New Delhi: Physicists in Germany have produced the coldest temperature ever recorded in a lab.
By dropping a gas down a 120-metre tower and switching a magnetic field on and off to bring its atoms to an almost complete standstill, the team managed to achieve a temperature 38 trillionths of a degree above absolute zero, or minus 273.15 degrees Celsius.
Absolute zero is the coldest temperature possible on the thermodynamic scale. At this point, there’s no atomic motion or heat at all. But it is not actually possible to reach that mark since kinetic energy from atoms cannot be removed completely.
This experiment is the closest that scientists have ever gotten to absolute zero.
They used a cloud of 1,00,000 atoms of rubidium (a silvery-white metallic element) trapped in a magnetic field in a vacuum chamber. The cloud was cooled down to form what is known as the Bose-Einstein Condensate, where the element begins to show strange quantum properties that are usually not observable.
They then dropped the experiment over 120 metres, during which the magnetic field was switched off and on repeatedly.
When the magnetic field is off, the gas begins to expand, and when it’s turned back on, the gas is forced to contract again. This switching slows the expansion of the gas, bringing the atoms to an almost complete stop. Reducing this molecular speed effectively reduces the temperature.
While the experiment only managed to achieve this record-breaking temperature for up to two seconds, simulations showed that it should be possible to maintain it for up to 17 seconds in a weightless environment, such as aboard a satellite.
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Human tobacco consumption likely dates back 12,300 years
Humans likely started using tobacco 12,300 years ago, much earlier than previously believed. A team of scientists from Utah, US, has discovered charred remains of tobacco seeds, which indicates some of the first people to arrive in the Americas used the plant.
The discovery pushes back the timeline of tobacco consumption by over 9,000 years before previously thought, the researchers said.
Of all the intoxicant plants that humans use and abuse, tobacco, the team says, has had the most social and economic impact.
Tobacco often played a role in ceremonies or healing in the ancient Maya and other indigenous American groups.
Until now, the earliest evidence of human tobacco use was nicotine found in smoking pipes in Alabama that dated back about 3,300 years.
The archaeologists involved in the study excavated the remains of a hunter-gatherer camp that had been exposed by wind over time in the Great Salt Lake Desert in Utah.
The team found an ancient fireplace surrounded by stone artefacts, such as spear tips. More than 2,000 bones and bone fragments, mostly belonging to ducks, were also recovered, suggesting that is what the people ate.
Within the fireplace, the scientists found the remains of four charred tobacco seeds.
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‘Earth’s evil twin’ Venus may not have had liquid oceans
Venus may not have been as hospitable as indicated by earlier studies, or even ever had liquid water oceans.
Using sophisticated simulations, researchers from Switzerland found that the temperatures never got low enough on Venus for the water in its atmosphere to form raindrops that could fall on its surface. Instead, water remained as a gas in the atmosphere and oceans never formed.
Venus has been referred to as Earth’s evil twin, because the two planets are comparable in terms of mass and size, and are made of mostly rocky material. Theories suggesting the presence of water on ancient Venus added to the comparison. However, a closer look reveals striking differences between them.
For instance, Venus has a thick carbon dioxide atmosphere, extreme surface temperature and pressure, and sulphuric acid clouds, which are in stark contrast to the conditions needed for life on Earth.
The team studied how the atmospheres of the two planets would evolve over time and whether oceans could form in the process.
The simulations also reveal that Earth could have easily suffered the same fate as Venus, if it had been just a little closer to the Sun or if the Sun had shone as brightly in its “youth” as it does nowadays.
The relatively weak radiation of the young Sun allowed the Earth to cool down enough to condense water that forms our oceans.
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Snake evolution expanded after dinosaurs’ extinction
Shortly after the dinosaurs were wiped off the face of the Earth, the evolution of modern snakes expanded rapidly as they had the opportunity to feed on a wide variety of prey, a US study has found.
An asteroid wiped out nearly all the dinosaurs and roughly three-quarters of the planet’s plant and animal species 66 million years ago, giving mammals the opportunity to diversify.
Snake species also evolved quickly after the asteroid hit, acquiring the ability to eat new types of prey. Mammals and birds, which were also diversifying in the wake of the extinction, began to appear in snake diets at the time. Specialised diets also emerged, such as snakes that fed only on slugs or snails, or snakes that ate only lizard eggs.
The researchers looked at a dataset that included more than 34,000 direct observations of snake diets, from published accounts of scientists’ encounters with snakes in the field and from the analysis of the stomach contents of preserved museum specimens.
They then looked at the genetic data in a new mathematical model that allowed them to infer what long-extinct snake species were like. The study also revealed that similar dietary shifts occurred when groups of snakes colonised new locations.
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Strange radio signals detected from centre of Milky Way
Astronomers in the US and Australia have discovered unusual signals coming from the direction of the Milky Way’s centre that suggest the presence of a new stellar object that has not been detected yet.
The radio waves detected by the team do not fit the currently understood pattern of variable radio source (a celestial object that emits variable radio waves).
Many types of stars emit variable light across the electromagnetic spectrum. With advances in radio astronomy, the study of variable or transient objects in radio waves is a huge field of study helping us reveal the secrets of the universe. Pulsars, supernovae, flaring stars and fast radio bursts are all types of astronomical objects whose brightness varies.
But the signals from this new source don’t match the known types of celestial objects. The scientists plan to keep a close eye on the object to look for more clues as to what it might be.
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