An invisible world of electromagnetic signals and radio waves.

电磁信号和电波的隐形世界。

At the very least, you'd think they'd be revealing their presence, deliberately or otherwise, through electromagnetic signals of one kind or another.

至少你想它们也会把它们的存在，有意或无意的，通过一种或其他的电磁信号告诉我们。

The idea is not new, but before AI, experts worried that navigation systems would not work due to the electromagnetic signal created by most aircraft.

这个想法并不新鲜，但在人工智能出现之前，专家们担心，由于大多数飞机产生的电磁信号，导航系统将无法工作。