Tag: upsc

Dark energy

Why in news?

—NASA’s latest study to test gravity confirms Einstein’s theory, dark energy remains an enigma.

Key takeaways

—Our universe is expanding at an accelerating rate and no one is really sure why. This seemingly contradicts current scientific knowledge of how gravity works and how it affects the world we live in. The cause of this acceleration is called “dark energy,” and it remains a mystery.

—But NASA scientists are helping probe this enigma by testing gravity. According to the space agency, this phenomenon where the universe is expanding at an accelerating rate is almost as if you threw an apple in the air and it continued to move upwards, getting faster and faster.

—According to NASA, “More is unknown than is known. We know how much dark energy there is because we know how it affects the universe’s expansion. Other than that, it is a complete mystery. But it is an important mystery. It turns out that roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest – everything on Earth, everything ever observed with all of our instruments, all normal matter – adds up to less than 5% of the universe. Come to think of it, maybe it shouldn’t be called “normal” matter at all, since it is such a small fraction of the universe.

One explanation for dark energy is that it is a property of space. Albert Einstein was the first person to realize that empty space is not nothing. Space has amazing properties, many of which are just beginning to be understood. The first property that Einstein discovered is that it is possible for more space to come into existence.

Then one version of Einstein’s gravity theory, the version that contains a cosmological constant, makes a second prediction: “empty space” can possess its own energy. Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear.

As a result, this form of energy would cause the universe to expand faster and faster. Unfortunately, no one understands why the cosmological constant should even be there, much less why it would have exactly the right value to cause the observed acceleration of the universe.

Another explanation for how space acquires energy comes from the quantum theory of matter. In this theory, “empty space” is actually full of temporary (“virtual”) particles that continually form and then disappear.

Another explanation for dark energy is that it is a new kind of dynamical energy fluid or field, something that fills all of space but something whose effect on the expansion of the universe is the opposite of that of matter and normal energy. “

—The latest effort to understand whether this is all a misunderstanding comes from a new study from the Dark Energy Survey (DES). DES is an international collaborative effort that maps hundreds of millions of galaxies, detects thousands of supernovae and finds patterns of cosmic structure.

—The new study uses the 4-metre Victo M Blanco Telescope in Chile to conduct what according to the space agency are the most precise tests yet of Albert Einstein’s theory of gravity at the cosmic scale. It finds that the current understanding appears to be correct. The results were presented at the International Conference on Particle Physics and Cosmology in Rio de Janeiro.

—Einstein’s Theory of General Relativity was developed more than a century ago and describes gravity in a way that has so far accurately predicted various phenomena, including the existence of black holes. But, according to some scientists, there may be a need to modify some of its equations or add new components if it can’t explain dark energy.

—To test that out, DES members looked for evidence that gravity’s strength has varied throughout the universe’s history or over distances. If that were the case, it would indicate that Einstein’s theory is incomplete, which would bring us closer to explaining the universe’s accelerating expansion.

—In addition to the Blanco telescope, the members also examined data from ESA’s Planck satellite. But the study found out that Einstein’s theory still holds, meaning that there is still no explanation for dark energy.

—In order to arrive at this conclusion, scientists needed to look deep into the universe’s past. They did this by looking at objects that are really far away. A light-year is about 9.5 trillion kilometres, or the distance that light can travel in a year. This means that an object one light-year away appears to as us as it was a year ago. That means that galaxies billions of light-years away appears to us as they were billions of years ago. The observations made by the scientist matched what is predicted by Einstein’s theory, once again leaving dark energy with no explanation.

—This research will be furthered by two upcoming NASA missions. Euclid, slated for a 2023 launch and Nancy Grace Roman Space Telescope, scheduled for a 2027 launch. Both telescopes will help scientists look further back in time to further probe the presence of dark energy.

—Everything we see – the planets, moons, massive galaxies, you, me, this website – makes up less than 5% of the universe. About 27% is dark matter and 68% is dark energy. While dark matter attracts and holds galaxies together, dark energy repels and causes the expansion of our universe.

—Despite both components being invisible, we know a lot more about dark matter, since its existence was suggested as early as the 1920s, while dark energy wasn’t discovered until 1998.

—Large-scale experiments like XENON1T have been designed to directly detect dark matter, by searching for signs of dark matter ‘hitting’ ordinary matter, but dark energy is even more elusive.

(source: science.nasa.gov)

Point to ponder: What is dark energy, and have scientists finally detected it?

1. MCQ:

Consider the statements and answer the following question

1. Dark matter attracts and holds galaxies together.

2. Large-scale experiments like XENON1T have been designed to directly detect dark matter.

Which of the following statements is/are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Digital rupee

Why in news?

—Reports on Monday (August 22) said the Reserve Bank of India’s (RBI) digital rupee — the Central Bank Digital Currency (CBDC) — may be introduced in phases beginning with wholesale businesses in the current financial year.

—In her Budget speech on February 1, Finance Minister Nirmala Sitharaman had said that the central bank would launch the CBDC in the financial year 2022-23.

—RBI, which has repeatedly voiced its opposition to private digital currencies, had proposed to the government in October last year to widen the scope of the paper rupee to include currency in a digital form.

Key takeaways

—According to the RBI, “CBDC is the legal tender issued by a central bank in a digital form. It is the same as a fiat currency and is exchangeable one-to-one with the fiat currency. Only its form is different.” The digital fiat currency or CBDC can be transacted using wallets backed by blockchain.

—Though the concept of CBDCs was directly inspired by Bitcoin, it is different from decentralised virtual currencies and crypto assets, which are not issued by the state and lack the ‘legal tender’ status. CBDCs enable the user to conduct both domestic and cross-border transactions which do not require a third party or a bank.

—There are several models proposed by technology experts and evangelists on how the digital rupee could be transacted, and the formal announcement by the RBI will likely provide the details. One chief difference could be that a digital rupee transaction would be instantaneous as opposed to the current digital payment experience.

Point to ponder: Green bonds, digital currency hold promise for India’s financial future. Discuss.

2. MCQ:

Which of the following statements is not true?

a) CBDC is the legal tender issued by a central bank in a digital form.

b) CBDC is the same as a fiat currency but cannot be exchangeable one-to-one with the fiat currency.

c) The digital fiat currency or CBDC can be transacted using wallets backed by blockchain.

d) CBDCs enable the user to conduct both domestic and cross-border transactions.

Per- and Polyfluoroalkyl substances (PFAs)

Why in news?

—A recent study published in Environment Science and Technology has found that rainwater from many places across the globe is contaminated with “per- and polyfluoroalkyl substances,” (PFAs), which are called “forever chemicals” because of their tendency to stick around in the atmosphere, rainwater and soil for long periods of time.

Key takeaways

—PFAs are man-made chemicals used to make nonstick cookware, water-repellent clothing, stain-resistant fabrics, cosmetics, firefighting forms and many other products that resist grease, water and oil.

—PFAs can migrate to the soil, water and air during their production and use. Since most PFAs do not break down, they remain in the environment for long periods of time.

—Some of these PFAs can build up in people and animals if they are repeatedly exposed to the chemicals.

—The United States Environmental Protection Agency (EPA) lists a variety of health risks that are attributed to PFA exposure, including decreased fertility, developmental effects in children, interference with body hormones, increased cholesterol levels and increased risk of some cancers.

—Recent research has also revealed that long-term low-level exposure to certain PFAs can make it difficult for humans to build antibodies after being vaccinated against various diseases.

—While the recently published research article did not include studies of samples collected in India, the nature of PFAs and the wide geographical breadth of samples and the nature of PFAs means that the results can be extrapolated to India, according to lead author Ian Cousins, who spoke to indianexpress.com over an email interaction regarding the same.

—While there is no known method that can extract and remove PFAs from the atmosphere itself, there are many effective, albeit expensive, methods to remove them from rainwater that has been collected through various rainwater harvesting methods.

—One way to do this would be to use a filtration system with activated carbon. The activated carbon will need to be removed and replaced regularly. Also, the old contaminated material must be destroyed.

—Recently, Science reported a cheaper method that EPA researchers led by William Dichtel and Brittany Trang stumbled upon by chance. The researchers first placed a PFA compound in a solvent called DMSO (dimethyl sulfoxide). They then mixed it with sodium hydroxide (lye) in water. They found that when this mixture was heated up to boiling temperature, the PFA compound began to degrade.

—However, this method doesn’t work for all PFAs and only works for certain PFA subsets. Scientists are now looking at ways to scale up their technique to include different types and also large amounts of PFAS.

Point to ponder: Rainwater globally is too contaminated for human consumption. This is especially problematic in a country like India. Explain.

3. MCQ:

Consider the statements below and answer the following question.

1. PFAs are used to make fluoropolymer coatings that can resist heat, oil, stains, grease and water.

2. PFAS are widely used, long lasting chemicals, components of which break down very slowly over time.

3. PFAS can be present in our water, soil, air, and food as well as in materials found in our homes or workplaces.

Which of the following statements with respect to PFAs is/are incorrect?

a) Only 1

b) Only 2

c) 2 and 3

d) None of the above

Over leveraging

Why in news?

—Bloomberg, quoting CreditSights, a unit of the credit ratings agency Fitch, reported this week that the Adani Group is “deeply over-leveraged”, and may, “in the worst-case scenario”, spiral into a debt trap and possibly a default.

Key takeaways

—A company or business is said to be “over-leveraged” if it has unsustainably high debt against its operating cash flows and equity. Such a company would find it difficult to make interest and principal repayments to its creditors, and may struggle to meet its operating expenses as well.

—In the latter case, the company may be forced to borrow even more just to keep going, and thus enter a vicious cycle. This situation can ultimately lead to the company going bankrupt.

—Just as a loan from a bank can help an individual buy a home or a car, lead to an improvement in her quality of life, and perhaps enable her to contribute better to her society in tangible and intangible ways, debt can help a company grow and expand, create more jobs and make profits, and ultimately contribute to the GDP growth of the country itself.

—However, it is critical for companies to manage their debt well, just as it is critical for individuals to make timely repayments of their loans. While taking on debt is sometimes a better option to raise capital than, say, issuing stock, which would dilute ownership, borrowing more than they can repay lands companies in trouble.

—Companies typically borrow in anticipation of demand, and when that does not work out, they find it difficult to sustain the debt burden. This is the reason many real estate companies that took on debt in anticipation of a housing boom went bust when the apartments they planned or built did not sell. A company that is less leveraged is better placed to manage situations in which revenues fall.

Point to ponder: What happens when a company is over-leveraged?

4. MCQ:

Consider the statements below and answer the question.

1. A company or business is said to be “over-leveraged” if it has an unsustainably high debt against its operating cash flows and equity.

2. A company that is less leveraged is better placed to manage situations in which revenues fall.

3. When a company is over-ledged it may lend even more than normal times.

Which of the following statements is/are not correct?

a) Only 2

b) 1 and 3

c) 2 and 3

d) All of the above

Tomato flu

Why in news?

—With cases of tomato flu reported from at least four states — Kerala, Tamil Nadu, Haryana, and Odisha — the Union Health Ministry on Tuesday (August 23) issued a set of guidelines on prevention, testing, and treatment of the infection.

—Attention was drawn to the condition, which has been intermittently reported from Kerala earlier, after a correspondence was published in the journal Lancet Respiratory Medicine recently.

—Researchers believe that it is a different clinical presentation of hand-foot-and mouth disease (HFMD) caused by a group of enteroviruses (viruses transmitted through the intestine).

Key takeaways

—Tomato flu or tomato fever is characterised by fever, joint pain, and red, tomato-like rashes usually seen in children below the age of five years. This is accompanied by other symptoms of viral fevers such as diarrhoea, dehydration, nausea and vomiting, and fatigue.

—This was thought to be an after effect of dengue and chikungunya that is commonly seen in Kerala. However, researchers now believe that it is HFMD caused by enteroviruses like Coxsackievirus A-6 and A-16.

—According to Dr Asawathyraj, who characterised the virus from Kerala and has been studying the infection, the current HFMD cases are mainly caused by Coxsackievirus A-6 and A-16. Another pathogen — Enterovirus71 — that also causes the disease is not very prevalent now, according to her.

—This is good because the pathogen was known to lead to severe neurologic symptoms, including fatal encephalitis (brain inflammation). “In almost all cases, say 99.9% cases, the disease is self-limiting. But, in a small number of cases it can lead to CNS (central nervous system) complications,” said Dr Asawathyraj.

—She added that the disease this time around has some atypical presentation as well. The red “tomato” rashes were traditionally restricted to the mouth (tongue, gums, and inside of the cheek), palms, and soles. However, now doctors are also reporting rashes on the buttocks, and a shedding of nails.

—Asked whether the rashes can be mistaken for monkeypox, for which states are on alert after an increased global spread, Dr Asawathyraj said that the rashes can be distinguished just by visual inspection. “The monkeypox rashes are more deep-rooted and the distribution is also different,” she said.

—There is no specific treatment or vaccine available for the disease. Those with the infection are treated symptomatically, such as prescription of paracetamol for fever.

Point to ponder: How can tomato flu be prevented?

5. MCQ:

Which of the following pairs is not correctly matched?

a) Hand-foot-and mouth disease – Coxsackievirus A-6

b) Lumpy skin disease – Enterovirus71

c) Coronavirus -SARS-CoV-2 virus

d) Chicken pox- Varicella-zoster virus

Answer to MCQs: 1 (c) , 2 (b) , 3 (d) , 4 (c) , 5 (b)