Longer version of the question:
Let's say I'm an immortal being (I could be artificial) going to "party" to IC1101, one of the biggest galaxies of the universe, 1 billion light-years away from us, and that the speed of my space ship is 50% c. ("c" is the speed of light). Later, I’m coming back to the local galaxy group. But then i'll want to go again several times. How many times back & forward can I go there, before the expansion of the universe would be like parents forbidding parties ?
Details:
First I want to mention that I'm surprised that some prestigious & popular vulgarisation channel, Kurzgesagt, in the video "How Far Can We Go? Limits of Humanity" states that it would be "impossible" go out of our local galaxy group, which is quite wrong according to THIS simple response, and THIS, and this paper about intergalactic spreading... of course, to the condition we have a sufficient travel speed. (Even if there is a point in the future where the expansion of the universe will makes it impossible to go out of the local group at any speed, of course.)
So, at 50% c, it takes me about 2,3B years to go to IC1101 (took me a bit more than 2B years because of the expansion of the universe), I’m having a bit of fun there, and then I come back to our local group of galaxies, which takes me another 2,6B years, since distances get bigger again as the universe keeps expanding... (Back home, I see the milky-way already fusing with andromeda, and takes a bit of time to find our sun in this mess) …But then I quickly get bored again, and decide to give another shot to IC1101… then later i'm back again, and etc.
My very awkward guess on a paper corner would be that I could go there, back and forward, about 4 or 5 times, before the expansion of the universe kind of lock me on one of the two sides… …At the end of a journey of 30 to 60 billions years i would guess (the last one-way travel might take quite long).
Am I far off, or slightly correct ? Same question with 90% lightspeed : How many parties at IC1101 ?
(Well, in the case this is not too far off, knowing the universe will last for a bunch of trillions of years, this - in cases we can travel at such speeds - lives time to choose the best spot to settle before the expansion of the universe isolate groups of galaxies from each other… …Which could give another possible answer to Fermi's paradox. Where are the Aliens?... ...Maybe they are just gone to look asap for another better galaxy group before the universe enters eternal lockdown!... Instead of staying in our small local-group, maybe they went checking the most energetic places possible, for example a huge galaxy like IC1101... huge galaxy also coming with a huge ultramassive black hole, for the old days, to farm its gravitational energy when the stars will be gone.)
