Milestone-Proposal talk:1972 - Rainer Weiss's Invention of the Gravitational Wave Antenna Used in the Large Interferometric Gravitational Observatory (LIGO)

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Advocates and reviewers will post their comments below. In addition, any IEEE member can sign in with their ETHW login (different from IEEE Single Sign On) and comment on the milestone proposal's accuracy or completeness as a form of public review.

Comments on Milestone Proposal -- Jbart64 (talk) 20:17, 4 September 2019 (UTC)

I am the Milestone Advocate for this proposal. I have worked closely with the proposer and other supporters, and my comments are already incorporated into the final proposal. I fully support this proposal.

This Milestone focusses on the 1972 initial conception of the design for the LIGO gravitational wave antenna. The efforts to construct prototype antennas spanned multiple decades and occurred in multiple locations, leading up to the construction of world-class observatories that are sensitive enough to detect gravity waves from astronomical phenomena. Hence, three plaque sites are proposed. The goal is to dedicate the plaques at the three operational observatories to commemorate the fifth anniversary of the detection of gravitational waves.

Rainer Weiss’ original copyrighted design for a Laser Gravitational Wave "antenna" is described in his 1972 report entitled "Electromagnetically Coupled Broadband Gravitational Antenna," Quarterly Progress Report, Research Laboratory of Electronics, MIT. 105: 54, which is available at This paper is notable since Weiss described in great detail the design and promise of using laser interferometry to detect gravitational waves. The paper laid out in 22 pages the blueprint for the Laser Interferometer Gravitational-Wave Observatory, which Weiss called an antenna at that time.

The Milestone proposal includes several supporting source documentation items, although many more are available. The successful implementation of this achievement resulted in the Nobel Prize in Physics being awarded to Weiss and two others (Barry Barish and Kip Thorne of Caltech), who worked to further develop and implement the initial concept. Quoting the Caltech announcement about their Nobel Prize award: “Today, no one disputes the fact that LIGO owes its very existence to Rainer Weiss.” (see Yet, the Milestone proposal comports with Milestone rules and focusses on the initial date of the achievement rather than the person. It thus recognizes the origins of the overall gravitational wave antenna concept, while quietly implying the successful work and contributions of the many thousands of people who enabled its successful development and implementation.

Therefore, while this Milestone is intended to be installed only five years after LIGO’s historic detection of gravity waves, it acknowledges nearly 50 years of work from conception (1972), through design, planning, testing and prototyping, as well as decades of research and engineering, invention and innovation, advances in computing, lasers, and optics, and especially the contributions of Barish, Thorne, and Weiss.

Since becoming operational through December 2018, LIGO has detected 11 gravitational waves: 10 from binary black hole mergers, plus the first detection of a collision of two neutron stars in August 2017 which simultaneously produced optical signals detectable by conventional telescopes. All 11 events were observed in data from the first and second observing runs of Advanced LIGO. (see The Virgo observatory joined the search and, on 14 August 2017, jointly detected with LIGO a binary black hole merger, followed by a binary neutron star merger three days later.

The LIGO and Virgo facilities are now working together in detecting gravity wave candidates. Because gravity waves propagate at the speed of light (which was only recently verified using these antennas), the waves arrive at each antenna at different times. By resolving these timing differences, it is possible to localize from which general direction these signals originated, and to alert other observatories where to conduct a search for that specific event. Since beginning its third observing run through 31 July 2019, the LIGO/Virgo collaboration has detected 18 binary black hole merger candidates and 4 binary neutron star merger candidates. (

Dave Bart Milestone Advocate

Expert Letter #1 Received by David Bart (Advocate) on Behalf of Committee -- Jbart64 (talk) 20:22, 4 September 2019 (UTC)

To: Members of the IEEE Milestone Award Committee From: Donald T. Gavel, PhD Re: Proposed LIGO Interferometer (Gravitational-Wave Antenna) Milestone Date: September 4, 2019

Dear Committee Members,

I would like to add my recommendation in support of the proposal for the recognition of the LIGO engineering achievement as being a significant milestone in the history of Electrical Engineering.

My own background is in optical engineering. I was affiliated with the University of California Observatories, now recently retired, as Director of the Laboratory for Adaptive Optics. Our laboratory developed state of the art high resolution astronomical instruments and electro-optics for the world’s largest ground-based telescopes. We fielded instruments at both the Keck and Gemini Observatories. Although I was not involved in the LIGO development, I am familiar with the types of optics technology used to achieve its extraordinary goals.

The detection of gravity waves from astrophysical processes requires an instrument of extraordinary accuracy, capable of measuring the strain of space to on the order of 10^-22. This is equivalent to measuring one kilometer distance to within the diameter of a proton. LIGO achieves this with an array of modern technologies that needed extreme development and calibration to meet the science goals. The LIGO antenna configuration is essentially a Michelson Interferometer operated in nulling mode. Typical such an interferometer set up in the lab could perhaps measure to accuracy of some number of pico meters (10^-12 m) using precision optics (we set up one in our lab that achieved 200 pico-meter accuracy over a 2 meter length, strain of 5x10^-13). To get to LIGO level, the engineers incorporated additional non-traditional techniques. First, the end mirrors are Gires-Tournois etalons, which have the function of greatly amplifying the phase shift in departure from null and so increasing the instrument’s sensitivity to strain by orders of magnitude. Secondly, a power-recycling scheme is used to boost the 20W of source laser light to on the order of 100 kW of circulating coherent light within the interferometer, which greatly increases the signal-to-noise. With these and other components all produced with extraordinary engineering quality and calibrated very carefully, the system is able to reach the desired 10^-22 science sensitivity level.

The first prototype gravitational wave detectors based on a light wave interferometer were developed in the 1960’s by aerospace engineer Robert Forward at Hughes Research Laboratories. After experiments in the 1970’s, the initial LIGO proposers, MIT Physics professor Rainer Weiss and colleagues deduced that the extraordinary sensitivity needed to detect astrophysical gravity waves was achievable with then available technology [Linsay, Saulson, and Weiss, “A Study of a Long Baseline Gravitational Wave Antenna System” Report to the National Science Foundation, October 1983]. Rainer Weiss, Kip Thorne, and Barry Barish won the 2017 Nobel Prize after the first successful gravity wave detection in 2016, and several other top prizes were awarded to LIGO science groups including the Gruber (Cosmology) and Kavli (Astrophysics) awards. That having been said, what is proposed here is that advanced LIGO is an extraordinary Engineering achievement, on par with the great achievements in the IEEE Milestone series. Although not itself an electrical technology that directly affects society through commercial application, the LIGO antenna development does, greatly, impact society by providing a giant scientific advance. It has enabled, for the first time, mankind’s use of the fourth force of nature, gravity, as a probe of the universe.

It should be noted that the advanced LIGO (aLIGO) improvements, implemented in the 2010-2016 time frame, brought system sensitivity to a level that enabled observing diverse types of astrophysical events with gravity waves. In addition to observing black hole mergers, it can also detect neutron star mergers, which could be simultaneously observed in the electromagnetic spectrum and with neutrinos. Thus the extra engineering that went in to aLIGO (an improved end-mirror suspension system) resulted in a versatile observatory. LIGO has since detected at least 11 gravity events one of which was “multi-messenger” (neutron star merter detected also in Gamma rays). The diverse observations contribute to our understanding of large-scale gravity events and provides additional confirmation of the theory of general relativity.

Expert Letter #2 Received by David Bart (Advocate) on Behalf of Committee -- Jbart64 (talk) 20:43, 4 September 2019 (UTC)

CALIFORNIA INSTITUTE OF TECHNOLOGY DIVISION OF PHYSICS, MATHEMATICS & ASTRONOMY LAURITSEN LABORATORY High Energy Particle Physics & Quantum Information Science and Technology CERN, Compact Muon Solenoid Collaboration(CMS) Alliance for Quantum Technologies - Intelligent Quantum NEtworks and Technologies (INQNET)

Maria Spiropulu 1200 East California Blvd Pasadena,CA 91125

IEEE History Committee IEEE Milestones Proposal: 1972-Rainer Weiss’s Invention of the Gravitational Wave Antenna Used in the Large Interferometric Gravitational Observatory(LIGO)

August 29, 2019

Distinguished Colleagues:

I was very impressed to learn of the IEEE Milestones Program and I most strongly and enthusiastically support the IEEE Milestones Proposal: 1972-RainerWeiss’s invention proposal.

In reviewing the citation, I find the while "Antenna" is not inaccurate, it deviates unnecessarily from the standard physics and engineering nomenclature used for this detector. Hence, I would suggest to revert to the widely known terminology: "Invention of the Gravitational-Wave Interferometer, 1972".

The proposal presents full evidence that Weiss is the primary inventor of the interferometer. He conceived it in great detail, identified all the worst noise sources, described how to deal with each, and estimated the resulting sensitivity. Weiss did all this and his amazing 1972 paper, cited appropriately in the IEEE proposal.

The proposed Milestone is a feat of engineering and physics that offered technology for un- precedented precision measurements and devices which established a novel cosmic observatory. The proposed milestone is indeed a technology leap that enabled the major and many by now, discoveries of LIGO and the foundation for the beginning of a new era in astronomy, astro-physics and gravitational physics.

If you have any questions please do not hesitate to contact me-

Sincerely Yours, Signed

Maria Spiropulu Shang-Yi Ch’en Professor of Physics, California Institute of Technology Caltech HEP PI / Chair, Caltech Faculty Board PI/Founder AQT/INQNET Chair,Fermilab Physics Advisory Committee / High Energy Physics Advisory Panel Chair, APS Nominating Committee / APS, Physics Policy Committee Fellow, APS, (2014) / Fellow, AAAS (2010)

Updated References -- Willie.from.texas (talk) 15:34, 6 September 2019 (UTC)

The html links were provided for the Virgo references #4 and #5. Two new Virgo references #11 and #12 were added.

General: Title, Dates and Citations -- JaninA (talk) 11:28, 14 September 2019 (UTC)

The discovery of Gravitational Waves was a great breakthrough in Astrophysics and at the right time, 100 years after Einstein's theory. The Nomination presents the invention of the Gravitational-Wave Interferometer in 1972, subsequent developments of working systems in three places, 1994-201,7 and first measurements of gravitational waves (2015-2017). Quoting from the nomination: "What features set this work apart from similar achievements? There are no other similar achievements. The direct measurement of gravitational waves is a fundamental achievement”).

However the Title of the Milestone is only for the invention in 1972! If it really is, the plague should be at MIT where R.Weiss worked and where Weiss developed the prototype.

I find this contradiction confusing. And suggest: to change the dates to 1972-2017, change the Title accordingly to Invention, Development and Detection, or similar. Also to add words "a part of LIGO program" to Citation of the first two plagues and explain what is LIGO in the third Citation.

Information on plagues' location and access is not complete.