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 CERN

I am just back from CERN, where I stayed over this week to visit Diego Blas at the CERN THeory Division and to give the talk "Compact Objects as Dark-Matter Probes".

Some sparse thoughts on the visit:

1) On the first night, I checked in at a hotel in Geneva instead of staying at the CERN hostel. That was a very bad move. Everything in Geneva is unbelievable expensive and the hotel (albeit 3 star and averaged rated) turned out to be quite bad. I got bed bugs, i am still full of pinches, and i'm still trying to disinfect my clothes at home...

2) On the other hand, the hostel at CERN (where I stayed for the rest of the week) was excellent. The room was clean and cozy and equipped with a large desk. Everything at CERN seems to be designed to simply researchers' life and work.

3) I was impressed by the low average age of people working at CERN. About 10K work at the center and most of them are young PhDs or postdocs. The comparison with the average Italian university, where most of the faculty members and staff are over 40, is impressive. I recently read an interview by CERN Director Fabiola Gianotti, who was precisely commenting on this fact. However, experiencing it directly is a different kettle of fish.

4) Although CERN is big and experiments are scattered around a 27-km underground ring, I enjoyed the fact that most offices are located in a handful of buildings which are connected among each other. This basically means that theorists can chat over a coffee with experimentalists, or that it is easy to attend the (enormous) number of talks and lectures that are organized on a daily basis. The canteen is also common for all buildings and researchers from different collaborations and experiments meet there to have lunch (and sometimes dinner) together.

5) Overall, the atmosphere is definitely suggestive, even for someone like me who's used to see so many physicists in the same place (I guess that for the numerous students who regularly visit CERN during a school trip it must be really a unique experience).

6) I had the opportunity to meet various friends with whom I went to college in Cagliari (some of them are also authors of this blog). Funny enough, the excess of physicists from Cagliari University, especially in the LHCb experiment, is beyond 5 sigma. Thus, I had the opportunity to visit the LHCb experiment and control room, as this picture testifies:

Visit to the LHCb experiment. 
From the left to the right: Andrea (aka Scrilly), Francesco (both CERN Fellows) and me.

7) BTW, I also had the opportunity to hear more rumors around the 750 GeV diphoton resonance. Every theorist I talked to was extremely excited and sometimes confident about the possibility that ATLAS and CMS experiments have detected something new. Funny enough, every experimentalist I talked to was instead extremely cautious and, most of the time, pessimistic. I should definitely write about this in a next post but, as you probably have heard, this coming week the spotlight will all be on LIGO's announcement of the first direct detection of gravitational waves (!) No doubts on the topic of my next post (after Thursday).

Vitor Cardoso's and Thomas Sotiriou's visits @Sapienza

In the last two months we had two guests at our Department:

• Vitor Cardoso, leader of the strong gravity group at IST, was a Visiting Professor at Sapienza in December and January; some weeks ago he gave a talk on "Black holes as laboratories of fundamental physics"
• Thomas Sotiriou, leader of the gravity group "Challenging General Relativity" at Nottingham University, visited our group during the last week of January and gave a talk on "Lorentz violations, causality, and black holes".

Group picture taken [1] after a goodbye social dinner in the historical center of Rome. 
From the left to the right: Leonardo, Thomas, Vitor, Paolo, Ana and Leonardo Macelloni (an old friend from the University of Mississippi who I met at the time of my first moka machine)

[1] By chance, this picture was taken by the bodyguard of President of the Senate Renato Schifani, who was passing by while we were looking for a random photographer.

Recommended by us: Science Pie - A podcast about physics, history, literature and much more

Dennis Schulz, a physics student, and Annika Brockschmidt, a history and German student, are two podcast enthusiasts based in Heidelberg (Germany).

They created the independent podcast Science Pie, focussing on the variety of subjects science can offer. Their topics range from history to physics, from literature to engineering, in particular interdisciplinary work - a range of topics hard to find in the jungle of podcasts. They often use interviews with an involved researcher or professor as a base for the episodes.
And all of this is provided in a bilingual version (English/German) and a special care for details.

Dennis and Annika’s podcast successfully meets the effort of joining science curiosities, interesting stories about people and a collection of knowledge and facts on history, literature and myths. Join them and enjoy!

AstronomiAmo

Domani saro' ospite della trasmissione web dell'Associazione AstronomiAmo  per parlare di "Stelle di neutroni e buchi neri come laboratori per la rivelazione di materia oscura".

La serata e' condotta da Stefano Capretti e sara' trasmessa in diretta sulla pagina web dell'associazione e sul canale Youtube, nel quale trovate tutte le trasmissioni precedenti e che vi invito caldamente a seguire.

Appuntamento domani, Martedi' 19 Gennaio alle 21:30.

La locandina dei prossimi eventi online organizzati dall'Associazione AstronomiAmo.

Aggiornamento: Ecco il video della serata

Meetings in Lisboa

Right before Christmas I visited Lisbon to attend a conference and a workshop held at the Instituto Superior Técnico. It was a great opportunity to come back to Portugal after almost one year and meet a lot of friends and colleagues there.

Visit to Shangai

Many things have happened in the last few weeks, including the Centenary of General Relativity. On November 25th, I wanted to write a post on this event, but I couldn't because I was visiting Cosimo Bambi's gravity group at Fudan University in Shangai and, as it is infamously known, Google products (including this webpage) are inaccessible from China. None of the standard workaround really worked for me so, as a part of my Chinese trip, I have experienced how one feels being without access to gmail, google maps, facebook, etc... (it turned out to be not that bad in fact..)

During the visit, we had a mini-workshop with astrophysicists Javier Garcia-Martinez (Harvard-Smithsonian CfA), Thomas Dauser (Erlangen-Nuremberg) and Matt Middleton (Cambridge) who are working on different aspects of the electromagnetic emission from accretion disks as a possible way to measure the black-hole spin.

Shangai's skyline as viewed from one of the skyscrapers of Fudan University. The city is simply ENORMOUS..