The book in question was written... probably around the '60s. It was printed in the Soviet Union and translated to my native language (Latvian), so there's a good chance it was never translated into English. But maybe it was, and if so, I'd like to re-read it. I read it back in the early 90's when I was still a kid, so I don't remember either the name or the author. And likely I remember it being better than it actually was.
Details I remember
- The book was told from the viewpoint of a male human that was one day abducted by aliens. I don't remember if the abduction was an accident or he was convinced to come willingly, but I don't think they forced him to come. The aliens were friendly.
- They took him back to their own homeworld which might have been in a different galaxy. The journey took, I think, either some hours or days.
- Their FTL method was a sort of hyperspace they called "Ahoon". (I'm transliterating here to make the same sound when pronounced as it would in Latvian language. It might have a different name in English.) They also somehow "took a piece of the real universe with them" when they entered it, in order to, well, exist. The trick with this hyperspace was that you had to do precise calculations in order to make the trip. If you miscalculated, you could end up in another universe and your chances of getting back would be slim. If you were extra unlucky, the alternate universe could be made of antimatter. Naturally, this happened to our hero at some point in the story, but after some nerve wracking moments the alien mathematicians on board figured out the mistake, recalculated, and managed to take everyone back home.
- Back on the alien's planet it was revealed that the aliens are in a war of sorts with some strange creatures from deep space.
- The creatures weren't very intelligent, but they weren't dumb either. Something like animals, I think, and you couldn't communicate with them.
- The creatures were strange in that they were made of weird metal alloys and could only survive in temperatures near absolute zero. Our aliens had managed to capture one and even then keeping it alive was a challenge, because too much light would heat it up and kill it.
- The creatures had evolved some sort of method for extinguishing stars. When they had infested a planet on the outskirts of a solar system, they formed giant towers from their bodies which then... did something to the star which extinguished it. Naturally this was pretty upsetting for all the other inhabitants of said star system.
- The aliens themselves had difficulties fighting the creatures because they were... somehow vulnerable to them. They had hypothesized that a species with red blood (large iron concentration) should be able to resist the creatures, but, apparently, red-blooded organisms were scarce, so they hadn't had a chance to test it yet. But our human was a ray of hope for them.
- There was also another red-blooded race recently discovered from the Andromeda galaxy, but for some reason they hadn't been tested against the creatures either.
- Our hero did go to meet the captured creature to see how it would fare and, indeed, was found to be resistant to the radiation or whatever that the creature was emitting. Unfortunately the creature then decided to simply pummel him to death, being much larger and heavier than a human. I think this was an unexpected reaction, otherwise they wouldn't have put our human in harm's way. Anyways, the alien's advanced medical knowledge managed to revive him and basically fix every bone in his body with advanced prosthetics and whatnot.
- They also tried another experiment to re-ignite an extinguished star. For some reason the device used to do that had to be activated manually, so our hero got to walk down to the surface of a cold star. Even with the anti-gravity generators of the nearby spaceship it was still a tough task that nearly killed him, but - happy end and a re-ignited star.
- There was also a scene where our hero was trapped with an Andromedan woman on a planet infested with the creatures. I think they found some old records from the original inhabitants of the planet (a video recording?) and also had to harvest frozen oxygen for survival. They thought they would die so they confessed their love for each other, but were rescued after all.
- At the end, the human was returned to Earth together with the Andromedan woman he married. The woman was quite humanoid and could easily pass for a human, except that she had 4 fingers on each hand, rather than 5.