@NgXinZhao and @cdpatton This happens to be a question of great interest to me since I am a physicist and have worked on astrophysics and gravitational waves long ago. It is indeed only at a speculative level for us right now but I am certain in a couple of hundred years it will be feasible to reach other nearby stars and send back information in reasonable amount of time.
What was surprising to me was that in DN (if I am not mistaken, Brahmajala sutta) we have descriptions of how towards the end of a universe cycle most beings, if you can call them that, are of streaming radiance type (I am paraphrasing here). That is exactly what is supposed to happen when the universe is in contraction phase - all matter gets progressively converted to pure energy, mostly light and if you could view it from a peripheral vantage point, it would appear as if the light is streaming towards the singularity. I maybe reading too much into it but the similarities are striking.
As far as the aliens go, they are almost certainly likely to exist - statistically, nothing happens just once in the universe. I have spent quite a bit of time mapping our imaginary vulcans, klingons, asgards, wraiths etc. with various orders of beings found in the suttas (guilty of pappancha, I know! ). I am not sure whether all of those passages are later additions/stories based on archetypes or indeed included in EBT for some specific reason.
PS: I apologize if I am not following posting guidelines by not citing and linking suttas I mentioned. I am a bit short on time right now. I can find the passages and edit the post later.