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Today in History – 2 March

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today-in-history-2-march

today-in-history-2-march

1930

Gandhiji addresses letter to Viceroy intimating his intention to break Salt Law if Congress demands are not conceded.

1949

Sarojini Naidu, “Nightingale of India”, freedom fighter, social worker and patriot, passed away when she was the Governor of Uttar Pradesh. She also holds a place of pride among the women freedom fighters of India. She presided over the Kanpur session of Indian National Congress. She took active part in Salt Satyagraha and represented Indian women in Round Table Conference, London.

1952

Sindri Fertilizer Factory, Bihar, formally inaugurated by Nehru. It was the first Government owned company.

Also Read: Today in History Articles

1957

Central Warehouse Corporation established.

1963

China reports troops have left disputed area in India.

1982

Indira Gandhi opened Mahatma Gandhi Road Bridge at Patna.

1984

Mother Teresa University inaugurated by Mother herself at Kodaikanal in Tamil Nadu.

1994

Autonomous Hill Council for Leh set up.

Also Read: Today in History – 1 March

Thunderstorm

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Thunderstorm

A thunderstorm is a storm with lightning and thunder. It’s produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail. The basic ingredients used to make a thunderstorm are a moisture, unstable air, and lift. Moisture needs to form clouds and rain. Heated air expands rises and forms clouds.

Thunderstorms can occur year-round and at all hours. But they are most likely to happen in the spring and summer months and during the afternoon and evening hours. It is estimated that there are around 1,800 thunderstorms that occur across our planet every day.

Must Read: Monsoon, Floods and Droughts

Lightning

Lightning is a bright flash of electricity produced by a thunderstorm. All thunderstorms produce lightning and are very dangerous. Lightning kills and injures more people each year than hurricanes or tornadoes; between 75 to 100 people.

What causes lightning?

Lightning is an electric current. Within a thunder cloud way up in the sky, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All of those collisions create an electric charge. After a while, the whole cloud fills up with electrical charges. The positive charges or protons form at the top of the cloud and the negative charges or electrons form at the bottom of the cloud.

Since opposites attract, that causes a positive charge to build up on the ground beneath the cloud. The grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and – zap – lightning strikes!

Also Read: Climate Change, Technology and Energy Sustainability

What causes thunder?

Thunder is caused by lightning. When a lightning bolt travels from the cloud to the ground it actually opens up a little hole in the air, called a channel. Once then the light is gone the air collapses back in and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound!

Also Read: Why is lightning accompanied by thunder ?

Hail

Hail is created when small water droplets are caught in the updraft of a thunderstorm. These water droplets are lifted higher and higher into the sky until they freeze into ice. Once they become heavy, they will start to fall. If the smaller hailstones get caught in the updraft again, they will get more water on them and get lifted higher in the sky and get bigger. Once they get lifted again, they freeze and fall. This happens over and over again until the hailstone is too heavy and then falls to the ground.

If Lightning is nearby

If you see dark clouds, then lightning could be present, but the best thing you can do is to listen for thunder. If you hear thunder, then you need to go indoors or get in a car. Don’t be outside, where lightning could strike! If your hair stands on end or your skin starts to tingle, lightning may be about to strike. Get down on your hands and knees and keep your head tucked in. Do not lay flat, because it can give lightning a better chance of strike you.

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Types of Pollution

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pollution types

Different Types of Pollution

Pollution can be classified mainly on the basis of (i) Environment (water, soil, and air etc.); and (ii) Pollutants (lead, carbon-dioxide, solid wastes etc.). On the basis of these two ways pollution may be classified as:

(i) AIR POLLUTION

Due to some natural processes or human activities the amount of solid wastes or concentration of gasses other than oxygen increases in the air which otherwise has fixed proportions of different gasses in it. The air thus becomes polluted, and this process is called the AIR POLLUTION.

The pollutants polluting the air range from visible particulars such as smoke and dust to invisible and odorless gasses such as carbofl- monodioxide. They originate from manufacturing processes, power generation, transportation, waste disposal, chemical processing, domestic activities, agricultural operations, forests fibers and a wide variety of other sources or events.
In big industrialized cities, air is contaminated with sulfur-dioxide, cotton dust, coal dust and chemicals etc. that are highly injurious to the lungs and the whole human body. The supersonic jets and jumbo-jets flying high in the air (about 1-5 km) pollutes the air by exhaust smoke which floats like thin clouds in the atmosphere. The water-vapour and suspended particles in such clouds react with sunlight to produce ‘smog’. This smog increases the atmospheric temperature and also cuts the ozone layer that saves the earth from being exposed to ultraviolet rays of the sun.
The main pathological effects (diseases) caused by air pollutants include respiratory disorders, jaundice, reduction in oxygen carrying capacity of blood, irritation of eyes and throat, causing headache, cancer, and death.

Read Also: Startling Facts about Pollution

(ii) MERCURY POLLUTION

In recent years increasing amounts metal have been discharged into the environment by industries and out of these ‘mercury’ has been responsible for several deaths in Sweden and Japan and has caused ‘Minamata’ disease particularly in Japan. Various rivers, lakes in Sweden have become heavily polluted by increased use of mercury compounds as fungicides and algicides in paper making and pulp lumber industries.

(iii) NOISE POLLUTION

‘Noise Pollution’ is gaining importance in over-crowded and large cities. During office times in the morning and evening, the noise reaches the bursting Jimits. Loud-speakers combined with traffic noise cross the limits of noise. The physical and mental health of people get adversely affected leading to nervous break-down and brain-haemorrhage etc.
It is true that traffic cannot be stopped but restrictions can be placed on the unnecessary blowing of horns, missing spark plugs, driving without silencers, increasing use of loud-speakers, music in celebrations, as these may create problems for heart patients. Noise increases the level of cholesterol in the blood, increa¬ses blood pressure and causes the headache etc.
Noise is measured in the unit of ‘decibel’ (dB) which is the tenth of the largest unit, the ‘bel’; when decibel value reaches above 80 dB it indicates noise pollution.

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(iv) PESTICIDE AND HERBICIDE POLLUTION

Pesticides and Herbicides are chemical compounds specifically used to destroy animal pests and weed pests and unwanted weed growth respectively. Ecologically, these have created two major problems which are not anticipated. Firstly, many of them have persisted and accumulated in the environment harming or contaminating numerous animal or plants and secondly, many of them have directly or indirectly affected human health.
The most commonly used pesticides are DDT, Dieldrin, heptachlore, and thiodan. Similarly, the important herbicides 2, 4-D; 2, 4, 5-T, dioxin have been extensively used for controlling weed pests and weeds. These chemical reach the water bodies and become the parts of animal bodies living therein.

(v) RADIOACTIVE POLLUTION

Radioactive Pollution is closely related to air and water pollution. It is due to the increase of radio isotopes in our environment as a result of fall¬out from nuclear bombs and emissions from the industrial use of nuclear energy.
Radioactive isotopes or radio nuclides have been grouped as radio nuclides of ecological impor¬tance into three categories :

  1. Those which occur naturally in rocks and soil, such as radium 226; uranium 235 or 238; thorium 232; potassium 40; or carbon 14.
  2. Those which are nuclides of natural constituents of living organisms.
  3. Those which occur as fission products from atomic testing of nuclear waste disposal.

Water used to cool the atomic reactors and later on discharged into rivers is usually warm and contains radioactive substances. One of the radio isotope of great biological interest is strontium-90. It behaves like calcium in the biochemical cycle. Thus, if strontium-90 gets into animal’s body, it stays in bone tissue close to the blood-forming tissue, throwing radiations that may kill the living tissues or produce cancer.

Also, Read: Pollution Definition, Aspects, and Solution

(vi) SOIL POLLUTION

The Majority of rural and about 10 percent of the urban population uses vacant land as open-air lavatory. The sink of such human wastes is sickening and is directly or indirectly responsible for many human diseases. This invites pigs, vultures, crows and flies (flies act as carriers of diseases). Waters like everyday domestic refuse consisting of vegetable’s skins, fruits, used cans, bottles, jars, plastics, saw dust, left over food, metal and or plastic caps of soft.drinks etc. also add to pollute the soil and create unhygienic conditions.

(vii) THERMAL POLLUTION

Discharge of heat in the form of effluents, hot water, and hot air industrial processes create ‘thermal pollution’. Such industries use water for cooling purposes and discharge it afterward into streams at a higher temperature. The hot water exerts lethal effect on animals living there. Some are even killed. Less hot water causes bacterial diseases in salmon fish.

(viii) WATER POLLUTION

The term ‘water pollution’ can refer to any type of aquatic contamination between two extremes:

  1. A highly enriched, over productive biotic (living) community, such as river and lake enriched with nutrients from sewage or fertilizers; or
  2. A body of water poisoned by toxic chemicals which eliminate many living organisms or even exclude all forms of life.

Increasing population, heavy industrialization, and urbanization is mainly responsible for the water pollution.
The main pollutants of water are nutrients, petrochemicals, pesticides, weedicides, industrial effluents, excreta, bacteria, radioactive substance, fertilizers, detergents, waste materials, silt, thermal and heavy metals.
Main pathological problems (diseases) caused due to water pollution include diarrhea, liver cirrhosis, lung cancer, colic gastro-intestinal tract disorders, kidney diseases, paralysis, colic pain, bone deformities, cancer and even death and so on.

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Father of Nation

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father of nation

Father of Nation (58 Countries)

Afghanistan — Ahmad Shah Durrani

Argentina — Don José de San Martín

Australia — Sir Henry Parkes

Bahamas —Sir Lynden Pindling

Bangladesh — Sheikh Mujibur Rahman

Bolivia — Simón Bolívar

Brazil — Dom Pedro I and José Bonifácio de Andrada e Silva

Burma — Aung San

Cambodia — Norodom Sihanouk

Chile — Bernardo O’Higgins

Republic of China — Sun Yat-sen

Colombia — Simón Bolívar

Sweden — Gustav I of Sweden

Croatia — Ante Starčević

Cuba — Carlos Manuel de Céspedes

Dominican Republic — Juan Pablo Duarte

Ecuador — Simón Bolívar

Ghana — Kwame Nkrumah

Guyana — Cheddi Jagan

Haiti — Jean-Jacques Dessalines

India — Mohandas Karamchand Gandhi

Indonesia — Sukarno

Iran — Cyrus the Great

Israel — Theodor Herzl

Italy — Victor Emmanuel II

Kenya — Jomo Kenyatta

Republic of Korea — Kim Gu

Kosovo — Ibrahim Rugova

Lithuania — Jonas Basanavičius

Macedonia — Krste Misirkov

Malaysia —Tunku Abdul Rahman

Mauritius — Sir Seewoosagur Ramgoolam

Mexico — Miguel Hidalgo y Costilla

Mongolia  — Genghis Khan

Namibia — Sam Nujoma

Netherlands — William the Silent

Norway — Einar Gerhardsen

Pakistan — Mohammad Ali Jinnah

Panama — Simón Bolívar

Peru — Don José de San Martín

Portugal — Dom Afonso Henriques

Russia — Peter I of Russia

Saudi Arabia — Ibn Saud of Saudi Arabia

Scotland — Donald Dewar

Serbia — Dobrica Ćosić

Singapore — Lee Kuan Yew

Slovenia — Primož Trubar

South Africa — Nelson Mandela

Spain — Fernando el Católico

Sri Lanka — Don Stephen Senanayake

Suriname — Johan Ferrier

Tanzania — Julius Nyerere

Turkey — Mustafa Kemal Atatürk

United Arab Emirates — Sheikh Zayed bin Sultan Al Nahyan

United States — George Washington

Uruguay — José Gervasio Artigas

Venezuela — Simón Bolívar

Vietnam — Ho Chi Minh

Quantum Clocks and Precision Timekeeping: Measuring Time at the Quantum Frontier

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Table of Contents

  1. Introduction
  2. Fundamentals of Timekeeping
  3. Limitations of Classical Clocks
  4. Role of Quantum Mechanics in Time Measurement
  5. Atomic Clocks: Principles and Types
  6. Optical vs Microwave Atomic Clocks
  7. Laser Cooling and Atomic Control
  8. Ramsey Interferometry in Atomic Clocks
  9. Optical Lattice Clocks
  10. Single-Ion Clocks
  11. Frequency Combs and Time Standards
  12. Quantum Projection Noise and the Standard Quantum Limit
  13. Spin Squeezing for Clock Enhancement
  14. Optical Clocks and the Redefinition of the Second
  15. Quantum Clocks in Gravitational Redshift Measurements
  16. Relativistic Geodesy with Quantum Clocks
  17. Applications in Navigation and Communication
  18. Timekeeping in Quantum Networks
  19. Future Challenges and Innovations
  20. Conclusion

1. Introduction

Quantum clocks represent the pinnacle of precision in timekeeping. They exploit quantum transitions in atoms or ions to achieve accuracies better than one part in 10^18, enabling new frontiers in science and technology.

2. Fundamentals of Timekeeping

Time is measured by counting periodic events. In clocks, the “tick” is provided by oscillations of a resonator—mechanical, electrical, or atomic in nature.

3. Limitations of Classical Clocks

Classical clocks suffer from:

  • Environmental drift
  • Mechanical instability
  • Limited frequency precision
    Atomic and quantum clocks overcome these by using intrinsic atomic transitions.

4. Role of Quantum Mechanics in Time Measurement

Quantum systems have discrete energy levels. Transitions between these levels define highly stable frequencies that serve as timekeeping references.

5. Atomic Clocks: Principles and Types

Atomic clocks use electromagnetic transitions in atoms (e.g., cesium, rubidium, strontium) as frequency standards. Key types:

  • Cesium fountain clocks
  • Hydrogen masers
  • Optical lattice clocks
  • Single-ion clocks

6. Optical vs Microwave Atomic Clocks

  • Microwave clocks: e.g., cesium (9.192 GHz)
  • Optical clocks: e.g., strontium (429 THz), aluminum
    Higher frequencies → smaller fractional uncertainties.

7. Laser Cooling and Atomic Control

Laser cooling techniques reduce atomic motion to μK or nK levels, minimizing Doppler shifts and enabling long interrogation times in optical traps.

8. Ramsey Interferometry in Atomic Clocks

Ramsey’s method of separated oscillatory fields improves frequency resolution. Two pulses create interference fringes sensitive to the transition frequency.

9. Optical Lattice Clocks

Neutral atoms (e.g., strontium) are confined in an optical lattice at the magic wavelength. This cancels light shifts and enables synchronous interrogation of many atoms.

10. Single-Ion Clocks

Isolated ions (e.g., Al+, Yb+, Hg+) are trapped and interrogated with ultra-stable lasers. Their long coherence times yield extreme precision and stability.

11. Frequency Combs and Time Standards

Optical frequency combs link optical frequencies to microwave standards, enabling precise frequency measurements across wide ranges and supporting international timekeeping standards.

12. Quantum Projection Noise and the Standard Quantum Limit

Measurement noise arises from quantum fluctuations:
[
\Delta f \sim rac{1}{\sqrt{N T}}
]
where \( N \) is the number of atoms and \( T \) the interrogation time. Quantum strategies aim to suppress this noise.

13. Spin Squeezing for Clock Enhancement

Using entangled spin states reduces projection noise:

  • Spin-squeezed ensembles outperform SQL
  • Quantum correlations enhance frequency stability

14. Optical Clocks and the Redefinition of the Second

Optical clocks are candidates for redefining the SI second. Their higher frequency and precision outperform cesium standards and support relativistic tests.

15. Quantum Clocks in Gravitational Redshift Measurements

Precision clocks detect tiny gravitational potential differences. According to general relativity:
[
rac{\Delta f}{f} = rac{g \Delta h}{c^2}
]
Used in tests of gravitational redshift and time dilation.

16. Relativistic Geodesy with Quantum Clocks

Clocks measure elevation differences based on gravitational time dilation. This “clock-based altimetry” enables new methods of Earth sensing and geodesy.

17. Applications in Navigation and Communication

  • GPS and GNSS systems use atomic clocks
  • Time synchronization for 5G/6G, financial networks
  • Quantum communication protocols require precision clocking

18. Timekeeping in Quantum Networks

Distributed quantum computers and sensors need phase coherence across nodes. Quantum clocks enable synchronization with femtosecond accuracy.

19. Future Challenges and Innovations

  • Better laser stabilization
  • Clock miniaturization for field use
  • Environmental isolation
  • Integration with quantum sensors and networks

20. Conclusion

Quantum clocks redefine our understanding of time and precision. From testing fundamental physics to revolutionizing global navigation, they are essential to the quantum future of metrology and technology.

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