Some metals are more rare than others; earth’s computer industry is lethally dependent in the so-called rare earth elements. They are rare because of how they are created: When a star dies violently. Each atom of gold, silver or copper was once created in an exploding star because the normal fusion process can only produce elements up to iron (fusing iron with anything else needs energy while fusing, say, hydrogen with itself produces a lot of energy). To see for yourself what is missing, check the elements beyond iron (Fe 26) in the periodic table.
In fact there are areas in the galaxy where metal is more rare on earth because there haven’t been many super novae around there: Maybe the stars are still too young, maybe they are too small to go nova. This is what you can find near the rim of the galaxy. Most metal can be found near the core of the galaxy where there are many massive, tightly packed stars. The problem here is that life is a tad difficult near the core because of the heavy radiation.
So there has to be a sweet spot between: Just enough metal but not too much radiation. This is where we life.
Does that mean life near the rim is impossible? No. Most elements to sustain life (carbon and oxygen, most prominently) are available everywhere in the galaxy (this is easy to prove by looking at the spectral lines of the stars in question). So there is life not no (or not much) metal there.
Now imagine a life without copper. No wires. No telephone. No computers. Maybe they could build wires with aluminium but for computers, you need semiconductors. For these, you need silicon (which they have) but also elements to “taint” the pure silicon – the rare earth elements. Germanium. Gallium. Arsenic. All beyond iron in the list of chemical elements. They could use silicon carbide but the material has a lot of problems.
Without all the elements beyond iron, it’s probably hard to build a complex civilization. Radio telescopes. Space ships.
They might exist but they probably can’t leave their planet. Or receive any of our signals.
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