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I want to point out the currently known composition of the universe, because I think that the whole aliens thing wraps up with it: ~5% matter. Most of this is
by Balgair 4y ago
I want to point out the currently known composition of the universe, because I think that the whole aliens thing wraps up with it:
~5% matter. Most of this is H and He though, bit of Li in there too. And it's all mostly burning in a star's gravity well. Like, 99.99999% of it. The stuff you and I are made of (C, N, P, Fe, etc), that we would wish aliens would be made of too, is really rare.
~25% dark matter. We know a little about it. We know that it falls down and doesn't like to touch just about anything. But that's really kinda it.
~70% dark energy. It falls ... up (?!). We know pretty much nothing about it. And it's the large majority of 'stuff' in the universe.
If there are buddies out there, then we may want to look at stuff that is a bit more common.
- remram 4y ago5% of what?
- Balgair 4y ago5% of literally everything.
- remram 4y ago5% of mass? Volume? Energy? The visible sky? If I said "this dessert is 30% milk, 40% sugar, and 30% good timing" you would be similarly confused.
- rstuart4133 4y agoYour question contains its answer. Volume would be an odd measure to use given it changes with speed (due to special relativity) and gravity (general relativity). The visible sky is over 99% empty, so it can't be that. Which leaves us having to choose between mass and energy. But as e=mc2, they are effectively the same thing, which means we don't have to choose.
- laverya 4y agoThere's about 1500 billion billion billion billion billion billion billion (1.5x10^48) tons of Carbon, Oxygen and Nitrogen in the universe. It might only be ~15 parts per thousand (and most of that is Oxygen), but there's a LOT of stuff out there.