Nobel prize in physics given for gravity wave detection

To no one’s surprise, this year’s Nobel prize in physics has been awarded for the detection of gravity waves in September 2015. This was a huge project involving large numbers of experimentalists and theorists because the waves have such a weak signal. It is not unlike the earlier discovery of the Higgs boson in that the final detection was received with relief rather than surprise because both were firmly believed to exist. In the case of the Higgs, the prediction had been made fifty years earlier and with the gravitational waves, it had been made 100 years earlier, as a consequence of Albert Einstein’s General Theory of Relativity. The challenge in both cases was to overcome the immense technical hurdles involved in detecting them.

What made this detection possible was the building of a pair of extremely large and sensitive L-shaped detectors each about 4 km long in the states of Washington and Louisiana. Scientists then had to wait for some cosmic event on a massive scale to generate a gravitational wave signal powerful enough to be detected. This happened when two black holes with masses 29 and 36 times that of the Sun merged 1.3 billion years ago in the Southern Hemispherical sky to produce a single spinning black hole. In the process, a mass about three times that of the Sun was converted to gravitational energy in a fraction of a second and this was the source of the waves that were detected. The use of two identical detectors separated by about 3,000 km served two purposes: both receiving identical signals would eliminate the possibility of some spurious local effect that could mimic a gravitation wave; and the separate detection locations enabled scientists to triangulate and thus locate the source of the gravitational waves.

As with all such major big science projects, picking just three people to win the award out of the large number involved will cause some unhappiness for those who felt that they had made major contributions but were not selected, as was the case with the award for the Higgs where at least five people had legitimate claims (a sixth had died) but only two got it. The Nobel rules limit the number who can share a prize to at most three people who are not deceased. I have no opinion as to whether this years three winners Rainer Weiss, Barry Barish, and Kip Thorne are the most worthy but have no reason to doubt it either.

The Nobel peace prize sometimes goes to organizations such as Doctors Without Borders thus avoiding the task of picking an individual from a large group but that is not possible in science since scientific collaborations tend to be informal and transient.


  1. Rob Grigjanis says

    the separate detection locations enabled scientists to triangulate and thus locate the source of the gravitational waves.

    Two locations can only give the position within an annulus. They’d need at least three to pinpoint.

  2. says

    What Rob said.

    However, for the very latest set of observed waves, the new Virgo observatory (OK, old, but with a new upgrade giving more sensitivity) added the necessary third location and they really were able to “triangulate”.

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