Sunday, February 7, 2016

Rumor of Gravitational Wave Detection.

One of the predictions of General Relativity (Einstein's theory of gravity) is the existence of gravitational waves. In theory, anytime a massive object accelerates (that is any motion that is not constant straight line motion and not simple rotation) it should generate gravitational waves. So in theory the universe should be filled with gravitational waves.

However despite years of trying, no one has succeeded in detecting them.

But in the past few days rumors have been circulating that LIGO, a project to detect gravitational waves, has finally succeeded.

Einstein thought gravitational waves would be impossible to detect, and in fact they have been difficult to detect. The tiny signals must be separated from other signals (such as earthquakes and passing trucks). Each time a potential signal is detected, a statistic analysis is performed. This in essence asks "What is the likelihood this a real signal, not something that only looks real." This is expressed in terms of "sigma". The higher the sigma, the more likely the signal is real.

According to the rumor, LIGO has in fact detected signals that exceed "five sigma." Normally results like this are not released until solid confirmation has been made, but one of the physicists spilled the beans.

This may prove to be false; but it seems to be real. We should know for sure on February 11th when an official report from LIGO is scheduled to be published.

Those of you living in or near Ann Arbor, might be interested in two upcoming lectures, which by a happy coincidence are on this very topic. Both are by Keith Riles, professor of physics at the University of Michigan.

Saturday, February 13 10:30am: "Gravitational Waves - Einstein's Audacious Prediction."

Saturday, February 20 10:30am: "The Hunt for Gravitational Waves - Was Einstein Right?"

Both events are held in rooms 170 & 182 Weiser Hall (formerly the Dennison Building), University of Michigan Central Campus, 500 Church Street, Ann Arbor, Michigan, 48109

See for more information about these lectures.


  1. LIGO consists of two installations: one in Livingston, Louisiana and one in Hanford, Washington. The following is a timeline of the events...

    18 September 2015 -- A set of improvements to LIGO have been completed. These improvements should make it easier to find gravitational
    waves. The first Observing Run of Advanced LIGO, called O1, starts.

    12 January 2016 -- O1 ends.

    4 February 2016 -- Supposedly two signals were detected after analysis of the O1 data: one at Livingston and one at Hanford. The two signals were separated by a short time interval as would be expected. Supposedly these signals are consistent with a binary black hole. This binary consists of two black holes, of 29 and 36 solar masses, swirling together and merging. The statistical significance of the signal is supposedly very high, exceeding the "five-sigma" standard that physicists use to distinguish evidence strong enough to claim discovery.

    I say supposedly, because we don't have direct confirmation of any of this. LIGO scientists have prepared a paper that is scheduled to appear
    in Nature. The normal procedure is to wait for the paper to appear; however Clifford Burgess (McMaster University) sends an email to his entire department. This email claims that a significant discovery has been made at LIGO and contains the details described above (which is the only reason we know any of this). Burgess admits he has not read the paper, but had talked with the LIGO scientists. Quickly news spreads.

    Note this isn't the first time. Lawrence Krauss, had leaked LIGO information earlier (on September 25 and again on January 11 to be specific). We will see if LIGO confirms this rumor, or not. Hopefully later this week.

  2. Earlier this morning, LIGO had a press conference. In short, LIGO in fact discovered the signals from a binary black hole. See