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Ancient rock shows there was life on Earth 3.75 billion years ago, much earlier than we thought

ScientiFix, our weekly feature, offers you a summary of the top global science stories of the week, with links to their sources.

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New Delhi: Scientists have found that diverse microbial life existed on Earth at least 3.75 billion years ago — much earlier than previously thought. 

Prior to this discovery, the oldest fossils ever reported were found in Western Australia and dated at 3.46 billion years old.

For the study, the team analysed a fist-sized rock from Canada, estimated to be between 3.75 and 4.28 billion years old. They found tiny filaments, knobs and tubes in the rock that appeared to have been made by bacteria.

However, not all scientists agreed that these structures were of biological origin.

Then, after extensive further analysis of the rock, the team discovered a much larger and more complex structure — a stem with parallel branches on one side that is nearly a centimetre long — as well as hundreds of distorted spheres, or ellipsoids, alongside the tubes and filaments.

The researchers say that, while some of the structures could conceivably have been created through chance chemical reactions, the “tree-like” stem with parallel branches was most likely biological in origin, as no structure created via chemistry alone has been found like it. 

The team have also provided evidence of how the bacteria got their energy in different ways. They found mineralised chemical by-products in the rock that are consistent with ancient microbes living off iron, sulphur and possibly also carbon dioxide and light through a form of photosynthesis not involving oxygen. Read more

Hubble confirms largest icy comet nucleus ever seen

NASA’s Hubble Space Telescope has determined the size of the largest icy comet nucleus ever seen by astronomers. With an estimated diameter of about 128 kilometres, the nucleus of the comet is about 50 times larger than those found at the heart of most known comets. 

Its mass is estimated to be a staggering 500 trillion tons, a hundred thousand times greater than the mass of a typical comet found much closer to the Sun.

The series of images shared by NASA show how the nucleus of Comet C/2014 UN271 was isolated from a vast shell of dust and gas surrounding the solid icy nucleus. 

The comet is travelling towards the Earth at over 35,000 km per hour from the edge of the solar system. But it will only get as far as the planet Saturn, and that won’t be until the year 2031.

The comet follows a 3-million-year-long elliptical orbit, taking it as far from the Sun as roughly half a light-year. It’s now less than 2 billion miles from the Sun, falling nearly perpendicular to the plane of our solar system. Read more

Also read: Squids can change colour to evade predators & scientists have spotted the farthest galaxy yet

Big John may have locked horns with another Triceratops 

Scientists from Italy have discovered why Big John, the most massive Triceratops skeleton ever found, has a keyhole-shaped opening on its frill. According to the team, more than 66 million years ago, Big John likely locked horns with another Triceratops.

The shape and size of the lesion suggest that it was caused by the horn of another Triceratops of similar size.

Big John measured about 8 metres long, and its skull was about 2 metres wide. The skeleton, discovered in South Dakota in 2014, is about 60 per cent complete. Last year, an auction house in Paris sold the fossilised remains for about $7.2 million.

But before the auction, the fossil was taken to Italy, where researchers prepared the specimen and noticed the hole on the right side of its frill. This prompted scientists to study the fossil further. 

The wound, however, didn’t kill Big John. There are signs of bone healing, although the Triceratops died before healing was complete.

The team hypothesised that an infection from the trauma may have eventually led to its death. Read more

Six new species of wētā discovered in New Zealand

Six new alpine species of wētā —  giant flightless crickets — have been discovered in New Zealand. 

There are between 70 and 100 species of wētā endemic to New Zealand. Some of these are among the heaviest insects in the world — comparable to the weight of a sparrow.

The alpine wētā have the impressive ability to freeze themselves solid during the harsh winter months, before thawing out again in spring.

However, the team also found that most of these new species are in habitats that are at risk of being wiped out due to climate change. 

Forests, grasslands, caves, and alpine terrains once crawled with wētā, but their populations have suffered with the introduction of foreign pests and increasing habitat decline due to dairy farming. 

Sixteen of New Zealand’s wētā species are at risk, and the rest are classified as threatened or endangered. Read more

New measurement of W boson differs from Standard Model

After 10 years of careful analysis and scrutiny, an international collaboration of scientists, working with researchers from the US Department of Energy’s Fermi National Accelerator Laboratory, have achieved the most precise measurement to date of the mass of the W boson, one of nature’s fundamental, force-carrying particles. 

Using data collected by the Collider Detector at Fermilab, or CDF, the scientists determined the particle’s mass with a precision of 0.01 per cent —twice as precise as the previous best measurement. 

The new precision measurement differs from what is predicted by the Standard Model of particle physics. 

The Standard Model is the theory that describes three of the four known fundamental forces in the universe and classifies all known elementary particles (subatomic particles that aren’t composed of any other particles).

The theory was developed through the work of many scientists worldwide throughout the latter half of the 20th century. In the mid-1970s, the existence of quarks was experimentally confirmed, giving credence to the theory. The discovery of the Higgs boson in 2012 was further evidence in support of the Standard Model. 

But the new measurements of the W boson particles shows that there is a potential need for improvements to the Standard Model calculations.

The new value is in agreement with many previous W boson mass measurements, but there are also some disagreements.  The measurement needs to be confirmed by another experiment before it can be interpreted fully. 

The W boson is a messenger particle of the weak nuclear force. It is responsible for the nuclear processes that make the Sun shine and particles decay. Using high-energy particle collisions produced by the Tevatron collider at Fermilab, the CDF collaboration collected huge amounts of data containing W bosons from 1985 to 2011.

The mass of a W boson is about 80 times that of a proton. The latest mass measurement pegs the W boson’s mass at about 80,433 MeV/c2 — which is about 70 MeV (megaelectron volts) more than what is predicted. Read more

Also read: Scientists discover 6-million-year-old fossil of day-hunting owl in China


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