Have you ever wondered how the Sun creates the energy that we get from it every day and how the other elements beside hydrogen have formed in our universe? Perhaps you know that this is due to fusion reactions where four nuclei of hydrogen join together to produce a helium nucleus. Such nucleosynthesis processes are possible solely due to the existence, in the first place, of stable deuterons, which are made up of a proton and a neutron. Probing deeper, one finds that a deuteron consists of six light quarks. Interestingly, the strong interaction between quarks, which brings stability to deuterons, also allows for various other six-quark combinations, leading to the possible formation of many other deuteron-like nuclei. However, no such nuclei, though theoretically speculated about and searched for experimentally many times, have yet been observed. All this may get changed with an exciting new finding, where, using a state-of-the-art first-principles calculation of lattice quantum... Read more
Global warming is a serious threat to the planet and the living beings. One of the main cause of global warming is the increase in the atmospheric CO2 level. The main source of this CO2 is from the burning of fossil fuels in our daily lives (electricity, vehicles, industry and many more). Researchers at TIFR have developed the solution phase synthesis of Dendritic Plasmonic Colloidosomes (DPCs) with varying interparticle distances between the gold Nanoparticles (NPs) using a cycle-by-cycle growth approach by optimizing the nucleation-growth step. These DPCs absorbed the entire visible and near-infrared region of solar light, due to interparticle plasmonic coupling as well as the heterogeneity in the Au NP sizes, which transformed golden gold material to black gold. The developed black gold acts like an artificial tree that uses CO2 , sunlight and water to produce fuel.
Mitochondria in neurons are the powerhouses that generate energy to execute cellular functions and regulate neuronal survival under conditions of stress. Collaborative research by Prof. Vidita Vaidya and Prof. Ullas Kolthur-Seetharam groups at TIFR, along with Dr. Ashok Vaidya, at Medical Research Centre, Kasturba Health Society, has demonstrated an unusual function for the neurotransmitter serotonin, in the generation of new mitochondria—a process called mitochondrial biogenesis—in neurons, accompanied by increase in cellular respiration and ATP, the energy currency of the cell.
Our understanding of the gravitational force has been evolving over centuries, but we still do not have the final picture. Newton showed that the force which makes planets go around the sun is the same as the gravitational force which makes objects fall to the ground. This led to the discovery of the famous inverse square law of gravitation.
Large differences in the ‘fogginess’ of the early universe were caused by islands of cold gas left behind when the universe heated up after the big bang, according to an international team of astronomers. The results, reported in the Monthly Notices of the Royal Astronomical Society, have enabled astronomers to zero in on the time when reionisation ended and the universe emerged from a cold and dark state to become what it is today: full of hot and ionised hydrogen gas permeating the space between the luminous galaxies.
Supernovae are spectacular explosions of super-massive stars, believed to be responsible for a variety of important phenomena ranging from the shaping of galaxies, the birth of neutron stars and black holes, to the creation of vital chemicals — the oxygen in our lungs, the calcium in our bones, and the iron in our blood. The observation of a nearby supernova in 1987 established Colgate and White's longstanding prediction that these stellar explosions are actually powered by neutrinos. However, a detailed understanding is still awaited, because of the enormous challenges in calculating the behavior of neutrinos inside a supernova.
Thunderstorms are a spectacular manifestation of electrical discharges of thunderclouds, and have fascinated humans through millennia. There is a dark side of thunderstorms as thousands of lives are lost every year worldwide, making them a leading cause of death by natural disasters. The technique of muon imaging developed by GRAPES-3 collaboration showed that huge voltages develop in supercharged thunderclouds. The voltage produced by a thundercloud on 1 December 2014 in Ooty measured 1,300,000,000 Volts (1.3 GV) across its height, which is 10 times larger than the previous record voltage of 0.13 GV. This verifies the 90-year-old prediction of 1,000,000,000 Volts (1 GV) by C.T.R. Wilson. Such massive voltages are essential for the production of high-energy (100 MeV) gamma rays in the Terrestrial Gamma Ray Flashes (TGFs) emanating from thunderstorms, first discovered 25 years ago.
Researchers at TIFR have discovered molecular anticipation of feeding in the liver that is essential to ensure that the body, after fasting, adapts to utilize incoming nutrients upon re-feeding. Their findings, published in the international journal Cell Reports, show that very small RNA molecules called microRNAs control major metabolic pathways by inhibiting synthesis of proteins, and thus contribute to maintenance of blood glucose levels.
There is a common belief among physicists that short-range interaction in a classical one-dimensional system cannot lead to a phase transition. Tridib Sadhu of TIFR Mumbai, along with collaborators Sushant Saryal and Deepak Dhar from IISER-Pune and Juliane U.Klamser from ENS-Paris, has now produced a clear counterexample showing that phase transitions can surely occur in one-dimension due to a fundamentally new mechanism related to geometrical changes in accessible phase space.
Precise predictions of the properties of subatomic particles using ab-initio calculations have been a big challenge for physicists. In a recent article published on 16th November in Physical Review Letters, Nilmani Mathur, Sourav Mondal from TIFR, Mumbai, and M. Padmanath, from the University of Regensburg, have predicted masses of several new subatomic particles with both charm and beauty quarks as their constituents.
Quantum computers store and process information using quantum two level systems (quantum bits or qubits) which unlike classical bits, can be prepared in superposition states. This key ability makes quantum computers extremely powerful compared to conventional computers when solving certain kinds of problems like finding prime factors of large numbers and searching large databases.
Using the X-ray data from two different satellites, AstroSat and Chandra, an international team of astronomers from multiple institutions, led by the Tata Institute of Fundamental Research (TIFR) in Mumbai, India, has measured the spin rate of a black hole in the binary stellar system 4U 1630−47.
Traffic jams are the bane of every driver on Indian roads. Crowding is similar both on Indian roads and neurons with many types of vehicles/neuronal cargo all using the same set of roads. Vehicular traffic stops at red lights, when road is occupied with other materials and with other cargo. The lab of neurobiologist Sandhya Koushika, TIFR in a inter-disciplinary collaboration with theoretical physicist Gautam Menon
Living life in the fast lane can be tremendously exciting, giving us the ‘time of our lives’ but how long does it really last? Experiments at the Tata Institute of Fundamental Research (TIFR), Mumbai have answered this question for a bunch of electrons traveling faster than light (fasten your seatbelts!) through a piece of glass. This study, done in collaboration with the Rutherford Appleton Laboratory in the UK and Centre for Intense Laser Studies and Applications (CELIA) in France appeared in Physical Review Letters on 05 February 2018.
AstroSat, India’s multi-wavelength space telescope, has successfully accomplished the extremely difficult task of measuring X-ray polarisation. In a paper published in ‘Nature Astronomy’, the team has documented the results of their eighteen-month study of the Crab pulsar in the Taurus Constellation and measured the variations of polarisation as this highly magnetised object spins around 30 times every second. This landmark measurement puts up a strong challenge to prevailing theories of high energy X-ray emission from pulsars.
In a significant breakthrough, scientists at the Ultrashort Pulse High Intensity Laser Laboratory (UPHILL) of this Institute have devised a high power radiation source in the much sought after terahertz (THz) region of the electromagnetic spectrum. This study, done in collaboration with laboratories in Greece and France, appeared in the journal Nature Communications on Oct 30, 2017. The search for new and brighter radiation sources is an enduring quest in science and technology [1,2]. While there are many sources across the entire electromagnetic spectrum, the terahertz region (wedged between the infrared/optical and the microwave regions) has been a challenge and it is only in the last twenty years that sources have started becoming available.
In a breakthrough experiment, researchers from the Tata Institute of Fundamental Research, Mumbai India and Open University, Milton Keynes, U.K. have shown — for the first time — that incoherent electrons, displaying their quantum-mechanical nature, can induce coherence in a molecular system on attachment. http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys4289.html?foxtrotcallback=true#auth-2
The beginning of gravitational-wave multimessenger astronomy 17 August 2017 saw a major breakthrough in astronomy, when gravitational waves from a pair of colliding neutron stars were detected for the first time by the US-based Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Europe-based Virgo. This happens to be the strongest gravitational-wave signal detected so far, owing to the relatively close location of about 130 million light-years from earth. The detection was also confirmed by a large number of telescopes around the world that studied various forms of radiation from the merger. This is a new milestone in the success saga of advanced gravitational wave detectors, which have announced the discoveries of four black hole mergers to date. The first such detection in 2015 led to the awarding of the Nobel prize in physics this year.
Predicting the properties of subatomic particles before their experimental discovery has been a big challenge for physicists. In a recent paper published on 28 July in Physical Review Letters Nilmani Mathur from the Tata Institute of Fundamental Research, Mumbai, and M. Padmanath, a former student from TIFR, have predicted the quantum numbers of five Ωc-0 baryons which have recently been discovered by an experiment at the Large Hadron Collider (the LHCb collaboration) at CERN. These results will help in understanding the nature of strong interactions in the Universe. A baryon is a composite subatomic particle made of three valence quarks and is bound by gluons through strong interactions. The most well known baryon is the proton which along with an electron constitutes a hydrogen atom. A simplistic picture of a proton is a combination of two up quarks and one down quark. In the theory of strong interactions there are six quarks each with three colours charges. This theory... Read more
Joint Release In the search of planets beyond our solar system especially habitable world, the biggest opportunities may be found in the cool dwarf stars. Nearly ~75% of our galaxy consists of such stars making them the most common planet host stars. Our nearest neighbour, Proxima Centauri, is one such star with a spectral type M5.5 and hosting an Earth-like planet, Proxima Centauri b, orbiting within its habitable zone. However, the habitability of the planet depends on the high-energy radiation as a result of the chromospheric and coronal activity of the host star. “The high-energy photons like the UV and X-ray photons are absorbed by the planetary atmosphere heating it to 10s of 1000s of Kelvin affecting the capability of the planet to sustain its atmosphere and in particular to sustain water in liquid form” says Dr. Lalitha Sairam (IIA, Bengaluru). Team member Dr. Christian Schneider (HS, Germany) says “to investigate the fate of this Earth-like planet, a... Read more
Turbulent magnetic field dynamics that explain astrophysical phenomena like the evolution of stars could thus far be obtained only through observations via telescopes and satellites. Now a team of scientists from India and Portugal have recreated such magnetic turbulence on a table top in the lab, using a high intensity ultrashort laser pulse to excite a hot, dense plasma on a solid surface and followed the extremely fast evolution of the giant magnetic field generated by the plasma dynamics. This ground-breaking study was published in Nature Communications on 30 June. Turbulence is everywhere- from tea cups to tokomaks and from water jets to weather systems, it is something we all see and experience. Yet, even after centuries of serious scientific study, fluid turbulence is still not properly understood and remains “Interesting. Vexing. Longstanding. Unsolved.”. While it is difficult to define turbulence simply, it has many recognizable features, the most common... Read more
Researchers at the Tata Institute of Fundamental Research in Mumbai have proposed a theory that predicts how dark matter may be annihilating much more rapidly in the Milky Way, than in smaller or larger galaxies and the early Universe. Anirban Das, with his advisor Dr. Basudeb Dasgupta, pursued this possibility because almost all observations made so far indicate no signals of dark matter annihilation anywhere — except the tantalizing signals from the Milky Way seen by the PAMELA and AMS02 detector and the Fermi gamma ray telescope. If the dark matter origin of these signals stands further scrutiny and signals aren't seen from anywhere except the Milky Way, their theory would explain why the Milky Way appears to be special. In the enchanting night sky, with myriad galaxies and stars, what we see is only about 20% of all the matter in the Universe. The remaining is in the form of a non-luminous and exotic form of matter that we know little about. This so-called dark... Read more
A quantum computer, when realized, will provide exponential speedup compared to contemporary computers which follow the laws of classical physics. This will also enable a universal quantum simulator that can emulate real-world quantum systems that are otherwise intractable. A quantum bit or “qubit” is the basic building block of a quantum computer which exploits the properties of quantum mechanics like superposition (the ability of a qubit to be in two states at the same time) and quantum entanglement. Information processing using quantum mechanics requires precise control and manipulation of single-qubit, multi-qubit interactions as well as protection of the qubits from accidental measurement by the environment (quantum error). Among the various architectures being explored, superconducting circuits operating at millikelvin temperatures provide unparalleled flexibility in designing efficient quantum hardware. The Quantum Measurement and Control (QuMaC) research group... Read more
Firmly transiting into the era of Gravitational Wave Astronomy The Laser Interferometer Gravitational-wave Observatory (LIGO) has made another successful detection of gravitational waves, ripples in space and time, from the merger of two massive black holes that happened three billion light years away. This firmly reiterates the remarkable launch, announced last year, of a new window of astronomy. The new detection occurred during the ongoing second observing run of the Advanced LIGO detectors in the USA, which began on November 30, 2016. The first direct observation of gravitational waves was made in September 2015 during the first observing run. A second detection was made in December 2015. The third detection, made on January 4, 2017, is described in a new paper accepted for publication in Physical Review Letters. These detections were made possible by contributions from more than thousand researchers from many different countries, setting a great example in collaborative... Read more
Reinout van Weeren and his collaborators have discovered a cosmic event never seen before. Galaxy clusters can contain many different sources of radio emission and two key types are radio halos and relics. Both these are associated with cluster–cluster mergers. Halos are detected in the central region of the cluster, whereas relics are detected as on the periphery of clusters. By combining data from Chandra X-ray Observatory, the Giant Metrewave Radio Telescope, Jansky Very Large Array, and other telescopes, these authors have found source of seed synchrotron emitting electrons that produce radio emission as the shock propagates through the intra-cluster medium. The authors also demonstrated the expected change in characteristics of the radio emission at the location of these seed synchrotron emitting electrons are re-accelerated by the passage of the shock. This work is published in Nature Astronomy, 2017. Reference:... Read more
Prehistoric human migration was mainly driven by human wanderlust and population pressures but relied critically on the habitability of available land. We have modelled such prehistoric population dynamics using a diffusion equation whose numerical solution is tempered by accurate geological data for the Indian subcontinent taken from satellite databases. We define the driving forces by assuming that people will move out of any given region if the neighbouring regions are habitable. In turn, we define habitability by quantifying parameters like the availability and proximity of water, and flatness and altitude of the land. We define relative habitability which takes into account the presence of the initial population. We then consult the archaeological evidence of early humans in the subcontinent and identify three possible locations in Kabul which would represent the Ancestral North Indian entry into India, Hyderabad which would represent the earliest Ancestral South Indian... Read more
On 11 April 2017, the Belle II detector at the High Energy Accelerator Research Organization (KEK) in Japan was rolled in from its construction area to the interaction region of the SuperKEKB particle accelerator. This event marks another milestone in our pursuit to decode the fundamental new principles of nature (‘new physics’) beyond that encompassed by the standard model of particle physics. Complementary to the direct search being carried out at the energy frontier experiments of LHC, Belle II will be a world-leading experiment on the intensity frontier by indirectly probing new physics with intense e+e- beams and extremely sensitive detector. Speaking of the ‘sensitive’ detector the Belle-II group at TIFR is leading the design and construction of the silicon vertex detector (SVD) of the experiment (For more on the SVD please see TIFR Science News). This device will be able to measure the position of charged particles emanating from e+e- collisions to an... Read more
A team of scientists at the Tata Institute of Fundamental Research (TIFR), Mumbai, India, have found new ways to detect a bare or naked singularity, the most extreme object in the universe. This finding has possible implications in the area of astrophysics. When the fuel of a very massive star is spent, it collapses due to its own gravitational pull and eventually becomes a very small region of arbitrarily high matter density, that is a`Singularity’, where the usual laws of physics may breakdown. If this singularity is hidden within an event horizon, which is an invisible closed surface from which nothing, not even light, can escape, then we call this object a black hole. In such a case, we cannot see the singularity and we do not need to bother about its effects. But what if the event horizon does not form? In fact, Einstein's theory of general relativity does predict such a possibility when massive stars collapse at the end of their life-cycles. In this case, we are... Read more
Poor quality nutrition during pregnancy results in smaller sized babies; remarkably, not all body parts decrease in size to the same extent. In humans, the brain is accorded preference for growth and will develop to near-normal size - an observation made in the early 1970s and termed “brain sparing”. It may not be surprising that a normal-sized brain would be a developmental priority – after all, by controlling our choices and behavior, it’s the brain that helps us adapt in life. How then does a developing brain cope with loss of nutritious food? The laboratory of Prof Gaiti Hasan at the National Centre For Biological Sciences has examined this question in fruit flies. In work recently accepted by the journal Development (http://dev.biologists.org/content/144/8/1484), Hasan and colleagues focused on a special type of cell in the brain that secretes hormones, called neuroendocrine (NE) cells. Hormones made in NE cells influence feeding and metabolism, key... Read more
While the search for elixir of life has captivated human imagination for millennia, researchers around the world have put in efforts to extend healthy lifespan and reduce the burden of morbid diseases in an increasingly aging population. Research over the past two decades has demonstrated how Sirtuin 1 (SIRT1) (popularly known as longevity gene) delays aging and plays a protective role in diseases such as diabetes, obesity, neuro-degeneration, atherosclerosis, auto-immune diseases, nephropathy and myopathies. Functionally, SIRT1 is known to be activated by reduced dietary inputs, commonly referred to as Calorie Restriction, and has been hotly pursued as a therapeutic target against age-related diseases. Researchers from the Tata Institute of Fundamental Research have now identified a control mechanism within this protein, which is key to unravelling its functional diversity and is likely to boost efforts at designing specific pharmacological agents (to activate it). This... Read more
Like the junctions in an electronic circuit between two semiconductors in an integrated computer chip, synapses in the brain constitute the logic of information flow. Simply put, neurons form functional synapses every time we learn something, and make us forget when they disappear. Loss of synaptic functions in the human brain is at the root of many progressive neurodegenerative disorders such as Alzheimer's Disease. Although research has identified several factors that can potentially cause such disorders, the critical trigger is still elusive. In a recent report, published in Cell Reports www.cell.com/cell-reports/fulltext/S2211-1247(17)30215-2, Swagata Dey and Krishanu Ray at the Tata Institute of Fundamental Research, Mumbai, India, in collaboration with Gary Banker at the Jungers Center for Neurosciences Research, Oregon Health Sciences University, USA, have found that supply of a small GTP-hydrolysis enzyme called Rab4, at the synapses, could make a significant difference... Read more
Catalysis is used in almost all industries. For instance, about 80% of chemical products are manufactured using catalysis. Catalysis is key for sustainable social development since it ensures more efficient use of natural resources. In this regard, nanocatalysts (catalysts with nano sized particles) have attracted tremendous interest in various fields due to their extraordinary efficiency as compared to conventional catalysts. We recently showed that, the combination of ultrasmall nanoparticles and pseudo-single atoms of gold (Au) and fibrous nanosilica (KCC-1) catalyzes the transformation of organosilanes to silanols, with a turn over number of approximately half a million. That means, just one mole of Au converts 5,91,000 moles reactant to product. For more details, Read our recent article Visit our lab website
Metals have a large density of electrons and to be able to see the wave nature of electrons one has to make metallic wires that are only a few atoms wide. However, in graphene - one atom thick graphite -- the density of electrons is much smaller and can be changed by making a transistor. As a result of the low density of electrons the wave nature of electrons, as described by quantum mechanics, is easier to observe in graphene. Often in metals like copper the electron is scattered every 100 nanometers, a distance roughly 1000 times smaller than the diameter of human hair, due to impurities and imperfections. Electrons can travel much longer in graphene, upto distances of 10 micrometer, a distance roughly 10 times smaller than the diameter of human hair. This is realized by sandwiching graphene between layers of boron nitride. The layers of boron nitride have few imperfections to impede the flow of electrons in graphene. Once electrons travel long distances, implying there are... Read more
Professor Sudip Bhattacharyya of the Tata Institute of Fundamental Research (TIFR), Mumbai, India, and Professor Deepto Chakrabarty (MIT, USA), an adjunct visiting professor at the same institute, have shown that a population of neutron stars should spin around their axes much faster than the highest observed spin rate of any neutron star. They pointed out that the observed lower spin rates are possible if these neutron stars emit gravitational waves continuously, and hence spin down. Neutron stars are the densest observable objects in the universe, with a fistful of stellar material outweighing a mountain on Earth. While such stars are not bigger than a city, in size, they have more material than in the Sun crammed inside them. A population of these stars can increase their spin rate by the transfer of matter from a normal companion star. Infact, some of them have been observed to spin several hundred times in a second around their own axes. In the 1970s, it was theoretically... Read more
The properties of the 83rd element of the periodic table, namely, Bismuth (Bi) have been studied for more than a century and still continues to draw enormous scientific interests due to its anomalous electronic properties. Bulk rhombohedral Bismuth (Bi) at ambient pressure is a semi-metal and it remains in the normal state down to 0.010 K. Unlike metals where there is roughly one mobile electron per atom, in a semi-metal like Bi, the concentration of mobile electrons is extremely low (100,000 atoms share a single mobile electron). Hence, the superconductivity (SC) in bulk is thought to be very unlikely due to this extremely low carrier density. Now, a group of TIFR scientists have discovered superconductivity of a high quality single crystal of Bi (99.998% pure) at 0.00053 K with a critical field of 0.000005 Tesla (nearly 1/8 of earth’s magnetic field). The discovery was made by observing a diamagnetic signal using a home made ultra sensitive magnetometer which is housed in a... Read more
In chemistry, in order to achieve efficiency of any chemical reaction, a catalyst is added that serves to ideally increase the rate of reaction without any deleterious effects. Specifically, a photocatalyst is one which is activated under light and can lead to improvement in rates of a variety of redox based reactions. An aspect of photocatalysis that normally does not get much recognition is recyclability. In fact, for a catalyst to be viable it must be able to withstand the reaction conditions repeatedly and the rates of reaction, upon re-using the catalysts, must not change dramatically (or at all infact). In reality, however, most catalysts eventually undergo degradation. Presented in this work from our group (http://www.nature.com/articles/srep35075) is a seminal observation where we noted an increase in rate of reaction upon recycling. The increase was 1.7 times higher in the second cycle (when compared to the first) and it was 3.1 times higher in the third cycle (again,... Read more
The GRAPES-3 experiment located at the Cosmic Ray Laboratory (CRL) in Ooty consists of two major components, first an array of 400 plastic scintillator detectors, and second a large area muon telescope. The GRAPES-3 led by Prof. Sunil K.Gupta, has participation of about 30 scientists from 7 universities in India, and from 5 in Japan. The GRAPES-3 muon telescope recorded a burst of galactic cosmic rays of about 20 GeV, on 22 June 2015 lasting for two hours. The burst occurred when a giant cloud of plasma ejected from the solar corona, and moving with a speed of about 2.5 million kilometers per hour struck our planet, causing a severe compression of Earth’s magnetosphere from 11 to 4 times the radius of Earth. It triggered a severe geomagnetic storm that generated aurora borealis, and radio signal blackouts in many high latitude countries. Earth's magnetosphere extends over a radius of a million kilometers, which acts as the first line of defence, shielding us... Read more
TIFR’s Giant Metrewave Radio Telescope (GMRT), on 16 Oct 2016, detected the first UHF radio signals emitted by the space probe of the European Space Agency’s ExoMars Mission. The GMRT is providing monitoring support to the ExoMars Mission as the earth based radio facility. The mission (see http://exploration.esa.int/mars/46124-mission-overview/ for details) aims to explore various properties of Mars. The GMRT achieved this historic target at the time of separation of the lander module (Schiaparelli) from the Orbiter, as they neared Mars after a 6 months journey from Earth. Importantly, the GMRT tracked the lander module all the way into its last phases of descent into the Martian atmosphere, an event that is very complex and hazardous. This signal detection, at 401 MHz (made possible by the upgraded GMRT feeds and receivers), was made with a phased array voltage signal from the GSB, further processed through special processing software developed in... Read more
Scientists from the Tata Institute of Fundamental Research provide the first ever description of the process of sperm release live in an animal using the fruit fly, Drosophila. Dubey et al., in their manuscript published in the 12 September 2016 issue of the journal, Developmental Cell reveal the cellular description of sperm release in the testis of live Drosophila. This is the first time that such a process has been video-graphed in any animal species. While investigating this process, they also discovered an unprecedented phenomenon of a cell reacting to the constant attempts of invasion by mature spermatids. They showed that the mature spermatids actively push into the neighbouring somatic cells during the final stages before exiting the testis. Each time, the cell mounts a local response and actively pushes the invading spermatids back. This phenomenon is driven by the local self-assembly of actin polymers and membrane dynamics. The results may have wider implications in... Read more
India's first dedicated astronomy satellite, AstroSat, which was launched by ISRO on Sept 28, 2015, has observed for the very first time rapid variability of high energy (particularly >20keV) X-ray emission from a black hole system. The Large Area X-ray Proportional Counter (LAXPC) instrument which is only instrument worldwide capable of such study, was designed & developed indigenously at the Tata Institute of Fundamental Research (TIFR) Mumbai. In black hole systems, mass from a regular star gets stripped off and falls towards the black hole forming a disk around the black hole. The temperature of the disk is more than ten million degrees and hence the system emits X-rays. The total power coming out of these systems is often more than ten thousand times that of the sun. Yet these systems vary rapidly in time-scales much less than a second. Astronomers have always been puzzled by the enigmatic black hole system called GRS 1915+105. It shows many different kinds of... Read more
Researchers from the Tata Institute of Fundamental Research, Mumbai, have demonstrated the ability to manipulate the vibrations of a drum of nanometre scale thickness – realizing the world’s smallest and most versatile drum. This work has implications in improving the sensitivity of small detectors of mass – very important in detecting the mass of small molecules like viruses. This also opens the doors to probing exciting new aspects of fundamental physics. The work, recently published in the journal Nature Nanotechnology, made use of graphene, a one-atom thick wonder material, to fabricate drums that have highly tunable mechanical frequencies and coupling between various modes. Coupling between the modes was shown to be controllable which led to the creation of new, hybrid modes and, further, allowed amplification of the vibrations. The experiment consisted of studying the mechanical vibrational modes, or ‘notes’, similar to a musical drum. The... Read more
IndIGO Press Release While the celebrations for the first detection of gravitational waves are still ringing down, we are excited to announce the observation of yet another binary black hole merger by LIGO. On December 26, 2015 at 09:09AM IST the LIGO detectors in Hanford, Washington and Livingston, Louisiana detected a signal from the coalescence of two black holes, with masses 14 and 8 times the mass of the sun, merging into a more massive, rapidly rotating black hole that is 21 times the mass of the sun. The event happened 1.4 billion years ago, lasted in LIGO's frequency band for about a second and released about 1 solar mass worth of energy in that short period. For comparison, only a tiny fraction of the sun's mass gets converted to light in its entire lifetime, which is enough to keep the earth warm for billions of years. Compared to the first binary BH merger event announced in February-2016, the present one is much less massive -- 62 solar mass vs 21 solar... Read more
In a recent development, scientists at the Tata Institute of Fundamental Research report that damage to DNA can be induced by ultrashort pulses of high intensity laser light. Published in Scientific Reports, these findings have important implications in clinical conditions, especially in reducing collateral damage to tissues surrounding the real target of conventional radiotherapy. High intensity femtosecond laser pulses were used to probe damage to aqueous DNA . In propagating through the water medium, the intense light pulses cause H2O molecules to ionize and break-up, giving rise to low-energy electrons and OH-radicals. Both are responsible for producing breaks in DNA strands. Infact, earlier work carried out by the same team [2, 3] showed that OH radicals were four times more likely than electrons to produce double strand breaks in DNA. A collaborative project between TIFR Mumbai, the Centre for Excellence in Basic Sciences, Mumbai, and Manipal University, the experiments... Read more
Climate change due to excessive CO2 levels is one of the most serious problems mankind has ever faced. This has resulted in abrupt weather patterns such as flood and drought, which are extremely disruptive and detrimental to life, as we have been witnessing in India in recent years. Mitigating rising CO2 levels is of prime importance. In a new development, scientists at the Tata Institute of Fundamental Research, Mumbai, have developed a novel design of CO2 sorbents that show superior CO2 capture capacity and stability over conventional materials. The immobilization of functional amines on a porous solid support can result in stable and efficient CO2 sorbent materials compared to similar liquid sorbents. A critical disadvantage however, is a drastic decrease in the textural properties of these supports (i.e., their surface area and pore volume), leading to a decrease in the CO2 capture capability. To overcome this challenge, scientists at the Tata Institute of Fundamental... Read more
In a recent breakthrough, scientists from the Tata Institute of Fundamental Research, and the Centre for Excellence in Basic Sciences, Mumbai, demonstrate an accurate method to simulate prehistoric movements of people based upon current topographical satellite data. Recently published in the journal PLOS ONE, population dynamics of prehistoric human migration into the island comprising England, Scotland and Wales was simulated by applying a diffusion equation tempered by geographical data determined from satellite-based information. Importantly, these findings are validated by recently-available genetic data. This method may prove useful in determining early human population dynamics even when no genetic information is available. Movement of people in prehistoric times was almost entirely determined by geography and human needs, both deterministic parameters when small populations move into unoccupied areas where conflicts and large group dynamics are not important. The... Read more
A recent observational campaign involving more than two dozen optical telescopes and NASA’s space based SWIFT X-ray telescope allowed a team of astronomers to measure very accurately the rotational rate of one of the most massive black holes in the universe. The rotational rate of this massive black hole is one third of the maximum spin rate allowed in General Relativity. This 18 billion solar mass heavy black hole powers a quasar called OJ287 which lies about 3.5 billion light years away from Earth. Quasi-stellar radio sources or 'quasars’ for short, are the very bright centers of distant galaxies which emit huge amounts of electro-magnetic radiation due to the infall of matter into their massive black holes. This quasar lies very close to the apparent path of the Sun's motion on the celestial sphere as seen from Earth, where most searches for asteroids and comets are conducted. Therefore, its optical photometric measurements already cover more than 100... Read more
SuperKEKB at the KEK laboratory in Japan has achieved "First Turns", a major milestone for any new particle accelerator. Designed to deliver the world's highest luminosity, the collider will enable the Belle-II experiment (placed at its interaction point) to probe physics beyond the standard model of particle physics. Involving an international collaboration of over 600 physicists, the Indian team, led by TIFR Mumbai, is designing and building the silicon micro-vertex detector (SVD) of the experiment. A new electron-positron collider, SuperKEKB, at the KEK laboratory in Tsukuba, Japan has achieved “First Turns” and is now in the test operation stage. This is the first new “atom-smasher” since the LHC, which is located at the CERN laboratory in Switzerland. The achievement of “first turns”, which means storing the highly energetic beam in the ring through many revolutions, is a major milestone for any new particle accelerator. In the... Read more
The Balloon Facility of the Tata Institute of Fundamental Research successfully launched a balloon flight carrying three lab rats in a space capsule upto an altitude about three times that of Mt. Everest. Conducting this experiment for a scientific collaboration with a Singapore based space technology firm, this marks the first successful experiment of its kind in India indicating a capacity to carry humans into space using scientific balloons. The 38,211 m3 balloon was designed, fabricated and launched at the TIFR Balloon Facility in Hyderabad by experienced scientists and engineers. This research facility designs and develops scientific balloons that are used for various applications. Mr. Lim Seng founder of the Singapore tech firm InGenius, said “TIFR’s sterling safety records and 45 years of ballooning experience ensured the success of this project”. This scientific achievement was accomplished at 5.30am on March... Read more
Cells of our immune system kill pathogens by enclosing them in a compartment called the phagosome. The phagosome undergoes programmed maturation, where the pathogen is degraded. Intimately linked to this degradation is active transport of the phagosome inside cells by nanoscale "Motor" proteins such as Dynein and Kinesin, which are force generators for many kinds of biological movements. Phagosomes carried by the Motors initially move in a back-and-forth manner near the cell periphery, and mature by fusing with other compartments. As time passes, there is a switch that causes the phagosomes to move in an almost unidirectional manner towards the cell centre. Here, they fuse with acidic lysosomes so that the pathogen can be degraded. The switch in the phagosome's motion is important for the degradation of pathogens as has been observed in the case of Mycobacterium tuberculosis and Salmonella who abort this switch as a strategy for survival and... Read more
Astrosat, India's first dedicated science space mission was launched on 28 September 2015. The Large Area X-ray Proportional Counter (LAXPC), designed and developed at TIFR, Mumbai, is one of the major payloads on ASTROSAT. The LAXPC instrument became fully operational on 19 October 2015 for the first time in space. LAXPC will provide the largest effective area among all satellite missions flown so far, worldwide, and will remain so for the next 10 years, for X-ray studies in the 3-80 keV energy range. “First light from LAXPC has allowed us to observe Black hole X-ray binaries, Microquasars, X-ray pulsars, Active Galactic Nuclei (AGN)s and Supernova remnants, providing us with very high quality data,” says Prof. JS Yadav, lead scientist of the LAXPC team. The LAXPC instrument is functioning perfectly and has achieved all detector parameters/goals as proposed initially. TIFR Director, Prof. Sandip Trivedi says “All the TIFR payloads on board Astrosat are... Read more
In a recent breakthrough to combat malaria, a collaboration of Indian and American scientists have identified a malarial parasite protein that can be used to develop antibodies when displayed on novel nanoparticles. This approach has the potential to prevent the parasite from multiplying in the human host and also inhibits transmission through mosquitoes. The finding points towards developing a powerful malaria vaccine in the hope of eradicating this debilitating and often fatal disease. Malaria takes a heavy toll on human lives. About half a million people die every year and several hundred million suffer from this disease across the globe. To add to the disease burden, the malaria parasite is increasingly becoming resistant to commonly used anti-malarial drugs. Development of an anti-malarial vaccine is an integral part of an effort to counter the socio-economic burden of malaria. Researchers in the malaria labs at Tata Institute of Fundamental Research (TIFR), Mumbai, India,... Read more
Astrosat First Light: CZT Imager Looks at Crab Astrosat - fondly named 'India's own space observatory' was put into orbit on September 28, 2015. Then began the process of putting each of the payloads into operation. CPM (Charge Particle Monitor) was the first payload to go operational followed by the Cadmium Zinc Telluride Imager, the hard X-ray detector on board Astrosat. CZTI was made fully operational on October 5 and on October 6, Day 9 of Astrosat, at 04:30 UT (10 AM IST), the satellite majestically turned towards Crab Nebula, remnant of the Supernova detected by Chinese astronomers in the year 1054. The celebrated Crab Nebula, which also includes the Crab Pulsar, is the brightest hard X-ray source in the sky, and is very often used to calibrate hard X-ray detectors. CZT Imager was ready to image the Crab Nebula. Detector Operation: The story so far CZTI consists of four quadrants of 16 pixelated detectors each, achieving a total geometric area of 976 cm2... Read more
The Soft X-ray focusing Telescope (SXT) onboard Astrosat, India’s first satellite dedicated to astronomical observations, saw its first light from an astronomical source on October 26th, 2015, after the camera door was opened at 06:30UT. The telescope door covering the optics had already been opened 10 days earlier. The SXT is India’s first X-ray telescope based on doubly reflecting grazing incidence optics, containing 320 mirrors assembled together in 2 sets of 40 co-axial shells. The golden mirrors and the precision structure for assembling them were all built in the Department of Astronomy and Astrophysics of the Tata Institute of Fundamental Research (TIFR), Mumbai. All the mirrors assembled at different radii from the central axis were aligned perfectly to image a single point, and the entire telescope was then further aligned with an X-ray camera, in TIFR. The camera was previously assembled independently in the Department of Physics and Astronomy, at... Read more
The first Indian astronomy satellite Astrosat was launched on 28th September, 2015, by the Indian Space Research Organisation (ISRO) from Sriharikota, on a PSLV (Polar Satellite Launch Vehicle) rocket. Astrosat has unprecedented capability to simultaneously observe cosmic objects in visible light, the ultraviolet waveband and the entire X-ray waveband from very low energy to very high energy X-rays. This unique ability to observe the universe in multi-wavelengths, simultaneously, is aimed at performing cutting-edge research in astrophysics. Researchers from the Tata Institute of Fundamental Research (TIFR) have led this multi institutional effort and have made significant contributions to the design, fabrication and development of three out of five payloads that are on board Astrosat. The Large Area Xenon Proportional Counters (LAXPC), a Soft X-ray Telescope (SXT), and a Cadmium-Zinc-Telluride Imager (CZTI), all of which will observe the universe in the X-ray wavebands, are the... Read more
Using a new method involving laser light and fat-coated silver nano-particles, scientists have caught a glimpse of the elusive toxic form of the Alzheimer's molecule, during its attempt to bore into the outer covering of a cell decoy. While the origin of Alzheimer’s Disease, one that robs the old of their memory, is still hotly debated, it is likely that a specific form of the Amyloid beta molecule, which is able to attack cell membranes, is a major player. Defeating this molecule would be easier if its shape and form were known better, but that has proven to be a difficult task until now. “Everybody wants to make the key to solve Alzheimer’s Disease, but we don’t know what the lock looks like. We now have a glimpse of something which could be the lock. Maybe it’s still not the real thing, but as of now, this is our best bet,” says Sudipta Maiti, who co-directed the efforts with P. K. Madhu (both from TIFR). If they are right, then designing the key, i.e. making a drug... Read more
In a landmark move for particle physics research, the Government of India has given its approval for the establishment of the India-based Neutrino Observatory (INO) which aims to build a world class underground laboratory, primarily to study neutrinos. A mega scale collaborative project, set to address big unanswered questions in particle physics, TIFR Mumbai is the host institute for the INO. With about 300 neutrinos in one cubic cm of our universe, they are the second most abundant particle after photons. Their origin lies in the natural environment that existed when the universe was created, in addition to the core of the sun, other stars, and cosmic rays that interact with the Earth's atmosphere. We are surrounded by these tiny neutral particles and do not even realize that trillions of them harmlessly pass through our body every second. As they interact very weakly with anything in their path they are even able to pass through the Earth. Neutrinos initially thought to be... Read more
Photosynthesis is a process by which light energy is converted into chemical potential and stored in the chemical bonds in form of carbohydrates. The complex light triggered events that drive photosynthesis primary takes place in the confines of the membrane and inside large protein complexes. Confining synthetic organic photochemistry inside water-soluble molecular hosts underscores a biomimetic approach towards artificial photosynthesis. Organic transformations using light classically make use of diffusion based interactions or kinetics which occurs in nanoseconds to microseconds, thereby ensuring that some part of photon's energy is wasted via relaxation processes. If bond making or breaking can be performed within few picoseconds of optical excitation, then most of the photon energy can be utilized efficiently for chemical transformations. Previously ultrafast electron transfer and proton transfer reactions independently have been demonstrated by researchers in many artificial... Read more
The high energy proton collider, the LHC machine at CERN, Geneva, has delivered a few collisions at the centre of mass energy of 13 TeV (13 million million electron-Volts) recently for the first time ever and thus broken its own record of Run1 (collisions at 7 and 8 TeV during 2010-12). By April 10 proton beams at LHC reached the energy of 6.5 TeV, and, by May 5 low energy collisions (900 GeV) were recorded by all the experiments. Recently the machine has been tuned well and it has started delivering good quality collisions on June 3. Analyzing this data physicists expect to peer into the secrets of the early universe. Members of the TIFR-CMS group are taking part in data collection, monitoring and analyses. During the shutdown period after Run1, which lasted for about two years (2013-14), the machine as well as the experiments were consolidated to meet the challenges of the current phase (Run2). The TIFR group participated in this upgrade of the CMS experiment. The Run1 of the LHC... Read more
Electron collision with atoms and molecules is one of the most efficient ways of transferring kinetic energy into potential energy thereby initiating and enhancing chemical reactions. This is at play in a variety of natural processes and in laboratory as well as industrial applications. While electron impact ionization is an important channel in this energy transfer process, other inelastic processes dominate at low energies where ionization is energetically disallowed. A wide variety of processing plasmas used for various industrial purposes like lighting, semiconductor etching, plasma assisted chemical vapour deposition, gas lasers, pollution control and nanolithography are examples where all these electron induced processes play a decisive role. It is also realized that the electron induced processes are the inevitable links in the creation of molecules, including biological molecules in interstellar medium and radiation damage in biological systems. For example, the initial atomic... Read more
Small oligomers of amyloid-beta (Abeta) peptide are believed to initiate Alzheimer's disease, but their fleeting nature makes their structures elusive. We combined fast fluorescence and slow solid-state NMR spectroscopies to probe these bio-active Abeta oligomers. Their structure substantially differs from the less-toxic mature fibrils only in two specific regions. Interestingly, 10 of 11 known disease-causing Abeta mutations occur in these two regions. Our results provide atomic-level structural markers for developing potential Alzheimer therapeutics. More details in Sarkar et al., Angew. Chem. Int. Ed., Volume 53, Issue 27, July 1, 2014, Pages: 6888 6892 (from the labs of S. Maiti and P. K. Madhu) Further References BIOPHOTONICS LAB
Topological insulators are one of the most interesting candidates in contemporary research because of their remarkably different surface and bulk states. Due to strong spin-orbit coupling these materials show relatively longer range quantum entanglement which makes them suitable for building next generation quantum computational devices. Amongst other such materials, Bi2Se3 is of particular importance due to its large bulk band gap and surface states with a single Dirac fermionic mode which shows a linear, lightlike dispersion. Recently Bi2Se3 came into the limelight by showing superconductivity when doped with Cu. While an intercalated CuxBi2Se3 (0.1xBi2-xSe3 does not exhibit any trace of superconductivity. This made researchers to believe that Cu intercalation into Bi2Se3 structure is crucial to make it superconducting. It was also reported that any long range ordering in Cu intercalation was absent in the bulk material so, in other words Cu intercalated regions of... Read more
To live is to move. You strike to swat that irritable mosquito, which skillfully evades the hand of death. How did that happen? Who moved your hand, and what saved the mosquito? Enter the Molecular Motors, nanoscale protein-machines in the muscles of your hand and wings of the mosquito. You need these motors to swat mosquitoes, blink your eyes, walk, eat, drink... just name it. Millions of motors tug as a team within your muscles, and you swat the mosquito. This is teamwork at its exquisite best. Paradoxically, a weak and inefficient motor (called dynein) is the one that generates large forces in many different biological processes. Why has nature made this counter-intuitive choice? Scientists at TIFR, led by Dr. Roop Mallik, have discovered that a team of dyneins is able to share a load much larger than any one of them can handle, due to the unique ability of each dynein to change gears. Because of this, dynein's do much better at teamwork than other stronger motors that... Read more
Conventional as well as compact laser-based particle acceleration schemes hinge on accelerating electric fields and are therefore ineffective for neutral atoms, which do not respond to these fields. Researchers at UPHILL lab in TIFR have generated the first table-top mega-electron-volt neutral atom source. The technique involves the stripping of eight electrons per Argon atom in a cluster, accelerate the ions and subsequently restore the electrons into the ions with 100% conversion efficiency. Charged particle accelerators have become crucially important to modern day life, be it in health care for cancer treatment or for answering important fundamental scientific questions like the existence of the HIGGS boson, the so called "God particle". In a simple picture, charged particles like electrons and protons are accelerated between two end plates across which an electrical voltage is applied. High energies need high voltages (millions and billions of volts) and long... Read more
Virtually all processes that are essential for life such as, photosynthesis, respiration, cell signaling, and energy production/storage are carried out by biological molecules we call proteins. Imagine if you had a microscope powerful enough to resolve individual atoms of a protein molecule. What would you see? You would see thousands of atoms linked together as amino acid peptide units creating a polypeptide chain. The chain often has a well defined three dimensional structure as reflected in the structure of a DNA synthesizing protein (Fig (a)). Sometimes different protein units can team up together to form larger complexes to carry out a specific task. For example, the rhodopsin-transducin complex located at cell boundaries (Fig (b)) gets activated by light to initiate a signaling process within the cells of the eye which ultimately leads to vision. What if our microscope allowed us to monitor atomic motions? What would we see? In their solvent environment and ambient... Read more
Self organization of large-scale structures in nature - either coherent structures like crystals, or incoherent dynamic structures like clouds - is governed by long-range interactions. In many problems, hydrodynamics and electrostatics are the source of such long-range interactions. The tuning of electrostatic interactions has helped to elucidate when coherent crystalline structures or incoherent amorphous structures form in colloidal systems. However, there is little understanding of self organization in situations where both electrostatic and hydrodynamic interactions are present. This work shows a minimal two-component oil-in-oil model system where the strength and lengthscale of the electrohydrodynamic interactions can be controlled by tuning the amplitude and frequency of the imposed electric field. A rich phenomenology of exotic structure and dynamics ranging from incoherent cloud-like structures to coherent droplet arrays is observed as a function of the hydrodynamic... Read more
The results on the search for the Higgs boson using LHC data of 2011 combined with that of 2012, has been announced at CERN on July 4th, 2012. Here is the webcast http://webcast.web.cern.ch/webcast To download two talks go to http://indico.cern.ch/conferenceDisplay.py?confId=197461 The press release about the result from CMS experiment is available in Hindi and English. CERN press release : http://press.web.cern.ch/press/PressReleases/Releases2012/PR17.12E.html The interactions among various elementary particles are described in the theory of the Standard Model based on various symmetry considerations. Though the predictions from this model has been confirmed by many experiments during last 30 years, it lacks the power to predict the masses of the elmentary particles. The mass generation is possible by the so called spontaneous electroweak symmetry breaking which was discussed first by Y.Nambu and taken to earnest by 3 teams of... Read more
Apart from black holes, neutron stars are the densest known objects in the universe. Moreover, while light from a black hole cannot escape, a neutron star can be seen directly by the light it emits. This makes these stars immensely important for probing some extreme aspects of the universe and for testing fundamental laws of nature, which cannot be done by experiments in terrestrial laboratories. For example, the density of a cold neutron star core is several times the nuclear density, and hence exotic matter (such as deconfined quark) may exist there. This is a fundamental problem of particle physics, and the only way to solve this problem is to measure the mass and radius of a neutron star using astronomical techniques. Another fundamental problem of physics is to test Einstein's general theory of relativity, the most accepted law of gravitation, in the strong gravity regime. X-rays originated from a region very close to the neutron star can be useful to test a law of... Read more
Writing is an epitome of the intellectual creation of a civilisation. It involves comprehension as well as abstraction of symbols that signify specific achievement of human creativity and communication. Renfrew points out that "The practice of writing, and the development of a coherent system of signs, a script, is something which is seen only in complex societies... Writing, in other words, is a feature of civilisations". When a civilisation leaves behind some written records, they are invaluable not only to understand their civic society but also to understand the basic thinking processes that moulded the civilisation. Decipherment of any script is a challenging task. At times it is aided by the discovery of a multilingual text where the same text is written in an undeciphered script as well as known script(s). Both Egyptian hieroglyphs and Mesopotamian cuneiform texts were deciphered with the help of multilingual texts. In some cases, continuing linguistic traditions... Read more
Field effect transistors (FETs) are switches that form the basis for electronics all around us - from high performance computers to mobile devices. A field effect transistor is like a tap, or a valve, where the turning of the tap knob controls the flow of water. In the case of transistor the gate electrode is the knob that modifies the flow of electrons between two terminals called the source and the drain. In order to make faster transistors that operate at high frequencies one has to make them really small, and also be able to rapidly turn off and on the flow of electric current which requires an efficient gate electrode. Such devices are fabricated from tiny semiconductor nanowires, 1000 times narrower than a human hair, and need to have gate electrodes with a high capacitive coupling to the semiconducting channel that connects the source and the drain electrodes. These devices are important not only from technological standpoint of future devices but are also interesting as they... Read more
Modern science has introduced us to many strange ideas on the universe, but one of the strangest is the ultimate fate of a massive star that reached the end of its life-cycle. Having exhausted the fuel that sustained it for millions of years, the star is no longer able to hold itself up under its own weight and the force of self-gravity, and it starts collapsing and shrinking catastrophically. Modest stars like the Sun also collapse but they stabilize later at a smaller size. However, if a star is massive enough, with tens of times the mass of the Sun, its gravity overwhelms all the forces that might halt the collapse. From a size of millions of kilometers across, the star crumples to a pinprick size, smaller than the dot on an "i." What is the final fate of such massive collapsing stars? This is one of the most exciting questions in astrophysics and modern cosmology today. An amazing inter-play of the key forces of nature takes place here, including the gravity and... Read more
Plasmonics is an active field that proposes to use the surface modes at the metal-dielectric interface in nanophotonics (sub-wavelength imaging and optics), spectroscopy (surface enhanced Raman spectroscopy), modifying the optical properties of materials among others. All these utilize the electron charge density wave or surface plasmon polaritons (SPP) at metal-dielectric interface. Plasmonic crystals are specially designed metal-dielectric nanostructures that modify material properties due to plasmon mediation. One would require good theoretical, nanofabrication and characterization tools to predict and demonstrate novel phenomena. One such proposal is the enhancement of magneto-optical properties in magnetic materials so that the Kerr and Faraday effects are enhanced. Similarly, absorption and emission from semiconductors can be modified by plasmon mediation. At TIFR, different types of plasmonic crystals are prepared. For example, Gold gratings of predetermined dimensions on... Read more
The ability of certain materials to conduct electricity without any resistance was discovered a hundred years ago when Kammerlingh Onnes found that the resistance of solid mercury dropped to zero below 4.2K, its so called transition temperature (Tc). Studies based on this spectacular phenomenon, coined as "superconductivity" , are now a century old, but they continue to thrive both from the point of view of newer applications as well as that of throwing up challenges on the fundamental physics governing the collective behavior of electrons in solids. All superconductors discovered in the first seven decades after Kammerleigh Onnes discovery had low transition temperatures (highest one being Nb3Ge with Tc~23K), well below the liquefaction temperature of nitrogen (77K). The physics behind these conventional superconductors has been well understood over the past 50 odd years based on Bardeen-Cooper-Schrieffer (BCS) theory. In these materials, an... Read more
The universe was born as a hot soup of quarks, gluons and other particles. As it cooled, the soup eventually congealed into protons, neutrons and the other atomic nuclei which exist today. The description of this soup at temperatures just above where it congeals is one of the hottest research topics in physics. Rutherford's discovery of the atomic nucleus in 1911 started the study of what came to be called the strong interactions of matter. From that starting point to building the theory of quarks and their interactions with the force carriers, called gluons, has occupied nuclear and particle physicists for the last one hundred years. The final theory is called Quantum ChromoDynamics, QCD in brief. It has been tested in part earlier, and indeed the long development of this theory gave rise to a string of Nobel-prize winning work. However, until now, it was not tested in the realm of bulk matter. One of the most interesting aspects of bulk matter is that... Read more
A porous medium is a material containing large number of randomly located voids (pores) of sizes greater than the microscopic interatomic scale such as wood, sponge, rocks etc. Flow of fluids through such porous media is of interest to many scientific and engineering disciplines. For example, petroleum engineers study the flow of water through rocks containing oil and gas, chemical engineers are interested in separation processes in packed-bed reactors, hydrologists are concerned with flow of water and contaminants through soil, geologists and geophysicists study the flow of molten magma in the mantle. We have studied the motion of two-fluid interfaces in a model porous media made by packing spheres in a pipe during the displacement of one fluid by another. If a less viscous fluid displaces a more viscous one in a pipe or in a porous medium, an initially flat two fluid interface spontaneously develops finger-shaped protrusions which grow unstably with time to result in a... Read more
To a layperson, the term LASER brings to the mind images of Luke Skywalker battling Darth Vader, with guns emitting resplendent red, green or blue beams of powerful light, which can cut through steel and shoot exactly in the direction the gunner wants. Power and directionality, precisely the two virtues that make the laser a laser, originate from a physical attribute called coherence, which essentially states that all light waves emitted by the laser are made of electromagnetic fields that oscillate in phase. Notwithstanding the Hollywoodish brouhaha, the term "laser" technically comes down to light with coherence; both power and directionality are the consequences thereof. However, to achieve this coherence in the laser device, a sophisticated amount of engineering has to go in, with precise alignments, ultrasmooth mirrors, exactly machined sizes etc required to make the laser. The precision engineering basically aims to create a mirror-based device (technically, a... Read more
A brief introduction to neutrinos Neutrinos are some of the most elusive particles in the universe. They are the second most abundant particles in the universe, and trillions of them pass through us every second without us even realizing it. At the same time, they help the sun shine, make stars explode, and allow us to see places from where light cannot reach us. First postulated by Pauli in 1932 to explain the energy-momentum conservation in nuclear beta decay, neutrinos took a quarter of a century to be actually observed. In the five decades since then, neutrinos have continued to spring surprises, challenging our knowledge of fundamental interactions. Neutrinos are elementary particles, and come in three ``flavours'': electron neutrino, muon neutrino and tau neutrino. They form an integral part of the Standard Model of particle physics, and are the particles that have only weak interactions. The interactions are so weak that the neutrinos from the Sun can pass through... Read more