The first life we encounter from another civilization might not be evolved at all. Presumably a civilization with the capability of interstellar travel might also have the technology to manipulate the underpinning of life itself.
In fact, if we do discover something from another civilization, it is quite reasonable that it would be some sort of Von Neumann probe. It might be made of mechanical parts, "biological" parts, or something in between.
A Von Neumann probe would be highly engineered, and might have no trace of evolution to it.
I recall a scifi story by Stephen Baxter where a human-made probe on Mars eventually evolved into advanced, aware, spacefaring Von Neumann probes. After a few million years, one curious probe traces serial numbers back to Earth in search of their creators. However, humans had devolved back into a type of monkey that was directly symbiotic with a literal tree of life. The probe concluded that such a primitive creature could never have developed technology, and left.
>> A Von Neumann probe ... might have no trace of evolution to it.
Except that the very fact that it exists represents many evolved traits. If they are sending probes then their are either curious or expansionist, both evolved traits tied to competition for resources and/or survival. A species totally devoid of any history of evolutionary pressures wouldn't act that way, which is one of many possible great filters: once we have access to the infinite resources of space, perhaps we just stop caring and don't bother expanding. Such logic allows us to learn much simply from the existence of an otherwise silent Von Neumann probe.
But when dealing with infinity, we must appreciate the likelihood of the unlikely too.
Personally, I favor the prospect of the insanely lucky idiot race, that clumsily and completely by chance manage to launch a probe so seemingly sophisticated that every sentient race that discovers it readily submit to its perceived superiority.
There are no real infinities. The universe might be infinite, but the bit of it we can see and/or ever interact with is not (speed of light + expansion). So there are a finite number of stars that we will ever be able to touch before the universe goes dark. And the universe seems to have had a finite starting point. So we can calculate which stars may ever reach out to us. These are very big numbers, but they are not infinite.
Unless star trek is real. Faster than light travel opens up the door to infinities.
Some forms of FTL travel also opens the door to time travel, so even if there is no multiverse and our universe has a point in its future where all energy is at its lowest possible state, we could still bounce around between the Big Bang and the heat death for quite a while.
Well also, a Von Neumann probe is a type of life. It's very unlikely that a self-replicating machine would not develop it's own technological drift in the replication protocol.
Not only that - for all we know a biological civilsiation could have existed 3 billion years ago which then spawned a machine civilisation that now has as much relation to its distant origins as we do to some prebiotic soup on Hadean earth.
> It might be made of mechanical parts, "biological" parts, or something in between
Or just a digital clone of a once-biological being that can live for infinity exploring the Universe. Why would you explore the Universe in a meat suit?
Or it could be designed to be very small so as to efficiently send out at near light speed, and designed to quickly adapt and replicate in any hospitable environment.
Unless it somehow came from nothing, then there must be some pathway from what came before to what they have now (thus evolution). It might be a long pathway, which is so long that it's hard for us to see the beginning from the end, but that doesn't invalidate the argument that it will still have characteristics of something that followed such a pathway.
In fact, if we do discover something from another civilization, it is quite reasonable that it would be some sort of Von Neumann probe. It might be made of mechanical parts, "biological" parts, or something in between.
A Von Neumann probe would be highly engineered, and might have no trace of evolution to it.