Dark energy is supposed to pull galaxies apart, their gravity not sufficient to escape or even slow the expansion of space. Notable scientists like Dr. Kaku all seem to agree that this results in heat death, wherein everything eventually is receding from everything else so rapidly that it has dropped off of our horizon. As a consequence, distant stars disappear until an observer will detect no light from anywhere. Without light or other effects of locality, structured matter cannot sustain its heat, hence the term heat death.
However, something seems awfully wrong with this story, even worse than its implication that all life is frozen to extinction permanently. If an object is receding from us and that object has mass, relativity tells us that the object cannot appear to travel faster than light. Massive objects, as they approach light speed in any frame of reference including ours, are to gain mass such that accelerating them will require more and more energy, asymptotically forbidding them from reaching c. Our observational horizon effectively expands at exactly c, so how is it possible to leave it?
Is this problem related to the image we should observe in perpetuity of something that falls into a black hole? I.e. the mass itself is long gone, but an external observer sees them falling indefinitely. If this is the case, what is the difference between our future dilemma and falling into a black hole, such that an image of a star will not remain in our view?
Finally, is there a way to measure how much normal matter has left our horizon due to dark energy already? If not, then we have apparently lost the information that would otherwise be available in their ever-redshifting image, so does entropy paradoxically fall as well?
