Tuesday, August 12, 2014

By the blue sea

Last month came a trip out of the blue and into the blue.  The location was the place where the blue of the sky mixes seamlessly into the blue of the sea, viz. the Greek island of Rhodes. The blue of the sea has to be seen to believed.  Turquoise and azure mix within 20 feet of the shore and darken into indigo. Beyond the horizon looms a grey blue shadow, the shore of Turkey.




For all Turkey is so near, the Turks and the Greeks share a complicated relationship, from medieval times to modern times. Rhodes was home to the Knights Hospitaller, who left behind a fortified enclave, and a harbour. The island boasts several places of worship, which have maintained their function, but alternated denominations during its chequered past. The  hostility lurks underneath the surface, even to this day! The Knights Hospitaller left behind the medieval portion of the town, which is a World Heritage site, with fortifications, the Palace of the Grand Master,  mosaics of the nine Muses, medieval streets (with markets selling modern bric-a-brac) and a quaint harbour.



Antiquity is a little far away. The famed Colossus succumbed to an earthquake in 226 BC, and its fragments lay around for nearly 800 years, until they were sold as scrap. The remnants of antiquity on the island   can be found in the broken pillars of the Acropolis at Rhodes, to which we could not make it, alas! As for modern times, they are embodied by cheerful teenagers enjoying the pristine beaches. They do seem to get a tad drunk and noisy at night, but they are on holiday, after all! The Aegean idyll was sandwiched between, the new international airport at Mumbai, (the White Peacock is indeed beautiful, may it last) , and Air India preening itself at Frankfurt, on having finally made it to the Star Alliance (long may that last too!). Altogether, it was a wonderful week, out of the hot summer in India, and the conference was pretty good too. Here's to the next time!


This blog post by Neelima Gupte and Sumathi Rao.









Wednesday, June 25, 2014

Bicep flexing 2 : After the dust up

This week saw the actual publication of the BICEP2 result on the detection and analysis of the polarisation signature of inflationary behaviour on the cosmic wave background in the final arbiter of all physics research, Physical Review Letters. The paper does an admirable job of explaining  the problem, its background, the data, the analysis, the results and the limitations, if not to the lay reader (not the purpose of PRL, anyway), at least to physicists in other fields. Here is a short summary of what it says.

First, the background. The central paradigm for the origin and evolution of the universe, is the Big Bang Theory, first proposed by Alpher, Bethe and Gamow. The validity of the Big Bang theory was established by the discovery of the cosmic microwave background by Penzias and Wilson. One of the most fruitful areas of research in recent times has been the observation of the anisotropies in the cosmic microwave background, and the consequent refinement of the cosmological models. The `standard model' of cosmology is known as `Lambda-CDM' model, where the Lambda refers to the cosmological constant and CDM stands for `cold, dark, matter'.  This model can account for observed properties like the existence and structure of the cosmic microwave background, the large scale structure in the distribution of galaxies, the abundances of gases like hydrogen, helium and lithium, and the accelerating expansion of the universe. It is particularly important to point out that cosmic microwave background measurements now have precision over angular scales ranging from the whole sky to arcminutes. As a result, the parameters of the Lambda-CBM model are constrained to a precision of less than 1 %.

Inflationary scenarios, including the first one proposed by Alan Guth,  extend the model above by adding an early period wherein a metastable state corresponding to a local minimum of the potential energy undergoes  nearly exponential expansion, which leads to the subsequent big bang.
The addition of inflation to the early scenario explains features like the flatness and isotropy, which cannot be explained within the standard framework above. Inflation also explains that the Universe's primordial perturbations  originate in quantum fluctuations stretched by this exponential expansion, which invokes quantum effects in curved space time at energy and time scales of the order of 10^16 GeV and 10^(-32) seconds, which are completely inaccessible in the real world, both in nature and the laboratory. It is therefore important to have a direct and clear test of this theory. The BICEP2 experiment provides such a test, and therein lies its importance.

 The signature is as follows. While a number of inflationary scenarios exist, they all have a common prediction. Inflation would have produced gravitational waves that would cause characteristic distortions in the cosmic microwave background, with a unique  signature in the radiation field.  The quadrupole nature of the  gravitational waves lead to a polarisation in the radiation field with the `B-mode' pattern characteristic of a curl on angular scales of the order of a degree. Such a pattern cannot be produced by density fluctuations which produce a  `E-mode' pattern characteristic of a gradient on smaller angular scales. It is the `B-mode' pattern seen at exactly the expected angular scales in the BICEP2 experiment that provides the unique signature of inflation. The ratio of the amplitude of the tensor perturbations  characteristic of gravitational waves, to the scalar modes associated with density perturbations, is used to identify the strength of the B-mode, and also to predict the energy density during the inflationary phase.

Since the `B-mode' pattern provides the signature of inflation, it is important to eliminate the effect of foreground sources  which can produce such a pattern. One of these is the effect of gravitational lensing. However, this is much weaker than the effect seen in the BICEP2 experiment. Hence this effect has been ruled out. One serious objection raised since the results were announced, is that such a pattern could be due to the impact of the galaxy's dust. Unfortunately, there is no convincing data on the distribution of dust. Hence the BICEP2 analysis has estimated the effects of cosmic dust based on theoretical models, and concluded that dust could not reproduce the magnitude of the observed signal. However,the validity of this conclusion depends on the accuracy of  hitherto experimentally unvalidated theoretical models. Critics of the BICEP2 result claim that the new data released by the PLANCK satellite is not incompatible with dust levels that lead to polarisation signatures  which are of the order of the BICEP2 signal. A number of measurements that are scheduled within the coming year are expected to resolve this ambiguity.

The BICEP2 experiment also leads to a variety of exciting theoretical implications. More on these can be read here. For the present, there is no doubt that the BICEP2 experiment constitutes an important landmark in understanding the mechanisms that lead to the formation of the universe and its subsequent evolution. We look forward to its further validation.

This blog post is by Neelima Gupte and Sumathi Rao.
 




Monday, April 28, 2014

The sacred and the secular

Last week was a combination of the sacred and the secular. First, the sacred. The sacred was multidenominational: viz. the dargah of Shaikh Moinuddin Chisti at Ajmer, and the Bramha temple at Pushkar. The dargah was complete with marble jalis and floors, chadars made of roses, threads to ask for wishes, and qawwals singing Sufi qawwalis. The mood was cheerful, and the atmosphere about half way between a  fair ground and Friday prayers. Pushkar was even more cheerful, the only sour note being Savitri Devi, Brahma's wife, sulking away in a temple on the hill side thanks to having been displaced at Brahma's side by a milkmaid named Gayatri Devi (to say nothing of an eponymous Maharani ruling the roost for many years in nearby Jaipur).





Speaking of sulking, the secular provided solid reasons for sulking,  the secular being the current Lok Sabha elections, and the reasons for sulking being bounced off the voter list for the sixth time despite filling Form Six, those self same six times! The cheerful polling officers at the polling booth pored over the list three times (six by two, get it?) and said sorry madam, name missing, thereby putting paid to hopes of recurrence of  the miracle that had happened six years ago (that of name being found on the supplementary list).    There was another six by two piece of numerology for those who made it to the polling booth. There were three electronic voting machines in the booth, thanks to forty two (six into seven, what else?) candidates being in the fray in Chennai South parliamentary constituency.  Hopefully, the elected candidate, whoever it be, will fulfil the fervent mannat made at the dargah and the tirth (oh, please, please, please, finally fix Taramani Link Road), and another trip to Ajmer and Pushkar can be made, this time complete with chadar and coconut. The next wish will be to be put back
on the voter list (at least for the duration of the municipal elections)!

This blog post by Neelima Gupte and Sumathi Rao.

Monday, March 24, 2014

Inflation flexes its biceps

Last week saw the announcement of a major discovery in Physics. Researchers at the Harvard Smithsonian Center for Astrophysics announced the discovery of the signature of gravitational waves in studies of the polarisation of the cosmic wave background data registered at the  Background Imaging of Cosmic Extragalactic Polarization 2 (Bicep2) experiment at the South Pole. The observations are also consist with scenarios called `inflation', which postulate that the universe underwent rapid expansion shortly after its creation in the big bang. The scenario goes as follows: gravitational waves are created due to quantum fluctuations in the structure of space time, right after the big bang. These were magnified to observable levels due to the rapid expansion that occurred during the inflationary epoch and imposed their signature on the cosmic microwave background in the form of a characteristic polarisation pattern. The BICEP2 experiment observed a distinctive twisting pattern called a curl or B-mode in the polarisation of the cosmic microwave background. Such a pattern had been observed before due to the effect of gravitational lensing (a warping of light due to the presence of nearby massive objects) but  this effect has been ruled out here. Measurements also indicate that the contribution of the gravitational waves to the signal is quite large compared to the contributions of the density fluctuations, increasing confidence in the reliability of the discovery. However, the cautious look forward to support of this discovery from other experiments, such as those carried out by the Planck satellite.

The excitement generated by the discovery is comparable to the excitement generated by the discovery of the cosmic microwave background by Penzias and Wilson, even though indirect evidence of gravitational waves has been obtained before in measurements from pulsars, and even resulted in the 1993 Nobel prize. This discovery supports the inflationary models of cosmology first proposed in the 1980-s by Alan Guth, Linde and others, and further analysis of the data may be able to support some inflationary models, and rule out others, and will keep astronomers and cosmologists busy and happy for several years!

This blog post is by Neelima Gupte and Sumathi Rao.

Wednesday, March 5, 2014

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

Each day since we first lost you
Life is not the same,
Each day we search for reasons
Each day we call your name.


But each day we're reminded
Of the joy that you would bring,
Each day we still remember
How you brightened everything.


So each day we live on
We will never be apart,
For in each day that passes
You're forever in our hearts.
 


Graham Allaway

This blog post is by Neelima Gupte and Sumathi Rao.



 

Wednesday, February 19, 2014

No hanging, this time!


The Supreme Court, in a landmark judgement yesterday, commuted the death sentences of Rajiv Gandhi's assassins, Murugan, Santhan and Periavelan to life imprisonment. The reason cited was the inordinate delay of 11 years, in giving a decision on their mercy petitions.  The Chief Justice said "...delay violates the requirement of a fair, just and reasonable procedure. Regardless and independent of the suffering it causes, delay makes the process of execution of death sentence unfair, unreasonable, arbitrary and capricious and thereby, violates procedural due process guaranteed under Article 21 of the Constitution and the dehumanizing effect is presumed in such cases." This decision was expected after the earlier Supreme Court decision on, January 21st, commuting the death penalty of 15 prisoners, citing the same reason, viz., the inordinate delay in a decision on their mercy petitions. Both these decisions have been hailed as a victory by the opponents of the death penalty. However,unlike the beneficiaries of the January 21st decision, the nature of the crime, i.e. the political assassination of a popular leader, and a former prime minister, as well as the fact that the assasination was a plot by the LTTE,  have led to polarised and highly charged opinions on both sides in the present case. In Tamil Nadu, longstanding sympathy for Srilankan Tamils, as well as the age of the assassins at the time of the crime, (two were 19 and one 24),  and their model conduct in prison, have led to jubilation at the verdict. Others find this a little mystifying.

A further layer has been added by  today's decision by the Tamil Nadu government of Jayalalitha, a known foe of the LTTE, to let the death row convicts as well as others who have been awarded life imprisonment  in the same case, walk free. A plus point in this, could be the reunion of families, some of whom have never accepted that their kin were involved in the conspiracy, and others who argued that they were bit players, the principal culprits being already dead. (The actual assassin, Dhanu, died in the suicide attack,  and her handler, the  One eyed Jack, Sivarasan, committed suicide by consuming the famed LTTE cyanide tablets when the police closed in on the conspirators in a rented house in Bangalore 22 years ago.) A particularly sad case is that of Harithra, the daughter of Nalini and Murugan, who has never seen her parents outside jail. However, even if the central government accepts the freeing of the convicts, life outside jail may still turn out to be rough for the releasees. Whatever the rights and wrongs of this case, it will be good if the right lessons are extended to other cases, like that of Afzhal Guru, where political considerations justified a hanging, that was  not warranted by the facts of the case.

This blog post is by Neelima Gupte and Sumathi Rao.
~                    

Saturday, December 28, 2013

The Breakthrough Prizes 2014

 The breakthrough prizes for fundamental physics and life sciences for 2014  were announced at a ceremony at the NASA, Hangar One building, at the NASA Ames Research Centre  in Mountain View, California, on December 12, 2013. This was the second function for the Milner fundamental physics prize -the first one was held on March 20th at the   Geneva International conference Centre, where the first nine 2012 awardees, Stephen Hawking, 6 CERN scientists ( for their role in the discovery of the Higgs particle)  and Polyakov were honored.  For the life sciences, this was the first function and hence, besides the 6  2014 breakthrough prizes in life sciences, and the 2014 breakthrough prize in fundamental physics (Michael Green and John Schwarz), the 11 initial  winners of the 2013 life sciences prizes were also honored.











The function was hosted by Kevin Spacey and had several other celebrities  from the American movie and TV industry including Conan O Brien, Glenn Close, Michael Hall, Anna Kendrick, Rob Lowe and Lana Del Rey. More of interest than the U.S. centric performances, (as compared to the Geneva show hosted by Morgan Freeman), were the Internet innovators and entrepreneurs - the charming and baby-faced Mark Zuckerberg  (of the Facebook  fame) and his wife Priscilla Chan,  Sergey Brin ( the Google co-founder) and his wife Anne Wojcicki, Larry Page (Google co-founder) and Jimmy Wales ( co-founder of Wikipedia), and of course, Yuri Milner, the founder of the Fundamental prize.

The format of the function this time, included  a fancy sit-down dinner, catered by Chef Thomas Keller and The French Laundry, for about 5000 invitees. Re the food, as a vegetarian and not a great connoisseur, I will not attempt to describe the food other than saying that it was fancy, but the  menu   should give an idea!




This was different from last time, when the guests had to go round Geneva in a state of semistarvation (refer Sunil Mukhi's blog). The composition of the invitees was also quite different. Last time, there were many scientists from CERN and from other places in Europe,
whereas this time, the invitees were mainly  Silicon valley entrepreneurs, besides the laureates and their families. The aim seems to be fund-raising for fundamental science and who better than silicon valley entrepreneurs to know the value of fundamental research?

This time, the new horizons prize in physics, awarded to promising junior researchers went to Shiraz Minwalla from TIFR, along with two others. These prizes were awarded at a lunch hosted by Mark Zuckerberg at the Facebook headquarters in Palo Alto. With no prior notice, the three awardees were given 2 minutes each to describe their work to a mixed audience including biologists, physicists and their family members.  The sartorial splendor of the scientists had to be seen to be believed, and shocked those used to their normal attire. Here you see Ashoke Sen and Shiraz Minwalla, in their full plumage.
The function ended with the announcement by Milner and Zuckerberg of a new three million dollar breakthrough prize in mathematics, whose details will be announced later.


Tailpiece:
A personal highlight for me was meeting Lucy Hawking. I am a fan of her children's science books co-authored with her father and came to know that she is finishing a new one on quantum computers very soon.



This blog post is by Sumathi Rao.