Greetings from Mons

Some of the participants of the Mons Meetings 14 held this week at Mons, Belgium, and greatly organized by my colleague and friend Terence Delsate (the guy wearing glasses in the group picture...)

Jordi on Dark Matter @ FameLab 2014

Fame Lab is a competition to find new voices of science across the world. In these events various speakers compete for the best popular science short talk. The events are hosted in various countries and there are competitions at regional, national and international level.

This year Jordi Casanellas (former PhD student in IST-Lisbon and now postdoc at the Albert Einstein Institute near Berlin) attended Fame Lab Germany. As the video below shows, in the first stages of the competition speakers cannot use blackboards (not to mention slides or projectors) and their talk has to be ~3 mins long.

Jordi talked about his field of research, Dark Matter, and in fact did a great job: he passed the regional competition and went to the national finals (see video below), where he placed second!

So, if you want to have an idea of what Dark Matter exactly is (or what scientists actually think it should be...) you don't have to do anything but listen to Jordi's speeches. Enjoy!

Pull back: "Scientist: Four golden lessons" by Steven Weinberg

Just came across this brilliant essay by Nobel Laureate Steven Weinberg, writing about his experience as a young scholar, his first steps in research and the connection between science and epistemology.

The essay is so short and clear that I could have copied it here in its entirety, but I'll just give you one inspirational paragraph:

[...]
Look back 100 years, to 1903. How important is it now who was Prime Minister of Great Britain in 1903, or President of the United States? What stands out as really important is that at McGill University, Ernest Rutherford and Frederick Soddy were working out the nature of radioactivity. This work (of course!) had practical applications, but much more important were its cultural implications. 
[...]

and leave the rest for the original

Vita dura per i neutrini sterili e non solo

Si è appena conclusa a Boston la conferenza NEUTRINO2014 dedicata, così come vuole il nome, ai nuovi risultati sperimentali e teorici che provengono dal mondo di queste elusive e misteriose particelle, per l’appunto, i neutrini.

Ci sono parecchie novità interessanti e volevo quindi fare un piccolo riassunto sulle cose più sfiziose.

Partiamo dalla ricerca dei cosiddetti neutrini sterili, e cioè di quelle particelle ipotetiche che sono state introdotte per spiegare alcune anomalie riscontrate nel corso degli anni da alcuni esperimenti che non si inquadravano nel modello delle oscillazioni a tre neutrini. Il primo esperimento a riscontrare un’anomalia è stato LSND (Liquid Scintillator Neutrino Detector) a Los Alamos, in cui è stato registrato un eccesso di antineutrini elettronici, con significatività di 3.8 sigma, su un fascio pressoché puro di antineutrini muonici. Se interpretati in uno schema di oscillazione a due neutrini, per la particolare configurazione della baseline, L, (la distanza tra sorgente di neutrini e rivelatore) e l’energia, E, da cui dipendono la probabilità di oscillazione di un neutrino muonico ad uno elettronico \[ P_{\nu_{\mu}\rightarrow\nu_{e}}\left(L,\, E\right)=\sin^{2}2\vartheta_{e\mu}\sin^{2}\left(1.267\:\frac{\Delta m_{41\,}^{2}L}{E}\right) \] questo eccesso sarebbe indicativo di un'oscillazione con una piccola ampiezza e un grande \(\Delta m^{2}\sim1\) \(\textrm{eV}{}^{2}\). Appare chiaro che un \(\Delta m^{2}\sim1\) \(\textrm{eV}{}^{2}\), non può essere incorporato in un modello a tre soli neutrini (elettronico, muonico e tauonico) in cui esistono solamente due differenze di masse al quadrato indipendenti. Infatti deve valere la relazione \[\Delta m_{21}^{2}+\Delta m_{32}^{2}+\Delta m_{31}^{2}=m_{2}^{2}-m_{1}^{2}+m_{3}^{2}-m_{2}^{2}-m_{1}^{2}-m_{3}^{3}=0\,\] e dal momento che la differenza di massa al quadrato dei “neutrini solari” è \(\Delta m_{SOL}^{2}=\Delta m_{21}^{2}=7.58_{-0.26}^{+0.22}\times10^{-5}\) \(\textrm{eV}{}^{2}\) e di “quelli atmosferici” è \(\Delta m_{ATM}^{2}=\left|\Delta m_{31}^{2}\right|\simeq\left|\Delta m_{32}^{2}\right|\simeq2.35_{-0.09}^{+0.12}\times10^{-3}\) \(\textrm{eV}{}^{2}\), non vi è spazio per una differenza di massa al quadrato dell'ordine dell'\(\textrm{eV}{}^{2}\), se non in uno schema in cui sia presente almeno un nuovo stato di neutrino massivo \(\nu_{4}\) sterile, per cui possa essere interpretata la differenza di massa al quadrato come \(\Delta m_{\textrm{new}}^{2}\equiv m_{4}^{2}-m_{1}^{2}=\Delta m_{41}^{2}\). Questo neutrino però deve essere sterile, e quindi non deve partecipare a nessuna delle interazioni (tranne quella gravitazionale) in quanto esistono delle misure effettuate al LEP sul decadimento del bosone Z in neutrini, che indicano che il numero di neutrini “attivi” (e cioè quelli che interagiscono per forza debole) deve essere esattamente tre.

"Science in the era of Facebook and Twitter – get used to it" by Heino Falcke

Astronomer Heino Falcke has recently wrote a nice post on the relation between science, dissemination of scientific results and social media.

The post was triggered by the recent debate on the BICEP2 results and contains interesting advices on the new role that scientists and journalists should learn to have in the era of Facebook.

“Science is wrong, most of the time” – I am not sure who said that first, but I am sure someone did so well before me. This is a banality for those who do science at the forefront of our knowledge, yet sometimes it seems very difficult to also accept that view in the public discourse. Well, in the days of Facebook and Twitter it is plain obvious to everyone.


Continue reading on Heino Falcke's blog

Recommended by us: "Is BICEP wrong?"

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Blockbuster Big Bang Result May Fizzle, Rumor Suggests

The biggest discovery in cosmology in a decade could turn out to be an experimental artifact—at least according to an Internet rumor. The team that reported the discovery is sticking by its work, however.

Eight weeks ago, researchers working with a specialized telescope at the South Pole reported the observation of pinwheel-like swirls in the polarization of the afterglow of the big bang, or cosmic microwave background (CMB). Those swirls are traces of gravitational waves rippling through the fabric of spacetime a sliver of a second after the big bang, argue researchers working with the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) telescope. Such waves fulfilled a prediction of a wild theory called inflation, which says that in the first 10^-32 seconds, the universe underwent a mind-boggling exponential growth spurt. Many scientists hailed the result as a "smoking gun" for inflation.

However, scientists cautioned that the result would have to be scrutinized thoroughly. And now a potential problem with the BICEP analysis has emerged, says Adam Falkowski, a theoretical particle physicist at the Laboratory of Theoretical Physics of Orsay in France and author of the Résonaances blog. The BICEP researchers mapped the polarization of the CMB across a patch of sky measuring 15° by 60°. To study the CMB signal, however, they first had to subtract the "foreground" of microwaves generated by dust within our galaxy, and the BICEP team may have done that incorrectly, Falkowski reports on his blog today.

To subtract the galactic foreground, BICEP researchers relied on a particular map of it generated by the European Space Agency's spacecraft Planck, which mapped the CMB across the entire sky from 2009 until last year. However, the BICEP team apparently interpreted the map as showing only the galactic emissions. In reality, it may also contain the largely unpolarized hazy glow from other galaxies, which has the effect of making the galactic microwaves coming from any particular point of the sky look less thoroughly polarized than they actually are. So using the map to strip out the galactic foreground may actually leave some of that foreground in the data where it could produce a spurious signal, Falkowski explains. "Apparently, there is something that needs to be corrected, so at this point the BICEP result cannot be taken at face value," he tells Science.

Continue to read on Science 

                                                                                                                                                                                        ”  
See also http://resonaances.blogspot.fr/2014/05/is-bicep-wrong.html
     

Radiazione Cherenkov: non si smette mai di imparare! La svista nel programma di divulgazione scientifica Cosmos.

Recentemente ho scritto un articolo riguardo al programma televisivo di divulgazione scientifica “Cosmos: a spacetime odyssey” trasmesso su National Geographic Channel (in Italia è trasmesso sul canale 403 di Sky) e da FOX. Nella sesta puntata della serie intitolata “Dove tutto si crea” (“Deeper, Deeper, Deeper Still” invece il titolo inglese [1]) si parla, tra le altre cose, di supernovae, e dei neutrini ed antineutrini emessi in queste spettacolari esplosioni stellari (per rivedere lo spezzone relativo alle supernovae clicca qui e guarda dal minuto 30 in poi, ma vale la pena di guardare tutta la puntata). In questo precedente articolo, di cui consiglio la lettura prima di continuare la lettura di quest’ultimo, mi sono soffermato nell’analisi dell’incredibile ricostruzione, realizzata con l’ausilio della computer grafica [2], della rivelazione di queste particelle emesse a seguito dell’esplosione di supernova.