How do does radio signal keep on travelling in space? Shouldn’t it just fade away.
In: Engineering
Radio and light waves are technically the same, and they behave identically on the science level, the only difference is that we can actually see one. Radio waves just pass though most objects, unlike light, those waves just see the world made out only glass
This allows us to do experiments using something *we can understand by observing it.*
If you have a light bulb, you can see it emitting light, and it is clearly visible. If you stand 10 meter away, you can probably still see it, but as you walk further away, it gets more and more dim compared to the surroundings. This is just like radio waves.
To compensate, we could use a bigger light bulb, that pumps more watts into the air, and we see it from further, [we clearly see a light house from a distance](https://www.youtube.com/watch?v=xxX36GEAJn4), but not a small AAA battery powered torch.
There is a standard for this called “signal to noise ratio”, which basically tells us how bright the wanted light is from what we want to see.
Eventually, going brighter and brighter doesn’t work, you cannot put a 1MW nuclear reactor on a small space ship. Other things are used. See it like putting a reflector behind the light bulb, to shine more light into the wanted direction, this allows a bigger distance. An extreme example of this is a laser. Compared to your light bulb, a laser light seems weak, [but over long distances](https://youtu.be/iEiOLGEO_KM?t=25), it suddenly becomes the brightest light source
We could also increase the receiver size, which allows us to better isolate the noise from the signal. We use big receivers to receive the signals from the Voyager space probes.
**TLDR**: The signal fades away, but we have ways to pick it up by increasing transmit power, or better receivers
Latest Answers