Arnab Bhattacharya is an Indian physicist and science communicator. He is a research professor at the Tata Institute of Fundamental Research, where he works in semiconductor optoelectronics. Since 2021, he has also served as director of the Homi Bhabha Centre for Science Education. Bhattacharya is an avid proponent of public engagement and science education. Since 2009, he has led and curated Chai and Why, a widely attended science café in Mumbai. In 2017, the Indian National Science Academy honored him with the Indira Gandhi Prize for the Popularization of Science, one of India’s most prestigious science awards, for his contributions to public science communication. In this wide-ranging and insightful InterDialogue, we explore interconnected questions surrounding science communication, education, and outreach in both Indian and global contexts. We also discuss Bhattacharya’s projects during the COVID-19 pandemic, when he helped create low-cost methods for decontaminating N95 masks for reuse by frontline responders. In addition, we talk about his research on nanomaterials and India’s potential for developing domestic industries centered on advanced technologies such as semiconductors, solar energy, and nuclear power. Beyond his scientific research and outreach work, we also touch on the importance of maintaining work-life balance, as well as Bhattacharya’s passion for Indian classical music, nature, and cooking. Timestamps 1:02 – Bhattacharya’s introduction to science and science communication 10:59 – Interventions in science communication in India 16:16 – Hands-on alternatives to theoretical learning 21:34 – Bhattacharya’s involvement in pandemic response in India 27:36 – Public health communication during the pandemic 33:09 – Problems facing public health and science communication in India 41:01 – Bhattacharya’s directorship of the Homi Bhabha Center for Science Education 45:04 – Impact of AI on science education in India 50:43 – Bhattacharya’s research on lighting technology 55:54 – India’s potential for a domestic semiconductor industry 1:00:57 –...

Earth’s Memory, Part One Abstract Every rock carries a fragment of Earth’s memory. Collectively, these fragments preserve an extraordinary geological record spanning more than 4.5 billion years of planetary evolution. This article traces that record through the deep-time history of our planet—from the formation of Earth’s earliest crust and the Great Oxidation Event, when microbial life transformed the planet’s atmosphere, to the five great mass extinctions that repeatedly reset the trajectory of life, and the Snowball Earth episodes, when our planet experienced its most extreme glaciation. Drawing on more than two decades of fieldwork across Himalaya and Peninsular India, among ancient rocks, minerals, and fossils that bear direct witness to these planetary transformations, it explores how geologists reconstruct Earth’s early history from evidence preserved in the geological archives. Taken together, these geological events reveal a recurring pattern: Earth is a dynamic system in which every major crisis has also created the conditions for new and often more complex forms of life to evolve. That pattern, written into rocks billions of years old, continues to shape the planet today.    I first learned to listen to rocks long before I had the words to describe what that meant.  It began in the Himalaya, the youngest mountain range on Earth, still rising, still deforming, and still recording the ongoing collision between continents. During my early fieldwork, I spent long days mapping folded strata, tracing fault scarps, and trying to understand how landscapes preserve evidence of processes operating across vastly different geological timescales. At that time, I often felt that the mountains were trying to say something in a language I had not yet learned. Over time, through fieldwork, mapping, and countless hours spent among rocks and sediments, I began to decipher that silent language.  The lesson deepened across many other landscapes of India....

Marta González is a Venezuelan-American physicist and complexity scientist whose research explores the dynamics of human mobility, urban systems, and sustainability through the lens of statistical physics and network science. She is a professor of civil and environmental engineering and city and regional planning at the University of California, Berkeley, where she also serves as associate director of the Transportation Sustainability Research Center. González is internationally recognized for pioneering the use of large-scale mobility data to better understand cities and inform public policy. In this wide-ranging InterDialogue, González reflects on her journey from physics into complexity science and urban research, explaining how statistical physics provides powerful tools for understanding human mobility and the collective dynamics of cities. We discuss the emergence of urban science as an interdisciplinary field, the opportunities and limitations of mobile phone and mobility datasets, and how these data can improve transportation planning, climate adaptation, and the design of more resilient and sustainable cities. González also explores the challenges of translating scientific research into public policy, including questions of data access, privacy, and collaboration between researchers, governments, and industry. We further examine the future of urban mobility, autonomous vehicles, and clean energy, as well as the importance of international collaboration and expanding scientific capacity across the Global South. Finally, she reflects on the broader promise of complexity science for addressing some of the most pressing social and environmental challenges facing rapidly urbanizing societies. Timestamps 0:00 – Introduction and Marta González’s path into complexity science 5:01 – From statistical physics to human mobility research 10:18 – Mobile phone data and the emergence of urban science 15:42 – Sustainable cities, climate adaptation, and resilience 20:24 – Privacy, data access, and international collaboration 25:42 – Using complexity science to inform urban policy 29:32 – Measuring the impact of remote work...

Jaishri Sanwal Bhatt is an Indian geologist and paleoclimatologist based at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, where she combines scientific research with a strong commitment to public outreach, advocacy, and science communication. For more than twenty years, Sanwal’s work has centered on reconstructing past climate change and active tectonic processes through the study of cave records and other geological proxies, especially paleolakes and speleothems. Her research has spanned the Indian and Nepalese Himalayas, the Andaman Islands, and both the eastern and western coasts of India, engaging major questions related to earth systems, water security, and natural hazards. In this wide-ranging and engaging InterDialogue, we discuss deep geological time, the proposed nuclear energy transition in India, the value of interdisciplinarity and clearer scientific communication, Sanwal’s efforts to organize science outreach initiatives in rural India, and much more. Timestamps 2:22 – Sanwal’s background and introduction to geology 8:43 – Big History and the evolution of the Earth through geology 14:25 – Sanwal’s research 16:45 – Tracking historical precipitation patterns through sediment 21:10 – Connecting paleoclimatology to contemporary climate science 25:53 – Tracking and analyzing extreme events through rocks 29:07 – Comparing chronological dating systems 32:52 – Sanwal’s work with lake cores 37:34 – Tracking tsunami episodes in the Andamans 44:09 – Evidence of tsunamis in mangrove forests 49:00 – Local knowledge and community collaborations 52:32 – Nuclear energy transition in India and waste disposal 57:18 – Risks of geological repositories for nuclear waste 1:00:16 – Sanwal’s rural science outreach and education initiatives

Omar Prias is an electrical engineer, professor at the National University of Colombia, and former president of the Colombian Energy and Gas Regulatory Commission (CREG). He has decades of experience in the energy sector working at the intersection between the academy, planning, and politics. This InterDialogue addresses the importance of decentralized energy technologies for sustainable development, the role of intercultural dialogue, national and global energy transition, and the possibilities of introducing advanced nuclear technologies, both new and projected, in non-nuclear countries such as Colombia. We begin by talking about the fundamental role of energy in all sectors of society. Timestamps 00:00 – Introduction 1:50 – Prias’s Background in Energy 7:57 – Industry and Energy Systems in Colombia 15:13 – Historical Development of the Energy Sector in Colombia; Energy and Conflict 22:06 – Geopolitics of Colombian Energy 26:32 – Hydroelectric Power in Colombia 44:40 – Intercultural Considerations and Energy Communities 53:15 – Intercultural Dialogue and Decision-Making 1:03:43 – Energy Transition in Colombia 1:13:41 – Nuclear Energy in Colombia 1:20:11 – Opening Spaces for Adopting New Technologies

Investment in science is a pillar for any dynamic, equitable modern society, and promoting scientific literacy across all levels of society can help foster innovation, dialogue, and consensus that crosses disciplinary and cultural boundaries. Science also helps to uncover answers to foundational questions that have captivated, confounded, and divided our species for millennia. But what is “science,” and what kind of “evidence” ensures that an approach is scientific? If we take “science” to broadly mean, in its purest sense, a “dynamic search for the truth,” or more explicitly, “the pursuit and application of knowledge and understanding of the natural and social world following a systematic methodology based on evidence,” as the Science Council aptly defines it, then science extends beyond the established, highly specialized disciplines of reductionist natural sciences (physics, chemistry, biology, geoscience, and space science) that have been so successful in fostering our understanding of our planet and the cosmos. Under this definition, science also includes the rigorous data-driven (qualitative and quantitative) social sciences, the inherently non-reductionist “holistic” sciences such as ecological and Earth system sciences, and the budding interdisciplinary field of complex systems science, as well as robust traditional knowledge systems based on multi-generational experiences, observations, and reasoning. As with science, “evidence” can mean a lot of things as well, including primary research, pre-existing data, past and planned experiments, and the referencing of peer-reviewed publications and primary sources. It can also include local and traditional knowledge, thought experiments, theoretical proofs, contemplation, verifiable personal experience, and empirical observation. Broadening and weaving together these forms of scientific evidence holds the potential to address complex, interconnected global challenges and explain deep mysteries that could help unify our polarized societies around foundational understandings. Foundational Questions Foundational questions can transcend the divides of generations and cultures: Cosmology, physics, and evolutionary biology have shed...