Science starts with curiosity. Learning happens by doing. Science flourishes where there is an encouraging environment.
These are our takeaways from the lecture delivered by Dr. Rainer Weiss, 2017 Nobel Prize Winner for Physics for his decisive contributions to the Laser Interferometer Gravitational-Wave Observatory (LIGO) detector and the observation of Gravitational Waves, at the Ontario Science Centre, Toronto on 28 November 2018. Dr. Weiss is a Professor Emeritus at Massachusetts Institute of Technology (MIT).
The lecture was delivered as a part of the “Charles Darrow Lecture Series” – a collaboration between the Royal Astronomical Society of Canada – Toronto Centre and the Ontario Science Centre. It was moderated by Dr. Sara Seager, a professor at the Massachusetts Institute of Technology who is doing pioneering work on extrasolar planets and their atmospheres.
Science Starts with Curiosity
The beauty of Dr. Weiss’s lecture on discovering Gravitational Waves from colliding black holes and neutron stars using LIGO was in its simplicity and elegance. Simplicity in scientific explanations comes from someone who understands the subject completely. It comes from someone who has built up that subject, derives joy in his work, and has advanced the science through decades of hard work, humility, and sacrifice.
On stage, Dr. Weiss was more of a teacher and a science communicator. He invoked that fundamental attribute in all of us: “Curiosity”. Asking “Why” followed by “How” is the start of all scientific journeys that lead to inventions and discoveries. What are Gravitational Waves? While Albert Einstein predicted the existence of gravitational waves in 1916 in his General Theory of Relativity, a century later, why did more than 1000 scientists from 20 countries collaborated to prove Einstien right? How did our understanding of the Universe advance when on 14 September 2015 LIGO detected gravitational waves resulting from the collision of two black holes 1.3 billion years ago?
To satisfy the curiosity of the audience Dr. Weiss used examples from everyday lives instead of laboratories. Dr. Weiss drew parallels between gravitational waves and waves produced by pebbles thrown into the water to show how they may appear moving forward but the particles are only oscillating up and down at the same place while relaying the energy forward. Calling them simply transverse waves would have deprived many in the audience to experience the joy of relating science in their everyday lives.
Even Arushi (9 years) could understand his lecture and ask questions about it. She asked if there was any difference in gravitational waves produced by a Black Hole and a Neutron Star, as the LIGO had detected far more black hole collisions than neutron star collisions.
To explain how the two arms of LIGO (each is 4 km long and are perpendicular to each other) are able to detect gravitational-waves strain (about 1/10,000th the width of a proton), Dr. Weiss gave an example of a rubber band. When stretched the points at end of the rubber band move more than points at the center. It was his way of explaining that “Constant Strain” is nothing but change in length divided by separation among the points. It made us appreciate why the arms of LIGO had to be made so long.
LIGO’s interferometers are sensitive and can measure tiny amounts of strains in their two arms perpendicular to each other. But how do the mirrors in the LIGO achieve stability? This time, Dr. Weiss made use of the pendulum – something familiar to most people. He asked people to go back and experiment by putting one pendulum below the other until 4 pendulums are suspended one below the other and see if that system is more stable than a single pendulum. This is how the mirrors which act as test masses in LIGO are suspended.
Learning is by Doing and through Failures
The balance between invoking curiosity and simply giving scientific answers is a fine one. Learning ultimately comes from years of doing and making things, whether they are space rovers, rockets, large hadron colliders (LHC) or even LIGO. The journey to learning is different from invoking curiosity. It requires dedication, hard work, and certain stubbornness to keep pursuing your goals even in face of constant failures or no success. Dr. Weiss and his team know it better than anyone else.
The initial LIGO (iLIGO) observatories collected data from 2002 to 2010 but no gravitational waves were detected. 9 years of hard work in pursuit of a single goal and finding nothing would be frustrating and disappointing for anyone.
But Dr. Weiss did not term it as a failure but a “Good Nothing”. Good Nothing teaches you why things did not work. It provides an opportunity to improve and make corrections and is very different from “Bad Nothing” where no learning happens.
A number of lessons were learned from this “Good Nothing” on how to operate, maintain, and improve one of the world’s most highly technological measuring devices. And these proved invaluable in the construction of Advanced LIGO’s (aLIGO). The construction, preparation, and installation of aLIGO took 7 years (from 2008 to 2015).
On 14 September 2015, the efforts of Dr. Weiss and thousands of scientists were ultimately rewarded by LIGO event: GW150914. LIGO observed ripples in the fabric of spacetime from 2 colliding black holes of around 36 and 29 solar masses that happened 1.3 billion years ago. Gravitational waves from some of the most violent and energetic processes in the Universe were discovered.
Persistence of the LIGO team and science won! Einstein proved correct once again!
Science needs an Encouraging Environment to Flourish
Dr. Weiss’s passion for science was contagious. He is looking forward to the next phase of LIGO – new LIGO detectors are coming up in India and Japan. As more LIGO detectors come online, they would improve the accuracy in locating which part of the skies the gravitational waves that were detected originated from. He is confident that they can improve the sensitivities of LIGO to have new detections every day or even every few minutes. This would improve multimessenger astronomy where observers would be able to observe the collision of neutron stars in different ways (in different wavelengths, through gravitational waves and even neutrinos). This would bring greater collaboration between different projects with the ultimate goal of improving our understanding of the Universe.
LIGO has paved the way for new generation of detectors, including space-based interferometers such as Laser Interferometer Space Antenna (LISA) and those using timings of pulsars for detecting gravitational waves. The ultimate goal is detecting primeval gravitational waves in the signature of the Cosmic Microwave Background through Polarization B Modes.
Dr. Weiss talked about the importance of surrounding yourself with people who derive joy in your projects and share your passion. They would lessen the disappointments which come when things do not work and give you strength to stay on track and keep pursuing science.
This was especially important in the journey of Dr. Weiss who came up with the initial design for LIGO some 50 years ago. To test his idea, Weiss initially built a 1.5-meter prototype. But to truly detect a gravitational wave, the instrument would have to be several thousand times longer and to realize this audacious design, Weiss teamed up in 1976 with noted physicist Kip Thorne at Caltech. Barry Barish soon joined the team as director of the project and was instrumental in securing funding for the audacious project, and bringing the detectors to completion. All three of them won the 2017 Nobel Prize for Physics.
Science flourishes in a society which encourages and nurtures scientific temperament. When LIGO was approved for funding by the National Science Foundation (NSF) in 1990, it was understood that it would likely take many years, or even decades for the observatory to reach its full potential. And yet it was an amazing decision of the National Science Foundation to provide long-term funding for the pursuit of fundamental science. The science which is not guided by commercial motives but for furthering our understanding of the Universe. And the outcomes of such science results are truly Global Public Goods. Everyone benefits from knowing a little more about the unknown.
It underscores how government involvement and funding can impact scientific advancement. The National Science Foundation’s multibillion-dollar budget funds thousands of research projects. It helps attract and retains students, scientists and researchers so that they can continue pursuing science without the pressure to make scientific results commercially viable.
We can remain science-driven civilization only if we make efforts to make science appealing to the younger generation by providing predictable and long-term funding and vision. There is no other alternative.
Thank you Dr. Weiss for encouraging us by signing our notes.