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Type: Prelims Only

  • Revising Guidelines to declare Eco-Sensitive Zones (ESZ)

    Why in the News?

    The Standing Committee of the National Board for Wildlife (SC-NBWL) has decided to review and revise the 2011 guidelines on the declaration of Eco-Sensitive Zones (ESZs) around wildlife sanctuaries and national parks.

    What are Eco-Sensitive Zones (ESZs)?

    • Overview: ESZs, also called Ecologically Fragile Areas (EFAs), are areas notified by the Ministry of Environment, Forest and Climate Change (MoEFCC) around Protected Areas (PAs) like national parks and wildlife sanctuaries.
    • Purpose:
      • Act as “shock absorbers” to protect areas by regulating potentially harmful activities.
      • Serve as transition zones from highly protected to less protected ecosystems.
      • Help conserve biodiversity, maintain landscape connectivity, and prevent fragmentation of habitats.
    • Legal Basis:
      • Environment (Protection) Act, 1986, particularly Section 3(2)(v).
      • Rule 5(1) of Environment (Protection) Rules, 1986.
    • Wildlife Conservation Strategy, 2002: Recommended declaring 10 km radius around PAs as default ESZ.
    • Demarcation Process:
      • ESZ boundaries vary in width based on ecological sensitivity and ground realities.
      • Factors considered: species presence, migration routes, landscape linkage, human settlements, etc.
    • Activity Zonation:
      • Prohibited: Commercial mining, polluting industries, major hydro projects, wood logging.
      • Regulated: Tree felling, large-scale agriculture change, road widening, tourism infrastructure.
      • Permitted: Rainwater harvesting, organic farming, green energy use.
    • Present Status:
      • 347 final notifications issued.
      • Where no ESZ is notified, a default 10-km ESZ is applicable (SC 2022 ruling).

    2011 Guidelines on ESZs:

    • Issued by MoEFCC to standardize and guide the process of ESZ declaration.
    • Key Features:
      • Emphasized flexibility and site-specific demarcation.
      • Classified activities into permitted, regulated, prohibited.
      • Directed preparation of a Zonal Master Plan (ZMP) within 2 years of ESZ notification.
      • Called for community involvement, scientific input, and buffer management.

    Recent Context:

    • Reasons Behind: Revision One-size-fits-all (10-km blanket rule) is not effective:
      • Urban examples: Sanjay Gandhi National Park (Mumbai), Asola Bhatti Sanctuary (Delhi).
      • In Himachal Pradesh, ~65% area already under forest cover.
      • Kerala: Fear of new sanctuary leading to more restrictions.
    • Over-generalized: Existing guidelines unsuitable for marine sanctuaries, need ecosystem-specific norms.
    [UPSC 2014] With reference to ‘Eco-Sensitive Zones’, which of the following statements is/are correct?

    1. Eco-Sensitive Zones are the areas that are declared under the Wildlife (Protection) Act, 1972.

    2. The purpose of the declaration of Eco-Sensitive Zones is to prohibit all kinds of human activities in those zones except agriculture.

    Select the correct answer using the code given below.

    Options: (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 *

     

  • ‘Maratha Military Landscapes’ included in the UNESCO World Heritage List

    Why in the News?

    The ‘Maratha Military Landscapes’ of India have been inscribed on the UNESCO World Heritage List under the cultural category during the 47th session of the World Heritage Committee held in Paris.

    About Maratha Military Landscapes:

    • Overview: A network of 12 forts showcasing the Maratha Empire’s military architecture and strategic fortification from the 17th to 19th centuries.
    • Time Period: Developed between 1670 CE (Shivaji’s era) and 1818 CE (end of Peshwa rule).
    • Geographical Spread: 11 forts in Maharashtra and 1 in Tamil Nadu (Gingee Fort), covering hill, coastal, forest, plateau, and island terrains.
    • Key Forts: Salher, Shivneri, Lohgad, Raigad, Rajgad, Pratapgad, Khanderi, Suvarnadurg, Panhala, Vijaydurg, Sindhudurg (Maharashtra); Gingee (Tamil Nadu).
    • Types:
      • Hill forts: Rajgad, Raigad
      • Hill-forest: Shivneri
      • Coastal: Suvarnadurg, Vijaydurg
      • Island: Khanderi, Sindhudurg
    • Protection:
      • 8 forts by Archaeological Survey of India (ASI)
      • 4 forts by Maharashtra’s Directorate of Archaeology & Museums
    • Ideology: Reflects Shivaji’s military decentralization, terrain-based defense, and self-sustaining fort systems.
    • Tagged under cultural criteria:
      • (iii) Exceptional testimony to a cultural tradition
      • (iv) Outstanding example of military architecture
      • (vi) Association with historic events and traditions

    What are UNESCO World Heritage Sites?

    • A WHS is a landmark or area recognized for its cultural, historical, natural, or scientific value to humanity.
    • It is governed by the UNESCO World Heritage Convention (1972).
      • India formally signed the Convention on November 14, 1977.
    • Sites are selected by the World Heritage Committee, comprising 21 elected state parties.
    • Categories include:
      • Cultural (e.g., forts, temples, cities)
      • Natural (e.g., forests, parks, biodiversity sites)
      • Mixed (having both cultural and natural value)
    • Selection is based on 10 criteria (6 cultural + 4 natural); at least one must be met.
    • Once inscribed, sites are eligible for global recognition, protection, and funding.

     

    [UPSC 2024] Consider the following properties included in the World Heritage List released by UNESCO:

    1. Shantiniketan 2. Rani-ki-Vav 3. Sacred Ensembles of the Hoysalas 4. Mahabodhi Temple Complex at Bodhgaya

    How many of the above properties were included in 2023?

    Options: (a) Only one (b) Only two* (c) Only three (d) All four

     

  • [pib] Sanchar Mitra Scheme

    Why in the News?

    The Department of Telecommunications (DoT) has launched an expanded Sanchar Mitra Scheme to engage engineering students as digital ambassadors for promoting telecom literacy, digital safety, and citizen engagement.

    What is the Sanchar Mitra Scheme?

    • Launching Body: An initiative by the Department of Telecommunications (DoT), Government of India.
    • Primary Aim: To engage student volunteers as “Sanchar Mitras” or digital ambassadors to spread awareness about telecom-related issues.
    • Purpose:
      • Bridge the communication gap between citizens and the telecom ecosystem.
      • Promote safe and informed use of telecom services.
      • Encourage public participation in India’s digital transformation.
    • Implementation Status:
      • Piloted in select institutions.
      • Now being scaled up for nationwide rollout.

    Key Features and Highlights:

    • Target Audience: It primarily targets students from engineering and technical backgrounds such as telecommunications, computer science, electronics, and cybersecurity.
    • Selection of Volunteers: Students will be nominated as Sanchar Mitras in consultation with DoT field units and educational institutions.
    • Training Modules: Volunteers will be trained to conduct grassroots campaigns on cyber fraud prevention, EMF radiation concerns, and responsible digital behavior.
    • Training Institutions: Training will be delivered by the National Communications Academy–Technology (NCA-T) and the Media Wing of the DoT.
    • Core Pillars: The scheme is structured around three key pillars: Connect, Educate, and Innovate.
    • Tech Awareness Promotion: Sanchar Mitras will promote awareness on emerging telecom technologies like 5G, 6G, AI, and cybersecurity.
    • Community Outreach: Students will engage with communities, NGOs, and schools to foster a culture of informed digital citizenship.
    • Strategic Alignment: It aligns with India’s strength in the “Four Ds”: Democracy, Demography, Digitisation, and Delivery.
    [UPSC 2010] Which among the following do/does not belong/belongs to the GSM family of wireless technologies?

    Options: (a) EDGE (b) LTE (c) DSL* (d) Both EDGE and LTE

     

  • What are Autonomous District Councils (ADC)?

    Why in the News?

    Mizoram Governor has imposed Governor’s Rule in the Chakma Autonomous District Council (CADC) due to prolonged political instability and repeated leadership changes.

    About Autonomous District Councils (ADCs):

    • Basis: They are local self-governing institutions established under the Sixth Schedule of the Indian Constitution.
    • Coverage: ADCs are constituted in tribal areas of the northeastern states—Assam, Meghalaya, Tripura, and Mizoram (ATM2) [Sixth Schedule] 
    • Purpose: These councils aim to provide autonomy to tribal communities to preserve their culture, customs, and govern their local affairs.
    • Notification: Each tribal area notified under the Sixth Schedule is declared an autonomous district, governed by its respective ADC.
    • Objective: The primary objectives of ADCs are to promote tribal self-governance, ensure local development, and protect tribal identity and rights.

    Note: The Constitution provides for the reservation of seats in Panchayats for STs.

    Key Features of ADCs

    • Legal Status: ADCs are formed through constitutional provisions under the Sixth Schedule and are not governed by state laws.
    • Council Composition: Each ADC comprises up to 30 members, of which 26 are elected by adult suffrage and 4 are nominated by the Governor.
    • Tenure: The tenure of an ADC is 5 years from the date of its constitution.
    • Scope of Authority: ADCs have legislative, executive, and limited judicial powers specific to the needs of tribal communities.
    • Applicability of Laws: State and Central laws do not automatically apply in ADC areas unless explicitly extended by the Governor.

    Powers and Functions of ADCs:

    • Law-Making Powers: ADCs can enact laws on land management, agriculture, and forest use (excluding reserved forests).
    • Customary Regulations: They can regulate inheritance, marriage, divorce, and social customs, and appoint traditional chiefs and headmen.
    • Local Administration: It oversee services such as primary education, dispensaries, roads, markets, and fisheries.
    • Judicial Functions: Councils can establish village courts to try civil and criminal cases involving tribal members, with sentencing powers up to five years.
    • Regulation of Trade: They may regulate money lending and trade by non-tribals, subject to Governor’s approval.
    • Revenue Sources: It can levy taxes on professions, trades, animals, vehicles, markets, ferries, and public infrastructure like roads and schools.

    Autonomy and Limitations:

    • Degree of Autonomy: ADCs enjoy substantial legislative and administrative autonomy within their territorial jurisdiction.
    • Non-Applicability of General Laws: Parliamentary and State laws apply only when directed by the Governor, ensuring self-rule.
    • Governor’s Oversight: Despite autonomy, the Governor retains discretionary powers and can approve, modify, or annul council decisions.
    • Financial Constraints: ADCs often face limited revenue generation, which restricts their developmental effectiveness.
    • Administrative Challenges: Operational issues include leadership instability, shortage of trained personnel, and state-level interference in council functions.
    [UPSC 2015] The provisions in Fifth Schedule and Sixth Schedule in the Constitution of India are made in order to:Options: (a) protect the interests of Scheduled Tribes * (b) determine the boundaries between States (c) determine the powers, authority and responsibilities of Panchayats (d) protect the interests of all border States

  • UNEP Frontiers 2025 Report on Legacy Pollutants

    Why in the News?

    The United Nations Environment Programme (UNEP), in its latest Frontiers 2025 report titled The Weight of Time, has warned that increased river and coastal flooding caused by climate change could unearth dangerous legacy pollutants from water bodies.

    About Legacy Pollutants:

    • Definition: Legacy pollutants refer to toxic substances like heavy metals and persistent organic pollutants (POPs) that continue to remain in the environment even decades after their use has been banned or restricted.
    • Examples:
      • Heavy Metals: Lead, Cadmium, Mercury, Arsenic.
      • Persistent Organic Pollutants (POPs):
        • Pesticides: DDT (Dichlorodiphenyltrichloroethane), Aldrin, Endrin, Chlordane.
        • Industrial Chemicals: PCBs (Polychlorinated Biphenyls), Dioxins, Furans.
        • By-products: Produced from incineration, metal smelting, and waste burning.
    • Persistence: These substances are highly resistant to environmental degradation and accumulate in riverbeds, lakes, estuaries, and other sediment-rich ecosystems.
    • Health Hazards: Even at low exposure levels, legacy pollutants can cause: Neurotoxicity (nervous system damage), Immunotoxicity (immune disruption), Hepatotoxicity (liver damage), Reproductive toxicity (infertility, birth defects), Carcinogenicity (various cancers), Endocrine disruption etc.
    • Sources:
      • Past industrial practices, use of banned agricultural chemicals, and obsolete pesticide stockpiles.
      • Improperly managed chemical landfills, which still hold an estimated 4.8–7 million tonnes of POP waste globally.

    UNEP Frontiers 2025 Report on Legacy Pollutants

    Key Highlights of Frontiers 2025: The Weight of Time (UNEP):

    • Retreat of Toxins: Climate change-induced flooding can unearth and redistribute toxic legacy pollutants from contaminated sediments into the environment and food chain.
    • How? Floodwaters re-suspend heavy metals and POPs trapped in sediment.
    • Case Studies Cited:
      • Hurricane Harvey (Texas, 2017): Released mercury and carcinogenic chemicals from flood-induced sediment dispersal into Galveston Bay.
      • Niger Delta Floods (Nigeria, 2012): Mobilised Polycyclic Aromatic Hydrocarbons (PAHs) from oil-contaminated sediments.
      • Pakistan Floods (2010 & 2022): Washed away obsolete pesticide stockpiles, spreading DDT and other POPs into floodwaters and soils.
    • India-Specific Findings:
      • Sediments of Ganga, Hindon, and Vaigai Rivers show dangerously high levels of Cadmium.
      • Cadmium is a known carcinogen and endocrine disruptor, with potential to cause kidney, bone, and reproductive harm.
      • Ayad and Vaigai Rivers also showed up deadly levels of Lead concentration.
    [UPSC 2016] Which of the following can be found as pollutants in the drinking water in some parts of India?

    1. Arsenic 2. Sorbitol 3. Fluoride 4. Formaldehyde 5. Uranium

    Options: (a) 1 and 3 only (b) 2, 4 and 5 only (c) 1, 3 and 5 only* (d) 1, 2, 3, 4 and 5

     

  • [pib] TALASH Initiative 

    Why in the News?

    The National Education Society for Tribal Students (NESTS) and UNICEF India launched TALASH (Tribal Aptitude, Life Skills and Self-Esteem Hub), a first-of-its-kind national initiative for holistic development of tribal students in Eklavya Model Residential Schools (EMRSs).

    About the TALASH Initiative:

    • Overview: TALASH (Tribal Aptitude, Life Skills and Self-Esteem Hub) is a national programme launched by the National Education Society for Tribal Students (NESTS) in partnership with UNICEF India.
    • Target Group: It is aimed at the holistic development of tribal students studying in Eklavya Model Residential Schools (EMRSs) across the country.
    • Objectives: The initiative fosters self-awareness, emotional resilience, life skills, and career clarity among tribal youth.
    • Focus: It is the first national initiative in India designed specifically for tribal students.
    • Broader Policy: TALASH aligns with the National Education Policy 2020, promoting inclusive, equitable, and competency-based education.
    • Coverage Goal: Over 1,38,336 students across 28 States and 8 Union Territories are expected to benefit.
    • Implementation: By the end of 2025, TALASH aims to be implemented in all EMRSs nationwide.

    Key Features of TALASH:

    • Psychometric Assessments:
      • Inspired by NCERT’s ‘Tamanna’, TALASH offers aptitude tests to help students discover their interests, abilities, and potential.
      • Based on the results, students receive Career Cards suggesting suitable career options.
    • Career Counselling: The platform offers structured career guidance to help students make informed decisions aligned with their strengths and aspirations.
    • Life Skills & Self-Esteem Modules: TALASH teaches communication, problem-solving, emotional regulation, and self-confidence through interactive modules.
    • E-Learning for Teachers:
      • A dedicated online portal provides training and resources to teachers to help them mentor students effectively.
      • So far, 189 teachers from 75 EMRSs have been trained to lead school-level sessions.
    [UPSC 2017]  With reference to ‘National Skills Qualification Framework (NSQF)’, which of the statements given below is/are correct?

    1. Under NSQF, a learner can acquire the certification for competency only through formal learning.

    2. An outcome expected from the implementation of NSQF is the mobility between vocational and general education.

    Select the correct answer using the code given below:

    Options: (a) 1 only (b) 2 only* (c) Both 1 and 2 (d) Neither 1 nor 2

     

  • [pib] Fossils reveal Kashmir Valley’s Climatic Past

    Why in the News?

    Researchers from Birbal Sahni Institute of Palaeosciences (BSIP), Lucknow, have found strong evidence that the Kashmir Valley, now cool and temperate, was once a warm, humid subtropical region.

    About the Study on Fossils:

    • Site of Fossil Discovery: The fossils were recovered from the Karewa sediments of the Kashmir Valley, known for preserving ancient plant remains.
    • Analysis: Researchers used CLAMP (Climate Leaf Analysis Multivariate Program) to analyze fossil leaf shape, size, and margins to estimate past temperature and rainfall patterns.
    • Coexistence Approach: It was also used, comparing fossil plants with their modern relatives to reconstruct the region’s ancient climate.

    Key Findings:

    • Past Climate Type: The Kashmir Valley once had a warm, humid subtropical climate, very different from the cool, Mediterranean-type climate it experiences today.
    • Vegetation Evidence: Fossilized leaves showed diverse subtropical plant types no longer found in the region’s current vegetation.
    • Role of Tectonic Uplift: The tectonic uplift of the Pir Panjal Range was identified as a key factor that blocked the Indian summer monsoon from entering the valley.
    • Climatic Transition: This led to gradual drying of the region and a shift from subtropical forests to temperate ecosystems.
    • Impact of Mountain-Building: The study shows that mountain-building (tectonic uplift) can directly affect climate patterns by altering monsoon routes.
    • Relevance to Climate Change: The findings provide insight into natural climate shifts over millions of years, helping contextualize modern climate change.
    • Ecological Vulnerability: It also highlights the fragility of mountain ecosystems like the Himalayas, which are vulnerable to both natural and human-induced environmental changes.

    Back2Basics:

    • Karewa Sediments: They are plateau-like terraces in the Kashmir Valley, made up of lacustrine (lake) and fluvio-glacial deposits; They are known to preserve ancient fossils, especially of plants.
    • Subtropical Climate: A warm and humid climate with moderate to high rainfall, supporting dense vegetation. Ex: Climate of northeastern India.
    • Mediterranean-Type Climate: Characterized by mild, wet winters and hot, dry summers; Ex: Current climate of parts of the Kashmir Valley.

     

    [UPSC 2025] Which of the following are the evidence of the phenomenon of continental drift?

    I. The belt of ancient rocks from Brazil coast matches with those from Western Africa. II. The gold deposits of Ghana are derived from the Brazil plateau when the two continents lay side by side. III. The Gondwana system of sediments from India is known to have its counterparts in six different landmasses of the Southern Hemisphere.

    Options: (a) I and III only (b) I and II only (c) I, II and III * (d) II and III only

     

  • What are Zonal Councils?

    Why in the News?

    Union Home Minister recently highlighted that 83% of issues discussed in Zonal Council meetings have been resolved, reaffirming their role as effective platforms for intergovernmental cooperation.

    What are Zonal Councils?

    • Establishment: They are statutory bodies established under the States Reorganisation Act, 1956; they are not constitutional bodies.
    • Purpose: Their main goal is to promote cooperation and coordination among states, union territories, and the central government.
    • Basis for Zoning: Zones were drawn based on natural divisions, cultural and linguistic affinity, river systems, and security needs.
    • Zonal Division: India is divided into five zones—Northern, Central, Eastern, Western, and Southern—with a separate Zonal Council for each:
      1. Northern Zonal Council: Haryana, Himachal Pradesh, Jammu & Kashmir, Punjab, Rajasthan, Delhi, Chandigarh
      2. Central Zonal Council: Chhattisgarh, Uttarakhand, Uttar Pradesh, Madhya Pradesh
      3. Eastern Zonal Council: Bihar, Jharkhand, Odisha, West Bengal
      4. Western Zonal Council: Goa, Gujarat, Maharashtra, Dadra & Nagar Haveli, Daman & Diu
      5. Southern Zonal Council: Andhra Pradesh, Karnataka, Kerala, Tamil Nadu, Puducherry

    Note: 

    • North-Eastern Council (NEC) (separate body): Assam, Arunachal Pradesh, Manipur, Tripura, Mizoram, Meghalaya, Nagaland, Sikkim (added in 2002)
    • The union territories of Andaman and Nicobar Islands and Lakshadweep are NOT members of any of the Zonal Councils. However, they are presently special invitees to the Southern Zonal Council.

    Composition and Structure of Zonal Councils:

    • Chairperson: Each Zonal Council is chaired by the Union Home Minister.
    • State Representation: The Chief Ministers of all states in the respective zone are members of the Council.
    • Additional Members: Each state nominates two additional ministers; administrators of union territories also participate.
    • Vice-Chairperson Role: The role of Vice-Chairperson rotates annually among the Chief Ministers.
    • Standing Committees: These are formed with Chief Secretaries of states and meet ahead of full sessions to finalize the agenda.

    Functions and Responsibilities:

    • Cooperation & Consensus: Promote interstate and Centre-state cooperation through dialogue and consensus-building.
    • Key Issues Addressed: Economic and social planning, Border disputes, Inter-state transport, Linguistic minority concerns etc.
    • Advisory Role: While the councils’ recommendations are advisory, they play a vital role in dispute resolution and coordinated policy formulation.

    Recent Developments and Significance:

    • Leadership in NEC: In 2018, the Union Home Minister became the Chairperson of the North Eastern Council, signaling a push for broader integration.
    • Revitalization under Modi Government: Zonal Councils have evolved into dynamic, action-oriented platforms rather than passive advisory bodies.
    • Strengthening Federalism: These councils now actively contribute to cooperative federalism, resolve disputes, and accelerate regional development.
    • Efficacy in Implementation: With 83% of agenda issues resolved, Zonal Councils demonstrate increasing political will and effectiveness in addressing regional challenges.
    [UPSC 2013] Which of the following bodies is/are not mentioned in the Indian Constitution?

    1. National Development Council 2. Planning Commission 3. Zonal Councils

    Select the correct answer using the codes given below.

    Options: (a) 1 and 2 only (b) 2 only (c) 1 and 3 only (d) 1, 2 and 3

     

  • [pib] Dhammachakra Pravartana Divas

    Why in the News?

    The International Buddhist Confederation (IBC) recently celebrated Ashadha Purnima, also known as Dhammachakra Pravartana Divas at Mulagandha Kuti Vihara, Sarnath.

    About Dhammachakra Pravartana Divas:

    • First Sermon: It marks the day when Gautama Buddha delivered his first sermon after attaining enlightenment.
    • Date of Observance: The day is observed annually on the full moon of Ashadha (Ashadha Purnima), usually in July.
    • Name and Location: The sermon, called Dhammacakkappavattana Sutta, was delivered at Deer Park (Isipatana), Sarnath, near Varanasi.
    • Core Teachings Introduced: It laid the foundational teachings of Buddhism by introducing the Four Noble Truths and the Noble Eightfold Path.
    • Formation of Sangha: His five former ascetic companions—Kaundinya, Bhaddiya, Vappa, Mahanama, and Assaji—became the first monks of the Buddhist Sangha.
    • Symbolic Representation: The Dharma Chakra (Wheel of Dharma) symbolizes this “turning of the wheel of law” and spread of the Buddha’s teachings.
    • Significance:
      • Monastic Practice: It marks the beginning of the Varsha Vassa, a three-month monastic retreat during the rainy season.
      • Religious Importance: It is the second most important Buddhist festival after Buddha Purnima.

    Modern Day Significance:

    • Ambedkarite Movement: In India, it is also significant for commemorating Dr. B.R. Ambedkar’s conversion to Buddhism with his followers at Deekshabhoomi, Nagpur (14 October 1956).
    • Social Commitment: On this day, millions reaffirm their commitment to Buddhist values and the 22 vows taken to renounce caste-based discrimination.
    • Global Observance: The day is celebrated internationally under various names—Esala Poya (Sri Lanka), Asanha Bucha (Thailand), and Asadha Purnima (India).

    Tap to read more about philosophical tenets of Buddhism.

    Back2Basics: Buddhist Councils

    Council Date & Venue Patron & President Objective Key Outcomes
    1st Buddhist Council 483 BCE, Rajagriha (Bihar) Ajatashatru (Haryanka dynasty), Presided by Mahakasyapa To preserve the Buddha’s teachings after his Mahaparinirvana – Vinaya Pitaka compiled by Upali (rules for monks)
    – Sutta Pitaka compiled by Ananda (discourses of Buddha)
    2nd Buddhist Council 383 BCE, Vaishali (Bihar) Kalasoka (Shishunaga dynasty), Presided by Sabakami To resolve disputes over lax discipline and the ‘Ten Points’ followed by Vaishali monks – Split into Sthaviravadins (orthodox) and Mahasamghikas (liberal)
    – Reaffirmation of stricter Vinaya rules
    3rd Buddhist Council 247 BCE, Pataliputra (Patna) Ashoka (Maurya dynasty), Presided by Moggaliputta Tissa To eliminate heretical monks and consolidate Buddhist doctrine – Compilation of Abhidhamma Pitaka
    – Composition of Kathavattu (philosophical debates)
    – Launch of Buddhist missions to 9 countries
    4th Buddhist Council 72 CE, Kashmir Kanishka (Kushan dynasty), Presided by Vasumitra (with Asvaghosha) To formalize doctrines and address doctrinal splits – Formal split into Hinayana and Mahayana schools
    – Compilation of Vibhasha Sastras (commentaries)
    5th Buddhist Council 1871 CE, Mandalay (Burma) Burmese Monarchy To preserve Buddhist texts – 729 stone slabs inscribed with the Pali Canon
    – Considered a Burmese affair; not internationally recognized
    6th Buddhist Council 1954 CE, Yangon (Burma) Burmese Govt & International Sangha To commemorate 2500 years of Buddhism and preserve Theravada canon – Global recitation and review of entire Pali Canon
    – Participation from monks across Buddhist countries

     

    [UPSC 2008] The concept of Eight-fold path forms the theme of-

    Options: (a) Dipavamsa (b) Divyavadana (c) Mahaparinibban Sutta (d) Dharma Chakara Pravartana Sutta*

     

  • What are Optical Atomic Clocks?

    Why in the News?

    Researchers conducted the most precise global comparison of 10 Optical Atomic Clocks to pave the way for redefining the second by 2030, replacing Caesium Clocks with more accurate Optical ones.

    Definition of a Second:

    • The current SI unit of time is based on caesium-133 (Cs) atomic clocks.
    • In 1967, one second was defined as the duration of 9,192,631,770 cycles of radiation corresponding to the transition between two hyperfine levels of the ground state of a Cs-133 atom.
    • In these clocks, a microwave signal is tuned until Cs atoms react maximally, ensuring the frequency is precisely 9,192,631,770 Hz.
    • Frequency dividers count this microwave frequency, providing one tick per second, thus realizing the SI second.

    About Caesium Atomic Clocks:

    • Overview: Caesium atomic clocks are devices that define the current SI unit of time (second) using the oscillation frequency of caesium-133 atoms.
    • SI Second Standard: One second is defined as the duration of 9,192,631,770 cycles of microwave radiation corresponding to the transition between two energy levels of the caesium-133 atom.
    • Working Principle: These clocks work by tuning microwave signals to resonate with caesium atoms and then counting the resulting waves to measure time precisely.
    • Stability and Usage: They are highly stable and have been used since 1967 to set international time standards.
    • Applications: They are used in GPS systems, telecommunications, scientific research, and by national metrology institutions like India’s National Physical Laboratory (NPL).
    • Accuracy: A typical caesium atomic clock loses about one second every 300 million years.

    What are Optical Atomic Clocks?

    • Overview: They are advanced timekeeping devices that use optical (visible light) frequency transitions in atoms like Strontium (Sr) or Ytterbium (Yb).
    • Measurement Basis: These clocks measure time based on the oscillation of light emitted when atoms transition between energy levels at hundreds of trillions of Hz.
    • Example Frequencies:
      • Strontium: ~429 trillion Hz
      • Ytterbium ions: over 642 trillion Hz
    • Precision Tools: They require lasers and optical frequency combs to count these rapid oscillations accurately.
    • Future Standard: They are being tested worldwide and are expected to replace caesium clocks by 2030 for redefining the SI second.

    How Optical Atomic Clocks are Better than Caesium ones?

    • Higher Frequency Operation: Optical clocks operate at much higher frequencies, allowing division of time into finer intervals.
    • Improved Precision: By counting 10,000 times more oscillations per second, optical clocks achieve significantly higher precision and stability.
    • Unmatched Accuracy: An optical atomic clock using strontium reportedly drifts by less than one second in 15 billion years, compared to 300 million years for caesium clocks.
    • Advanced Applications: Their precision is critical for: Next-gen GPS systems, Gravitational wave detection, Climate monitoring and research etc.
    • Ultra-High Synchronization: Optical clocks enable cross-continental synchronization at 18 decimal place accuracy, essential for global time coordination.
    • Noise Resilience: They offer greater resistance to environmental noise and external disturbances, improving long-term reliability.
    [UPSC 2023] Which one of the following countries has its own Satellite Navigation System?

    Options: (a) Australia (b) Canada (c) Israel (d) Japan*