Entropy is claimed to be the end of the physical universe by most modern physics. Eventually, according to Einstein, et al., all the matter in the universe would wind up sucked into black holes, and that's all the universe would be. Then Stephen Hawking pointed out that the seething quantum foam sometimes produced virtual particle pairs that erupted right at the Schwarzchild radii of black holes, where one of them would get sucked in, but the other would not, and some of the mass of the black hole would be transferred to the new actual particle that was born thereby.
This put the kibosh on Einsteinian predictions that black holes would persist by demonstrating that even the largest black holes would eventually evaporate by this means, and the universe would truly become empty of matter.
Now, however, it seems this mechanism isn't confined to black holes, but is a feature of all massive bodies, from Uranus to your hat. My favorite pop science content provider Anton, whatdamath on Odysee , published this brief video explaining the new research that physicists published stating that since all massive bodies bleed off mass by this mechanism, the universe would become devoid of mass much sooner than Hawking's fuzzy black holes provided.
But this isn't what I want to discuss. I have for a while now understood that consciousness is a complete mystery. Research has shown that consciousness does not arise in brains, because single celled creatures - that by definition do not have neural networks of brain cells - demonstrate consciousness by taking actions that require conscious thought, such as remembering where food is, choosing to take a route through a maze (of sorts), actions that show consciousness is something these cells possess. Further research has shown that our gut fauna participate in human intellectual processes, explaining why we have as many neurons in our guts as we have in our brains (roughly speaking). So, even though we experience ourselves as singular, the evidence suggests our consciousness is a collective comprised of multiple species.
All sorts of speculation regarding what consciousness is and where it comes from have been discussed, but without any evidence suggesting any particulars. We know only a few things consciousness is not, because we have empirical evidence for those things not being the case. We can assume that consciousness is not EMF, so not light, electricity, magnetic, or etc., because we do a lot of exotic things with EMF, such as radio, lasers, and extremely powerful magnetic fields, none of which are shown to impact consciousness itself. We can destroy our bodies, which eliminates our ability to make and reveal conscious decisions by our actions, with those forces (such as by cooking in a microwave oven, or near powerful radar antennae, or etc.), and this very strongly suggests consciousness isn't any form of EMF or we'd have changed it with some of the kinds of EMF tricks we play.
We have very strong evidence consciousness doesn't arise in brains, because single celled creatures, like slime molds, that don't have brains, make conscious decisions, remember things, and etc. The only way we can detect consciousness is by creatures taking physical actions, such as choosing to go towards where the food is, or the many ways people demonstrate consciousness, such as tap dancing. Then we can indirectly tell a creature is conscious. There is no meter that detects consciousness directly. Because of this, as preposterous as it may seem, we cannot tell if rocks or inanimate objects are conscious, because they aren't capable of taking actions that demonstrate they make conscious decisions. That doesn't mean they aren't conscious. It only means they aren't able to take actions that reveal conscious thought. Since we have no other means of detecting consciousness, we have no evidence whatsoever that electrons, rocks, or planets aren't, or are, conscious.
I mention this in the context of the heat death of the universe because we have no evidence that suggests that event will affect consciousness in any way. Whatever our conscious minds are, all we know about them is that we subjectively experience ourselves, and they have no known connection we can experimentally demonstrate to matter. We know anecdotally we experience being in meatsicles. We don't know how or why, or what it is we actually are, that is being in our bodies. We don't know that we aren't really trapped in our meatsacks, and can actually just astrally project away, nor that we are trapped and can't.
So there is no evidence that suggests the heat death of the universe will affect consciousness in any way, or that the death of our bodies will either. Life after death has neither evidence for it - other than anecdotal claims of some people that have been dead briefly - nor against it. Obviously no one that has died and ceased to exist as a conscious being has come back and told us that there isn't any life after death. In fact, even though the evidence we have is entirely anecdotal, hearsay, and subjectively experienced, it is evidence. It's just not quantifiable in any way. We can't say a damn thing about it scientifically, as frustrating as that is.
It is pretty difficult not to consider consciousness our spiritual essence, and affirm we are spiritual beings having a material experience, based on the very scant and unquantifiable evidence we have. A variety of claims are made by folks regarding our spiritual beings, and we have no way of judging any of them, no way to test them, count them, weigh them as more or less true. It is unreasonable to suppose we do not have consciousness, because we demonstrably personally experience having it. That is the only quantification of it we can apply: we have it, therefore it exists. We have evidence other creatures have it too, so it is reasonable to make that same claim about creatures that demonstrate what we know are conscious decisions. They also have consciousness.
But the claims some people make about continuing to have consciousness after dying aren't able to be confirmed, can't be tested, nor quantified in any way. There is so much we don't know about biology we cannot be sure that whatever links our bodies to our minds doesn't remain operant until our bodies are shat out by worms. However, there are additional aspects of these claims regarding supernatural beings, love, light to go to, and etc. Anecdotal in it's entirety, and utterly unable to be tested or quantified in any way, but evidence nonetheless.
I am led to conclude that, as crappy as the evidence is, such that we have suggests our spirits outlive our bodies, at least as functional living creatures. Given a fairly substantial body of claims that we will persist as spirits thereafter, the only evidence we do have suggests that is the case. Whether we are reincarnated, live as conscious entities in a spiritual realm, or some other continuance, there is no firm conclusion able to be drawn from different faiths.
But I see no evidence whatsoever that the heat death of the universe matters at all to us as spiritual beings. Do you?