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Old Dusty Kilogram Swapped for Something More Stable: Scientists

It has taken years of work to fine-tune the new definition to ensure the switchover will be smooth.

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Kilogram
The International Prototype of the Kilogram (IPK) is pictured in Paris, France, in this undated photo obtained from social media. VOA

After years of nursing a sometimes dusty cylinder of metal in a vault outside Paris as the global reference for modern mass, scientists are updating the definition of the kilogram.

Just as the redefinition of the second in 1967 helped to ease communication across the world via technologies like GPS and the internet, experts say the change in the kilogram will be better for technology, retail and health — though it probably won’t change the price of fish much.

The kilogram has been defined since 1889 by a shiny piece of platinum-iridium held in Paris. All modern mass measurements are traceable back to it — from micrograms of pharmaceutical medicines to kilos of apples and pears and tons of steel or cement.

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Border Security Force officials showing 17 kilogram heroine.

The problem is, the “international prototype kilogram” doesn’t always weigh the same. Even inside its three glass bell jars, it gets dusty and dirty, and is affected by the atmosphere. Sometimes, it really needs a wash.

“We live in a modern world. There are pollutants in the atmosphere that can stick to the mass,” said Ian Robinson, a specialist in the engineering, materials and electrical science department at Britain’s National Physical Laboratory.

“So when you just get it out of the vault, it’s slightly dirty. But the whole process of cleaning or handling or using the mass can change its mass. So it’s not the best way, perhaps, of defining mass.”

What’s needed is something more constant.

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The Kilogram. Flickr

So, at the end of a week-long meeting in the Palace of Versailles, Paris, the world’s leading measurement aficionados at the International Bureau of Weights and Measures will vote Friday to make an “electronic kilogram” the new baseline measure of mass.

Just as the meter — once the length of a bar of platinum-iridium, also kept in Paris — is now defined by the constant speed of light in a vacuum, so a kilogram will be defined by a tiny but immutable fundamental value called the “Planck constant.”

The new definition involves an apparatus called the Kibble balance, which makes use of the constant to measure the mass of an object using a precisely measured electromagnetic force.

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The kilogram has been defined since 1889 by a shiny piece of platinum-iridium held in Paris.VOA

“In the present system, you have to relate small masses to large masses by subdivision. That’s very difficult — and the uncertainties build up very, very quickly,” Robinson said.

“One of the things this [new] technique allows us to do is to actually measure mass directly at whatever scale we like, and that’s a big step forward.”

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He said it had taken years of work to fine-tune the new definition to ensure the switchover will be smooth.

But while the extra accuracy will be a boon to scientists, Robinson said that, for the average consumer buying flour or bananas, “there will be absolutely no change whatsoever.” (VOA)

Next Story

Scientists Take Peek Behind Those Sad Puppy Dog Eyes and Find a Unique Muscle

Pooches use the muscle to raise their eyebrows and make the babylike expression

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Scientists, Sad, Puppy
FILE - Lexy, a therapy dog, is seen at Fort Bragg, N.C., Feb. 18, 2014. A study released June 17, 2019, suggests that over thousands of years of dog domestication, people preferred dogs that could pull off the "puppy dog" eyes look. VOA

What’s behind those hard-to-resist puppy dog eyes?

New research suggests that over thousands of years of dog domestication, people preferred pups that could pull off that appealing, sad look. And that encouraged the development of the facial muscle that creates it.

Today, pooches use the muscle to raise their eyebrows and make the babylike expression. That muscle is virtually absent in their ancestors, the wolves.

“You don’t typically see such muscle differences in species that are that closely related,” said Anne Burrows of Duquesne University in Pittsburgh, an author of the study released Monday by the Proceedings of the National Academy of Sciences.

Scientists, Sad, Puppy
FILE – A female red wolf emerges from her den sheltering newborn pups at the Museum of Life and Science in Durham, N.C., May 13, 2019. VOA

Dogs differ from wolves in many ways, from having shorter snouts, smaller sizes and more expressive faces. And unlike wolves, dogs heavily rely on human eye contact, whether to know when someone’s talking to them or when they can’t solve a problem, like hopping a fence or getting out the door.

Burrows and her colleagues examined the eye muscles in the cadavers of six dogs and two wolves. They found dogs have a meaty eye muscle to lift their eyebrows and make puppy dog eyes. But in wolves, the same muscle was stringy or missing.

The scientists also recorded 27 dogs and nine wolves as each stared at a person. Pet pooches frequently and intensely pulled back their eyebrows to make sad expressions, while the wolves rarely made these faces, and never with great intensity.

The researchers believe dogs, over their relatively short 33,000 years of domestication, used this eye muscle to communicate, possibly goading people to feed or care for them — or at least take them out to play. And people, perhaps unwittingly, obliged.

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‘Profound’ implications

Dog experts not involved with the study were impressed.

“The implications are quite profound,” said Brian Hare from Duke University, who edited the article. Hare wrote in an email that these muscles almost certainly developed because they gave dogs an advantage when interacting with people, and people have been unaware of it.

“The proof has been in their puppy dog eyes all this time!” he said.

Scientists, Sad, Puppy
Over thousands of years of dog domestication, people preferred pups that could pull off that appealing, sad look. Pixabay

Evan MacLean at the University of Arizona called the findings fascinating, but cautioned that the muscle difference could be an indirect effect of other changes rather than a specific response to human influence.

Clive Wynne of the Canine Science Collaboratory at Arizona State University said: “Kudos to the researchers for thinking of a cool way to investigate an important aspect of dogs’ success” with humans.

But he noted in an email that the study has a few snags, particularly the small sampling — only five dog breeds were examined and videos were mainly of Staffordshire bull terriers — and the lack of background information about each animal.

“Did these wolves regularly meet people bearing gifts that might be worth asking for with an endearing face?” he asked.

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Burrows said she planned follow-up studies to examine more breeds. (VOA)