That is because, like light waves, sound waves can be focused.

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Like light, they are waves.

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Mapping nearby features, spotting road edges and lane markings, reading signs and traffic lights and identifying pedestrians is done using a combination of cameras, radar and lidar (which works like radar, but with pulses of light rather than radio waves).

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If the gas sheet had the same density throughout, radio waves would pass through it without distortion, like light through a window pane.

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When we talk about telescopes, we're usually referring to devices that "see" the visual spectrum of light, but astronomers also build telescopes that gather radiation like radio waves and X rays in order to peer deep into outer space.

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Like its cousins radar and sonar, lidar (light detection and ranging), works by broadcasting electromagnetic waves towards a target and then building up a picture from the reflection.

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Amateur video show by Russian television depicted a white streak of light like the cloud from a jetliner quickly expanding to a large white ball that eventually sent shock waves throughout the city of Chelyabinsk.

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