On September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) measured gravitational waves from the merger of two black holes, kicking off a new era of gravitational-wave astronomy. This was the first direct measurement of gravitational waves — ripples in space-time that Albert Einstein predicted 100 years ago in his general theory of relativity.
The LIGO project and gravitational-wave physics have long been a major focus of research at MIT, which operates the LIGO facilities with Caltech. MIT faculty have also played a large role in developing gravitational-wave science.
Below is an annotated collection of technical reports, peer-reviewed articles, conference papers, and theses freely available in the DSpace@MIT repository that describe work done at MIT in this field, from the earliest science to post-detection research. Included at the end are other useful resources.
Early ideas for gravitational wave detection
These papers, all published as Quarterly Reports of the Research Laboratory of Electronics, describe early ideas by Professor Emeritus Rainer Weiss to develop sensitive antennae to measure gravitational waves. Professor Weiss is one of the founders of the LIGO project.
The April 1972 report is of particular interest: Starting on page 54 Professor Weiss writes in great detail about the sensitivity and anticipated noise that can be expected in a kilometer-scale interferometer to measure gravitational waves. This report presciently describes almost all of the major challenges that must be overcome in order for such a detector to work, and lays the foundations for the next four decades of experimental research in this field.
The two reports included prior to April 1972 very briefly describe plans further developed in the April 1972 report. The reports from 1973 to 1978 are short progress updates on initial development of gravitational-wave interferometers, after which time the project was transferred to MIT’s Department of Physics.
“Initial LIGO” refers to the LIGO instruments in their first interferometer configuration, from roughly 2001 until 2010. During this time, the LIGO facilities in Hanford, Washington and Livingston, Louisiana, were significantly overhauled and upgraded. The term “Advanced LIGO” (see below) is used to describe the LIGO interferometers following this upgrade.
These papers from 2009* to the present cover instrument development and data analysis algorithms, as well as actual searches done by Initial LIGO instruments.
(*Why 2009? In March 2009 MIT faculty passed an open access policy, and after doing so they began making scholarly articles openly available in DSpace. The Initial LIGO papers are all in the Open Access Articles collection of DSpace@MIT; in this collection a majority of papers have been published since the policy passed.)
Advanced LIGO detector development
The process of upgrading the LIGO facilities to advanced detectors began in 2010, shortly after the conclusion of the final Initial LIGO data run.
These papers describe experimental work relevant to the development of the advanced detectors. Much additional work on the development of Advanced LIGO can be found in certain Ph.D. theses, linked below.
The discovery event
After the September 14 event (known as GW150914), researchers began a long process of data and detector validation in order to ensure the accuracy of the discovery and understand in detail the waves that LIGO measured.
Gravitational wave theory
Gravitational wave theory has been a major focus of research at MIT over the last decade and a half. These papers sample work done by faculty, postdocs, and graduate students on theoretical analyses of gravitational waves generated by sources like black holes and neutron stars, as well as analyses of astronomy and strong-gravity physics that can be enabled by gravitational-wave measurements.
Many students have written theses on topics related to gravitational-wave physics. This link goes to a collection of Ph.D., Master’s, and Bachelor’s theses on a wide span of topics in this field, from early studies of gravitational-wave antennae to technology development for Advanced LIGO and theoretical models of gravitational wave generation by important astrophysical sources.
LIGO’s database also includes companion papers related to the initial detection article that was published in the American Physical Society’s journal Physical Review Letters. Many of these articles will appear in DSpace@MIT after they’ve been accepted for publication.
— There were thousands of news articles after the detection event. A few notable ones that featured interviews with MIT researchers:
“Gravitational Waves Detected, Confirming Einstein’s Theory,” New York Times, Feb. 11, 2016.
“Gravitational Waves Exist: The Inside Story of How Scientists Finally Found Them,” on the New Yorker website, Feb. 11, 2016.
“What the discovery of gravitational waves means,” a TED talk by MIT physicist Allan Adams, February 2016.
“Music of the Spheres,” on the London Review of Books blog, by MIT physicist Scott Hughes, February 23, 2016.
Soon after scientists announced on February 11, 2016, that LIGO had detected gravitational waves, the MIT Libraries deposited the detection paper to the open access collection in DSpace@MIT. This was possible because the Libraries have a long-standing agreement with the American Physical Society in which the publisher automatically sends papers to DSpace@MIT soon after they’re published, for immediate open access.
In this case, researchers in the LIGO Scientific Collaboration had paid to release the article under a Creative Commons license, which allows anyone to download, share, or build on the work. “Why make it open access? Well maybe that doesn’t need much explanation — for the most important publication in the life of the collaboration, the only reason not to is that it costs us something, but there was never any question that we would pay for it,” says Peter Fritschel, LIGO’s chief detector scientist and co-chair of the team that coordinated work on the discovery paper.
We’ve received several comments about the DSpace paper from interested readers, including these:
“When I heard of the LIGO gravity wave detection, all I could find were these general articles, but no real details of the detection. Only through the open access I got from the notification I got from MIT was I able to quickly get the article. Thank you for doing the right thing and making this very significant discovery as a freely available article.”- independent researcher, US
“On September 14, 2015, our species developed new eyes—a new way to experience the world. My thanks to the faculty at MIT for making the details of this development available to all of us. Forty years ago, I studied general relativity at CCNY. I loved the elegance of the wave solution to the field equations. I am thankful that I have lived long enough to see the waves I imagined ripple through observational reality. Reading this paper erases 40 years (for a few minutes).” -interested amateur, Brooklyn, NY
The Libraries collaborated with MIT gravitational wave researcher Scott Hughes to create this guide, and also consulted with scientists from the MIT LIGO group. It would not have been possible without their input.
Questions or comments? Contact Katharine Dunn: firstname.lastname@example.org