[PDF] Bitcoin mining guzzles energy - Nature

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It takes about the same amount of energy to

mine a dollar's worth of cryptocurrency as it does to mine a dollar's worth of certain metals.

Cryptocurrencies such as Bitcoin have

raised environmental concerns because 'mining' virtual coins (pictured) requires energy-intensive computer calculations. But quantifying the environmental impact of cryptocurrency production is difficult.

Independent researchers Max Krause and

Thabet Tolaymat calculated that it takes about

17 megajoules of computer power to generate

US$1 in Bitcoin, even when the energy used

for peripheral activities, such as cooling computers, is not factored in. By comparison, it takes 5 megajoules to mine US$1 in gold and 7 megajoules to mine an equivalent value of platinum. Aluminium-mining energy requirements, at 122 megajoules, topped the researchers' list.

Over 30 months from 2016 to 2018, the

authors report, Bitcoin mining produced an estimated 3 million to 13 million tonnes of carbon dioxide. That range does not account for activities such as building maintenance and computer cooling; even so, it is roughly equivalent to the range of carbon dioxide produced by about 1 million cars, although it is still less than 0.01% of global emissions.Nature Sustain. http://doi.org/cws8 (2018)

ENERGY

Bitcoin mining guzzles energy

GENETICS

Roots of a

dairy empire

Ancient Mongolians picked up

a fondness for milk from their neighbours, evidence from human skeletons suggests.

ATOMIC PHYSICS

Nuclear particle's

swifb escape

An atom has been caught

spitting out a fundamental nuclear particle in fewer than

18 nanoseconds, setting a speed record for a particular type of

radioactive decay.

Many radioactive elements,

including tellurium-104, emit alpha particles, which have two protons and two neutrons.

Nuclear theory predicts that

tellurium-104 should emit an alpha particle rapidly, because doing so creates tin-100, which has an especially stable nuclear configuration. But tellurium-

104's decay to tin-100 is too

rapid for current methods to observe directly.

Kalle Auranen at the

Argonne National Laboratory

in Lemont, Illinois, and his colleagues produced tiny amounts of the element xenon-

108 and isolated them using

the Fragment Mass Analyzer at

Argonne's ATLAS accelerator.

They then watched for the

emission of two alpha particles in succession, as xenon decayed first to tellurium-104 and then to tin-100.

The team determined that

tellurium-104's half-life is under 18 nanoseconds. The atom's brief life span lends credence to models predicting that heavy nuclei composed of equal numbers of protons and neutrons should experience enhanced nuclear forces, leading to swift ejection of alpha particles.

Phys. Rev. Lett. 121, 182501

(2018)Archaeological sites show that after about 1500 bc, the people of what is now

Mongolia kept livestock. To

learn whether those were dairy animals, Choongwon Jeong and Christina Warinner at the

Max Planck Institute for the

Science of Human History

in Jena, Germany, and their colleagues analysed human skeletons buried in northern

Mongolia and dated to 1380-

975 bc. Proteins on some of

the individuals' teeth showed that they had consumed either milk or milk products from sheep, goats and animals related to dairy cattle.

During the period of the

skeletons' burial, people known as the Western Steppe herders had spread across

Eurasia to the region just west

of Mongolia. But the buried

Mongolians' DNA shows little

genetic influence from these people.

This suggests that, rather

than being replaced by the influx of western strangers, Mongolian hunter-gatherers took lessons from them in

JAMES MACDONALD/BLOOMBERG/GETTY

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RESEARCH HIGHLIGHTS

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