellow of the American Physical Society (Division of Gravitational Physics), 2015
Ph 12 abc. Waves, Quantum Physics, and Statistical Mechanics. 9 units (4-0-5); first, second, third terms. Prerequisites: Ph 1 abc, Ma 1 abc, or equivalents. A one-year course primarily for students intending further work in the physics option. Topics include classical waves; wave mechanics, interpretation of the quantum wave-function, one-dimensional bound states, scattering, and tunneling; thermodynamics, introductory kinetic theory, and quantum statistics. Instructors: Weinstein, Filippone.
FS/Ph 4. Freshman Seminar: Astrophysics and Cosmology with Open Data. 6 units (3-0-3); first term. Astrophysics and cosmology are in the midst of a golden age of science-rich observations from incredibly powerful telescopes of various kinds. The data from these instruments are often freely available on the web. Anyone can do things like study x-rays from pulsars in our galaxy or gamma rays from distant galaxies using data from Swift and Fermi; discover planets eclipsing nearby stars using data from Kepler; measure the expansion of the universe using supernovae data; study the cosmic microwave background with data from Planck; find gravitational waves from binary black hole mergers using data from LIGO; and study the clustering of galaxies using Hubble data. We will explore some of these data sets and the science than can be extracted from them. A primary goal of this class is to develop skills in scientific computing and visualization - bring your laptop! Instructor: Weinstein.
Ph 20. Computational Physics Laboratory I. 6 units (0-6-0); first, second, third terms. Prerequisites: CS 1 or equivalent. Introduction to the tools of scientific computing. Use of numerical algorithms and symbolic manipulation packages for solution of physical problems. Python for scientific programming, Mathematica for symbolic manipulation, Unix tools for software development. Instructors: Mach, Weinstein.
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