Thursday, September 28, 2017

Gravitational waves: The fourth event

A new gravitational wave signal arising from a black hole collision was detected on August 14, this year, and was announced by the National Science Foundation today. A special feature of this observation was that it was observed by the pair of LIGO detectors in Livingston and Hanford in the  U.S.A as well as by the Virgo detector in Pisa. As a result, the location of the event, which involved the merger of two black holes of 25 and 31 solar masses, into one  spinning black hole of 53 solar masses, could be pinpointed 10 times more accurately than it could be using the LIGO detectors alone. The event, designated GW170814 was located in a region of size 60 square degrees which is about 1.8 billion light years away.

Further details are awaited in a forthcoming Physical Review Letters. Meanwhile, here is  a video of a numerical simulation uploaded by the Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut).

This blog post is by Neelima Gupte and Sumathi Rao.

Tailpiece : Rainer Weiss, Barry Barish and Kip Thorne have won the  Physics Nobel prize for 2017 for their work on the Ligo/Virgo  experiment and the detection of gravitational waves. See link. 

Monday, September 4, 2017

Once again on a Greek island: Corfu

 The first part of July was the beautiful island of Corfu, which may well be the prettiest of the Greek isles. The island boasts of Venetian, Byzantine and Greek ancestry, with monuments from each part casually strewn around in an eclectic mixture.

Here is the monastery Vlacherna, favourite of all post cards and fridge magnets, in the middle of the turquoise bay, with aeroplanes taking off behind it at all times of the day.

The older part of the town lies in between two Venetian forts, the new fort and the old fort.  Winding medieval  streets, and a grand esplanade complete the picture, with numerous sun burnt tourists flocking (and  gawking) everywhere. By the way, there's probably no place where the locals are more kind to tourists, than here.

The Mon Repos palace reposes on top of the Analipsis  hill  of Kanoni, in the middle of a magnificent park, and opposite less than magnificent, but undoubtedly ancient, Greek ruins. It is a beautiful colonial building, and happens to be the birthplace of the Duke  of Edinburgh.

There was much to see, and not enough time. However, this is not the first time this blog has been to Corfu. Readers  in pursuit of completeness may kindly pursue the earlier links, in fact, onetwo , three.
May we meet again, Corfu, Αντιο σας.

This blog post is by Neelima Gupte and Sumathi Rao.

Monday, June 26, 2017

Two big science stories

There were two big science stories last month, of vastly differing natures.

Our knowledge of human evolution took a giant leap backwards this fortnight. The oldest known remains of the species homo sapiens have been found in Morocco.  The fossils have been dated to be about 3,00,000 years old. The oldest specimens found before this, were about 1,95,000 years old, which means that the current discovery pushes back the origin of our species by about a 100,000 years. The geographic locations of the fossils, the Jebel Irhoud site in Morocco also indicates that humankind evolved at multiple locations in Africa, and there is no single cradle of humanity, as was thought earlier. The remains were dated by dating the artefacts, in this case, flint blades, found in the neighbourhood of the fossils. The fossils were clearly of the homo sapiens type, but were much, much older than anything found so far. The fossil evidence indicates that the specimens looked much like more modern members of the species, but their brain structure and shape resembled the long low shapes of other homonims, rather than the round shape of homo sapiens. The discovery will keep paleoanthropologists busy for a good long time.

The second story was of the type that makes us scientific types blasé these days. Two black holes  collided again, and the universe chirped again, yawn..... , exactly what we were squawking with excitement about, a scant 15 months ago! The Ligo detectors detected a third signal from the gravitational collapse of two massive spinning  black holes, of 19 and 31 solar masses, with spins which were not aligned,  to create a black hole of 49 solar masses, about 3 billion light years away. The surprisingly large frequency of such occurrences has led scientists to predict the birth of  a new area, namely, black hole astronomy.  The theoretical advance should come in the direction of identifying the reason for the frequent occurrence of black hole binaries, which then merge to set off the detected gravitational waves. In short more work for the practitioners of the current discipline.

To summarise, as always, the exciting discoveries need to be followed by huge amounts of painstaking analysis. Meanwhile, it is a pleasure to report that Indian scientists, including a colleague from IIT Madras, have been a part of the LIGO discovery. We look forward to more exciting results.

This blog post by Neelima Gupte and Sumathi Rao.

Sunday, May 14, 2017

The Chennai Metro II

The third stretch of  the Chennai metro, and the first underground stretch, was inaugurated today by the Union Minister Venkaiah Naidu and Tamil Nadu Chief Minister  E. Palanisamy today. The trains were crowded, but the crowds were cheerful and applauded  the arrival of the trains. The trains run between Thirumangalam and Nehru Park, a distance of about 8  kms. The Chennai crowds missed the late CM J. Jayalalitha, who had inaugurated the first two stretches.

Here is a video of the first train service. This time, there were  garlands and decorations inside the cars, as well, and free rides till 2.00 pm. Hopefully the rest of the network will get completed in time (scheduled to be July 2018), so that overground commuters can get access to roads cleared of the construction and obstructions required for the Metro. If travel times and access for commuters get as seriously cut as they are supposed to, the entire exercise would have been worth the time and trouble, to say nothing of the expense. Here's hoping for the best, and also for no safety issues. The train stations have been constructed with all modern safety measures, but Anna Salai did cave in a  little bit three weeks ago! However, let us not be needlessly alarmist.  We look forward to taking the train.

This blog post by Neelima Gupte and Sumathi Rao.

Friday, April 28, 2017

Lord of the Rings

The Cassini spacecraft dove through the rings of Saturn yesterday, and sent back its first pictures today. Here you are. These are raw images, and have not been prettified like the Juno pictures. That makes the cyclopean eye of the hurricane even more petrifying!

The other  pictures appear to be a close up of the hurricane, and perhaps a Saturnian cloud formation. Many more pictures are expected before Cassini plunges to its fiery death on 15 th  September. It is hoped that its fiery incineration will keep it from contaminating the Saturnian environment with earthly debris, and even worse, earthly bacteria. We plan to update this post  with  more Saturnian pictures, but hopefully, with no earthly bugs in sight.

This blog post is by Neelima Gupte and Sumathi Rao.

Sunday, April 2, 2017

Juno and Jupiter 2

Who is the best photographer in the universe? Juno, of course, helped by the magnificent  planetscape it is visiting, and some help from digital enhancement by human hands. The Juno spacecraft of NASA, on its fifth flyby by Jupiter, has sent back stunning pictures on Monday.  Here are two pictures from the flyby

followed by a composite image, composed over four months;

and, not the usual red spot, but a local storm.

Just for comparison, an old one from Voyager 1, also a composite picture ( a similar picture by New Horizons was posted on this blog earlier).

Finally, just for the heck of it, do you think Van Gogh did better?

This blog post by Neelima Gupte and Sumathi Rao.

Photos: NASA (Juno Images), Bhagyashree Gupte (Starry Night photo).

Sunday, March 5, 2017

Rahul Basu 04/03/1956-05/03/2011


Memory can tell us only what we were,
In company with those we loved;
It cannot help us find out what each of us,
Alone, must now become.
Yet, no person is really alone;
Those who live no more still echo
Within our thoughts and words,
And what they did has become
Woven into what we are. 

Richard Fife.

This blog post by Neelima Gupte and Sumathi Rao.

Wednesday, January 4, 2017

The IPA Rahul Basu Memorial Award Ceremony, 2016.

The  IPA Rahul Basu Memorial Award ceremony was held at the 22nd DAE  symposium in High Energy Physics  at the University of Delhi on December 16th, 2016. As mentioned in an earlier post, the award winners were Dr. Bhawna Gomber and Dr. Roji Pius, and Dr. Md. Rihan Haque and Dr. Kirtimaan Mohan had received honourable mention.

Dr. Bhawna Gomber gave a very clear and well argued talk on her thesis which primarily concerned the analysis of what could be construed as signatures of dark matter at the LHC, and also the comparison of the observed data with an alternate scenario, the  signatures of extra high dimensions via theoretical models. A major contribution of the thesis was the derivation of model independent bounds on the cross sections. It was especially delightful that Dr. Bhawna could present her talk in person, and receive her award from Prof. Probir Roy, a long standing leader of the HEP community.

Dr. Md. Rihan Haque, presented his talk via Skype. Dr. Haque presented his work on the STAR experiment, where he had analysed the beam energy dependence of the  physical properties light nucleii to understand their production mechanism. Since coalescence processes are important for light nucleii as well as for hadrons, this helps to understand hadronization
in high energy nuclear collisions.

Dr. Roji Pius had received the award for important technical contributions to the perturbative analysis of string theories. Dr. Roji's thesis  studied various aspects of the problem of mass renormalization in string theory including the computation of  the mass of a spinor in  heterotic string theory, and analysed its stability. He also developed the general algorithm for computing the renormalized mass
in string theory, which  goes  beyond the conventional approach. His video recorded talk did an admirable job of providing a flavour of these highly technical results in accessible terms. Unfortunately, this video could not be played due to system limitations. We hope to make this video accessible in a suitable forum.

Finally, Dr. Kirtimaan's thesis analysed various properties of the Higgs boson at the LHC. A special feature of his thesis has been the analysis of features of the Higgs Boson production that go beyond the conventional Standard Model. For this he has studied non standard decay modes, jet substructure properties and charge and colour breaking constraints.

The award ceremony went off well. It was particularly heart warming that it was held in Prof. Rahul Basu's alma mater, viz. the University of Delhi. This led to the presence of  supportive friends, collaborators and associates in the audience. The ceremony was preceded by talks on ongoing research problems by young HEP students. It is hoped that the talks of the awardees will have helped set the standards which will be reflected  in future nominations to this award.

Profs. Bedangdas Mohanty and Debajyoti Chowdhury, Chair and Member of the award committee were also present. Heartfelt thanks to them and other members of the committee for carrying out the herculean task of sifting through 30 nominations. Thanks are also due to the Indian Physics Association which administers the award. We hope the next round of the award will see equally enthusiastic participation from the HEP community of India.

This blog post by Neelima Gupte and Sumathi Rao.