ELI5. why do scientists always search for radio sygnals in space? Why do they think aliens use that to communicate?
In: Technology
Radio waves are easy to detect, and an artificial sequence would be easy to identify, so it is a very practical search to undertake.
We also have gravity detectors, which could potentially pick up organised signals if such things existed, but because we don’t know how to produce such signals, it would be a lot harder to know if the signals picked up were artificial or not.
Because imagine they also went through that phase of radio waves and now the waves are travelling the cosmos. You can pick up that.
Ultimately, there only are four ways that matter and energy can influence each other. We call these the *fundamental forces*.
**1. The Strong Force**
This is, as the name implies, the strongest of the four forces. It binds quarks together to form protons & neutrons, and in turn binds those together to form atomic nuclei. It’s responsible for the existence of the very elements. However, its range is ludicrously short. It can only reach across the width of an atomic nucleus before it vanishes, and so cannot be used for communication across any distance.
**2. The Weak Force**
This is the weaker of the two nuclear forces. It’s responsible for nuclear decay. Its range is also ludicrously short, rendering it useless for communication.
**3. Gravity**
This is by far the weakest of all four forces, although it does have a long range. It’s created by mass, but it’s so weak that you need planet-sized clumps of mass to get a noticeable amount of gravity. Generating signals for communication is nigh-impossible; gravitational waves are so weak that we only managed to prove that they exist a few years ago, and it took the collision of two supermassive black holes to create a signal big enough to detect.
**4. Electromagnetism**
This is the other long-range force, and it’s responsible for almost everything we experience in our everyday lives. It creates atoms and molecules, and dictates the behavior of solids, liquids, and gases. *Light itself* is a wave passing through the electromagnetic field, as are microwaves, x-rays, radio waves, and others. Electromagnetic waves are so easy to generate & so common that we have two organs embedded in our faces that are evolved to detect them. You can generate a radio signal simply by moving an electric charge back and forth rapidly, and detect it by watching the radio wave move an electric signal in a wire somewhere else.
TL;DR: Radio is a type of light, one of the most basic components of our universe, and the only such component that’s suited for long-distance communication.
Radio waves are extremely easy to detect from long distances. In addition, a lot of various high-energy electromagnetic radiation sources (i.e. anything that produces light, visible or not) will end up putting out radiation in the radio spectrum. Thus, if you search in the radio spectrum, you end up seeing *everything* that goes on in the cosmos.
The radio spectrum is a pretty big part of the entire electromagnetic spectrum, including things like radar, ultra-sonic communication, microwaves, etc. It also has the capacity to travel long distances with minimal deterioration in signal strength. If there are beings out there who wanted to use more than just their bluetooth keyboard or their 5G Samsung S20’s, they would need to delve into the radio spectrum so they could communicate further out to their friends and neighbors.
It’s pretty much the only thing we can actually search for. It’s not as if we have any idea how to look for some kind of Startreklike subspace communications or similiar SciFi inventions
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