Our Best Lamps Still Can’t Equal the Luminosity of the Sun

White LEDs offer better luminous efficacy and a color balance more pleasing than any previous lamp, but they still have a way to go

3 min read
Illustration of an eye.
Illustration: Greg Mably

Illustration of an eye. Illustration: Greg Mably

You can roughly track the advance of civilization by the state of its lighting—above all, its power, cost, and luminous efficacy. That last element refers to the ability of a light source to produce a meaningful response in the eye, and it is the total luminous flux (in lumens) divided by the rated power (in watts).

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Practical Power Beaming Gets Real

A century later, Nikola Tesla’s dream comes true

8 min read
This nighttime outdoor image, with city lights in the background, shows a narrow beam of light shining on a circular receiver that is positioned on the top of a pole.

A power-beaming system developed by PowerLight Technologies conveyed hundreds of watts of power during a 2019 demonstration at the Port of Seattle.

PowerLight Technologies
Yellow

Wires have a lot going for them when it comes to moving electric power around, but they have their drawbacks too. Who, after all, hasn’t tired of having to plug in and unplug their phone and other rechargeable gizmos? It’s a nuisance.

Wires also challenge electric utilities: These companies must take pains to boost the voltage they apply to their transmission cables to very high values to avoid dissipating most of the power along the way. And when it comes to powering public transportation, including electric trains and trams, wires need to be used in tandem with rolling or sliding contacts, which are troublesome to maintain, can spark, and in some settings will generate problematic contaminants.

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