Could we actually fight a war against an alien race?

[Dodece]

@Superchunk

You might want to acquaint yourself with the theories regarding Nucleosynthesis. Unfortunately the heavy elements necessary for a complex biology. Were not created by the inflation of the cosmos, but were instead readily made in the fusion that takes place within stars. So first generation, and second generation stars. Were the sources of most everything heavier then Lithium. Their potential for planet formation were quite limited, and not at all conducive to the formation of life carbon based or otherwise. You need more then a couple ingredients to allow for biology.

This isn't even very speculative. The first generation stars could only spawn worlds of hydrogen and helium. The second generation stars could only do marginally better. They might have more heavier elements, but you need a lot of heavy elements to get biology going. It is only the interplay between different elements that allows for the formation of complex molecules. Which would be capable of converting, transferring, and releasing of energy. You should also know that first and second generation stars themselves were poor prospects for habitability. They were gluttonous to say the least. They had a lot to eat so the majority of them were spoiled. They grew massive, and massive stars do not last long. They fuse a lot of material really fast, and lose their equilibrium. Then they go on to explode.

Our own star is probably a fourth generation star. In reality you should probably limit your conjecture to third or fourth generation stars as real candidates for life. Only in those systems will you find all the elements needed to create a biology. So you should really think of the first third of the Universes life as dead space. No life would have had a chance of forming in that period of time. In the same way as most of the Earths history was very much inhospitable to complex life. Only the Oxygen rich biosphere that developed over time allowed for life to really explode, and that isn't a form of chauvinism. Free Oxygen is truly a powerful tool as far as biology is concerned. It simply does a lot of things really well.

You shouldn't consider the Universe as a whole as being habitable either. Dwarf galaxies are resource poor since the stars are stunted due to lacking raw materials, and large galaxies have regions that have too much of a good thing going. Globular clusters, and the central bulge in the Milky Way are probably very hostile to life. There will be much more radiation present in these areas. Drop a planet like Earth in the middle of them, and you would be lucky to keep a significant atmosphere going.

Sadly too many scientists overstate the case. When it comes to habitability in the cosmos. Want a laugh go read some of the astronomical literature from the sixties. My personal favorite has to be the views on Venus. It was actually quite sad how willing they were to overlook the evidence to make the planet into what they wanted. The same holds true today with the willingness to ignore the hot Jupiter phenomena. Prior to discovering these big worlds close in. Theory typically held that other solar systems would mimic our own. These worlds indicate that systems are actually overwhelmingly unstable. Perhaps we are in a fortuitous spacing. Maybe Saturn, Uranus, and Neptune kept Jupiter from plummeting inward. What might have happened if Jupiter was ten percent heavier, or the others were a few percent lighter. Maybe we just hit a one or two percent lucky break.

Anyway their utter willingness to overlook these things, or to look for what they want to find. Kind of makes their arguments hokey. Twenty thousand advanced civilizations in our galaxy is probably pure fantasy. I think we would be lucky to see twenty. All of the evidence at present is painting the Universe as a pretty inhospitable place, and our solar system was fortuitous indeed. The Earth itself is the product of some rather insanely lucky breaks. The collision with another planet at the right angle gave us a super charged core for our planets size. Which gave us a very powerful magnetic field for its size, and far greater longevity. It even gave us our moon which stabilizes, our axis. The position of Jupiter protects us from a whole host of comets, asteroids, and it along with the other giants appears to have trapped most of the large free floating bodies in the primary system. Even the fact that we will in a single star system is a blessing. It means the Oort cloud, and the Kuiper belt are probably incredibly stable. That is a solid break too since most stars live in multiple star systems.

Anyway you wanted to know.