Editorial 1 : How fast is the universe expanding? New data keeps the mystery open
Introduction
A big open problem in cosmology is the Hubble tension. There are two equally valid ways to measure how fast the universe is expanding, but they have yielded two very different estimates.
Model to understand the universe
- This model is called cold dark matter, or “lambda CDM”.
- It’s currently the simplest model that explains various features of the universe, including radiation leftover from the Big Bang, the arrangement of galaxies in the universe, and the fact that the universe is expanding.
- But cosmologists are also looking for a new, better model that can explain some things the CDM model can’t, such as the Hubble tension.
Open, closed or flat?
- Our universe started to expand after the Big Bang event around 14 billion years ago.
- It may continue to expand unabated forever. If it does, it will be an open universe.
- But if at some point the expansion stops, because of the gravitational forces exerted by the galaxies, say, the universe could collapse and become closed.
- A closed universe is said to have a positive curvature of space — like a sphere. Such a universe will be finite even if it has no bounds. That is, in this universe, we can travel forever without falling off an ‘edge’.
- In an open universe, space will warp in the opposite direction. That is, it will have a negative curvature, resembling a saddle.
- There is another possibility between these assumptions: that the universe will continue to expand forever, but the rate of expansion, which is currently increasing, will eventually start decreasing thanks to the gravitational forces.
- The rate will take an infinite amount of time to drop to zero, so the universe will keep expanding, just slower and slower.
- This special approximation leads to a flat universe. And according to many cosmologists, this is the state of our universe at this time.
The Big Bang’s afterglow
- Cosmologists deduced this based on studying the cosmic microwave background (CMB).
- This is a sea of photons, the particles of light, present throughout the universe.
- They are leftover from the Big Bang, its afterglow.
- Scientists have measured temperature changes in the CMB and studied its large-scale properties using complicated trigonometry. And they found that it has nearly zero curvature.
- The Wilkinson Microwave Anisotropy Probe (WMAP),BOOMERanG, and’Planck’ are three telescopes in space.
- They study the CMB and their data is clear: the observable universe is flat with a 0.4% margin of error.
- Based on these studies, cosmologists have estimated space to be expanding at around 68 kilometres per second per megaparsec ((km/s)/Mpc).
- That is, an object one megaparsec (3.26 million lightyears) away is moving away at 68 km/s.
The cosmic distance ladder
- The CMB is one way to study the universe’s expansion.
- The other is called the cosmic distance ladder — a set of techniques used to measure the distance to objects that are close, further away, and very far away from the earth. One object in particular is the Cepheid variable star.
- The Cepheid variables have a unique feature: their brightness varies in a predictable way over time. Based on how bright a Cepheid variable is, scientists can estimate how far away it is.
- Using this, cosmologists have estimated based on various Cepheid variables the expansion of the universe is 73 (km/s)/Mpc.
Hubble versus JWST
- The best way to follow these stars is using the near-infrared radiation they emit.
- Unlike visible light, such radiation can pass through intervening dust clouds and reach us. Cepheid variable stars may also be crowded in some places.
- Fortunately, NASA’s James Webb Space Telescope (JWST) can track both near-infrared radiation and has instruments good enough to distinguish between radiation from two Cepheid variable stars close to each other in the sky.
- The superior resolution of JWST negates crowding noise, the largest source of variance in the near-infrared [brightness] relations measured with the Hubble space telescope.
Conclusion
In sum, the Hubble tension is real and its origins remain a mystery.
Editorial 2 : Decoding the judgment on Jim Corbett
Context
In its ruling in March, the Supreme Court brought to light the unholy nexus of politicians, forest officials, and local contractors responsible for the felling of 6,000 trees in the Jim Corbett National Park in Uttarakhand.
The issue
- This state of affairs underlines one fact clearly: despite conservation goals receiving priority through policies and laws including the Wildlife Protection Act, 1972, Project Tiger, and the Forest (Conservation) Act, 1980, the state’s main interest remains increasing revenue.
- The illegal destruction of trees in Jim Corbett can be seen in contravention of the 1983 Supreme Court judgment in Rural Litigation and Entitlement Kendra vs. State of Uttar Pradesh, which said that “economic growth cannot be achieved at the cost of environmental destruction and people’s right to healthy environment.”
The judgment
- National and State forest authorities have leaned on ecotourism to simultaneously attain conservation goals, enhance revenue, and improve the livelihoods of local people.
- In its recent judgment, instead of treating eco-tourism as a panacea for conservation and revenue generation, the Supreme Court said that the approach must be of eco-centrism and not anthropocentrism.
- The court directed the banning of tiger safaris in core areas and the constitution of a committee to explore the feasibility of permitting tiger safaris in peripheral areas in not just Jim Corbett, but across India.
- It also disagreed with the 2019 guidelines of the National Tiger Conservation Authority permitting a tiger safari on the lines of a zoo in a national park.
- According to British environmentalist Norman Myers, the precautionary principle is becoming an established principle for policymakers tackling environmental problems.
- The principle says that where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent such environmental degradation.
- In salient respects, the principle applies to biodiversity more than any other environmental problem.
- This is because the mass extinction gathering force will, if it proceeds unchecked, not only eliminate half or more species but will leave the biosphere impoverished for at least 5 million years.
- The International Union for Conservation of Nature’s Red List of Threatened Species monitors 1,212 animal species in India. In 2021, it found that 12% of them are endangered.
- According to a report of the Centre for Science and Environment in 2021, India has lost 90% of the area under its four biodiversity hotspots. The precautionary principle therefore applies not only in the case of tigers, but also other species, especially endangered ones.
Cost of restoration
- To identify the cost of restoration and recover the same from the errant individuals and officers appears to be a mirage in the absence of a well-defined methodology.
- Recovering the cost of restoration does not amount to necessarily recovering the loss of the ability of the environment to provide goods and services.
- In India, the framework of valuation which predated the T.N. Godavarman case (1996) was aimed at replacing lost natural forest with compensatory plantations.
- The two choices which are supported legally and institutionally and serve as the background for the valuation of forest land in India are now compensatory afforestation levy and net present value (NPV).
- The levy is essentially a form of replacement cost, designed to replace the forest land which was lost as a result of diversion of forest towards non-forestry use.
- Since the levy is found to be insufficient in terms of making good the loss, the Court introduced the NPV in 2002 as an additional payment obligation.
- But both these methodologies do not rightly account for the correlation between the removal of trees and the harm caused to other environmental goods and services.
Way forward
- In the context of the growing degradation of biodiversity hotspots and the support to revenue-generating eco-tourism, a valuation method which is based on ecosystem services (food, water, and services regulating the climate and floods, etc.) is a must.
- The system refers to the benefits people obtain from natural ecosystems in contrast with man-made structures.