How do does radio signal keep on travelling in space? Shouldn’t it just fade away.
In: Engineering
There’s very little to impede an electromagnetic wave in the vacuum of space, but what *does* cause some “fade” is the [Inverse Square Law](https://en.m.wikipedia.org/wiki/Inverse-square_law).
Basically, no matter how focused you make a signal, the beam will spread out, and as it does, the original power is spread out over that whole surface area.
You can demonstrate this with a laser pointer. If you shine it on the wall in front of you, it’ll be a tightly organized dot. But shine it down the street and the dot will be several inches across.
*Disclaimer* if you want to experiment, be careful where you shine a laser pointer, certainly not towards any kind of aircraft.
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