Gravitational waves and the slow pace of scientific revolutions

[bsteadman]

Relativity changed everything, but it took its time in doing so.

ars TECHNICA
by John Timmer
6/30/2018

Excerpt:

LIGO's detection of gravitational waves came almost exactly a century after Einstein had formulated his general theory of relativity and an ensuing paper mathematically describing the possibility of gravitational waves. Or at least that's the story as it was presented to the public (including by yours truly). And in some ways, it's even true.

But the reality of how relativity progressed to the point where people accepted that gravitational waves are likely to exist and could possibly be detected is considerably more complicated than the simple narrative described above. In this week's Nature Astronomy, a group of science historians lays out the full details of how we got from the dawn of relativity to the building of LIGO. And, in the process, the historians show that ideas about scientific revolutions bringing about a sudden, radical shift may sometimes miss the point.

Has your paradigm shifted?

The popular conception of scientific revolutions (to the extent that it exists) was shaped by Thomas Kuhn. Kuhn described a process where data gradually pushes an existing theory into crisis, allowing nearly everyone to see it doesn't work. After a period of crisis, a revolution takes place and a new theory emerges. The theory's ability to solve all the problems that precipitated the crisis quickly draws support, and a new period of theory-driven—in Kuhn's language, "paradigm-driven"—science begins.

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View the complete article at:

https://arstechnica.com/science/2018...c-revolutions/

[bsteadman]

Gravitational Waves Detected 100 Years After Einstein's Prediction

LIGO - Laser Interferometer Gravitational-Wave Observatory

News Release • February 11, 2016

Excerpt:

LIGO Opens New Window on the Universe with Observation of Gravitational Waves from Colliding Black Holes

WASHINGTON, DC/Cascina, Italy

For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.

The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About 3 times the mass of the sun was converted into gravitational waves in a fraction of a second—with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals—the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford—scientists can say that the source was located in the Southern Hemisphere.


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View the complete article at:

https://www.ligo.caltech.edu/news/ligo20160211