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Massive News: Kilogram Redefinition Heads Into Crucial Test

Superprecise standard masses are on their way to Paris for a critical weigh-in

3 min read
Massive News: Kilogram Redefinition Heads Into Crucial Test
Masses in Motion: Canada will send a cousin of this kilogram mass to Paris for a dry run of the unit’s redefinition. It’ll be joined by masses from around the world.
Photo: National Research Council of Canada

K50 is going on a trip.Sometime soon, the golf-ball-size cylinder of platinum and iridium, which makes its home in Ottawa, will be carefully packed up and hand carried by a member of Canada’s diplomatic corps on a plane to France, with special instructions that its case not be opened by customs or airport security.

This precious cargo will join a small clutch of similar objects that will trickle into Paris in the coming weeks. Their destination: the International Bureau of Weights and Measures (BIPM) just outside the city, where they’ll be compared with one another to see just how well their estimated masses match up.

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Deep Learning Could Bring the Concert Experience Home

The century-old quest for truly realistic sound production is finally paying off

12 min read
Image containing multiple aspects such as instruments and left and right open hands.
Stuart Bradford

Now that recorded sound has become ubiquitous, we hardly think about it. From our smartphones, smart speakers, TVs, radios, disc players, and car sound systems, it’s an enduring and enjoyable presence in our lives. In 2017, a survey by the polling firm Nielsen suggested that some 90 percent of the U.S. population listens to music regularly and that, on average, they do so 32 hours per week.

Behind this free-flowing pleasure are enormous industries applying technology to the long-standing goal of reproducing sound with the greatest possible realism. From Edison’s phonograph and the horn speakers of the 1880s, successive generations of engineers in pursuit of this ideal invented and exploited countless technologies: triode vacuum tubes, dynamic loudspeakers, magnetic phonograph cartridges, solid-state amplifier circuits in scores of different topologies, electrostatic speakers, optical discs, stereo, and surround sound. And over the past five decades, digital technologies, like audio compression and streaming, have transformed the music industry.

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