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Real Science

Gravitational Waves

Michael Rosenthal

(5/2016) February 2016 was a landmark month for astrophysicists. Scientists from LIGO, the Laser Interferometer Gravitational-Wave Observatory, a worldwide team of scientists, along with a group of scientists from Europe known as the Virgo Collaboration, published a report in Physical Review Letters with more than 1000 authors, that they had heard and recorded the sound of two black holes colliding a billion light-years away. This fact confirmed the last prediction of Albert Einsteinís General Theory of Relativity.

The fact, esoteric to the non-scientist, is the first direct physical evidence of gravitational waves, the ripples in the fabric of space-time that Albert Einstein predicted a century ago. The piece of experimental data of which we are speaking is that power 50 times greater than the output of all the stars in the universe combined vibrated a pair of L-shaped antennas in Washington State and Louisiana last September 14. Spending on this project has been 1.1 billion dollars over the decades of its existence, awaiting a result.

In 1915 Einstein said that matter and energy distort the geometry of the universe, producing gravity. A disturbance in the cosmos could cause space-time to stretch, collapse, and jiggle like a mattress shaking when a sleeper rolls over, producing ripples of gravity, i.e. gravitational waves.

There have been some false starts toward achieving this result. In 1969, physicist Joseph Weber at The University of Maryland claimed to have detected gravitational waves, but his result could not be duplicated, an essential for scientists to prove a proposal. In 1978, Joseph H. Taylor Jr. and Russell A. Hulse at the University of Massachusetts Amherst discovered a pair of neutron stars that they proposed, from experimental observation, was radiating gravitational waves. Hulse and Taylor were awarded the Nobel Prize in Physics in 1993.

Further progress was slow, and agreement among the scientists was not obtained until a consolidation of several teams of researchers occurred in 1987. The current experimentation began in 2000 and ran for ten years. In the last five years, the entire system in its two locations was rebuilt to increase its sensitivity. The LIGO antennas are L shaped, with perpendicular arms 2.5 miles long. Inside each arm, enclosed in steel and concrete, is a vacuum chamber containing 2.5 million gallons of empty space. At the end of each arm are mirrors hanging by glass threads. The lasers can then detect changes in the length of one of those arms as small as one ten-thousandth the diameter of a proton (thatís really small!), as a gravitational wave sweeps through.

Unless the reader has a background in astrophysics, this highly acclaimed experiment seems so far away from everyday life that its importance seems vague. To scientists trying to understand the nature of the universe, however, this is one of scienceís greatest achievements.

Would you like to learn more about this accomplishment? There have been understandable articles in major newspapers, including The Washington Post and The New York Times, as well, of course in many scientific publications. An online search will turn up many reports of this experiment at varying levels of scientific complexity.

On a lighter and more amusing note, I have two Albert Einstein related stories to convey, more for amusement than for an understanding of physics. Both occurred during my years as a chemistry faculty member at Bard College in the Hudson Valley of New York.

One day, sitting in my office, a visitor was brought to my door by a college staff member. The visitor was the famed film director, Otto Preminger, visiting the Bard campus seeking a shooting site for a new film. I had in my office a dart board, and next to it was a photo of Albert Einstein, whom I revered as one of the greatest scientists of all time. Preminger saw it and suggested that I shouldnít be using Albert as a dart board! I explained that I never would have done such a thing. Was he joking? Iíll never know. He did not pick Bard College as his movie site.

Some years later, Bard College hired Dr. Abraham Gelbart, a distinguished retired mathematician and science administrator from Yeshiva University in New York, to join the faculty in a limited post-retirement capacity. As I was Chair of the Science Division, Abe and I became colleagues, and we and our spouses became good friends. Abe and I jointly created a Distinguished Scientist Lecture Series, for which we obtained National Science Foundation funding, which brought many Nobel laureate scientists to campus to speak, possibly because a number of them were personal friends of Abeís. It was a wonderful experience for all of us, students and faculty alike, at Bard. Among other professional activities, Abe told me that he had worked at The Institute For Advanced Study in Princeton, New Jersey, where "he assisted Albert Einstein with his mathematics." Meeting those scientists, many of whom were Nobel Prize winners, was a uniquely remarkable experience for us in the Bard College community. In the course of their visits we knew them as people, brilliant people, but with the same range of personalities as other humans. Some were certainly more likable than others! What a wonderful opportunity it was for our students to be exposed to so much scientific genius!

Weíve written about a number of energy sources in previous columns, addressing their advantages and disadvantages. This now gives me added incentive to look at the energy source report that comes with my monthly electric bill from Potomac Edison. My latest report states that coal and nuclear are the leading sources of my electricity here in Emmitsburg, with coal providing 36.58% and nuclear 35.77 % of our electricity. Next in line is gas with 22.98%. Oil produces a miniscule 0.28%, and non-renewable fuel cells 0.03%. This adds up to 95.64 %. Renewable energy sources, which include captured methane gas, hydroelectric, solar, solid waste, wind, wood or other biomass, adds up to 4.36%. Also listed on the report are air emissions, which report low levels of sulfur dioxide and nitrogen oxides (thatís good!), which contribute to acid rain. But there was a sizable amount of carbon dioxide, the greenhouse gas that certainly (in my mind) contributes to climate change. The Potomac Edison report states "CO2 is a "greenhouse gas," which may contribute to global climate change."

To close, letís follow up on the impact of the Flint, Michigan water crisis, which I wrote about in March. Since then, an increased consciousness has brought to light many more cases of drinking water contaminated by lead, which was leached from lead pipes. A New York Times editorial in March reported on high levels of lead in the Newark, New Jersey, public schools, existing for years. Higher than safe lead levels have also been detected in school districts in Washington, D.C, Seattle, and Los Angeles; bottled water has been used in schools in Baltimore and Camden, New Jersey. Older school buildings often have lead pipes. It makes me wonder about the 1940s house in which I grew up and my grade school drinking fountain in Youngstown, Ohio!

Michael is former chemistry professor at Mount. St. Marys

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