Public Lecture

The contemporary hydrology is faced with great challenges of resolving known problems of water scarcity, anthropogenic pollution, geogenic contamination, dwindling surface flows, inequitable distribution and salinity ingression. The scientific processes underlying these hydrological problems are well understood and can be mitigated by appropriate field engineering measures, treatment technologies, improved water use efficiency and policy interventions. However, these problems have not been completely resolved yet. Beyond these known problems, that we are still grappling with, lies a mind-boggling ignorance about certain aspects of hydrological processes, their natural course and response to perturbing stimuli. In particular, the hydrological response to climate change, engineered interventions and anthropogenic perturbations are not well understood because of longer response time of natural hydrological systems. India is world’s largest user of groundwater, the 90% of which is used for agriculture. Agriculture, with its allied sectors, is the largest source of livelihoods in India. About 70 percent of its rural households depend primarily on agriculture for their livelihood. Agriculture sector also accounts for ~18% of total electricity consumption in India and contributes to ~15% of GDP. Thus, There is a complex relationship between water resources, social health and economy of India. Therefore, any undesirable change in hydrology of India needs to be monitored and prevented. Hydrological responses to natural and man-made changes are sluggish and silent. Therefore, adverse hydrological and ecological effects are often noticed only when it is too late and too difficult to recover. This ignorance about hydrological response poses greatest challenge for scientists, engineers, planners and policy makers, and defines the frontier of research. Modern humans have solved many difficult problems but water is more challenging, because it is not as simple as it seems. Some of the above aspects will be discussed in the talk.

Nonlinear optics is one of the most fascinating sub-fields of the science of light. It enables to efficiently generate radiation at wide range of wavelengths, from the ultraviolet to the mid-infrared. The talk will cover basic properties of light waves and of light sources, fundamentals of nonlinear wave mixing and finally some advanced topics, related to patterned nonlinear crystals, all-optical shaping of structured light, and the generation of non-classical light by spontaneous parametric down-conversion.

India embarked on planetary exploration starting with the Chandrayaan-1 orbiter mission in 2008. This was followed by a mission to Mars, the Mars Orbiter Mission (MOM), launched in November 2013 and arrival on Mars in September 2014. The ongoing Indian planetary mission is Chandrayaan-2. India also has a planned a mission to study the Sun called Aditya-L1. This lecture will briefly highlight the challenges and science of Indian planetary missions.

The discovery of frozen water ice in the polar regions of the Moon by the M3 experiment on the Indian Chandrayaan-1 mission has ushered in a completely new era of lunar exploration. From now on, the establishment of a permanent lunar colony would become a realistic goal of the international space community. In this talk, we will give an overview on the recent and on-going scientific efforts in the search for water resource on the Moon. We also try to take a peek at what might happen up there in 20 years, perhaps including the possibility of an ice skating rink.

Photonics manipulates photon or light, and thus consider its generation, detection and processing for various applications. Its emergence has been marked with the invention of semiconductor lasers and optical fibres. Initial research focus was its application in high speed communications and thus benefitted from the invention of erbium doped fibre amplifiers and wavelength division multiplexing. However today, it has a range of very important applications, such as data storage, display, material processing, healthcare applications, optical sensing, and illumination beside its original focus on high data rate communications. In the new Horizon 2020, Photonics has been identified as the Key Enabling Technology with its likely impact to shape the overall technologies for this century. In this lecture I will focus on these issues, from its emergence to being a key dominating technology of the future. Following that, I will focus a bit on the prospect and challenges of silicon photonics, an emerging area of photonics research and present some results in this area, arising from my research group.

Electrons are fast and elusive, yet their arrangement in time determines how chemistry proceeds and materials function. Insight into their dynamics holds the key to design new substances or to tailor materials with specific functionality. I will explain how we can use extreme light to manipulate electrons into taking snapshots during a reaction or excitation.

The Sun is the first astronomical object in which magnetic field were discovered in 1908 by using Zeeman effect. Even before this discovery of magnetic fields in supports, it was known that there is a 11- year cycle of sunspots, which could be identified as the magnetic cycle of the Sun after this discovery. The magnetic field of the Sun is also behind many other phenomena, such as the violent explosions known ass solar flares, the corona much hotter than the solar surface and the solar wind. Only within the last few decades, major developments in plasma physics and magnetohydrodynamics (MHD) have at last provided a broad framework for the theoretical understanding of these phenomena connected with the solar magnetic fields. I shall give a general introduction to this field- with some emphasis on the research interests of our group, A more detailed account of this field can be found in my recently published popular science book: http://www.amazon.in/Natures-Third-Cycle-Story-Sunspots/dp/0199674752/

Light has been an essential element of existence since the earliest days of human life. It has taken many forms, from the natural sunlight, to lanterns and light bulbs, to modern-day lasers. At every stage in human history, light has been generated, manipulated and exploited to nourish and enhance the the quality of our life. The impact of light on human life has never been as great as in the past 50 years, following the invention of the laser. Since then, the laser has become a vital enabling tool in many fields of knowledge in physics, chemistry, biology, and medicine, and has had an unprecedented impact on the technological progress of mankind. In this lecture, I will provide a brief overview of the history of light, from the early observations and descriptions, to later scientific discoveries in the 20th century, which led to the invention of the laser. I will also describe the ubiquitous applications of lasers in various scientific and technological areas with direct impact on our daily life.

Humans have always aspired to explore the heavens. It was exactly 55 years ago this month, in April of 1961, that the first human being, Yuri Gagarin, was launched into space. Since then we have come a long ways, and the future of human space exploration is bright! I will discuss the current and future prospects of human space exploration based on my own experiences as a NASA astronaut for 17 years (1992-2009), during which time I flew five missions aboard the Space Shuttle and conducted seven space walks.

The field of superconductivity, hundred and odd years young, is witnessing remarkable developments and changes. Its history is marked by surprises and anticipations. Once BCS theory was in place, the depth and relevance of this quantum phenomenon began to emerge. It inspired Nambu, Anderson and Higgs to discover an universal mass generation mechanism for elementary particles, crowned by a recent experimental discovery of Higgs particle at LHC. High Tc superconductivity in curates discovered in 1986, a milestone, lead to RVB theory and emergent gauge fields. It opened doors to novel quantum entanglement structures, a world of quantum phases and phenomena. New theoretical developments are in place. Another recent milestone is an experimental discovery of superconductivity with a Tc ~ 203 K, in molecular solid H2S under pressure. Young superconductivity is at cross roads.

The theoretical understanding of the black body radiation led Planck to discover the quantum theory in 1900. He introduced the idea of light quanta which later were termed as photons. The 20th century saw the formulation of many new principles and laboratory confirmations of the predictions following the new ideas. As far as light is concerned the biggest invention was the discovery of the lasing principle by Townes which was based on Einstein's ideas on spontaneous and stimulated emission and today we see lasers in all walks of life. While 20th century essentially used classical technologies, the 21st century is expected to be the century where quantum and in particular single photon technologies would be at work. This lecture will present an overview of some of these developments.

This talk describes possible extreme space weather impacts and their economic and societal costs. Modern society depends heavily on a variety of technologies that are vulnerable to the effects of intense geomagnetic storms and solar storms. Strong currents flowing in the ionosphere can disrupt and damage Earth-based electric power grids and contribute to the accelerated corrosion of oil and gas pipelines. Magnetic storm-driven ionospheric disturbances interfere with high-frequency radio communications and navigation signals from Global Positioning System (GPS) satellites. Exposure of spacecraft to solar particles and radiation belt enhancements can cause temporary operational anomalies, damage critical electronics, degrade solar arrays, and blind optical systems such as imagers and star trackers. Moreover, intense solar particle events present a significant radiation hazard for astronauts during the high-latitude segment of the International Space Station (ISS) orbit as well as for future human explorers of the Moon and Mars. In addition to such direct effects as spacecraft anomalies or power grid outages, a thorough assessment of the impact of severe space weather events on present-day society must include the collateral effects of space-weather-driven technology failures. For example, polar cap absorption events due to solar particles can degrade ? and, during severe events, completely black out?radio communications along transpolar aviation routes, requiring aircraft flying these routes to be diverted to lower latitudes. Modern technological society is characterized by a complex set of inter-dependencies among its critical infrastructures. A complete picture of the socioeconomic impact of severe space weather must therefore include both direct, as well as collateral, effects of space-weather-driven technology failures on dependent infrastructures and services. It is also imperative that we-as a global society-develop a truly operational space weather observing and modeling system in which the benefits of accurate forecasts are clearly established.

This talk will summarize some ideas on the possibility that Extra Terrestrial Civilizations are sending out signals into space using neutrino beams. If so, we can try to intercept them by detecting them. It will also describe a very speculative possibility that they might use neutrinos to modulate the period of a Cepheid variable star to magnify the signal and send it out over huge distances. The so-called Fermi Question/Paradox will also be discussed.