TechnologyWeather sensors could float forever in the stratosphere using sunlight A device that uses differences in temperature to levitate could keep small sensors floating indefinitely in the stratosphere, such as for monitoring the weather ¿ìè¶ÌÊÓÆµ
TechnologyFibre-optic cables could be used to spy on people a kilometre away A device can eavesdrop on someone talking near a fibre-optic cable, even if there is a large distance between them ¿ìè¶ÌÊÓÆµ