“What Can We Learn from Gravitational Waves?” – Tiffany Summerscales
Date: 27 August 2016
Speaker: Dr. Tiffany Summerscales
Position: Professor, Department of Physics, Andrews University
Topic: “What Can We Learn from Gravitational Waves?”
Venue: Garber Auditorium, Chan Shun Hall
Attendance: 64
Presentation: Dr. Summerscales, an AU alum, explained that gravitational waves were predicted by Einstein (“curvature in the fabric of space-time”). They had been shown to exist based on their effects on systems that produced them, but had not been measured themselves. Now they have been measured for the first time, and Dr. Summerscales was a member of the large team that did so. It had previously been demonstrated that light coming from distant stars is indeed bent by gravity, as observed during eclipses when light passed a large mass object (the sun). “Ripples” from an object through space are what we refer to as gravitational waves. They are, however, very faint. The most powerful waves cause a change in the width of an object the size of the earth of less than the diameter of a proton.
In this case, the team was able to measure the gravitational waves produced by a pair of neutron stars that spiraled into each other and then merged. She went on to describe the interesting effects of binary pulsars which will also interact and pull closer to each other.
In the United States the National Science Foundation has funded the construction of the Laser Interferometer Gravitational-Wave Observatory (LIGO) with detectors in Richland, Washington and in Livingston Parish, Louisiana. There are also gravitational wave detectors in Germany and Italy, and others under construction or planned in India, and Japan. There is even a proposal for one in space.
Dr. Summerscales showed the actual data received from the LIGOs during an observation run that took place from September 2015-January 2016, and how the data matched up well with expectations. The system they were viewing is some 1.3 billion light years away.
She also described some of the things that were learned, including that the black holes produced by the collapse of stars are unexpectedly big and that they is a much bigger population of black holes than was previously realized. They also demonstrated that stellar models with weak solar winds, which predict larger black holes, are more likely.
There were numerous questions. One asked whether she could guess the effects of this new knowledge on practical science in the future and whether it might be possible to harness the energy of gravitational waves. She noted that we are mainly learning more about the basic rules of the universe, while adding that gravity waves are so very weak that it’s hard to think we could harness them….”although never say never.” Some of the technology used in building LIGO also can have industrial implications.
When asked if the discovery caused any new thoughts about natural theology, Dr. Summerscales responded that she was not aware of any, except that she highlighted Einstein’s comment that the real miracle is that the universe is understandable.
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