Second detection of gravitational waves from a binary coalescence

Breaking news are all around the globe after yesterday's press conference by the LIGO/Virgo collaboration, which announced a second very solid gravitational-wave event on Boxing Day, Dec 26 2015, dubbed GW151226.

The waveforms of the 3 events detected by LIGO during O1 (the first observation run). GW150914 and GW151226 are events which are very solidly detected (at more than 5 sigma), whereas LVT151012 has a (small) probability of being a statistical fluctuation. From this page. The inspiral phase of the new event GW151226 lasted much longer than the original GW150914 (about 80 cycles in total)

I warmly suggest you to check this beautiful multimedia page, made by Marc Favata and his group.

As the LIGO/Virgo collaboration put it, the era of gravitational-wave astrophysics is officially started!

One cannot get rich with fundamental physics, they said...

..unless you make a landmark discovery such as the first detection of gravitational waves. In such case, you might win a $3 million Breakthrough Prize in Fundamental Physics!

The three funding fathers of LIGO, Ronald P. Drever and Kip. S. Thorne and Rainer Weiss, are going to share $1 million, and the other other $2 million will be split among 1,012 scientists who authored the milestone article in Physical Review Letters and a list of key contributors to the theoretical and experimental understanding of gravitational waves (Luc Blanchet, Thibault Damour, Lawrence Kidder, Frans Pretorius,
Mark Scheel, Saul A. Teukolsky, Rochus E. Vogt) without which LIGO outstanding discovery would not have been possible.

As Richard Feynman brilliantly put it:

This also applies to the economical reward that might following great discoveries, and it is probably the reason why reckless and economically inconvenient science is pursed: because it is passion driven rather than money driven.

Kudos to the LIGO/Virgo Collaboration!

Hey Grandma look: I finally study something that exists!

So much has been already written about today's announcement of the first direct discovery of the gravitational waves from two merging black holes by the advanced LIGO detector. Some examples:

[1], [2], [3] (this beautiful piece by my friend and colleague Emanuele Berti)

In Italian press: [1], [2], [3]

Exactly 100 years ago, Albert Einstein proved that his theory of gravity, General Relativity, predicted the existence of gravitational waves.

This is nothing but one of the most outstanding historic discoveries in science. However, since you can find much deeper posts on this topic, here are some random, not-so-serious, thoughts hastily written down while watching today's live streaming announcement (sorry for typos, this is written on the wings):

1) Look Grandma: I finally study something that exists!
[Last time someone told my grandma that maybe black holes didn't exist after all.. she literally cried!]

2) Wow, my field of research has finally become mainstream! [is this good of bad? Anyway, the largest lecture hall at the Physics Department at Sapienza was full 30 mins before the live streaming..that's pretty uncommon for something related to gravity...]

3) The first direct detection of gravitational waves is really great, but what is emitting these waves is even more interesting: these are two black holes orbiting each other, loosing energy through gravitational-wave emission and finally merging to form a final big black hole. All of this is beautifully predicted by Einstein's theory of General Relativity and required several decades of theoretical, experimental and computational work.

4) Now everyone claims they have predicted that the signal from a binary black hole merger would have been detected. Truth is, just 6 months ago nobody would have bet on this particular source.

5) Related to this, isn't it amazing how physics works? It takes just a single observation to completely change the paradigm that theorists have built over decades. Just 6 months ago very few people would have predict that LIGO -even in the case of a detection- would have been able to test General Relativity or just to make some science or astrophysics out of this discovery. Well, judging from the result of the paper published today (and the companion papers to come) this expectation was completely wrong.

6) Finally, my bets for the Nobel Prize (in random order)

Rainer Weiss, one of the founders of LIGO

Roy Kerr, who discovered the unique solution of General Relativity describing a spinning black hole

Kip Thorne, one of the cofounders of LIGO, and of the fathers of modern General Relativity
(plus one of the creator of the movie Interstellar)

Visit to EGO-VIRGO

A meeting of the theoretical and experimental groups of the Italian Institute for Nuclear Physics (INFN) working on the detection of gravitational waves and on theoretical aspects related to them was held at the European Gravitational Observatory (EGO) in Cascina, near Pisa.

The site hosts Virgo, a detector of gravitational waves which -in one year from now- will be ready to join its U.S. cousin Ligo in the decade-long search of gravitational waves from compact objects.

Me standing in front of one of the 3-km long arms of Virgo. Is the motion due to the passage of a gravitational wave? Hope not since the detector is still offline...

What is a gravitational wave?