Ginjinha physics in Lisbon

Most of the participants of the "Strong Gravity Beyond to GR: from theory to observations" Workshop,
having a typical Ginginha in Lisbon's city center.

The workshop is going great, as you may see. Besides drinking ginjinhas, all talks have been excellent and plenty of interesting discussions are going on. This totally compensates for the 18h/day-effort that we are putting on it!

This picture was taken 10 sec after the previous one. Funny thing: the guy on the bottom left, the lady at the center and the two guys on the right (who were not in the previous one) are just pedestrians who joined the photo for the sake of it, without even paying the workshop fee!

Picture of the day: Hubble ha visto uno 'Space Invader'!!

Ricordate il famosissimo gioco "Space invaders!"? Probabilmente alcuni di voi sono troppo giovani per averci giocato ma sicuramente hanno chiara nella mente l'immagine delle "navicelle aliene" da abbattere!

Il gioco si basa su una struttura semplicissima ma efficace: il giocatore controlla un cannone mobile posto sul fondo dello schermo, che si muove orizzontalmente, e deve abbattere tutti gli alieni che piano piano si avvicinano alla Terra. Ora questa immagine ormai storica di questi alieni è stata osservata dal telescopio spaziale Hubble ed è stata diffusa, con il tono scherzoso, niente di meno che dal sito ufficiale della NASA.

Immagine distorta di una galassia a spirale che assume le fattezze degli alieni del famoso gioco "Space Invaders!". L'effetto è dovuto alla distorsione dei raggi luminosi provenienti dalle galassie sullo sfondo e che attraversano il fortissimo campo gravitazionale generato dall'ammasso di galassie chiamato Abell 68. L'immagine di una galassia a spirale è stata allungata e riflessa su un asse a causa dell'effetto "lente gravitazionale" previsto dalla teoria delle Relatività Generale di Einstein. Image Credit: NASA/ESA 

Reblog: "Ricominciare dalla Città della Scienza"

MADE IN ITALY

di Marco Cattaneo

Ricominciare dalla Città della Scienza

“ 

Sono più di due ore ormai che fisso sgomento le foto sempre più ravvicinate, sempre più desolate di ciò che rimane della Città della Scienza di Napoli.

E ancora adesso continuo disperatamente a cliccare sul link di google per rimandarvi al sito, ma deve essere andato in fiamme anche il server.

Erano le 23 quando ho visto di sfuggita la prima notizia, che annunciava l’apocalisse nelle 140 battute di un tweet. Erano appena uscite le prime agenzie. Luigi Amodio, direttore della Città della Scienza, era quasi senza parole al telefono, mentre osservava un simbolo della speranza di riscatto di Napoli andare in fumo sotto i suoi occhi. Perché Luigi abita a pochi passi da lì, e ci ha messo cinque minuti ad arrivare quando, intorno alle 22, le fiamme hanno avvolto in un amen i capannoni dell’ex complesso Italsider di Bagnoli dove sorgeva uno dei più visionari poli museali italiani. 

”Continua a leggere su Le Scienze Blog.

Leggi anche il Blog di Robberto Battiston: "Napoli, Bagnoli, 4 Marzo".

Workshop + School in Lisbon

Next two weeks will be very busy in Lisbon (i'm flying back tomorrow). Next week at IST we have the pleasure to host and organize the first "Strong Gravity Beyond GR: from theory to observations" workshop.

The workshop logo. Here is the webpage

The purpose is to organize a friendly and relaxed meeting for a limited number of scientists who work on gravitational theories aiming at correcting General Relativity and on experimental tests of gravity in general. Next few years will witness a wealth of new astrophysical data: second-generation interferometers promise to detect gravitational waves for the first time, very precise observations of the Milky Way center will allow to infer the properties of the supermassive black hole lurking at it and the exponential grow of cosmological observations will open new windows through which "The Theory" of gravity will reveal itself. This is just the perfect time to organize such a meeting in Europe! I'll try to report on the ongoing events, although each time i promise that I failed miserably...

The logo of the NR/HEP2: Spring School

Moreover, in two weeks from now the IST will host a Spring School on topics at the edge between Numerical Relativity and High Energy physics. The NR/HEP2: Spring School is an event organized within a long-term initiative involving the Universities of Aveiro, Instituto Superior Técnico in Lisbon, Rome Sapienza”, Barcelona, Belém do Pará in Brazil, Mississippi and the DAMTP at Cambridge U. Five intense days of lectures are scheduled and, beside one silly guy, i guarantee the speakers are all excellent and it will be fun.

Anyway, these are wonderful excuses for me to take a rest from Boston and enjoy Portuguese weather, food and friends... more soon from Lisboa!

De devulgationi eloquentia

Our gravity group in Lisbon have just published a series of short movies where many group members describe some general aspect of Einstein's theory and beyond.

Have a look at Videoteca do Gravitão, muito boa!

Check out all cool resources at our group's outreach webpage

NuSTAR on the spin of supermassive BHs

Some month ago, in this post, we reported about the launch of the Nuclear Spectroscopic Timing Array (NuSTAR).

Today NASA scheduled a media teleconference to announce one of the first scientific achievements of this mission: the first precise measurement of the spin of a supermassive black hole. 

The discovery will appear in this week Nature's issue.

It turns out that NGC 1365 hosts a rapidly spinning supermassive black hole at its center, and this black hole rotates very close to its theoretical limit imposed by Einstein's General Relativity.

Curiosity: 

one usually refers to these black holes as "extremal" because their spin is close to its maximum value. In "God-given" natural units, the angular momentum of an extremal black hole is J=M^2. 

Indeed, what is usually called the "Kerr limit" is J/M^2 = 1.  This is by no means an "extremal" value!! [For example, Earth also spins around its axis and it has J/M^2~ 10^9 in natural units!]

This doesn't mean that these black monsters in the sky don't spin fast, quite the opposite: because their mass is HUGE, the angular momentum of an extremal black hole of about 10^6 solar masses [roughly the mass of the black hole at the center of the NGC 1365 galaxy]  is as large as 10^13 times that of Earth... a pretty huge and fast spinning top!

PS:

The first author of the paper, Guido Risaliti is an Italian astrophysicists who works here at the Harvard-Smithsonian CfA and at Italian Institute for Astrophysics in Arcetri.

Harvard Stories #1

My personal excuse not to post on the blog.
We are literally submerged in snow, I spent my few spare time in shoveling snow and enjoy the storm.

Good news: 1) I survived Nemo blizzard; 2) i'm more or less settled in Cambridge (moving to the "definitive" apartment in two weeks); 3) I can do nothing but work; 4) eventually i'll have time/willing to post again here. 5) You can fetch good food in Boston. 6) Finally, I live in a bike-friendly city (this is not completely true, but it's way better than Rome, Lisbon and Cagliari).

Bad news: 1) You can fetch good *expensive* food in Boston. 2) My flatemates have an interaction cross section which is a substantial fraction of that of neutrinos. 3) My spouse is still in Italy, still experiencing some problems with the VISA. She was supposed to come here before me, unfortunately she will arrive in March (hopefully). Bad news #2+#3 are main responsible for Good News #3.

Anyway, I wanted to tell another story (nonetheless related to my life here).