> I like this characterization of it. Basically we can't prove that it isn't an alien artifact yet, which is impressive given all the things that we can state conclusively are not alien artifacts.

That seems like the height of human hubris - we are stuck on a little rock in the corner of the galaxy, but somehow assume we are authorities on things astronomical.

> I base that on the following conjecture, if we were to become capable of travelling among the stars with relative ease, then we'll go collect these two little artifacts and put them in a museum. But if we go extinct, these ships will continue on their way forever. So any alien that comes across them can know we're extinct.

You're assuming that we will at some point have the ability to catch up to them - we may develop interstellar flight, but it may be stuck in very slow speeds, we may never catch up to them with our giant colony ships as we sleep away the eons.

>That seems like the height of human hubris - we are stuck on a little rock in the corner of the galaxy, but somehow assume we are authorities on things astronomical.

The basic idea of science is that it's possible to do better than "assume we are authorities..." I don't want to come across as unsocial but in dismissing astronomy without knowing enough about it you may be guilty of some hubris yourself.

I'm not dismissing astronomy at all. I'm saying that if we can't explain something, that doesn't mean it can't be explained in some other mundane way. When we look at a problem and go "well, we don't really know what caused it, therefore aliens" seems ridiculous when there's unlimited things that could be the cause, just because we aren't aware of those causes.

I'd like to conjecture that even if we did develop interstellar travel, we will let them travel.

Now instead of collecting them, we will mostly build a mobile museum, to show the then humans, achievements of early humans, still moving through space.

Eventually we will get so advanced we wont really worry about collecting them at all, for the same reasons, the current humans don't go looking for the first wheel ever made.

Is it necessarily true that our species will not exist when Voyager 1 and 2 fly through in a galaxy far far far away a long long time in the future?

Are you talking about Terran homosapiens specifically and the consideration that once we populate other planets that we'll become genetically different enough to no longer be considered the same species - or do you think we'll never get up there?

A couple of things; time and circumstances.

First we know there are many ways in which life on the planet can be eradicated that are not yet preventable by humans. Asteroid impact, solar flare, volcanic eruption, and climate change, while humans also can kill ourselves off with a large exchange of nuclear weapons. So if you plot the chance of our existing over time, as long as we stay a single planet species that plot heads to zero long before Voyager interacts with another star system.

Then we have Voyager, which will take 17 thousand years (and some change) to go one light year. Nearest star system is Alpha Centauri at just over 4 light years away so conservatively 80 thousand years before Voyager gets there (assuming it is on a path that takes it to Alpha Centauri)

Doing the math, the probability that humans exist in 80 Kyrs versus human ability to travel at a significant speed (say > 0.5c) between the stars vs human nature to retain artifacts when they can from historic events.

It is a thought exercise, which I doubt we'll live to see any affirmative answer to :-)

Voyager 1 is going 38,610 mph, 2 is slightly slower than that.

Andromeda, one of our closest galactic neighbors is 220,000 light years away.

Imagining that Voyager 1 is going in the right direction and ignoring that the Andromeda is going to collide with us regardless, that works out to 3,821,000,000 years to get there. And that's for a very very close galaxy, on an astronomical scale.

Pretty optimistic to think we'll be around on that time scale, but I suppose it could happen.

Aren't both Voyagers still gravitationally bound to our galaxy? They have escaped the sun but not milky way. In this case they will never leave our galaxy.

Good point. A quick google gives 537 km/s as the Milky Way's escape velocity, or 1,201,000 mph. Not going fast enough for that.

Moot point for Andromeda since that's coming here, but it'll never ever get to any other galaxies.

Voyager’s stated velocity is relative to the solar system, which imparts its own velocity relative to the Milky Way to Voyager. Another quick google suggests Sol is swinging around the galaxy at 200 km/s so Voyager’s 17 km/s is really nothing.

Also depends on whether Voyager's velocity is in a useful direction, it could just as easily be counterproductive. But not much difference either way.

But might they not travel through another star system in this galaxy before getting anywhere near another galaxy?

"Voyager 1 will eventually come within 1.6 light-years of the star Gliese 445 — in astronomical terms, this will be a near-miss. But don't hold your breath; the "encounter," for lack of a better term, won't occur for another 40,000 years.

After that, it gets a little difficult to predict Voyager's journey, as chaotic motions within the galaxy make accurate predictions of stellar movements challenging. But given the wide swaths of empty space between the stars, the spacecraft's visit near Gilese 445 is probably the closest that Voyager 1 will approach another star, ever."

https://www.space.com/39161-fate-of-the-voyager-spacecraft.h...

OP said star system. You’re quoting distances to another galaxy.

I’m responding to

>Is it necessarily true that our species will not exist when Voyager 1 and 2 fly through in a galaxy far far far away a long long time in the future?

Thanks for your answer btw, it was exactly what I was looking for as I didn't know the speeds of the Voyagers.